Abstract The simulation of a Solid Oxide Fuel Cell-Gas Turbine (SOFC-GT) hybrid system for a locomotive application is presented. Using Matlab Simulink, a 2.8 MW SOFC system was combined with a 500 kW GT and simulated to travel the route from Bakersfield to Mojave in California. Elevation data was imported using the Google API Console and smoothed in order to calculate the dynamic power demand for the SOFC-GT system, assuming 480 tons of freight per 120 ton locomotive traveling at an average speed of 45 mph. The SOFC-GT system model follows this demand without causing a significant disruption to the speed of the locomotive. A lithium-ion battery was included into the system model to improve the net system efficiency and make the operation smooth enough for the highly dynamic route. The overall efficiency along the simulated route has been calculated as 57% operating on partially pre-reformed natural gas fuel. These results suggest the development of a physical prototype of the simulated system and are very promising for the future of freight rail transportation throughout the US. CO2 and particulate matter emissions are significantly reduced compared to current diesel-electric locomotives and it is also possible to operate the system on hydrogen, i.e., completely emission-free. A techno-economic analysis to assess the economic feasibility of this system is currently being prepared.

Abstract The fuel cell program at the United States Department of Energy (DOE) National Energy Technology Laboratory (NETL) is focused on the development of low-cost, highly efficient, and reliable fossil-fuel-based solid oxide fuel cell (SOFC) power systems that can generate environmentally-friendly electric power with at least 90 percent carbon capture. NETL’s SOFC technology development roadmap is aligned with near-term market opportunities in the distributed generation sector to validate and advance the technology while paving the way for utility-scale natural gas (NG)- and coal-derived synthesis gas-fueled applications via progressively larger system demonstrations. The present study represents a part of a series of system evaluations being carried out at NETL to aid in prioritizing technological advances along research pathways to the realization of utility-scale SOFC systems, a transformational goal of the fuel cell program. In particular, the system performance of utility-scale NG fuel cell (NGFC) systems with and without carbon dioxide (CO 2 ) capture is presented. The NGFC system analyzed features an external auto-thermal reformer (ATR) feeding the fuel to the SOFC system consisting of planar anode-supported SOFC with separated anode and cathode off-gas streams. In systems with CO 2 capture, an air separation unit (ASU) is used to provide the oxygen for the ATR and for the combustion of unutilized fuel in the SOFC anode exhaust along with a CO 2 purification unit to provide a nearly pure CO 2 stream suitable for transport for usage in enhanced oil recovery operations or for storage in underground saline formations. Remaining thermal energy in the exhaust gases is recovered in a bottoming steam Rankine cycle while supplying any process heat requirements. A reduced order model (ROM) developed at the Pacific Northwest National Laboratory (PNNL) is used to predict the SOFC performance. The ROM, while being computationally effective for system studies, provides other detailed information about the state of the stack, such as the internal temperature gradient, generally not available from simple performance models often used to represent the SOFC. Such additional information can be important in system optimization studies to preclude operation under off-design conditions that can adversely impact overall system reliability. The NGFC system performance was analyzed by varying salient system parameters, including the percent of internal (to the SOFC module) NG reformation — ranging from 0 to 100 percent — fuel utilization, and current density. The impact of advances in underlying SOFC technology on electrical performance was also explored.

Abstract Greenhouse gas emission reduction and the consequent decrease in the environmental impacts of fossil fuel can be achieved by cutting back on energy consumption in the building sector that consumes around 30% of total final energy around the globe. The building sector is a complex component of the modern economy and life and includes diverse types of structures, uses, and energy patterns. Such variability is a result of the way that buildings are designed, built, and used in addition to the variations of their materials, equipment, and users. From the start of the construction phase until their demolition, buildings involve energy consumption. A single building’s energy consumption pattern can be called its energy inertia, that is the way it consumes energy throughout its lifetime. Energy consumption also varies according to the age of the buildings. As a building gets older, its structure and equipment start losing their efficiency and often lead to increasing energy consumption over time. At any given time, the building sector is composed of structures of various ages. Some are under construction, others are recently built, some have lived to be mature and some quite old enough to be demolished. This complexity in the building sector creates a momentum against implementation of policies that reduce energy consumption. In this study, a system dynamic model is developed to perceive the temporal evolution of energy consumption and efficiency measures for the villa-type building stock in Qatar. This model tests energy efficiency policy measures such as renovation rates of 15 and 30 years, for buildings that are considered old, and also examines implementation of technology and building codes for new buildings. Results reveal savings of between 157 GWh and 1,275 GWh of electricity and reduction in CO 2 emissions ranging from 77,000 tonnes to 602,000 tonnes.

Abstract In Singapore, roughly 20% of the energy consumed by households is used for water heating and almost all the energy consumed by conventional electric water heaters. One of the significant potential energy saving opportunities lies in using energy-efficient water heating appliances. Recently, there has been a move towards energy-saving design and the use of natural refrigerants over fluorocarbons. Unlike conventional electric storage water heaters, which use electricity to heat water directly, heat pump storage water heaters use electricity only to operate a pump that circulates refrigerants around the system. This refrigerant collects heat from the surrounding atmosphere and transfers it to the water. CO 2 heat pumps have low global warming potential when compared to other refrigerants based heat pumps, has zero ozone depletion potential, inexpensive, non-flammable, generate high temperature. In this project, a comparative analysis of three different water heater types has been presented based on real-time usage and living-lab conditions under the tropical climate of Singapore. These three types are: 1. Electrical heater storage type 2. Hybrid heat pump with auxiliary electrical heating water heater 3. CO 2 heat pump water heater without auxiliary heating Study found significant energy saving using CO 2 heat pump compared to other water heating system and also better for environment.

Abstract This paper presents an exergy-based sustainability analysis of manufacturing roof tiles from plastic waste in Uganda. Exergy analyses measure the sustainability of industrial processes. This work focuses specifically on the developing country context and on utilizing waste material. A summary of the current plastic waste situation in Uganda, the environmental and health issues associated with plastic waste, current means of recycling plastic waste into new products, and an analysis of the Ugandan roofing market are presented. The motivation for this study is to examine the resources utilized to improve overall exergy efficiency, reduce production costs, and reduce negative environmental impacts. The company, Resintile, is the only manufacturer of roof tiles from plastic waste in Uganda. Their tiles comprised mainly of sand and plastic waste are manufactured in an industrialized process involving drying, extrusion, and pressing. The exergy consumed at each stage including transportation is presented. The extruder consumes the majority of the exergy, but wrapping insulation around the barrel could save over 3 MJ, and a heat engine could provide over 7.5 MJ of usable exergy. The total exergy consumed to produce one batch of seventy-five tiles is over 122 MJ, the potentially recoverable exergy is over 5 MJ (4.3% of consumed exergy), and the realistic recoverable exergy is nearly 10.7 MJ (8.7% of consumed exergy). The realistic can be greater than the potential by adding a heat engine to the sand drying process to generate usable exergy rather than merely recover consumed exergy. Resintile’s plastic roof tiles save a net 86.3 kg of CO 2 from entering the atmosphere per batch of tiles and adoption of the suggested improvements to the manufacturing process would save an additional 3.8 kg of CO 2 per batch.

Abstract Recent studies have shown that the emissions from conventional torrefaction processes is the second largest contributor to the supply chain. This article presents a torrefaction unit that operates based on oxy-combustion concept, whereby preventing carbon dioxide and nitrogen oxides emissions. The oxygen required in the process is supplied from an Air Separation Unit (ASU) and the working fluid of the new system is carbon dioxide. The process model is implemented in Engineering Equation Solver (EES) and simulation is conducted using the design data of a conventional plant which torrefies wood at 553 K for 17.5 minutes. The overall efficiency of the plant which accounts for both thermal and electrical energy requirement of the process is found to be 88%. The total energy consumption of the system exhibits a minimum at an optimum torrefaction temperature. With willow as the feedstock, the optimum temperature is determined to be 536 K at a residence time of 20 minutes, at which the total equivalent thermal energy required is 2 MJ/kg dry biomass and the energy yield is as high as 91%. The results show that the optimum torrefaction temperature is feedstock dependent and it is lower for a longer residence time.

Abstract The global energy demand has increased at a very large rate, and in parallel, the Municipal Solid Waste (MSW) has also increased, both posing enormous technological challenges to world sustainable growth. Therefore, in order to contribute with concrete alternatives to face such quest for sustainability, this work presents an analysis of an integrated power plant fired by municipal solid waste that uses a biological filter for the combustion emissions fixation. The facility located in the Sustainable Energy Research & Development Center (NPDEAS) at Federal University of Parana is taken as a case study to analyze the process of technical and economic viability. For that, an exergoeconomic optimization model of the waste-to-energy power plant that generates electricity and produces microalgae biomass is utilized. An incineration furnace, which has a 50 kg/h capacity, heats the flue gas above 900°C and provides energy for a 15 kW water-vapor Rankine cycle. A set of heat exchangers preheats the intake air for combustion and provides warm utility water to other processes in the plant, which assures that the CO 2 rich flue gas can be airlifted to the microalgae cultivation photobioreactors (PBR) at a low temperature, using a 9 m high mass transfer emissions fixation column. Five 12 m 3 tubular photobioreactors are capable of supplying up to 30,000 kg/year of microalgae biomass with southern Brazil solar conditions of 1732 kWh/m 2 per year. The results show that considering the incineration services, the integrated power plant could have a payback period as short as 1.35 years. In conclusion, the system provides a viable way to obtain clean energy by thermally treating MSW, together with microalgae biomass production that could be transformed in a large variety of valuable bioproducts (e.g., nutraceuticals, pharmaceuticals, animal feed, and food supplements).

Biomass offers the potential to economically produce hydrogen via gasification from an abundant and renewable feedstock. When hydrogen is produced from a biomass gasifier, it is necessary to purify it from syngas streams containing components such as CO, CO 2 , N 2 , CH 4 , and other products. Therefore, a challenge related to hydrogen purification is the development of hydrogen-selective membranes that can operate at elevated temperatures and pressures, provide high fluxes, long operational lifetime, and resistance to poisoning while still maintaining reasonable cost. Palladium based membranes have been shown to be well suited for these types of high-temperature applications and have been widely utilized for hydrogen separation. Palladium’s unique ability to absorb a large quantity of hydrogen can also be applied in various clean energy technologies, like hydrogen fuel cells. In this paper, a fully analytical interatomic Embedded Atom Potential (EAM) for the Pd-H system has been developed, that is easily extendable to ternary Palladium based hydride systems such as Pd-Cu-H and Pd-Ag-H. The new potential has fewer fitting parameters than previously developed EAM Pd-H potentials and is able to accurately predict the cohesive energy, lattice constant, bulk modulus, elastic constants, melting temperature, and the stable Pd-H structures in molecular dynamics (MD) simulations with various hydrogen concentrations. The EAM potential also well predicts the miscibility gap, the segregation of the palladium hydride system into dilute (α) and concentrated (β) phases.

This work addresses the development and construction of a sustainable alkaline membrane fuel cell (SAMFC). The SAMFC couples an alkaline membrane fuel cell (AMFC) with a hydrogen generation reactor that uses recycled aluminum from soda cans to split the water molecule through the oxidation of aluminum catalyzed by sodium hydroxide. An innovative cellulosic membrane supports the electrolyte, which avoids the undesirable characteristics of liquid electrolytes, and asbestos or ammonia that are substances that have been used to manufacture alkaline electrolyte membranes, which are knowingly toxic and carcinogenic. Aluminum is an inexpensive, abundant element in the earth’s crust and fully recyclable. Oxygen is supplied to the cell with atmospheric air that is pumped through a potassium hydroxide (KOH) aqueous solution in order to fix CO 2 , and in this way avoid potassium carbonate formation in order to keep the cell fully functional. A sustainable alkaline membrane fuel cell (SAMFC) system with one unitary cell, the reactor, and CO 2 purifier was designed and built in the laboratory. The results are presented in polarization and power curves directly measured in the laboratory. Although recycled aluminum was used in the experiments, the results demonstrate that the cell was capable of delivering 0.9 V in open circuit and approximately 0.42 W of maximum power. The main conclusion is that by allowing for in situ sustainable hydrogen production, the SAMFC could eventually become economically competitive with traditional power generation systems.

Biomass torrefaction is a thermal pretreatment which takes place at a temperature between 200–300 °C in a non-oxidative environment. The process requires thermal energy for drying and torrefying the raw biomass. The amount of the required heat may vary depending on the biomass moisture content, operating temperature and residence time. The volatiles released during the torrefaction are usually burnt in a combustor to meet the heat requirement of the process. If the energy content of the volatiles is less than the thermal energy required for the process, the operation of the torrefaction unit is below the autothermal mode so an auxiliary fuel such as natural gas is burnt together with the volatiles. This paper investigates autothermal operation of a torrefaction unit which consists of a dryer, a torrefaction reactor, a combustor, and two heat exchangers. An experimentally validated process model is employed to identify a relation between the moisture content, torrefaction temperature, and residence time at autothermal operation. The model is capable of predicting the composition of volatiles and torrefied biomass, mass and energy yields, process heat requirement, and CO 2 emissions. The results are graphically presented allowing one to determine whether a torrefaction unit operates below or above the autothermal mode at given torrefaction temperature, residence time and moisture content. Furthermore, the effect of the main operating parameters on the carbon dioxide emissions of the torrefaction unit is discussed.

A work on biogas potentials evaluation of household wastes in Johannesburg metropolitan area using the Automatic Methane Potential Test System (AMPTS) II is presented. The AMPTS II consists of three units — the sample incubation unit, CO 2 absorption unit and the gas volume measuring device. Organic fraction of wastes collected from households within Johannesburg metropolis were sorted, ground and prepared into slurry by mixing with water. Microcrystalline cellulose powder with 3.5% loss on drying and 0.28g/cc density was used as control substrate while anaerobic sludge collected from a functional biogas reactor was used as inoculum. Anaerobic sludge was classified as sample A, household waste containing mainly non-food waste was labelled sample B, sample C was microcrystalline cellulose used as positive control while household waste composing of mainly food waste was classified as sample D. Each sample was fed into a 50 mL bottle reactor in triplicates and stirred in a clockwise direction continuously for 5 minutes with a pulse interval of 1 minute at a set temperature of 37°C for 30 days retention time. NaOH solution was prepared into solution following standard procedure and mixed with a prepared 0.4 % Thymolpthalein solution. The resultant solution was poured into the 100 mL bottles of the CO 2 unit. Produced biogas was measured through water displacement in the volumetric bath and values read off through a data-logger connected to a laptop. Results indicated biochemical methane potential (BMP) of 69–800 NmL/g vs and biogas composition with more than 50% methane before CO 2 fixing and over 80% after CO 2 fixing. Given that the average amount of waste generated per person per day in South Africa is over 0.7 kg, there is huge potentials for biogas production from household wastes in Johannesburg.

One of the biggest issues associated to Carbon Capture and Utilisation (CCU) applications involves the exploitation of the captured CO 2 as a valuable consumable. An interesting application is the conversion of CO 2 into renewable fuels via electrochemical reduction at high temperature. Still unexplored in the literature is the possibility of employing a Molten Carbonate Electrolysis Cell (MCEC) to directly converting CO 2 and H 2 O into H 2 , CO and eventually CH 4 , if a methanation process is envisaged. The introduction of this concept into a reversible system — similarly to the process proposed with reversible solid-oxide cells — allows the creation of a cycle which oxidises natural gas to produce CO 2 and then employs the same CO 2 and excess renewable energy to produce renewable natural gas. The result is a system able to perform electrochemical storage of excess renewable energy (from wind or solar) and if/when required sell renewable natural gas to the grid. In this work, a simulation of a reversible Molten Carbonate Cell (rMCC) is proposed. The reference MCFC technology considered is that from FuelCell Energy (USA) whose smaller stack is rated at 375 kW (DC). A simplified 0D stack model is developed and calibrated against experimental data. The Balance of Plant (BoP) is in common between the two operation modes MCFC and MCEC. In the former case, natural gas is electrochemically oxidised in the fuel compartment which receives carbonate ions (CO 3 2− ) from the air compartment, fed with air enriched with CO 2 produced during electrolysis mode. The CO 2 in the anode off gas stream is then purified and stored. In electrolysis mode, the stored CO 2 is mixed with process H 2 O and sent to the fuel compartment of the MCEC; here, electrolysis and internal methanation occur. An external chemical reactor finalises the production of methane for either natural gas grid injection or storage and reuse in fuel cell mode. A thermodynamic analysis of the system is performed the yearly round-trip efficiency is assessed considering an assumed availability operating time of 7000 h/y. Finally, the overall green-house gas emission is assessed.

Solid particles can operate at higher temperature than current molten salt or oil, and they can be a heat-transfer and storage medium in a concentrating solar power (CSP) system. By using inexpensive solid particles and containment material for thermal energy storage (TES), the particle-TES cost can be significantly lower than other TES methods such as a nitrate-salt system. The particle-TES system can hold hot particles at more than 800°C with high thermal performance. The high particle temperatures increase the temperature difference between the hot and cold particles, and they improve the TES capacity. The particle-based CSP system is able to support high-efficiency power generation, such as the supercritical carbon-dioxide Brayton power cycle, to achieve >50% thermal-electric conversion efficiency. This paper describes a solid particle-TES system that integrates into a CSP plant. The hot particles discharge to a heat exchanger to drive the power cycle. The returning cold particles circulate through a particle receiver to absorb solar heat and charge the TES. This paper shows the design of a particle-TES system including containment silos, foundation, silo insulation, and particle materials. The analysis provides results for four TES capacities and two silo configurations. The design analysis indicates that the system can achieve high thermal efficiency, storage effectiveness (i.e., percentage usage of the hot particles), and exergetic efficiency. An insulation method for the hot silo was considered. The particle-TES system can achieve high performance and low cost, and it holds potential for next-generation CSP technology.

Indoor Air Quality (IAQ) studies the air quality inside different types of environments and relates it to the health and comfort of occupants. Understanding and controlling common pollutants indoors can help in decreasing effects and the risks associated with these pollutants. Unhealthy indoor environment could lead to serious problems in people health and productivity. According to ASHRAE, 80–90% of personal time is spent indoors. As a result, indoor air pollution has gained a lot of interest and the number of studies on occupant health inside buildings grew very significantly in the last decades. The purpose of this study is to investigate the effect of indoor air quality inside an educational buildings on occupants’ comfort and performance. Various indoor pollutant such as, Carbon dioxide, Carbon monoxide, Volatile organic compounds, Particulates, and formaldehyde, are measured. The indoor air contaminants will be detected using IAQ measurement devices. The value of the pollutants is compared to maximum allowed values in ASHRAE standard 62.1. In addition, the occupant thermal comfort is reported using two indices which are Predicted Mean Vote (PMV) and Predicted Percentage of Dissatisfied (PPD). The relationship between the performance and the indoor air quality is also discussed. The results will discover the sources of the indoor air pollutants and accordingly suggestions will be given toward improving the indoor air quality. The final results showed that the IAQ is generally in a good condition for the majority of classrooms except for the TVOC which was always at high concentrations. Also, for some classrooms, the CO2 level and the relative humidity were exceeding the maximum limit. Regarding the thermal comfort, all the classrooms do not comply with ASHRAE Standard 55-2013. Therefore, they are not thermally comfortable.

When a coal-fired power plant is considered for closure, arguments are commonly made about the loss of jobs and unrealized investments. Facing this pressure, governments are reluctant to enact enforceable emission standards, and these plants continue to emit pollutants into the atmosphere. As the equipment ages, the plants may retire, but in their lifetime they will cause irreversible environmental damage. This report presents a method to mediate this damage, create jobs, maintain the efficiency of the turbine, and maintain or increase the capacity factor of the plant. Solar parabolic troughs using molten salt technology are scalable and can meet the steam conditions of a standard Rankine cycle coal-fired power plant. A marriage of these technologies allows the parabolic trough field to be installed without new power generation equipment. The turbine, generator, and transmission equipment are already in place, and when compared to a standalone concentrated solar power (CSP) plant, can be amortized over a greater number of operational hours without the use of very large amounts of thermal storage. That allows for a reduction in capital investment compared to a greenfield CSP plant, and reduces the levelized cost of energy (LCOE) from the solar contribution to well below current US Department of Energy SunShot targets. Coal-fired plant operators note that they typically cannot operate at partial power output without reducing the efficiency of their turbine accordingly. So, while a photovoltaic hybridization can take advantage of existing transmission infrastructure, it will require that the coal-fired system reduces its output and will consequently reduce the efficiency of the coal cycle. If we have to burn coal, we should do it in the most efficient way possible. Hybridizing with a molten salt parabolic trough installation makes use of the same turbine as the coal-fired system, which maintains the overall efficiency of the turbine at its design point and optimal load. With this model, the coal plant can operate at full power, reduce overall usage of coal while maintaining or even increasing employment opportunities, and reduce CO2 emissions.

Combined Cooling Heat and Power (CCHP) attained significant attention among energy professionals and academicians recently due to its superior thermal, economic and environmental benefit in comparison with conventional energy producing systems (internal combustion engine (ICE), micro-turbine, etc). Despite the abundance of literature on CCHP, only a few studies emphasized on the selection of appropriate prime mover for an economically sustainable CCHP system. Furthermore, the effect of part load efficiencies is commonly neglected during CCHP analysis. We had introduced these two new concepts of economic sustainability of specific prime mover and part load effects on efficiency to CCHP system in our previous paper. An algorithm based on hybrid load following method was utilized to determine the optimum prime mover for a particular location and weather type. No studies explored the effects of efficiency parameters and the selection strategies of prime mover in different building types for any particular location using this newly developed algorithm. Since building types dominates the electric, heating and cooling demand extensively, it is imperative to extend the prime mover selection analysis for building types for efficient CCHP operation. Economic, energy, and emission performance criteria have been utilized for the prime mover selection systems in different building types. Computer simulations were conducted for five different building categories (primary school, restaurant, small hotel, outpatient clinic and small office buildings) for each of three different types of prime movers (reciprocating internal combustion engine (ICE), micro-turbine and phosphoric acid fuel cell) in a cold climate zone (Minneapolis, MN). The simulation results of different prime movers were compared with the outcomes of a reference case (for each building in the same climate zone) that has a typical separate heating and power system. The cold climate zone (Minneapolis, MN) helped to explore the heating load effects on economic, energy, and emission performance of the buildings in comparison to other energy demands (i.e. electric and cooling demand). A hybrid load following method was executed, using improvements shown in our previous article. Performance parameters and other outcomes of this study showed that economic savings were observed for the ICE in all building types, and the micro-turbine in some building types. Internal rate of returns of ICE are 22.4%, 14.7%, 20.5%, 14.6% and 6.5% for primary school, restaurant, small hotel, outpatient clinic and small office respectively. ICE also shows highest energy savings among all three prime movers with an energy savings of 20%, 17.2%, 25.7%, 23.8% and 9.7% for primary school, restaurant, small hotel, outpatient clinic and small office respectively. For all types of prime mover based CCHP systems, lower CO 2 emission was observed for all building types. However, unlike ICE, which is preferable in terms of economic and energy savings, emission analysis shows that micro-turbine poses better emission characteristics compared to other types of prime movers. CO 2 emission for micro-turbine savings are 67.1%, 62.2%, 82%, 43.2% and 81.4% for primary school, restaurant, small hotel, outpatient clinic and small office respectively. The relationship between the power and thermal demand of the different buildings was determined to be a significant factor in CCHP system performance. A sensitivity analysis determining the effects of heat exchanger and heating coil efficiencies on the performance of CCHP systems shows that the economic performance was most sensitive to the heat exchanger efficiency, while energy consumption and emissions was most sensitive to the heating coil and boiler efficiency.

Increasing grid penetration of intermittent renewable power from wind and solar is creating challenges for the power industry. There are times when generation from these intermittent sources needs to be constrained due to power transmission capacity limits, and times when fossil fuel power plant are required to rapidly compensate for large power fluctuations, for example clouds pass over a solar field or the wind stops blowing. There have been many proposals, and some actual projects, to store surplus power from intermittent renewable power in some form or other for later use: Batteries, Compressed Air Energy Storage (CAES), Liquid Air Energy Storage (LAES), heat storage and Hydrogen being the main alternatives considered. These technologies will allow power generation during low periods of wind and solar power, using separate discrete power generation plant with specifically designed generator sets. But these systems are time-limited so at some point, if intermittent renewable power generation does not return to its previous high levels, fossil fuel power generation, usually from a large centralized power plant, will be required to ensure security of supplies. The overall complexity of such a solution to ensure secure power supplies leads to high capital costs, power transmission issues and potentially increased carbon emissions to atmosphere from the need to keep fossil fuel plant operating at low loads to ensure rapid response. One possible solution is to combine intermittent renewables and energy storage technologies with fast responding, flexible natural gas-fired gas turbines to create a reliable, secure, low carbon, decentralized power plant. This paper considers some hybrid power plant designs that could combine storage technologies and gas turbines in a single location to maximize clean energy production and reduce CO 2 emissions while still providing secure supplies, but with the flexibility that today’s grid operators require.

Successful deployment of large amounts of renewable solar and wind energy has created a pressing need for significant additions of grid connected energy storage. Excess renewable generation is increasingly necessitating curtailment or derating of renewable or conventional generators. The CAISO Duck Curve [8] illustrates the challenge caused by very large quantities of solar generation. Both large scale energy storage and flexible ramping are needed for renewable resources to be financially sustainable and to meet CO 2 reduction goals. The Dispatchable Solar Combined Cycle (DSCC) integrates Concentrating Solar Power (CSP) with Thermal Energy Storage (TES) in a holistic combined cycle configuration to meet the challenges of the CAISO Duck Curve by delivering flexible capacity with dispatchable solar power. Energy cost from DSCC is comparable to that from a Combined Cycle Power Plant (CCPP), and substantially below the alternatives: Photovoltaic plus battery or Photovoltaic plus combustion turbine. DSCC also enable far higher integration of renewable power and far larger renewable capacity factors than the Integrated Solar Combined Cycle (ISCC), which typically has no storage. The innovative DSCC system: • uses energy storage to deliver power when it is most valuable, • increases the capacity factor to deliver more renewable energy, • improves the power plant Heat Rate to reduce fuel consumption, and • reduces the cost of power while addressing RPS and storage mandates. In DSCC, the CSP and TES are used primarily for latent heat: the evaporation of steam, and the Combustion Turbine (CT) exhaust gas is used primarily for sensible heating, especially superheating steam. This simplifies the integration of low-cost storage media, such as paraffinic oils or concrete, instead of molten salt, since high temperature storage is not needed. A single pressure, non-reheat steam cycle suitable, allowing for simplicity of design and operation, reducing costs and facilitating faster startup and ramping. With DSCC, the steam turbine generates about the same power as the CT, unlike a typical CCPP where about half the power comes from the steam cycle. The additional steam production reduces the Heat Rate about 25% compared to CCPP. The DSCC approach is ideally suited for repowering existing CSP plants, to provide firm capacity that can dispatch at valuable evening peak periods, increase the power output, and reduce fossil fuel use compared with conventional CCPP or peaking plants. This paper will outline the DSCC concept, and provide performance estimates for a reference plant.

Air pollution is a leading public health concern that needs to be tackled. About 30% of the total greenhouse gas emissions, such as CO, HC and NOx are due to automobiles. By 2030, the US Department of Transportation aims to reduce light duty vehicle emissions by 18%. This can be achieved by public policy approaches such as implementing emission control norms and performance improvements such as exhaust system design. In this work, the implementation of a pure Zeolite catalyst to reduce the exhaust CO 2 emission of a SI engine is studied theoretically and experimentally. The complete exhaust system including the catalytic converter, muffler, and pipes is modeled in a 3D CAD modeling software, using the engine specifications. Current expensive precious metals in the catalytic converter are replaced with a binding agent along with Zeolite catalyst. The exhaust system is fabricated and the experimental tests are performed at the maximum engine RPM to obtain threshold emission reduction values. The results showed obtaining an emission reduction of CO 2 at a lower cost. Furthermore, it is found that employing Zeolite sieves can further reduce the pollutant emission at a similar cost.

A molten carbonate electrolysis cell (MCEC) is capable of separating carbon dioxide from methane reformate while simultaneously electrolyzing water. Methane reformate, for this study, primarily consists of carbon dioxide, hydrogen, methane, and a high percentage of water. Carbon dioxide is required for the operation of a MCEC since a carbonate ion is formed and travels from the reformate channel to the sweep gas channel. In this study, a spatially resolved physical model was developed to simulate an MCEC in a novel hybrid reformer electrolyzer purifier (REP) configuration for high purity hydrogen production from methane and water. REP effectively acts as an electrochemical CO 2 purifier of hydrogen. In order to evaluate the performance of REP, a dynamic MCEC stack model was developed based upon previous high temperature molten carbonate fuel cell modeling studies carried out at the National Fuel Cell Research Center at the University of California, Irvine. The current model is capable of capturing both steady state performance and transient behavior of an MCEC stack using established physical models originating from first principals. The model was first verified with REP experimental data at steady state which included spatial temperature profiles. Preliminary results show good agreement with experimental data in terms of spatial distribution of temperature, current density, voltage, and power. The combined effect of steam methane reformation (SMR) and water electrolysis with electrochemical CO 2 removal results in 96% dry-basis hydrogen at the cathode outlet of the MCEC. Experimental measurements reported 98% dry-basis hydrogen at the cathode outlet.