Qatar Foundation Annual Research Conference Proceedings Volume 2016 Issue 1
- تاريخ المؤتمر: 22-23 Mar 2016
- الموقع: Qatar National Convention Center (QNCC), Doha, Qatar
- رقم المجلد: 2016
- المنشور: ٢١ مارس ٢٠١٦
141 - 160 of 656 نتائج
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Effects of Environmental Factors on Dust Particle Adhesion on Glass Substrates
المؤلفون: Bing Guo, Eugene Chen and Hong LiangQatar is a dessert country full of solar resource to be further exploited. Despite the fact that Qatar has abundant petroleum resources, the first major solar power plant is expected to operate by 2016. Several projects related to solar power plants are also ongoing as well, which indicates that electricity generated by solar power will become more important and gradually have higher percentage among total electricity production. However, one of the major issues of PV power system is the dust soiling on photovoltaics (PV) panels due to the dusty weather conditions in Qatar. The dust soiling on PV panels has been confirmed to cause a significant performance loss due to the dust deposited on the surface of PV panels resulting in blocking the transmission of light. The performance loss can be from 5% up to 35%. Maintaining the surface with minimum dust soiling will be crucial to keep PV panels performing at higher efficiency.
This research aims to investigate the effects of environmental factors on dust particle adhesion of common materials used at Doha as glass windows and solar panels, among others. The main scientific question is to how the dust particles are attached to the surfaces of different morphology. From Rumpf and Rabinovich theory, the surface roughness of substrate has a significant impact on adhesion force of particles on surface. Other theories such as Johnson-Kendall-Roberts (JKR) and Derjaguin-Muller-Toporov (DMT) theories all assume that surface of particle and substrate are atomically smooth, which does not take surface roughness into consideration. However, there are surface roughness in nanoscale existed on both surfaces of particles and substrates. The surface asperity is assumed to be hemisphere on the substrate for model development. When particles are attached to substrate, the contact area actually reduces due to the existence of surface asperity of substrate and roughness of dust particles. Since the contact area is reduced, the adhesion force of particles reduces.
This research is to investigate the effects of environmental factors on adhesion of dust particles on glass substrates. The factors include Doha's climate such as temperature, humidity, wind gust, and among others that may contribute to the change in surface morphology of glass substrate. Surface roughness and morphology of glass substrates is evaluated by atomic force microscope. Morphological evaluation of dust particles is carried out using microscopic techniques such as optical microscope, scanning electron microscope. The particle analysis of optical images is conducted by using image-processing software ImageJ, which can provide the detailed information of shape, diameter, and size distribution of dust particles. The comparative study of adhesion of particles in terms of particle area density is conducted. The purpose of the study is to evaluate the soiling tendency or dust adhesion of glass substrates with various surface conditions. The result of dust adhesion of glass substrate is shown in terms of particle area density. The Results indicate that optimization of surface roughness could lead to better control of dust adhesion. The research is expected to give more fundamental study on dust to mitigate the dust soiling on PV panels.
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2015, A Year of Climate and Air Quality Anomalies
المؤلفون: Mohammed Ayoub, Luis Ackermann, Adam Skillern and Jennifer StricklandWe report on a number of climate and air quality anomalies during 2015 and their potential impacts on human health, solar power generation and water security in Qatar and the wider region. The anomalies include a strong cut-off low pressure system and accompanying sand-storm in early April, elevated Sea Surface Temperatures (SST) from early summer through October in the Arabian Gulf, substantially higher year-on-year particulate matter concentrations (PM10 and PM2.5) in Qatar, and the development of two late season record strength cyclones in the Arabian Sea.
The impacts of climate change and air quality on sustainable development and human health are important considerations for all countries. The manifestations of climate change may differ from region to region, but the effects of a warming anomaly in the world's oceans, known as El Niño, has global reach. We present an analysis of surface observations, upper air and satellite data over Qatar and the GCC that relate the occurrence of these anomalies to the development of El Niño within the context of a changing climate.
The summer of 2015 saw increased ambient temperatures, dew point temperatures (a measure of relative humidity) and SST, compared to climatological averages, throughout much of the region. The July heat wave [Schär, 2015] resulted in temperatures in excess of 45C and SST exceeding 34C on July 31st. We report a substantial increase in particulate matter concentrations in the Doha urban area, as high as 20%-50% higher than the same period in 2014, during the summer months and into late October and early November. The higher concentrations of particulates are linked to increased evaporation and flux of sea salt particles during the warmer summer and their growth by interaction with emissions from the urban environment.
Tropical cyclones Chapala and Megh, developed one week apart in late October and early November, and were unprecedented in the historical record. Tropical cyclone Chapala developed over the warmest ever-recorded sea surface temperatures in the Arabian Sea and intensified to a Category 4 storm, causing severe damage.
The Southwest Monsoon keeps tropical cyclones from forming in the Arabian Sea for much of the year, allowing only a short season from May to early June before the monsoon arrives, and another short season in late October through November after the monsoon has departed. Arabian Sea tropical cyclones during the pre-monsoon period in May and June have become stronger over the past thirty years owing to a reduction in vertical wind shear brought about by dimming of sunlight from air pollution particles primarily emitted in India [Evan et al., 2011].
[Evan et al., 2011] also speculated that continued growth in air pollution emissions might also reduce wind shear in the post-monsoon October-November period, thus increasing the likelihood of development of intense tropical cyclones during that time. This is corroborated by evidence of the substantially higher year-on-year particulate matter concentrations in Doha presented earlier and the development of the two tropical cyclones in October and November.
Finally, we correlate the observed anomalies with projected climate trends to predict the contributions from climate change and air quality to human health impacts as well as those related to solar power generation and water security in Qatar and the region.
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Tropospheric Thermodynamic Behavior Over Qatar
المؤلفون: Luis Ackermann, Mohammed Ali Ayoub, Adam Skillern, Dunia Bachour and Daniel Perez-AstudilloUnderstanding the mechanisms driving the development of the Planetary Boundary Layer (PBL) and the Subtropical Subsidence Inversion (SSI) over Qatar is essential for accurate prediction of surface meteorology and air quality. Using the vertical backscatter profile of the atmosphere from a ceilometer located at Qatar Foundation, coupled with a novel Layer Identification Algorithm (LIA) developed by scientists at QEERI, a continuous time series of the PBL and SSI has been constructed. LIA was developed in response to limitations in the original software from the ceilometer, that was only able to analyze data up to 4 km altitude, but radiosonde observations indicated the existence of the SSI at higher altitudes (between 4.5 and 8 km above sea level). LIA has been validated against in-situ measurements through spatial and temporal coincident radiosonde launches by QEERI (more than two years of weekly measurements). The LIA algorithm uses image recognition methods to identify boundary layers not only by their vertical characteristics; but also by their temporal and spatial signatures. The algorithm was written in Python and is designed to process the ceilometer's output data in real time or as a post-processing step. A short conceptual description of the algorithm's structure will be included in the methodology.
During the winter months the mean PBL depth in Doha was found to be higher compared to the summer months; in addition, the diurnal amplitude was higher during winter. Apart from seasonal variations in the PBL depth behavior, short term ?uctuations in the daily signature of the PBL structure were observed; with some days exhibiting a well-developed PBL followed by a day with no significant PBL variation. This behavior of the summer PBL (lower daily mean depth and lower diurnal amplitude relative to winter) is explained by two factors. An increase in the intensity of the sea breeze circulation; coupled with intense temperatures and humidity, the latter increases the energy ?ux towards latent heat. As a consequence, the development of the PBL is diminished during the summer. On the other hand, It was observed that the SSI is strongest during the summer months. The strength was established quantitatively via temperature inversion from the weekly radiosondes and qualitatively by continuity via LIA output. In addition to seasonal variations, the SSI exhibits short term fluctuations; in some occasions with height variations on the order of 2 km in three days. The details of the mechanism driving the SSI behavior are been studied using global circulation meteorological models.
The behavior of the PBL can exacerbate poor air quality events. This can be even worse in the case of Qatar; since during the months of higher photochemical activity (because of increased surface insolation, temperature and humidity) the PBL depth tends to be lower, therefore increasing the concentration of emitted pollutants (either anthropogenic or biogenic). Therefore, understanding the PBL and SSI seasonal and diurnal behavior is critical for predicting surface atmospheric conditions, as well as occurrences of poor air quality. This knowledge will help define possible mitigation strategies and inform urban planning and sustainable development.
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Road Accidents and Fatalities in Qatar: Is it the Environmental Factors to Blame?
المؤلفون: Wafaa SalehThis paper is aiming at raising awareness, informing decision makers and informing the transportation community of the implications of road accidents and high accident rates and severities in Qatar and similar Gulf countries. The paper is also recommending to adopt an integrated approach with a set of measures and actions to policy makers in Doha, including environmental measures which can aim at improving pedestrian safety and reducing accidents while walking or crossing the roads in urban areas in Doha. The recommendations will be applicable for implementation in other similar cities in the region.
The statistics of those killed as a result of road traffic accident is very alarming and comparable to those caused by communicable diseases as shown in Table 1.1. Although road traffic accidents affect all age groups, but its fatality rate is conspicuously highest among young people. In fact, it is consistently one of the top three causes of death for people between the ages of 5 and 44 years (WHO, 2009). These unprecedented fatality rates has prompted the World health Organization (WHO) to call for urgent action to be taken to curb this menace or else the fatalities could rise to become the fifth leading cause of death by 2030 (WHO, 2009). Table 1.1: Leading causes of death, 2004 and 2030 compared
(Source: Peden et al., 2004)
These safety concerns are worldwide; the UK Department for Transport reports that in 2011, the fatality rate for pedestrians has increased by 12% compared to 2010. In the United States, statistics show that there are 5,000 killed and 64,000 injured pedestrians in vehicle accidents annually. Other western and Eastern countries also face similar problems and concern about pedestrian traffic accidents. In order to manage and improve pedestrian accidents, it is important to have a good understanding of pedestrian movements while walking and crossing the roads.
The fatality rate of road traffic accidents vary geographically depending on several factors which may include: the population of the place (i.e. level of crowdedness); environmental factors (e.g. its quality of road networks, design of the roads); economy of the region (e.g. income of the people); government policies of implementing road safety regulations etc. For instance, road traffic accidents have claimed more lives in North America than any other geographic region. Pedestrian accidents are of major concern in Qatar as well as in other Gulf countries that could discourage individuals to walk. Statistics show that the large majority of pedestrian deaths occur in urban areas. It has been claimed that pedestrians are involved in more than 25% of total deaths in these accidents. Pedestrian accidents in urban areas occur largely on the main roads where pedestrian traffic is more frequent and the vehicle traffic is heavier or faster; all of which make crossing action more difficult. Infrastructure, road design as well as other environmental factors all contribute to the volume of pedestrian, as well as other types’ of accidents.
Despite effort by the Gulf governments to improve road safety regulations, road traffic accidents are becoming increasingly prevalent in in these states, thereby, constituting a serious public health problem (Barrimah et al., 2012; Ansari et al., 2000; Bener & Jadaan, 1992; Ofosu et al., 1988). In fact, researches have shown that road traffic accidents are the major cause of morbidity and mortality at a rate that is comparable to heart diseases and cancer (WHO, 2009; Al Ghamdi, 2002 & 2003). In Saudi Arabia, road traffic accidents have been found to be second major health problem, after infectious diseases (Mufti, 1983). Since the oil boom in 1973, the Gulf states have experienced rapid expansion of their economy and urban development of most of its cities (Ofosu et al., 1988). Again, there has been rapid population growth triggered by its economic prosperity causing an influx of foreign workers (Ansari et al., 2000; Ofosu et al., 1988). The Gulf states are also attractive destinations to a large number of employees because of the high salaries and free income taxes in these states. Moreover, there have been an increased motorization of the highways and rapid expansion of road networks in all Gulf states (see for example Ansari et al., 2000; Ofosu et al., 1988). This is because motor vehicles are the principal means of transportation in these countries due to the convenience and speed they offer in facilitating the movement of people and goods to their various destinations (Ansari et al., 2000). Road transportation also has positive impacts on both the nations and individuals by enabling increased access to economic activities, job opportunities, education, recreation and health care service.
In Doha, as in other Gulf cities the mixed population composition and backgrounds and different walking and crossing behaviour add to the complexity of understanding pedestrian behaviour. Land use characteristics in these countries also have to be considered as a major contributor to accidents in these countries. Therefore, pedestrian flows have to be managed in a more efficient way in order to consistently cut the number of fatalities.
To address the above, the paper is designed to investigate the main factors that influence pedestrian behaviour at congested locations in urban areas in Doha and the appropriate way forward to influence this bahaviour. The paper presents an in-depth investigation and characterisation of pedestrian interaction with motorised traffic. The way forward to overcome some of the discussed factors will also be proposed.
References:
Al-Ghamdi, A. S. (2002) ‘Pedestrian–vehicle crashes and analytical techniques for stratified contingency tables’, Accident Analysis and Prevention, 34(2): 205–214.
Al-Ghamdi, A. S. (2003) ‘Analysis of traffic accidents at urban intersections in Riyadh’, Accident Analysis and Prevention, 35(5): 717–724.
Ansari, S., Akhdar, F., Mandoorah, M. and Moutaery, K. (2000) ‘Causes and effects of road traffic accidents in Saudi Arabia’, Public Health, 114(1): 37–39.
Barrimah, I., Midhet, F. and Sharaf, F. (2012) ‘Epidemiology of Road Traffic Injuries in Qassim Region, Saudi Arabia: Consistency of Police and Health Data’, International Journal of Health Sciences, Qassim University, 6(1): 31–41.
Bener, A. and Jadaan, K. S. (1992) ‘A perspective on road fatalities in Jeddah, Saudi Arabia’, Accident Analysis & Prevention, 24(2): 143–148.
CNN World Report (2008) http://money.cnn.com/2008/03/05/news/economy/AAA_study/ (Accessed on 21st June 2012).
International Road Federation (2008) World Road Statistics 2008, Data 2001 to 2006. http://www.irfnet.org/files-upload/stats/2008/WRS2008_Publication.pdf (Accessed on 21st July 2012).
Mufti M. H. (1983) ‘Road traffic accidents as a public health problem in Riyadh, Saudi Arabia’, Int. Assoc. for Accident and Traffic Medicine, 11: 65–69.
National Statistical Office (2011) Central Department of Statistics, Ministry of Economy and Planning, Published by the Saudi Arabia Monetary Agency. http://www.indexmundi.com/saudi_arabia/population.html (Accessed on 24th July 2012).
Ofosu, J. B., Abouammoh, A. M. and Bener, A. (1988) ‘A study of road traffic accidents in Saudi Arabia’, Accident Analysis & Prevention, 20(2): 95–101.
Peden, M., Scurfield, R., Sleet, D., Mohan, D., Hyder, A., Jarawan, E. and Mathers, C. (Eds.) (2004) ‘World Report on Road Traffic Injury and Prevention’, World Health Organization, Geneva.
World Health Organization (2009) ‘Global Status Report on Road Safety: Time for Action’.
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Methanotrophically Mediated Bioaggregation to Control Sand Dust in Qatar
المؤلفون: Ann-Marie Grace HarikSandstorms are commonplace in many parts of the world including Qatar, these storms have significant negative impacts on the economy, environment, infrastructure, and public health. Traditional prevention techniques use chemical stabilizers and cementing agents; however, their application is not only expensive, but may also have negative impacts on the environment and public health. Recently steep regulations on chemical grouts from Japan and the United States has caused many countries to follow suit and propose bans. In turn organic polymers and microbial biogrout have been proposed. However, organic polymers still have significant negative impacts on the environment; while biogrout has proven effective, it has not been tested for surface stabilization and releases harmful ammonia as a byproduct. Our research team has proposed using native extracellular polysaccharide (EPS) producing bacteria, specifically methanotrophic bacteria, for bioaggregation. EPS, sugars formed by the cell and then released outside the cell wall, make up much of the adhesive characteristics of biofilm and have been known to naturally form microbial crusts in Chinese desert sand. EPS is composed of a wide variety of sugars, not all of which are useful for stability, hence multiple species and their EPS must be tested. The proposed technique would involve application of an EPS producing methanotrophic bacterial culture to the sand's surface, or, application of the liquid culture followed by application of purified EPS. Methanotrophic bacteria are capable of using Methane as a carbon source and can produce large amounts of EPS and have been widely studied. The preference is for native methanotrophic bacteria to be used, to prevent introduction of non-native species or genes, and to minimize the disruption to the native ecosystem. We have collected native methanotrophic bacteria from Qatar sand. Samples of sand were incubated in Nitrate Mineral Salt (NMS) media under a 1:1 headspace ratio of air to Methane, and then streaked onto agar plates of the same media. The plates showed growth and EPS production. Since the media contains no carbon source the only accessible carbon source is the methane in the headspace so the bacteria can be assumed to be Methanotrophic. This will be confirmed along with determining species identifications through 16S rRNA Gene Amplicon Sanger Sequencing of the isolates; however, at the time of submission for this abstract sequencing and interpretation of the data are still underway. Until native methanotrophic bacteria can be identified and researched, two well studied strains of Methanotrophs – Methylococcus capsulatus (Bath) and Methylosinus trichosporium OB3b – are being used for preliminary EPS testing. Application of purified EPS, extracted with an Ethanol precipitation extraction method, to sand has shown signs of significant aggregation, along with increases in shear strength. Once a strain of bacteria is chosen by the research team, and the EPS production optimized, a lab scale bioreactor will be built to produce large amounts of EPS for lab scale sand stabilization studies. Lab scale studies will monitor time dependent changes in shear strength during application, microbial community changes, and ability to withstand critical threshold wind velocities. Future plans include field scale studies and the construction of a fluidized bed bioreactor for production of the liquid medium and EPS. Methanotrophic bacteria are easily adapted to large bioreactors and in situ applications. Bioaggregation with EPS producing bacteria would potentially provide an environmental friendly application for the prevention of sandstorms, utilizing methane – an indigenous resource to Qatar – for cost saving benefits.
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Necessity of the Adaptive Comfort Standard for the Middle East in the Times of Rising Energy Use
المؤلفون: Madhavi Indraganti, Djamel Boussaa and Somayeh AsadiMiddle East (ME) supplies more than 47% oil exported in the world (IEA 2013) and has highest energy self-sufficiency in the world. It includes 12 countries and has a population of 205 million in 2010, which increased by about 61.4% from 1990 (IEA 2010). Its energy demand has increased astronomically at the rate of 7% per year, since 1971–2013, faster than in any other region in the world. Buildings majorly contribute to this. Building energy (residential, commercial and public use buildings) use in the ME has increased by about 46% in the period 2003–13 (IEA 2010).
Ironically ME houses only about 3% of the world's population, but it contributes to 13% of global CO2 emissions. Understandable, its per capita CO2 emission is one of the highest in the world at 7.53 tons of CO2/capita, 68% higher than the world average. Therefore improving the energy efficiency remains a key challenge for the region. International Energy Agency (IEA) identifies the development and enforcement of building energy codes coupled with energy consumption data generation as the top energy efficiency policy recommendations for this region (IEA 2014).
Qatar's per capita energy consumption is one of the highest, consuming 30.184 TWh as of 2012 (IEA 2012) Buildings contribute majorly (80%) to this, with air-conditioning taking a lion's share. With the absence of custom-made energy/thermal comfort standards, the buildings tend to follow western standards meant for colder climates verbatim. Cheap energy availability and tariffs exacerbate this practice (Fattouha and El-Katiri 2013). Often times, energy analysis and conservation come as postmortem ideas than at the design stage. And the energy subsidies often prove to be unrealistic and unsustainable in the long run.
Qatar has little research on occupant thermal comfort and preferences in buildings. Energy efficient building design necessitates this. As part of large energy conservation web tool design for Qatar, we conduct year long occupant surveys in office buildings to understand the nature of the building stock and occupant thermal comfort and preferences along side their thermal adaptations.
Saudi Arabia stands sixth in world's oil consumption and already uses a quarter of its own production. Building energy consumption in Saudi Arabia went up astronomically by 60.8% in five years from 2007 to 2012. Energy analysts argue that Saudi Arabia could turn into a net oil importer by 2030 if current demand, growth patterns continue. Air conditioning majorly contributes to this. Recent research posits that the building envelope codes have a limited role to play in reducing energy consumption (Radhi 2009).
Saudi building code specifies two design temperatures of 20 °C and 25.5 °C for winter and summer, for all climate and building types, much similar to the building codes of other countries like UAE (SBCNC 2007). Relying on Fanger's heat balance model (Fanger 1972), the American Society of Heating, Refrigerating, and Air-Conditioning Engineers (ASHRAE) Standard -55 (1992) formed the basis for this. This Standard is long since superseded (ASHRAE 1992).
Environments designed based on this model produce thermal monotony (uniform indoor temperatures yearlong), with the indoor environments delinked from the outdoors. It ignores the local climate, clothing, culture or comfort practices of Saudis. Researchers all across the globe criticized such rigid and unsustainable indoor temperatures.
The Adaptive model of Thermal Comfort on the other hand hinges on the field studies in real life buildings. People in their everyday environments are studied in order to develop the temperature standards that truly represent local climate, people, their comfort practices and adaptation mechanisms. Saudi Arabia is yet to develop its Adaptive Thermal Comfort Standards (ACS) (Nicol and Humphreys 2009) (CIBSE, (The Chartered Institution of Building Services Engineers) 2006, Indraganti, et al. 2014) (ASHRAE 2010) (ASHRAE 2010).
The potential of occupant's adaptation and the ACS is in producing sustainable indoor environments is long since been recognized. Therefore, this presentation highlights the necessity of the Adaptive Comfort Standards for the ME in the context of its growing energy concerns. It relies on the results of the first field studies we have conducted in Japan and India, KSA and Qatar and also draws heavily from the current research around the world.
References
ASHRAE. ANSI/ASHRAE Standard 55–1992, Thermal environmental conditions for human occupancy. Atlanta: American Society of Heating, Refrigerating, and Air-Conditioning Engineers, Inc., 1992.
ASHRAE. “ANSI/ASHRAE Standard 55–2010, Thermal environmental conditions for human occupancy”. Standard, American Society of Heating, Refrigerating and Air-Conditioning Engineers, Inc, Atlanta, 2010.
CIBSE, (The Chartered Institution of Building Services Engineers). “Environmental Design Guide, Vol. A”. London, 2006.
Fanger, P. O. Thermal Comfort, Analysis und Applications in Environmental Engineering. New York: McGraw-Hill, 1972.
Fattouha, Bassam, and Laura El-Katiri. “Energy subsidies in the Middle East and North Africa”. Energy Strategy Reviews 2, no. 1 (2013): 108–115.
IEA. “Regional Energy Efficiency Policy Recommendations, Regional Energy Efficiency Policy Recommendations Arab-Southern and Eastern Mediterranean (SEMED) Region”. 2014.
IEA. “Energy balances of non-OECD countries”. International Energy Agency, 2010.
IEA. “Energy balances of non-OECD countries”. International Energy Agency, 2012.
Indraganti, Madhavi, Ryozo Ooka, Hom B Rijal, and Gail S Brager. “Adaptive model of thermal comfort for offices in hot and humid climates of India”. Building and Environment 74, no. 4 (April 2014): 39–53.
Nicol, Fergus, and Michael A Humphreys. “New standards for comfort and energy use in buildings”. Building Research & Information 37, no. 1 (2009): 68–73.
Radhi, H. “Can envelope codes reduce electricity and CO2 emissions in different types of buildings in the hot climate of Bahrain?”. Energy, 2009: 34(2009)205–215.
SBCNC. Saudi Building Code Energy Conservation Requirements: 601. 601, Saudi Building Code National Committee, Riyadh: Government of Saudi Arabia, 2007, 198.
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Identifying Current BIM Practices in Qatar and Proposing a Framework for Whole Life Cycle BIM Processes
المؤلفون: Mian Atif Hafeez, Vladimir Vukovic, Racha Chahrour, Mohamad Kassem and Nashwan DawoodThe research is part of a wider project aimed to develop a whole lifecycle information flow approach enabled by BIM protocols and technologies for Qatari construction industry. We consider the lifecycle information flow as enabler of a consistent and continuous use of building information from design, through construction, to the facility management stage. Building Information Modeling (BIM) is increasingly used by the Architecture, Engineering, Construction and Operation (AECO) professionals around the world. BIM has proven and potential benefits to facilitate Whole Life Cycle (WLC) information flow described above. It is generally accepted fact that AECO industry is fragmented in nature. Using BIM for WLC information flow is seen as one of the potential solutions to contribute towards a more cohesive AECO industry.
Within the global construction sector, Qatar's construction market is one of the fastest growing in the world throughout the next decade in alignment with the Qatar National Vision 2030. Currently ongoing and planned construction projects exceed US$220 billion (Kilani, 2014), e.g. Lusail City projects, new Doha Port, new Hamad International Airport, Qatar Rail project, Qatar National Museum project as well as construction of stadiums and related infrastructure projects ahead of the Qatar 2022 FIFA World Cup.
This paper aims to identify current BIM related practices, existing procedures, technology and standards being used in Qatar using qualitative data collection and analysis technique and then proposes a framework for BIM processes across whole life cycle of the project to facilitate whole life cycle information flow. 28 semi-structured interviews were conducted with different stakeholders (clients, contractors, consultants) involved mainly in design and construction project lifecycle stages in Qatar. Results of the conducted interview analyses are presented in relation to policy, people, process and technology (3P + T) pillars that have been proposed for use in Qatar.
The following key findings were reported by majority of the interviewees (values in brackets indicate the agreement percentage): (Vukovic, Hafeez, Chahrour, Kassem, & Dawood, 2015)
- Usage of FIDIC contract template (67%) and BS 1192:2007 BIM standards (60%) is prevalent on projects in Qatar. However, specific BIM information/standards should be developed at a government level for the Qatari construction industry (86%), including standard project stages with clear process maps (82%). Also in comparison to the situation in other countries, based on the examined literature, Qatari government should do more to drive the construction industry transformation by undertaking BIM related initiatives.
- BIM competency is usually a criteria for prequalification and selection during the procurement process (71%).
- Organizations in Qatar mostly use in-house BIM trained staff (75%).
- BIM roles are specifically defined in the contract (86%), BIM standards are required by contracts (68%), and should be enforced by contracts (75%).
- There is no need to create more BIM specific roles/positions (64%), but there is a need to upgrade the skills of people on BIM specific positions (89%). There is also a need to educate other project participants how to collaborate using BIM (96%). Such identified needs are similar to the situation in other countries covered by the literature review.
- LOD 300 is mostly required in design/construction stages of ongoing projects in Qatar (64%), which is the owners' responsibility (71%). The owner usually also initiates design changes (68%).
In alignment with the above findings this paper proposes a framework (Fig. 1) consisting of ‘Project DNA’, BIM Processes and Whole Life Cycle of the projects and their inter relationship. Future work will elaborate on the BIM processes and protocols and validate the proposed framework using case studies.
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Long Term Energy System Planning: to a 100% Renewable Energy System by 2050
المؤلفون: Pieter Lodewijks and Jan DuerinckIntroduction: To date, a variety of studies have been published on the topic of long term energy system transition. Most studies on future energy systems, however, have a shorter time frame or adopt a supranational focus (e.g. the Energy Roadmap, 2011 or the World Energy Outlook, 2015). It then constitutes a sincere challenge to perform a national energy system transition study with as time horizon 2050 and covering a far-reaching transformation of the energy system.
VITO, together with the FPB (Federal Planning Bureau) and ICEDD, performed a study to scrutinise the transition of the Belgian national energy system towards a future mix entirely based on renewable energy sources. The focus on renewable energy sources and on building a national energy system completely running on renewable energy can be traced back to three main concerns:
- – Climate change: Renewable energy sources (RES) are a major instrument in the fight against climate change as RES do not release (net) greenhouse gas emissions.
- – Security of supply: Most renewable energy sources make use of technologies that ultimately derive energy from natural phenomena like wind, wave, tidal, sun, water, etc. Renewable electricity can be generated from wind power, wave, solar photovoltaics (PV), hydro, geothermal and biomass. Since most RES are then cultivated or naturally available within a nation's territory, RES can help to reduce Belgium's (and Europe's) growing dependence on imported fossil fuels. As a 100% RES based system is independent of imported fossil fuels, it goes without saying that security of energy supply should benefit from a transition to a 100% RES based system.
- – Economy/competitiveness: creating or expanding a renewable market with a considerable number of direct and indirect jobs can seem appealing. Moreover, an energy system entirely based on renewable energy presupposes considerable efforts in the field of energy savings to drastically diminish the amount of energy needed, which in its turn instigates the activity of a.o. the building sector (through e.g. Insulation, heat pumps, airco systems, etc.). Not only job creation can prompt economic growth, also cost cutting does. As to costs, (most) RES, once in operation, have no fuel costs and less maintenance is needed to keep them functioning (IEA, 2005). However, it is also worth noting that most RES today need subsidies to compete with other technologies. These subsidies should nonetheless decrease steadily over time because of the “learning by doing” process and economies of scale so as to reach a level playing field with the “old” fossil fuels whose prices, due to scarcity issues, will likely not stop increasing in the coming decades if no global action is taken.
The Integrated MARKAL-EFOM System) is an economic model generator for energy systems, which provides a technology-rich basis for estimating energy dynamics over a long-term, multi-period time horizon. Reference case estimates of end-use energy service demands (e.g. car travel; residential lighting and heating/cooling; steam heat requirements in industrial sectors; etc.) are provided by the user. In addition, the user provides estimates of the existing stock of energy related equipment in all sectors and the characteristics of available future technologies, as well as present and future sources of primary energy supply and their potentials.
Using these as inputs, the TIMES model aims at supplying energy services at minimum global cost (at minimum loss of surplus) by simultaneously making equipment investment and operating decisions. For example, an increased demand for electrical appliances in the residential sector due to population growth leads to a number of reactions.
First, it involves a choice of appliances as the market provides different types corresponding to different energy efficiency levels (energy labelling) at different costs. Second, the increased demand for electricity has to be met and either existing generation equipment is used more intensively or new – possibly more efficient – equipment must be installed. The choice of the model of the generation equipment (type and fuel) is based on the analysis of the characteristics of alternative generation technologies, on the economics of the energy supply, and on environmental criteria.
The cost minimisation approach covers the full time horizon, which involves comparing different costs at different points in time. For this purpose all costs are discounted to the base year, using a uniform (social) discount rate.
The TIMES model is less suited as a projection tool. The main purpose of TIMES is the analysis of alternative scenarios, i.e. the impacts of measures are evaluated by comparing two scenarios which have been constructed in a transparent and consistent manner. The approach is more normative from the point of view of the public authorities (prescribing what optimally should happen). Transparency is guaranteed by the explicitness.
Challenges of intermittent energy
When dealing with high penetrations of intermittent renewable energy sources like wind and solar, fluctuations in supply occur and prevail over demand fluctuations. In the case of solar energy, the decomposition of the yearly production profile comprises 3 components: first, day/night fluctuations, second, a long wave starting at close to zero levels in January, peaking in the summer months and ending at similar close to zero levels by the end of the year, and third, a pattern that looks purely random. For wind we observe many cycles, defining periods with low availability extending from a couple of days to a couple of weeks. Dealing in a correct way with the intermittent nature of wind and solar energy is a major challenge for developing renewable energy scenarios and the high share of renewable energies required several model improvements for which we defined specific model adjustments that are also applicable for TIMES models for other countries. Different approaches for dealing with intermittent energy can be thought of: a better integration of the Belgian network in a European network, installing back-up installations, implementing smart grids, using storage technologies, adapting demand to supply.
Storage options are included in order to represent different alternatives in dealing with the volatility of energy supply. So far, the only mass storage available in Belgium is the pumped water storage facility in Coo, representing a capacity of 5 GWh, allowing producing electricity at a power rate of 1.2 GW. Additional storage facilities are included in the model: day/night and seasonal storage options for electricity, electricity to hydrogen and hydrogen to electricity options (electrolysis and fuel cells) and hydrogen storage options.
Standard TIMES models consider 12 sub-periods in one year, representing 4 seasons and 3 daily levels: night, day and peak. Usually this distribution in twelve time slices is chosen to represent the variability in demand and one peak demand slice simulates a peak close to historical levels. Empirically it has been found that this level of detail is sufficient for dealing with fluctuations in demand when supply is steerable. However, when dealing with high penetrations of intermittent renewable energy sources like wind and solar, fluctuations in supply occur and prevail over demand fluctuations. In order to represent this in the model the number of time periods within one year has been extended to 78 periods, equivalent to 26 two-week periods and 3 daily levels. Results: The main goal of this study is to examine the feasibility and the impact of a 100% renewable energy target on the future Belgian energy system 63. Although the realisation of such a transformation within a 40-year perspective may at first seem highly ambitious in a nation rather poorly endowed with natural resources and possessing both a highly energy-intensive industry and an energy-greedy residential sector, it appears to be technically feasible.
1. Extensive electrification and almost 100% renewable electricity by 2030
Moving to a 100% renewable energy system implies a radical transformation of nearly all sectors of the economy. The model shows that the strongest growth of renewable technologies is concentrated in the period 2030–2050. Nevertheless, some sectors experience thorough impacts earlier on through high growth rates of renewable energy technologies. This is particularly the case in the electricity production sector, which has to be transformed almost completely into a renewable based sector by 2030, since investments in the power generation sector appear to be the least expensive. Furthermore, the results of the model indicate that a 100% renewable energy system needs extensive electrification, causing a doubling or even tripling of the current electricity production by 2050.
2. Energy imports strongly diminish, but remain important
Transforming the energy system into a 100% renewable system will require considerable investments in demand-side management technologies, storage capacities and energy production installations. On the other hand, a higher share of renewable energy or lower energy consumption implies less fossil fuel purchases, which may reduce the national external fuel bill. Indeed, it is evident that solar, wind, hydroelectric or geothermal energy production installations do not need fuel input to produce useful energy for final consumers. The only exceptions to this rule are biomass and electricity imports which will tilt the balance of payments. Even so, the share of total imported energy tumbles from 83% in the reference scenario to a range between 15% and 42% in the renewable scenarios.
3. Additional energy system costs are rather stable over the different scenarios
The energy system cost is the sum of all energy expenses in an energy system. It consists of variable, fixed and investment costs. We calculated that the increase of the energy system cost amounts to approximately 20% in 2050, or 2% of Belgian GDP in 2050 (GDP2050). The necessary power sector investments vary between 1.0% (scenario focusing on demand decrease) and 1.7% (PV and WIND) of GDP2050. In conclusion, we can say that from today up to 2050, 300 to 400 billion € of investments are needed to transform our current energy system into a 100% renewable energy system.
4. Creation of additional employment
Although total system costs may appear considerable, one has to bear in mind that orienting our energy future towards renewable energy sources also entails benefits. One of those positive effects is further analyzed in the course of this study: the creation of additional employment through the renewable value chains. It was estimated that, by the end of 2030, this effect would create 20 000 to 60 000 additional full-time equivalent jobs compared to the reference scenario. At any point in time, the renewable scenarios create more full-time equivalent jobs than the reference scenario. The high end of the interval is taken in by the PV scenario, given that it necessitates many discrete panel installations combined with a large installation component in PV employment.
5. A new paradigm on energy perception
A new paradigm is arising in the way we think about energy. In a world without excess overcapacity of intermittent renewable energy sources and only limited access to biomass and geothermal energy, long-term (seasonal) storage is becoming extremely expensive. This leads us to believe that, in a cost-optimal modelling approach, a transformation of the energy system towards abandoning strict equilibria and replacing it by installing overcapacity in intermittent renewable energy sources is to be preferred. In other words, it may be more cost-efficient for the Belgian society to adapt in a certain way to the variability of the solar energy flow instead of trying to store enough energy in order to keep our current socio-economic paradigm unchanged. This in turn can impact the current industrial organisation towards more seasonal production oriented sectors, using necessary energy commodities such as electricity only during the cheapest periods of the year when e.g. sunlight is abundantly available and closing down during the darker winter months. This flexibility within the industry can then be perceived as having the same effect as a giant battery in which electricity can be stored in the aggregation state of e.g. steel.
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Petroleum Geochemistry Serving Oil Fields Production
المؤلفون: Frank Haeseler, Fatima Mahdaoui and Ahmad AldahikIn the oil industry when commingled wells are producing from different reservoirs (different geological layers) or even when production wells are connected to a common flowline, it is often necessary to quantify the fluid origin. This is a way to obtain material balance and to allocate the oil production. Production allocation is particularly important for a better reservoir management (history matching with the reservoir models). Several methods can be used aiming to determine the fluid flow like the Production Logging Test (PLT) or geochemical tools. The geochemical techniques (e.g. molecular fingerprinting of oil) are based on specificities of the oil composition and represent a profitable alternative method (less risk, no well intervention, no production losses, cost savings and higher frequencies) to PLT. The geochemical differences affecting oil composition can be attributed to many reasons: different source rocks, process of migration and filling histories, reservoir communication leading to oil mixture, and several in-reservoir alteration processes. Therefore, chemical differences between the oils are always existing can be used to determine and quantify the contribution of each fluid source.
Molecular fingerprinting using high resolution gas chromatography is a reference technique widely used for geochemical production allocation. This conventional type of techniques allows discriminating very similar fluids even so similar fluids as condensates (Sabatier et al., 2015). Nevertheless alternative techniques should be explored.
In the present work we investigated the possibility to discriminate oils form the same fields according to possible differences in composition of aromatic compounds. Specific geochemical analyses where performed in Doha in a joint Qatar Petroleum – Total project. The analytical approach used was Gas Chromatography coupled with Mass Spectrometry and a typical chromatograph is shown in figure 1.
Figure 1: gas chromatogram of the aromatic fraction of a petroleum sample (m/z 128: Naphtalene, m/z 142: methyl-naphtalenes, m/z 156: dimethyl-naphtalenes, m/z 170: trimethyl-naphtalenes, m/z 184: tetramethyl-naphtalenes, m/z 198: pentamethyl-naphtalenes).
As shown in an example presented in figure 2, the reservoirs from the studied fields coming from all around the world could be discriminated considering the composition in diaromatic hydrocarbons. This discrimination is possible considering both the height of the peaks or their surface.
Figure 2: comparison of the proportion of diaromatic hydrocarbon in the oils from different reservoirs of the same field.
The present study concerns the ability to discriminate oils according dicyclic aromatic hydrocarbons, but the same conclusions applies to tri, tetra and penta aromatic compounds (results not shown).
The results shown in the present study clearly allow envisaging fast analysis techniques based on aromatic hydrocarbons detection. This opens the way for future work focusing on quantifying such kind of compounds (involving quick separation techniques and smart detection methods). Literature reference: Sabatier L., Haidar F., Mahdaoui F., Dessort D., and Philippe Julien, 2015, Gas Reservoir Management: How to improve Gas Production Allocation per Reservoir in commingled Wells using Geochemistry Technology?, Proceedings of the International Petroleum Technology Conference, December 6th to 9th, Doha, Qatar.
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Metasurfaces for Far-Field Wireless Power Transfer and Energy Harvesting
المؤلفون: Omar RamahiThe concept of electromagnetic energy harvesting and wireless power transfer had been proposed more than half a century ago. In all published works related to electromagnetic energy collection, classical antennas have been used while the focus shifted to the rectification circuitry. Recent works showed that the weakest link in the traditional energy harvesting chain is the antenna itself. Here, we show that metasurfaces provide a viable alternative to classical antennas yielding efficiencies approaching unity. This presentation will be confined to the microwaves frequency regime.
Far-field wireless power transfer (WPT) is a relatively old concept where antennas are used to transfer power between two distant points. WPT perhaps dates back to Tesla but it was Brown in the 1950s that demonstrated its viability [1]. In recent years, WPT has been reconsidered as practical means to transfer power from outer space where satellites collect solar power with high efficiency using photovoltaic technology and then convert the power to microwaves for beaming to antenna farms at specific locations on earth. This would facilitate availability of plenty of power everyday throughout the year.
Conventional antennas have been the traditional microwaves transducers used for WPT applications. Conventional antenna types include log-periodic, patch, dipole or any of the varieties of antennas that were conceived in the past 100 years. Almost all antennas that were considered for WPT applications were designed in the first place for communication applications where traditional parameters such as gain, directivity and efficiency were considered the most critical. For WPT applications, at the transmission stage, the gain, directivity and efficiency play an important role in the design. At the receiving stage, however, the primary concern is to collect as much power as possible per footprint and based on specific polarization and incident angle. In applications of classical communication antennas, the real estate or footprint of the antenna has partial relevance. For instance, a patch printed antenna occupies some space on copper but its antenna parameters assume the antenna is present in a larger empty sphere. In other words, its functional space extends beyond its size.
Metamaterials are made of a three-dimensional ensemble of electrically-small resonators. Metasurfaces are considered as a two-dimensional version of metamaterials. The interesting and desired properties of metamaterials or metasurfaces are achieved when all elements of the ensemble operate at their resonance frequency (for simplicity, we assume all elements are identical). The resonance of each particle of a metamaterial or metasurface is fundamentally indicative of its ability to store energy. Metamaterials, therefore, can be effective energy collectors. This does not come as a surprise since metamaterials have been shown to be highly effective absorbers. However, in the case of absorption, the absorbed energy is mostly dissipated in the dielectric host. For the effective use of metamaterial as energy harvesters or collectors, not only the energy absorption is of high importance but also channeling the absorbed energy into energy collection channels is critical.
In this paper we demonstrate that metasurfaces can indeed be effective electromagnetic energy harvesters and can provide energy harvesting efficiency appreciably higher than what classical antennas can achieve. The effectiveness of the metasurface for energy harvesting arises from the close proximity between the electrically-small resonators that constitute the metasurface. While the spacing between electrically-small resonators is critical to achieve homogenization for classical metamaterial applications, in energy harvesting as the case in our work, the spacing between elements allow for careful input impedance tuning of all elements, thus enabling highly efficient energy transduction [2].
In this talk, we present metasurfaces composed of different types of resonators including split-ring resonators, electric-inductive-capacitive resonators, complementary split-ring resonators and dielectric resonators. We show that it is possible to achieve energy absorption with approximately 100% efficiency. In fact, using the concept of stacking of metasurfaces (which does not necessarily lead to metamaterials), it is possible to achieve efficiencies significantly higher than 100% as based on the efficiency definition provided in [3–4]. Simulation and experimental results will be provided to fully validate the feasibility and practicality of electromagnetic energy harvesting using metasurfaces.
References:
[1] Brown, W. C., “The History of Power Transmission by Radio Waves,” IEEE Transactions on Microwave Theory and Techniques, Vol. 32, No. 9, pp. 1230–1242, 1984.
[2] Almoneef, T. and O. M. Ramahi, “Split-Ring Resonator Arrays for Electromagnetic Energy Harvesting,” Progress in Electromagnetic Research B, in press.
[3] Ramahi, O.M., T. Almoneef and M. AlShareef, “Metamaterial Particles for Electromagnetic Energy Harvesting,” Applied Physics Letters, Vol. 101, No. 17, pp. 173903–173908, 2012.
[4] Almoneef, T and O. M. Ramahi, “A 3-Dimensional Stacked Metamaterial Array for Electromagnetic Energy Harvesting,” Progress in Electromagnetic Research B, Vol. 146, pp. 109–115, 2014.
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Usefulness of In-Situ Synchrotron Study on Scale Formation during CO 2 Corrosion of Mild Steel: A Review
المؤلفون: Mobbassar Hassan Sk (Shaikh)Despite the availability of the detailed knowledge about the chemical, electrochemical and transport processes associated with the formation of ferrous carbonate during CO2- corrosion of mild steel, information available about the mechanism of early nucleation stages of FeCO3 (siderite) film formation was only speculative. In depth knowledge related to the early stage nucleation of siderite scale and its subsequent development and gradual growth were revealed only recently by judicious exploration of in-situ synchrotron based experimentation. Moreover, application of in-situ synchrotron x-ray diffraction technique rendered ability to monitor the gradual real time growth of FeCO3 scale with the efficacy of simultaneous controllability of the corrosion conditions electrochemically. This work shades light on how in-situ synchrotron study revealed apparent mysteries related to formation & growth of siderite scale during CO2- corrosion of mild steel. Keywords: In-situ synchrotron, CO2-Corrosion of mild steel, Nucleation mechanism during CO2- corrosion.
Figure 1 (a) and (b) illustrate the photograph and schematic of experimental set up for in-situ synchrotron X-ray diffraction experiments using the powder diffraction Australian beam line.
Figure 2 shows the anodic current as a function of time in a potentiostatic test in the NaCl solution at pH 6.3 (pCO2 = 1bar) and an applied potential of − 500 mV (vs SCE), together with the intensities of the Fe and FeCO3 signals from the in-situ synchrotron XRD [1]. There is a clear peak in the current transient, with the XRD results showing FeCO3 formation during the increasing portion of this transient and then a rapidly decreasing rate of FeCO3 formation as the anodic current decreases towards the end of the test, indicating the growth of a protective surface scale. In these studies, it is shown that siderite only forms once the critical super-saturation is exceeded within a defined boundary layer and that the steel microstructure has critical role in developing a surface texture within which the critical super-saturation could develop. This idea of siderite nucleation in solution with a critically saturated boundary layer close to the metal surface is unlike the heterogeneous nucleation and growth phenomenon which occurs directly on the surface via solid state formation [1]. Establishment of this ideology was able to resolve the apparent thermodynamic anomaly observed in practice.
One of the apparent thermodynamic anomalies in CO2- H2S mixed system is couched on the fact that in spite of the higher (∼3 time) aqueous solubility of H2S compared to CO2 under similar temperature and pressure conditions, the formation of iron sulfide has been observed to be faster and predominant over iron carbonate under most parametric conditions even at a trace level of H2S concentration in CO2-H2S system. This fact indicates the formation of iron sulfide and iron carbonate films to be regulated by different mechanisms. In-situ synchrotron study revealed the early stage nucleation of iron carbonate (siderite) film and indicated that to be a gradual process giving rise to the formation of crystalline siderite phase only after the critical supersaturation stage is reached. Given that, there is significant time lag between the start of supersaturation and critical supersaturation limit, there is a possibility for iron sulfide formation during that time lag, as it forms by solid state formation mechanism which is a faster process. It is the in-situ synchrotron study which made it possible to illustrate the appreciable time lag between the start of supersaturation and critical supersaturation limit.
Ingham et al. [2] used in-situ synchrotron small- and wide-angle X-ray scattering (SAXS and WAXS) to demonstrate that the formation of crystalline siderite (FeCO3) during the corrosion of steel in CO2-saturated brine is actually preceded by the formation of a colloidal precipitate and an amorphous surface layer, both assumed to be amorphous ferrous carbonate. Grazing incidence SAXS showed that upon the application of an anodic potential, film forms instantaneously and then a separate population of particles develops in the later stage followed by the formation of the ultimate crystalline FeCO3, observed by WAXS. Ingham et al. [2] interpreted these observations in terms of crystal nucleation within the amorphous surface layer. This observation was speculated to bear a significant consequence on the morphology of the corrosion scale and hence its protectiveness. However, it would be important to understand the effects of local pH change as well as variation in temperature in this gradual formation and development of siderite scale and then to find out a quantitative correlation of this process with the mentioned parameters.
The fact of stable, adherent and protective siderite film formation in presence of trace amount Cr3+ was known [3, 4]. However the associated mechanism was not clearly understood until in-situ synchrotron x-ray diffraction study revealed a clearer picture of the mechanistic aspect of the expedited siderite film formation in presence of traces of Cr3+[2, 5]. This recently done in-situ synchrotron study made it clear that traces of Cr3+ in the solution significantly expedites the precipitation rate of the colloidal precursor and thus accelerate the appearance of the crystalline scale through its catalyzing influence on the nucleation process by modulating the local pH level at the steel surface and thus reducing of the critical supersaturation for precipitation.
Another interesting and critical factor in developing surface texture within which the critical supersaturation can be developed is steel microstructure. Consequently, steel microstructure must have intimate relationship with the corrosion process and morphology of the scale as microstructure can change the diffusion conditions at the steel surface affecting the local supersaturation of siderite. However, in-depth mechanistic information related microstructural effect on adherent and protective scale formation was hardly available in the literature. It is recommended to perform in-situ synchrotron X-ray diffraction experiment in order to make a detailed investigation of such a phenomena. Ko et al [6] recently conducted such a study in order to investigate the effect of microstructure and boundary layer conditions on CO2 corrosion of low alloy steels. This recent investigation clearly demonstrated that the nucleation of crystalline scales onto the surface of steels under CO2 corrosion at elevated temperature is critically dependent on the initial surface roughness, microstructure-related surface roughness developed during corrosion. This study also indicated the interdependence between microstructure and chromium-enhanced siderite nucleation. However, finding out the quantitative effects of surface roughness on the initial nucleation process (rate) of the scale as well as the stability of the scale would be a good addition to this study.
References:
[1] B. Ingham, M. Ko, G. Kear, P. Kappen, N. Laycock, J. A. Kimpton and D. E. Williams, “In-situ synchrotron X-ray diffraction study of surface scale formation during CO2 corrosion of carbon steel at temperatures up to 90°C”, Corrosion Science, 52 (2010), 3052–3061.
[2] Bridget Ingham, Monika Ko, Nick Laycock, Nigel M. Kirby, David E. Williams, “First stages of siderite crystallisation during CO2 corrosion of steel evaluated using in-situ synchrotron small- and wide- angle X-ray Scattering”, Faraday Discussion, 2015.
[3] M B Kermani, J C Gonzales, G L Turconi, D Emonds, G. Dicken, L Scoppio, “Development of Superior Corrodion Resistance 3% Steels for Downhole Applications”, NACE Annual Conference & Exposition, paper 3116, 2003.
[4] R M Garrels, C L Christ, “Solution, minerals, and equilibria”: San Francisco, California, Freeman, Cooper & Company, 1965, p 450.
[5] M Ko, B Ingham, N Laycock, D E Williams, “In-situ synchrotron X-ray diffraction study on the effect of chromium additions to the steel and solution on CO2 corrosion of pipeline steels”, Corrosion Science, Vol 80, 2014, pp 237–246.
[6] M. Ko, B. Ingham, N. Laycock, D.E. Williams, “In situ synchrotron X-ray diffraction study of the effect of microstructure and boundary layer conditions on CO2 corrosion of pipeline steels”, Corrosion Science, Vol 90, 2015, pp 192–201.
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Resource Allocation Under Footprint Constraints in Industrial Parks
المؤلفون: Dhabia M Al-Mohannadi, Kholoud Abdulaziz, Sabla Y. Alnouri and Patrick LinkeWith growing climate change concerns, depleting natural resources and decrease in oil and gas prices, it is more vital than ever to efficiently manage natural resource allocation. Methane, the key component in natural gas and a raw material for numerous chemicals, is Qatar's more abundant resource. Natural gas can be monetized through many alternative paths. It can be sold as natural gas, either through pipelines or in liquefied form, or converted into diverse sets of fuels and materials using many alternative processing technologies. In the meantime, concerns of the effects of increased carbon dioxide concentration in the atmosphere, majority of which are emitted from large industrial stationary sources and fuel consumption, have caused the global society to seek ambitious emission reduction targets.
While on the one hand natural gas provides a clean fuel associated and enables carbon dioxide emissions through fuel switching globally, its local processing is associated with significant footprints. In the case of Qatar and its small population, this has resulted in very high per capita emissions. Most of the emissions are stationary and spatially concentrated in industrial clusters, where they originate mainly from natural gas processing, hydrocarbon processing, petrochemicals and metals production, and power and water generation.
The industrial sector is challenged to balance profit making activities from natural gas monetization with increasing pressures to reduce overall carbon dioxide emissions. Conventional design of industrial parks centering on natural gas are carried out in an ad-hoc process that depends on the expertise of designers, available capital, market demand and regulations. Reduction methods in the past have been limited in technology, energy integration or geographical proximity to apply carbon capture and sequestration (CCS).
Recently, carbon integration (Al-Mohannadi and Linke, 2015a,b) has been introduced as a systematic approach to determine the most efficient carbon dioxide reduction options in industrial parks by considering multiple carbon dioxide sources, potential carbon sinks, the layout of the city and the associated costs of transmission and conditioning. Carbon integration looks into the various conversion routes that take carbon dioxide into value added products, which can be converted chemically, biologically or through geographical utilization such as Enhanced Oil Recovery (EOR) applications. This creates incentives to reduce carbon emissions, to create synergies between firms and to produce additional products in the cluster, while adhering to required emission reduction targets.
Beyond focusing on low cost carbon dioxide emissions reduction, the broader design challenge for a natural gas monetizing industrial cluster is to identify the most promising configurations from the vast number of alternatives that exist from the possible combinations of many alternative natural gas monetization processes, and the many alternative carbon management options that could be applied, whilst exploiting synergies between natural gas conversion and carbon management. Most previous works have focused on different aspects of the overall problem: optimizing gas conversion processes, and managing carbon dioxide emissions reductions. Very few works have considered monetization in industrial clusters, and there is no published work on how to systemically make gas monetization decisions under carbon dioxide emissions constraints.
This work introduces the first systematic approach to allocate natural resource under carbon dioxide footprint constraints. The approach yields integrated natural gas and carbon dioxide management schemes that yield the maximum profit for the given gas monetization and carbon dioxide management options and constraints that exist in the industrial cluster. The work explores different carbon dioxide emission reduction scenarios; expansion plans and determines most profitable product mix from an industrial cluster. By taking into consideration the tradeoff between environmental performance and potential profitability of natural resource allocation, it provides valuable information to decision makers from an optimization based tool. Policy makers and regulators can use the tool for developing strategies and for planning of more sustainable industrial clusters, parks or cities.
The work is illustrated using a case study to demonstrate the application of the method on industrial cluster resembling a configuration of gas monetization options often observed in oil and gas centered economies.
Keywords
Resource Allocation, Climate Change, Carbon Dioxide emissions, Carbon Integration, Natural Gas Allocation, Gas Monetization, Carbon Reduction, Process Integration, Industrial Parks, Planning, Modeling, Optimization.
References
Al-Mohannadi, D.M., P. Linke (2015). On the Systematic Carbon Integration of Industrial Parks for Climate Footprint Reduction. Journal of Cleaner Production, DOI: 10.1016/j.jclepro.2015.05.094.
Al-Mohannadi, D.M., S.K. Bishnu, P. Linke, S.Y. Alnouri (2015b). Systematic Multi-Period Carbon Integration in an Industrial City. Chemical Engineering Transactions 45, 1219–1224.
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Improved Gas and Water Pollution Sensors Based on AlGaN/GaN HEMTs for Air and Water Treatment Systems
At the present time, serious threats are being posed to the environment due to pollutants in both the air (e.g. automotive exhaust emissions) and water (e.g. phosphates, nitrates, heavy metals). In an effort to improve these environmental hazards, automotive emissions standards and regulations on water pollutants are becoming more and more strict each year. One of the major limitations in meeting these regulations is the ability to quickly and accurately detect low concentrations of the target molecules.
We report the fabrication and experimental testing of a new generation of microsensor technology that can detect a wide range of gases in the air as well as pollutants in a liquid environment. These sensors are based on AlGaN/GaN high electron mobility transistors (HEMT) with functionalized gate contacts acting as the sensing layer. The use of high bandgap, group-III nitride semiconductor materials gives the sensors a high thermal and chemical stability, making them suitable for high temperature applications (above 600°C) and in harsh chemical conditions. Depending on the type and structure of functional layer, the adsorption of the target molecules leads to change the surface depletion layer which has a direct affect on the sensitivity and the selectivity of the device. Extensive modeling and design of the AlGaN/GaN HEMTs has been performed to optimize the devices for detection of exhaust gases and water pollutants. This includes the design of each of the material parameters (e.g. AlGaN thickness, Al incorporation) and the functionalized contacts (e.g. material, dimensions, morphology).
Experimental results using a Pt sensing layer show detection of 10–1000 ppm NO and NO2 gas with changes in current of 0.8 and 2.8 mA, respectively. Detection of NH3 gas in a range of 150 ppb–15 ppm was also demonstrated, and can be compared to detection limits of only 35 ppm for similar devices. This is the first time that detection of NO has been demonstrated using a HEMT sensor, and the first time selective detection of NO, NO2, and NH3 has been demonstrated using a single transistor device. Furthermore, the sensitivity to NO2 and NH3 were significantly higher in our optimized device compared to other HEMT sensors. Dynamic response times were shown to be between 1–3 seconds for each gas, showing that these sensors can perform in real-time applications.
In addition to exhaust gas detection, an open-gate HEMT sensor was designed and fabricated as a water pollution sensor and showed detection of both phosphates and nitrates in water. This is the first time that phosphates have been detected using a HEMT sensor, and shows that HEMT sensors can be useful in the prevention of eutrophication of fresh water bodies. We are currently exploring HEMT sensor designs for the detection other water pollutants such as heavy metals, inorganic and organic molecules that damage or contaminate water supplies.
The experimental results presented in this abstract demonstrate that the functionalized AlGaN/GaN HEMT sensors we have developed are promising for real-time air and water treatment applications due to their low detection limits, high sensitivities, fast response times, and selectivity by functionalizing the sensing layer for specific target molecules. Therefore, this technology has the potential to drastically improve the reduction of pollution in the air caused by automotive exhaust and other gases, as well as pollution in lakes and other viable sources of water.
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Facile Synthesized Mo 2 C Electrocatalyst Supported on Mesoporous Carbon for Hydrogen Generations
المؤلفون: Belabbes MerzouguiThe surge in the field of renewable energy aiming to develop clean energy technology is continuing to rise. Quest for a H2-based economy derived from non-fossil resources remains at the forefront of future fuels. During the past few decades there has been intense research on the utilization of electrical energy to produce H2 in an energy efficient and environmentally benign way. Electrocatalytic hydrogen generation via water electrolysis provides an important alternative to that extracted from hydrocarbon resources. One of the most crucial components which could revolutionize H2 production is that the design and development of a novel electrocatalyst that can efficiently split water to generate H2. Currently, platinum (Pt) is known as the state-of-the art electrocatalyst for hydrogen evolution reaction (HER). However, due to cost and scarcity of Pt, research focus shifted to precious-metal-free based materials for efficient HER reaction. As results, a wide variety of transition-metal-based electrocatalysts have been developed and investigated. To this end and due to unique d-band electronic structure, Mo-based electrocatalyst such as, Mo2C and MoS2 has been the subject of intense investigation for HER reaction. Yet, functional and robust catalysts operating with reasonable current densities (J) at low overpotential in brine water are still scarce.
Herein, we demonstrate a facile synthesis of β-Mo2C embedded on mesoporous carbon support; Metal Organic Framework (MIL 53(Al)) was utilized as a novel source for mesoporous carbon support. Microscopic studies revealed the formation of monodisperse Mo2C with
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Microbial Desalination Cell: An Integrated Approach for Wastewater Treatment and Desalination Systems for Sustainable Water Desalination and Wastewater Treatment
المؤلفون: Suraj Sevda, Ibrahim M Abu Reesh and Zhen HeThe availability of drinking water from the current available sources is decreasing due to the high demand and population increase. Seawater is a potential source for drinking water but the current desalination technology is energy intensive, therefore energy efficient desalination technology is desired. In the past decade microbial fuel cells (MFC) were emerged for simultaneous wastewater treatment and bioelectricity generation, in the anodic chamber of MFCs, microbes work as a biocatalyst to generate electrons from the oxidation of the organic compounds (wastewater) and transfer them to the anode electrode. These electrons flow through an external circuit to the cathode electrode where they used to reduce terminal electron acceptors (e.g., oxygen). Microbial desalination cells (MDC) are new potential technique for seawater desalination, in this device energy from wastewater is extracted by using microbes and without any external energy source, water desalination is driven. To convert an MFC to an MDC, a middle chamber is inserted in between the anodic and cathodic chambers of MFC using a pair of anion and cation exchange membranes. This middle chamber works as a desalination chamber in the MDC (Fig. 1). The cations and anions from the desalination chamber moved to the anodic and the cathodic chambers, respectively, due to the cell potential difference between the anode electrode and the cathode electrode; as a result, salts are removed from the saltwater.
The first MDC study was reported in 2009 and since then there have been nearly 74 papers published about various aspects of MDC design and development, indicating a strong interest and rapid development of this technology. During this short period of time, various MDC designs were developed for salt removal and wastewater treatment. The desalination chamber volumes were increased from 3 ml to 105 liters and further progress is going on for salt removal and at the same time wastewater treatment. The performance of MDC was investigated using various concentrations of saline water in desalination chamber using industrial or synthetic wastewater in the anodic chamber. Different MDC designs were reviewed here. These developed new MDC designs named as air cathode MDC, stacked MDC (SMDC), up flow MDC (UMDC), recirculated MDC (RMDC), microbial electrodialysis cell (MEDC), submerged microbial desalination- denitrification cell (SMDDC), microbial capacitive desalination cell (MCDC) and osmotic microbial desalination cell (OsMDC). Different anion and cation exchange membranes were compared for power generation and desalination efficiency. This paper also reviews different substrates that have been used in MDCs so far. The MDCs provide an energy self-sustainable system in that water desalination and wastewater treatment conducted by using microbes as catalyst in the anodic chamber. Still the available MDCs were very small in volume that can't meet today's water desalination needs. In the long term operation of MDC, the membrane fouling and electrode stability are still two major problems limiting the development of MDCs. The possibility of scale-up, possible future potentials for synchrony of the MDCs with current desalination techniques were also discussed. Case study with real wastewater in the anodic chamber and real seawater in the desalination chamber were also discussed.
Acknowledgements
This work was made possible by NPRP grant # 6-289-2-125 from the Qatar National Research Fund (a member of Qatar Foundation). The statements made herein are solely the responsibility of the authors.
Reference
Sevda, S., Yuan, H., He, Z., Abu-Reesh, I.M., 2015. Microbial desalination cells as a versatile technology: Functions, optimization and prospective. Desalination 371, 9–17. doi:10.1016/j.desal.2015.05.021
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Toxicity of Chlorine to Five Marine Species from Various Trophic Levels of Qatari Waters
المؤلفون: Suhur Saeed, Nandita Deb, Sarah Bacha and Christopher WarrenBackground
Chlorine is extensively used as a powerful oxidizing agent in the countries surrounding the Arabian Gulf for water treatments and biofouling control. The usage has been increasing significantly as demand for water grows considerably both in industry and domestic use. This is due to the fact that it is a well-tested technology, has had a history of long-term worldwide industrial use and is of acceptable cost. Sodium hypochlorite (NaOCl, commonly termed chlorine) is a common form of chlorine that is used and in all cases it is produced on site by means of an electro-chlorination plant (ECP). In seawater, chlorine produces a mixture of hypochlorous acid (HOCl) and hypochlorite ion (OCl − ). These rapidly react with the bromide ion to form a mixture of hypobromous acid (HOBr) and hypobromite ion (OBr − ). The acute oxidants formed by chlorination are therefore short lived and are not persistent in seawater, but can be quite toxic. Further complicating the environmental concern of chlorination is the production of numerous, and more persistent, compounds formed by complex reactions between chlorine/bromine and the organic constituents of seawater, collectively described as chlorination by-products (CBPs). Many CBPs are persistent and may be toxic to marine organisms subjected to long-term exposures. The Gulf waters support a range of coastal and marine habitats including mangrove swamps, seagrass beds and coral reefs. However, marine organisms in the Arabian Gulf are living close to their tolerance limits due to the extreme environmental stressors of temperature and salinity. Anthropogenic stressors such as chlorine may further exacerbate these natural stressors.
Objectives
In order to evaluate the risks of chlorine exposure to Arabian Gulf marine organisms, the aims of this study were to 1) develop protocols for acute and chronic toxicity tests involving native species at different trophic levels, 2) correlate sensitivity to other marine organisms used as indicator species in risk assessments, 3) draw conclusion from the results and explore ways that this could be used for informing environmental management activities.
Methodology
Materials and methods
Stock solution of calcium hypochlorite was prepared in filtered artificial seawater (0.45 μm filter paper) daily in dark bottles. Concentration of chlorine in the experimental chambers were verified daily by the N,N-diethyl-p-phenlenediamine (DPD) colorimetric method. Different concentrations of chlorine were either administered as a continuous flow through or via daily renewal.
Exposure to test species
Species were collected from different location around the coastal areas of Qatar. They were then cultured in the laboratory using conditions of the Arabian Gulf. Species used in the tests include phytoplankton (Synechococcus sp.), zooplankton (Uterpina acutifrons), pearl oysters (Pinctada radiata), sea urchins (Diadema setosum) and killifish embryos (Aphanius dispar).
Results
Sensitivity varied across the trophic levels for each species and was found to be in line with other test organisms that are used in established toxicity procedures. All five species used were found to be useful for certain types of toxicity testing. For example, Pinctada radiata and Diadema setosum were excellent in testing for successful fertilization and early development stages, while local Aphanius dispar embryos were useful for following sub-lethal effects such as malformation and hatchability. Embryos of oysters and urchins were found to be the most sensitive to chlorine (Fig. 1.). Effect of chlorine was only observed near or after hatching has occurred. Continuous exposure showed more effective than the semi-renewal method.
Discussion and conclusion
While chlorine continues to be used heavily globally, available toxicology data are either very limited or out dated especially those based on the Arabian Gulf. The purpose of this study was to increase the knowledge of chlorine chemistry and toxicity especially the sensitivity towards the Arabian Gulf species. Results obtained reveal that the sensitivities of all five species used in this study are in line with species used internationally in similar tests. LC50s were determined for all species and are currently being used in modelling tools to determine the fate and environmental risks of chlorine. Chlorine being a powerful oxidizing agent asserted its effect immediately after contact. It loses its potency within the first hour in seawater and this may contribute to the low effect shown in this study compared those in fresh water. Given the short-lived nature of chlorine as an oxidant in seawater, our attention has also been focused on the sub-lethal effects that may be attributed from the by-products. Work is ongoing in this area. Expanding tests with species used in this study to evaluate their sensitivity towards chlorine by-products will further increase our understanding of their chemistry and environmental risk in the Arabian Gulf and will provide a science-based tools for making management decisions.
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Lubrication in Desert Environments: Oil-Soluble Organo-Silver Molecules Designed for In-Situ Deposition of Metallic Silver at High Temperatures
The quest for improved engine performance and reduced emissions drives the design of increasingly sophisticated lubrication technologies. Lubricating oils and greases are engineered to function over a broad range of temperatures and loading conditions. Modern engines operate at higher temperatures, speeds and pressures than previous engines, and therefore require lubricants capable of handling harsher conditions. Reliable performance in extreme conditions is also necessary in emergency and combat situations. Thus, a major challenge for next-generation lubrication technology is to improve performance at extreme temperatures exceeding the thermal degradation limits of conventional engine oils.
In automotive engines, the surface temperature of critical tribological components can easily reach 200°C, while asperity contacts can generate ‘flash temperatures’ up to 1000°C. These extreme pressures and temperatures in the contact zones can lead to plastic deformation, wear away mating surfaces, and catalyze chemical reactions which damage the surfaces and lubricant. Tests carried out on PAO4 and 15W40 motor oils show that they decompose at 275°C, irreversibly losing viscosity and generating oil-insoluble acids and salts that corrode surfaces and form sludges.
Surface coatings, such as diamond-like carbon, and texturing can be used to reduce friction at temperatures which lead to motor oil thermal degradation. However, such treatments are costly for large components, and these coatings cannot be replenished without dismantling the treated machinery. Soft metal ductility can also be utilized in lubrication. The low shear-strengths of metallic films can form smooth “glaze layers” on tribosurfaces which lubricate sliding contact. Noble metals have oxidative stability, enabling lubricious performance at extreme temperatures. Silver-coated contact surfaces exhibit reduced friction and wear from 25–750°C. However, a method is required to dissolve metallic silver precursors in base oil for deposition at high temperatures.
Silver nanoparticles are known to increase surface fatigue life, decrease friction, and wear, and work synergistically with other lubricant additives. However, silver nanoparticles are expensive, difficult to suspend in nonpolar media, and typically require a surfactant to prevent agglomeration. An alternative, described here, is to use a silver-containing molecular precursor. Organic ligands impart solubility to silver atoms and control the organosilver complex decomposition temperature to deposit silver only when and where it is needed. Controlled silver deposition is arguably more economical than full protective coatings. Also, a lubricant additive can be replenished during oil changes to provide more lubricious silver to high asperity engine contact regions. We report here the synthesis, characterization, and tribological implementation of a silver-pyrazole complex, silver 3,5-dimethyl-4-n-hexyl-pyrazolate (HPzAg)3. This complex is oil-soluble and undergoes clean thermolysis at ∼310°C to deposit lubricious, protective metallic silver on mechanical surfaces. Temperature controlled tribometer tests show that an optimized 2.5 wt% (HPzAg)3 loading reduces wear by 60% in PAO4 (poly-α-olefin lubricant) and 70% in a commercial fully-formulated motor oil (military grade 15W40). This organosilver complex also imparts sufficient friction reduction that the tribological transition from oil as the primary lubricant through its thermal degradation, to (HPzAg)3 as the primary lubricant, is experimentally undetectable.
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Research in Irrigation Canal Lining: An Experience from Sudan
المؤلفون: Tarig El Gamri Ibrahim and Amir Bakheit SaeedThe amount of water below 1000 m3 per capita per annum is considered as the water poverty zone. With business as usual scenario it is estimated that by the year 2025 half the world's people will live in countries with high water stress. Based on Global averages irrigation water demands accounts for about 70% of all water uses. Meanwhile water use efficiencies of irrigated projects are generally very low particularly those under traditional surface methods. On the other hand conveyance losses vary within a range of 25–50% of the total diversion. Generally canal lining can save about 75% of the conveyance losses. However, high quality linings were found to practically eliminate such losses. The paper reviews the benefits of canal lining, which include hydraulic, economic and environmental benefits. Since seepage from irrigation canals is the most important factor in lining considerations the paper presents some review on the phenomenon. Canal lining is usually classified into four main types: hard surface linings, membrane linings, earth linings and soil sealants. The paper critically discusses the different types and highlights the criteria for selecting the appropriate lining technique. The paper also reviews the recent technical developments and research at the global level in this field; these include the development of new materials and techniques. Finally the paper presents a review of the canal lining related research executed by the National Centre for Research, Sudan during the last 20 years. These include development of low cost lining (building) materials using locally available aggregates (sand and gravel), lining irrigation canals on expansive soils and development of low cost concrete pipes and production of precast canal-lets. Canal lining was found conserve irrigation water, reduce fuel consumption, reduce irrigation time and reduce labour requirements. Development of Low Cost Building Materials for Canal Lining:: Four low cost building materials have been studied, these are namely khafgi, ferrocement, kenaf sheets and concrete made of small-sized gravel available near RDRC. Kenaf sheets were rejected because of the low durability expected. The other three materials were found to be feasible based on strength, permeability and durability. Water transported sand near RRS was found to be suitable for building works including lining whereas wind transported sand can hardly be recommended for such works.
Hand placement cast in-situ was adopted using the semicircular configuration, as besides improving structural integrity of the canal, it is the most hydraulically efficient section particularly for small canals. A semi circular cast-in situ form was made to construct channel sections that accommodate maximum discharges at RDRC. The work is done in alternate sections and the lap-joint technique was used. Pipe Casting:: It have been noticed that some desert farms the canalization system is liable to be buried by wind-blown sand. To avoid this problem the system should adopt pipes instead of open channels; however, traditional farmers cannot afford to cover such expenses since such pipes are relatively expensive in the local market. To overcome such problems the study was extended to develop intermediate technologies for pipe casting. A form was designed and constructed in a local workshop. The form is made of PVC pipe equipped with a handle as an internal unit the external unit is made of sheet metal also a wooden base is used. The external unit is composed of two semi-cylinders; a steel channel is welded to each end of each semi-cylinder to facilitate fastening meanwhile a rubber strip used to prevent water leakage. Again locally available aggregates were used. Laboratory tests (Impact Value and Crushing Value) showed that locally available gravel is suitable for pipe casting. The internal unit of the form is removed about an hour after the end of the casting process and the external one after a day. The pipes were then cured for 7 days. Compressive Strength and permeability tests proved that the produced pipes comply with the Known International Standards. Additionally the pipes were tested in the field by passing a tractor, which represent the maximum expected load in such farms without being damaged. Lining Irrigation Canals on Expansive Soils:: Um Jawaseer Desert Farm Project, which is located in Wadi El Magadam, the Northern State was established in the year 1989 for the settlement of the nomads of El Hawaweer Tribe. The project harnesses water from an aquifer of about 40 m below ground surface for irrigation and other purposes. Evaluation studies showed that the project is successful in creating better livelihood for the people of the area.
Huge water losses were encountered in the first two phases. In the third phase the project adopted stone lining, which is estimated to conserve about 1/3 of the irrigation water. However, stone lining is known to be one of the least effective lining techniques. Identification tests were carried out in accordance with the British Standards and showed that Um Jawaseer soil possesses swelling properties.
To reduce (mitigate) the expansive potential of Um Jawaseer soil some additives (cement, lime, bituminous emulsion and refuse oil) were tested, these additives were added to the soil at a rate of 6% by weight as recommended by some authors.
To avoid damage the linings a combination of soil treatment and construction technique was used for the lining of Um Jawaseer irrigation system. The soil was first excavated to a depth of 60 cm and mixed with the additive (cement). Water is added to the soil/ cement mixture till the optimum moisture content (plastic limit) was reached. Finally the mixture was compacted into two layers (30 cm each). As for the construction technique the semi-circular channel cross section was used since it produces integrity in structure and the channels so constructed can resist external forces. This combination gave very encouraging results since it is found to mitigate upheaval damage and produce strong and efficient conduits. Precast concrete canal-lets:: The merits of precasting are attributed to the high quality control coupled with the technique. Precasting was advised by some authors for mass production of tertiary canals. The J- Section was selected for ease of casting the form is made of metal sheets.
The form was filled of concrete, while being compacted with steel rod, left for an hour to allow for setting of concrete and then released. The finished section is allowed to dry for 24 hours and then cured for 7 days by wetted kenaf sacks. Keyword: Seepage, Irrigation, Canal lining, Pre-casting, efficiency
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Solar Thermochemical CO 2 Utilization via Ceria Based Redox Cycle
المؤلفون: Rahul Rambhau Bhosale, Anand Kumar, Fares Almomani, Ujjal Ghosh, Ivo Alxneit, Jonathan Scheffe and Shiva YousefiAccording to the recent studies, it is expected that the global energy requirement will increase from 14 TW to 30 TW by the year 2050. Currently, fossil fuels are the major energy source utilized for the fulfillment of the energy requirement. Due to the excessive utilization of fossil fuels, the concentration of greenhouse gases in the atmosphere is increasing day by day and hence there is a pressing need to develop technologies to produce carbon free renewable fuels. The liberated CO2 can be re-energized into CO via ferrite based thermochemical looping process using concentrated solar energy. The CO produced via solar thermochemical CO2-splitting can be combined with H2 derived from ferrite based solar thermochemical water-splitting process to produce solar syngas which can be further processed to liquid fuels such as Methanol, Diesel, and Kerosene via the Fischer-Tropsch process. The current research trends in solar thermochemical community are focused towards high and constant levels of solar fuel production in multiple cycles and it is believed that non-volatile mixed metal oxides such as undoped and doped ceria will significantly improve the production of solar fuels. Ceria based redox cycle comprises of two steps. First step belongs to solar endothermic reduction of ceria at higher temperatures releasing O2. The second step corresponds to the non-solar exothermic re-oxidation of the reduced ceria at lower temperatures by H2O, CO2, or a mixture of the two producing H2, CO or syngas.
In this investigation, Zr and Hf doped ceria based redox nanoparticles (various doping combinations) were synthesized using a co-precipitation method. The respective metal precursors were dissolved in water. Upon complete dissolution, excess ammonium hydroxide (NH4OH) was added drop-wise to the mixture under vigorous stirring to precipitate the mixed-metal hydroxides (final pH = ∼9). The obtained precipitates were filtered, washed with water until free from anion impurities and oven dried at 100 °C for 8–10 h. Subsequently calcination was performed at different temperatures in air. The calcined powders were characterized by powder X-ray diffraction, BET surface area analysis, scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The compositional purity of the derived Zr/Hf doped ceria was identified using powder XRD and the obtained results indicate phase pure composition of the derived materials (based on the stoichiometry selected during synthesis). The derived Zr/Hf doped ceria also possess high specific surface area (SSA) and porosity which is confirmed by BET analysis. The SEM and TEM analysis indicate formation of Zr/Hf doped ceria nanoparticles in the range of 10 to 50 nm. Synthesized Zr/Hf doped ceria nanoparticles were further tested for thermochemical CO2-splitting by using a high-temperature thermogravimetric analyzer (TGA). Multiple thermal reduction and oxidation (by CO2) cycles were performed at various operating conditions by using TGA while the O2 and CO was quantified by gas chromatography. Results obtained indicate that the derived Zr/Hf doped ceria is capable of producing higher amounts of solar CO as compared to previously investigated undoped and doped ceria materials. Also, the Zr/Hf doped ceria was examined in 20 thermochemical cycles towards successive thermal reduction and CO2 splitting reactions and the obtained findings indicate stable redox reactivity and thermal stability.
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Reactive Absorption of CO 2 Using Ethylaminoethanol Promoted Aqueous Potassium Carbonate Solvent
Atmospheric concentration of CO2, which is considered as one of the major greenhouse gases (GHGs), has increased up to 398 ppmv as of 2015. CO2 concentration in atmosphere was 280 ppmv in pre-industrial era, and due to the continuous discharge, it is expected to increase up to 550 ppmv by 2050. Many of the major industrial sources of CO2 emissions are natural gas fired power plants, synthesis gas used in integrated gasification combined cycle (IGCC) and power generation, gas streams produced after combustion of fossil fuels or other carbonaceous materials, and oxyfuels. Reactive absorption of CO2 from the industrial off gases by using chemical solvents is considered as one of the most common, efficient, and cost effective technologies utilized by the industry for CO2 capture. The captured CO2 can be stored by using the geological or oceanic sequestration approaches. As an alternative to geological or oceanic sequestration, the captured CO2 can be re-energized into CO by using solar energy and combined with H2, which can be generated from different methods, to produce syngas. The syngas produced can be further processed to liquid fuels such as methanol, gasoline, jet fuel, etc. via the catalytic Fischer-Tropsch process.
In past, a variety of chemical solvents (mostly aqueous amines and there derivatives) have been used for CO2 capture from different gaseous streams via reactive absorption. Though the amines are attractive for the CO2 capture application, there are several disadvantages such as very strong corrosion to equipment and piping, high energy requirement during the stripping of CO2 and they are prone to oxidative and thermal degradation. Recently, use of aqueous potassium carbonate (K2CO3) as a solvent for the absorption of CO2 has gained widespread attention. The usage of K2CO3 has been employed in a number on industries for the removal of CO2 and H2S. Due to its high chemical solubility of CO2, low toxicity and solvent loss, no thermal and oxidative degradation, low heat of absorption, and absence of formation of heat stable salts, K2CO3 seems to be more attractive compared to the conventional amines towards CO2 capture. However, K2CO3 solvent shows slow rate of reaction with CO2 and, consequently, low mass transfer in the liquid phase as compared to the amine solvents. Hence, several investigators are focused towards improving the rate of reaction of CO2 in K2CO3 solvent with the help of different types of promoters.
In this paper, the kinetics of absorption of CO2 into an aqueous K2CO3 (20 wt %) promoted by ethylaminoethanol (EAE) solution (hereafter termed as APCE solvent) was studied in a glass stirred cell reactor using a fall in pressure method. Reactive absorption of CO2 in EAE promoted aqueous K2CO3 solution (APCE solvent) was studied at different initial EAE concentrations (0.6 to 2 kmol/m3) and reaction temperatures (303 to 318 K). The reaction between the CO2 and APCE solvent was very well represented by the zwitterion mechanism. The N2O analogy was employed for the determination of H_(CO2) in the APCE solvent. The H_(CO2) was observed to be decreased by 5 and 31% due to the increase in the EAE concentration from 0.6 to 2 kmol/m3 and reaction temperature from 303 to 318 K, respectively. The D_(CO2) in the APCE solvent was also decreased by 21% due to the similar increase in the initial EAE concentration. In contrast, the D_(CO2) increased with the rise in the reaction temperature from 303 to 318 K by a factor of 1.678. The rate of absorption of CO2 in the APCE solvent was observed to increase by 35.10% and 47.59% due to the increase in EAE concentration (0.6 to 2 kmol/m3) and reaction temperature (303 to 318 K). The absorption kinetics was observed to be of overall second order i.e. first order with respect to both CO2 and EAE concentrations, respectively. The rate constant (k_2) for the absorption of CO2 in the APCE solvent was observed to be equal to 45540 m3/kmol√s at 318 K. The temperature dependency of k_2 for the CO2 – APCE solvent system was experimentally determined as: k_2 = (1.214 × [10]^18)√exp(( − 9822.7)/T). Findings of this study indicate EAE as a promising promoter for the aqueous K2CO3 solution.
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