Publications
15 results found
Mersch M, Sunny N, Dejan R, et al., 2024, A comparative techno-economic assessment of blue, green, and hybrid ammonia production in the United States, Sustainable Energy & Fuels, Vol: 8, Pages: 1495-1508, ISSN: 2398-4902
Alternatives to fossil fuels as energy carriers are required to reach global climate targets. Hydrogen and ammonia are promising candidates that are carbon emission-free at point of combustion. Ammonia is critically important for fertiliser production and thus global food production. Additionally, low-carbon ammonia is a potentially valuable fuel for shipping, power generation, and industry. However, ammonia production today accounts for about 2% of total global carbon dioxide emissions. Conventional ammonia production based on methane reforming can be decarbonised by using carbon capture and storage, creating so-called blue ammonia. Alternatively, low-carbon electricity from additional clean energy sources can be used for electrolytic (green) hydrogen and ammonia production. Production tax credits (PTC) for clean hydrogen production via the 45V and carbon sequestration via the 45Q under the Inflation Reduction Act (IRA) in the United States have sparked interest in large-scale commercial low-carbon ammonia projects. In this work, we analyse different blue and electrolytic low-carbon ammonia production processes under economic and practical considerations. We propose and evaluate two novel designs: integrating a biomethane supply into the reformer; and combining blue and green ammonia production processes. Results show that all low-carbon ammonia plants can significantly reduce emissions compared to the conventional process. With the production tax credits, blue ammonia is likely to be the most economical production route in the near-term, being cheaper than conventional ammonia which is not eligible for any credits. The economics of electrolytic ammonia depend heavily on the price of reliable low-carbon electricity. A levelised cost of electricity of about 35 $/MWh and lower is required for electrolytic ammonia to be competitive with blue ammonia at average gas prices and upstream emissions. Of the two novel process designs, blending in biomethane shows promise as
Mersch M, Dejan R, Moustafa N, et al., 2024, The role and value of BECCS in the USA, The role and value of BECCS in the USA, London, UK, Publisher: Drax Group Plc, 1
This study assesses the role of bioenergy with carbon capture and storage (BECCS) in the deep decarbonisation of the US energy system. We evaluate the impacts of the existing policy support measures, such as the Bipartisan Infrastructure Law (BIL) and Inflation Reduction Act (IRA), for achieving a net-zero economy. Three major regional grids (CAISO, MISO, and ERCOT) are analysed, with six scenarios per regional grid for a total of 18 illustrative scenarios. We compare low-carbon power generation, energy storage, and CDR technologies to assess least-cost electricity system evolutions, relying on data from regional electricity system operators (ESOs) and government projections. Three core scenarios (reference scenario without emission constraint, netzero power system by 2035, net-negative power by 2050 for overall net-zero) are created to represent varying climate ambitions. These are further divided based on the inclusion of policy support measures, providing insights into their impact on the low-carbon transition. The results are evaluated using key performance metrics, such as the cost of electricity supply, size and composition of the generation mix, gross value added, and job creation over time.
Tafuni A, Giannotta A, Mersch M, et al., 2023, Thermo-economic analysis of a low-cost greenhouse thermal solar plant with seasonal energy storage, Energy Conversion and Management, Vol: 288, Pages: 1-11, ISSN: 0196-8904
Reduction of greenhouse gas emissions is today mandatory to limit the increase of ambient temperature. This paper provides a numerical study of a thermal solar plant using a seasonal dual-media sensible heat thermal energy storage system for supplying the total energy demand of a greenhouse located in the South of Italy, avoiding the use of the gas boiler. The aim of the work is to assess the technical and economic performance of a low-cost pit storage system, made of gravel and water, placed under the greenhouse to save surface. The study provides an original analysis of the charging and discharging phases during one year of operation on the basis of the real hourly heating demand and on real weather data. A sensitivity analysis of the levelized cost of heat is carried on with respect to the solar-collector area and to the storage-pit volume. The analysis shows that a minimum-cost design solution exists to cover 100% of the heat demand with an estimated levelized cost of heat of 153.3 EUR/MWh. The results demonstrate that dual-media thermal energy storage systems with solar thermal collectors represent a viable solution for reducing the environmental impact of greenhouses.
Mersch M, Sapin P, Olympios AV, et al., 2023, A unified framework for the thermo-economic optimisation of compressed-air energy storage systems with solid and liquid thermal stores, Energy Conversion and Management, Vol: 287, Pages: 1-15, ISSN: 0196-8904
Compressed-air energy storage is an attractive option for satisfying the increasing storage demands of electricity grids with high shares of renewable generation. It is a proven technology that can store multiple gigawatt hours of electricity for hours, days and even weeks at a competitive cost and efficiency. However, compressed–air energy storage plants need to be designed carefully to deliver these benefits. In this work, a consistent thermo-economic optimisation framework is applied to assess the performance and costs of different compressed–air energy storage configurations across different scales. Special attention is paid to the thermal energy stores, with both solid packed-bed stores and liquid stores examined as viable options for advanced compressed–air energy storage plants and different storage materials proposed for both options. The comprehensive thermo-economic optimisation, considering different system layouts, thermal energy storage technologies and storage materials, and system scales is a key novelty of the presented work. A configuration with two packed–bed thermal energy stores using Basalt as the storage material is found to perform best, achieving an energy capital cost of 140 $/kWh, a power capital cost of 970 $/kW and a roundtrip efficiency of 76% at a nominal discharge power of 50 MW and a charging / discharging duration of 6 h. The best-performing liquid storage material is solar salt, which is associated with an energy capital cost of 170 $/kWh and a power capital cost of 1,230 $/kW. Systems with liquid thermal energy stores however are found generally to perform worse than systems with packed–bed thermal energy stores both in terms of cost and efficiency across all scales.
Sapin P, Olympios AV, Mersch M, et al., 2023, Paper No 715 - Design and operational optimisation of an integrated thermal energy storage ground-source heat pump with time-varying electricity prices, 14th IEA Heat Pump Conference 2023
A detailed methodology is proposed to design and optimise the operation of a ground-source heat pump(GSHP) coupled to a phase-change material (PCM) thermal battery. The objective is to minimise the cost ofsupplying space heating and hot water to a medium-demand house in the UK during a typical winter day withfluctuating electricity prices. A bespoke 8-kW GSHP is designed and used to optimise the charging scheduleof the thermal battery to minimise daily operational costs while meeting the heat demand. If no limit is imposedon the size of the thermal battery, in the best scenario, a 41-kWh thermal battery is required to achieve costsas low as 1.85 £/day. However, large PCM batteries mean high upfront costs and little space restrictions.Therefore, a constraint is imposed on the thermal store capacity to identify the optimal trade-off that can beachieved between PCM battery size and daily power consumption costs. Operational costs strongly depend onthe battery size, increasing from 1.85 £/day for a 41-kWh thermal battery to 3.50 £/day for a 6.3-kWh store.
Mersch M, Markides CN, Mac Dowell N, 2023, The impact of the energy crisis on the UK’s net-zero transition, iScience, Vol: 26, Pages: 1-24, ISSN: 2589-0042
Recent drastic increases in natural gas prices have brought into sharp focus the inherent tensions between net-zero transitions, energy security, and affordability. We investigate the impact of different fuel prices on the energy system transition, explicitly accounting for the increasingly coupled power and heating sectors, and also incorporate the emerging hydrogen sector. The aim is to identify low-regret decisions and optimal energy system transitions for different fuel prices. We observe that the evolution of the heating sector is highly sensitive to gas price, whereas the composition of the power sector is not qualitatively impacted by gas prices. We also observe that bioenergy plays an important role in the energy system transition, and the balance between gas prices and biomass prices determines the optimal technology portfolios. The future evolution of the prices of these two resources is highly uncertain, and future energy systems must be resilient to these uncertainties.
Bakkaloglu S, Mersch M, Sunny N, et al., 2023, ECOS 2023: How far should the UK go with negative emission technologies?, Pages: 2939-2949
Negative Emissions Technologies (NETs), such as Bioenergy with Carbon Capture and Storage (BECCS) and Direct Air Carbon Capture and Storage (DACCS), are potentially valuable to offset carbon emissions and therefore commonly deployed in global climate change mitigation scenarios. However, they are controversial and sometimes seen as a means of delaying or avoiding emissions reduction efforts. Nonetheless, the UK has set an ambitious target of engineering 57 Mt CO2 per year of removals by 2050 to achieve net zero emissions[1]. This study uses the UK TIMES, technology-rich bottom-up energy system model to investigate the nationwide deployment of NETs in the energy system, while varying model parameters to provide an overview of decarbonisation in line with the UK's net zero ambitions. We investigated DACCS and BECCS NETs technologies with regards to technological uncertainties and sensitivities. We revised the TIMES model structure for NETs implementation to ensure proper integration with industry. Our analysis estimates that the UK can remove 78.5 Mt CO2 by 2050 under the balanced Net Zero Scenario. However, by integrating an updated characterisation of removal technologies, and enabling tighter integration of DACCS into industrial clusters, we can achieve a removal capacity of up to 209 Mt CO2 by 2050 based on our preliminary results. Additionally, a 50% reduction in DACCS cost could further increase the removal capacity to 218 Mt CO2. This study provides valuable insights for policymakers and stakeholders in the UK and beyond, highlighting how NETs can be integrated in industrial strategy.
Aunedi M, Olympios AV, Pantaleo AM, et al., 2023, Role of energy storage in residential energy demand decarbonization: system-level techno-economic comparison of low-carbon heating and cooling solutions, Pages: 2309-2321
This paper explores various combinations of electric heat pumps (EHPs), hydrogen boilers (HBs), electric boilers (EBs), hydrogen absorption heat pumps (AHPs) and energy storage technologies (electric and thermal) to assess their potential for matching heating and cooling demand at low cost and with low carbon footprint. Thermodynamic and component-costing models of various heating and cooling technologies are integrated into a whole-energy system cost optimisation model to determine cost-effective configurations of heating and cooling systems that minimise the overall investment and operation cost for both the system and the end-user. Case studies presented in the paper focus on two archetypal systems that differ in terms of heating and cooling demand and availability profiles of solar and wind generation. The proposed approach quantifies how the cost-efficient portfolios of low-carbon heating and cooling solutions are driven by the characteristics of the system such as share of variable renewables or heating and cooling demand. Modelling results suggest that capacity choices for heating and cooling technologies will vary significantly depending on system properties. More specifically, air-to-air EHPs, with their cost and efficiency advantages over air-to-water EHPs, could make a significant contribution to low-carbon heat supply as well as cooling, although their contribution may be constrained by the compatibility with existing heating systems. They are found to be a useful supplementary source of space heating that is able to displace between 20 and 33 GWth of capacity of other heating technologies compared to the case where they do not contribute to space heating.
Olympios AV, Aunedi M, Mersch M, et al., 2022, Delivering net-zero carbon heat: technoeconomic and whole-system comparisons of domestic electricity- and hydrogen-driven technologies in the UK, Energy Conversion and Management, Vol: 262, ISSN: 0196-8904
Proposed sustainable transition pathways for moving away from natural gas in domestic heating focus on two main energy vectors: electricity and hydrogen. Electrification would be implemented by using vapour-compression heat pumps, which are currently experiencing market growth in many countries. On the other hand, hydrogen could substitute natural gas in boilers or be used in thermally–driven absorption heat pumps. In this paper, a consistent thermodynamic and economic methodology is developed to assess the competitiveness of these options. The three technologies, along with the option of district heating, are for the first time compared for different weather/ambient conditions and fuel-price scenarios, first from a homeowner’s and then from a whole-energy system perspective. For the former, two-dimensional decision maps are generated to identify the most cost-effective technologies for different combinations of fuel prices. It is shown that, in the UK, hydrogen technologies are economically favourable if hydrogen is supplied to domestic end-users at a price below half of the electricity price. Otherwise, electrification and the use of conventional electric heat pumps will be preferred. From a whole-energy system perspective, the total system cost per household (which accounts for upstream generation and storage, as well as technology investment, installation and maintenance) associated with electric heat pumps varies between 790 and 880 £/year for different scenarios, making it the least-cost decarbonisation pathway. If hydrogen is produced by electrolysis, the total system cost associated with hydrogen technologies is notably higher, varying between 1410 and 1880 £/year. However, this total system cost drops to 1150 £/year with hydrogen produced cost-effectively by methane reforming and carbon capture and storage, thus reducing the gap between electricity- and hydrogen-driven technologies.
Song J, Olympios A, Mersch M, et al., 2021, Integrated organic Rankine cycle (ORC) and heat pump (HP) systems for domestic heating, ECOS 2021 - The 34rth International Conference On Efficiency, Cost, Optimization, Simulation and Environmental Impact of Energy Systems, Publisher: ECOS
Space and water heating represent a significant share of the overall energy consumption in the domestic sector. Decarbonising heat, though challenging, is acknowledged as having a key role to play(as exemplifiedby the Domestic Renewable Heat Incentive launched in 2014 in the UK, amongst other)in achievingemissionsreduction targets andalleviatingproblems related to energy shortage and environmental deterioration. Novel, highly efficientheating technologies have attracted increasing interest in this context, in particular in regions with colderclimatesand higherheating demands. Specifically, thermally-driven heat-pumping technologies are a promising solution to meetingenergy-efficiency targets by increasing the effectiveheat-to-fuelratio(HFR)of heatingsystems. In this paper,thermally-driven integrated organic Rankine cycle (ORC) and heat pump (HP) systems are proposed for domestic heating applications, in which the ORC system is driven by heat from fuel (e.g., gas) combustion and generates power to drive an air-source vapour-compression HP system. A heat-transfer fluid is heatedin the condensers of the two sub-systems to the required temperature for heat provision. Two system configurations with reversed heat-transfer fluidflow directions are presented and compared. Suitable, lowglobal-warming-potential (GWP) working fluids for both the ORC and HP systems are considered and parametric optimisation is performed to determine optimal thermodynamic performanceand system layouts. In aconfiguration in whichthe heat-transfer fluidflows firstthroughthe HP condenser andthen through the ORC condenser in series,the HFRreaches values of 1.26-2.04 forair-source temperaturesranging from -15 to 15 °C and for heat provision temperaturesfrom 35 °C to 60 °C.Aperformance enhancement up to 8-19% relative to theconfiguration withthe heat-transfer fluidflowingin thereversedirection, i.e., through the ORC condenser and then theHP condenser in serie
Mersch M, Olympios A, Sapin P, et al., 2021, Solar-thermal heating potential in the UK: A techno-economic whole-energy system analysis, ECOS 2021 - The 34rth International Conference On Efficiency, Cost, Optimization, Simulation and Environmental Impact of Energy Systems, Publisher: ECOS
We investigate the potential of solar-thermal collectorsas a sustainable heat-generation technology in the UK. The costs and performance of commercially-available collectors are surveyed and four representative collectors are investigated using a techno-economic model of solar heating for households. A parametric study of different collectorsand storage tank sizes is conducted to assess the potential and economics of different system layouts. It is shown that moderately-sized systems with a collector area of 4m2 and a tank size of 150L can provide up to 70% of the domestic hot water demand of a typical household in the UK. Based on the data from the solar-thermal heating model at household scale, performance maps are developed to estimate the heat output from different systems under varying operating conditions. These are then used to assess solar-thermal systems in a heating-sector decarbonisation model.The model is a mixed-integer linear programming model that optimises the capacity expansion of the UK domestic heating sector until 2050 as well as the annual operating schedules of the different technologies. It is found that solar-thermal heating requires incentives in order to be competitive with hydrogen boilers or electric heat pumps. However, if solar thermal collectors are deployed, they provide significant system value by reducing the demand for carbon-neutral hydrogen or electricity. An investment incentive of £3,000per solar-thermal system leads to a deployment of over150GW of solar-thermal capacity by 2050, which reduces the annual hydrogen demand by 240 TWh compared to the baseline without solar-thermal heating, while the electricity demand increases by 90 TWh due to heat pumps and electric resistive heatersbeing used as backup heatingtechnologies.
Olympios A, Krishnaswamy A, Stollery C, et al., 2021, Techno-economic comparison of hydrogen- and electricity-driven technologies for the decarbonisation of domestic heating, 16th Conference on Sustainable Development of Energy, Water and Environment Systems (SDEWES 2021)
Sustainable transition pathways currently being proposed for moving away from the use of natural gas and oil in domestic heating focus on two main energy vectors: electricity and hydrogen. The former transition would most likely be implemented using electric vapour-compression heat pumps, which are currently experiencing market growth in many industrialised countries. Electric heat pumps have proven to be an efficient alternative to gas boilers under certain conditions, but their techno-economic potential is highly dependent on the local climate conditions. Hydrogen-based heating systems, which could potentially utilise existing natural gas infrastructure, are being proposed as providing an attractive opportunity to maximise the use of existing assets to facilitate the energy-system transition. In this case, hydrogen can substitute natural gas in boilers or in thermally driven absorption heat pumps. Both heating system transition pathways may involve either installing new technologies at the household level or producing heat in centralised hubs and distributing it via district-heating systems. Although the potential of hydrogen in the context of heating decarbonisation has been explored in the past, a comprehensive comparison of electricity- and hydrogen-driven domestic heating options is lacking in literature. In this paper, a thermodynamic and economic methodology is developed to assess the competitiveness of a domestic-scale ammonia-water absorption heat pump driven by heat from a hydrogen boiler compared to a standalone hydrogen boiler, a classic vapour-compression heat pump and district heating, all from a homeowner’s perspective. Using a previously developed electric heat pump model, the different systems are compared for various climate conditions and fuel-price scenarios under a unified framework. The coefficient of performance of the absorption heat pump system under design conditions and the total system cost are found to be 1.4 and £5400, resp
Liu Z, Romagnoli A, Sapin P, et al., 2021, Dynamic control strategies for a solar-ORC system using first-law dynamic and data-driven machine learning models, 6th International Seminar on ORC Power Systems, Pages: 1-14, ISSN: 2709-7609
In this study, we developed and assessed the potential of dynamic control strategies for a domestic scale 1-kW solar thermal power system based on a non-recuperated organic Rankine cycle (ORC) engine coupled to a solar energy system. Such solar-driven systems suffer from part-load performance deterioration due to diurnal and inter-seasonal fluctuations in solar irradiance and ambient temperature. Real-time control strategies for adjusting the operating parameters of these systems have shown great potential to optimise their transient response to time-varying conditions, thus allowing significant gains in the power output delivered by the system. Dynamic model predictive control strategies rely on the development of computationally efficient, fast-solving models. In contrast, traditional physics-based dynamic process models are often too complex to be used for real-time controls. Machine learning techniques (MLTs), especially deep learning artificial neural networks (ANN), have been applied successfully for controlling and optimising nonlinear dynamic systems. In this study, the solar system was controlled using a fuzzy logic controller with optimised decision parameters for maximum solar energy absorption. For the sake of obtaining the optimal ORC thermal efficiency at any instantaneous time, particularly during part-load operation, the first-law ORC model was first replaced by a fast-solving feedforward network model, which was then integrated with a multi-objective genetic algorithm, such that the optimal ORC operating parameters can be obtained. Despite the fact that the feedforward network model was trained using steady-state ORC performance data, it showed comparable results compared with the first-principle model in the dynamic context, with a mean absolute error of 3.3 percent for power prediction and 0.186 percentage points for efficiency prediction.
Olympios A, Hoisenpoori P, Mersch M, et al., 2020, Optimal design of low-temperature heat-pumping technologies and implications to the whole energy system, The 33rd International Conference on Efficiency, Cost, Optimization, Simulation and Environmental Impact of Energy Systems.
This paper presents a methodology for identifying optimal designs for air-source heat pumps suitable for domestic heating applications from the whole-energy system perspective, accounting explicitly for a trade-off between cost and efficiency, as well as for the influence of the outside air temperature during off-design operation. The work combines dedicated brazed-plate and plate-fin heat-exchanger models with compressor efficiency maps, as well as equipment costing techniques, in order to develop a comprehensive technoeconomic model of a low-temperature air-source heat pump with a single-stage-compressor, based on the vapour-compression cycle. The cost and performance predictions are validated against manufacturer data and a non-linear thermodynamic optimisation model is developed to obtain optimal component sizes for a set of competing working fluids and design conditions. The cost and off-design performance of different configurations are integrated into a whole-energy system capacity-expansion and unit-dispatch model of the UK power and heat system. The aim is to assess the system value of proposed designs, as well as the implications of their deployment on the power generation mix and total transition cost of electrifying domestic heat in the UK as a pathway towards meeting a national net-zero emission target by 2050. Refrigerant R152a appears to have the best design and off-design performance, especially compared to the commonly used R410a. The size of the heat exchangers has a major effect on heat pump performance and cost. From a wholesystem perspective, high-performance heat pumps enable a ~20 GW (~10%) reduction in the required installed power generation capacity compared to smaller-heat-exchanger, low-performance heat pumps, which in turn requires lower and more realistic power-grid expansion rates. However, it is shown that the improved performance as a result of larger heat exchangers does not compensate overall for the increased technology cost, with
Sapin P, Simpson M, Olympios A, et al., 2020, Cost-benefit analysis of reversible reciprocating-piston engines with adjustable volume ratio in pumped thermal electricity storage, 33rd International Conference on Efficiency, Cost, Optimization, Simulation and Environmental Impact of Energy Systems (ECOS 2020), Publisher: Curran Associates, Inc.
Decarbonisation of heating, cooling and/or power services through the utilisation of renewable en-ergy sources relies on the development of efficient and economically-viable energy storage technolo-gies, ideally without geographical constraints. Pumped thermal electricity storage (PTES) is a strongcandidate technology – along with reversible Rankine cycle, (advanced adiabatic) compressed airenergy storage (CAES), and liquid air energy storage (LAES). One of the leading PTES variants isthe reversible Joule-Brayton cycle engine, where energy is stored as sensible heat in hot and coldthermal stores, while the temperature difference is achieved through gas compression and expansionprocesses. For cost reasons, and to achieve high round-trip efficiencies, it is advantageous for thecompression and expansion machines used in PTES plants to be reversible. Positive-displacementdevices offer this possibility. In particular, recent developments in pneumatically or electromagneti-cally actuated intake and exhaust valves could pave the way for high-efficiency reversible reciprocat-ing compression-expansion devices based on variable-valve control in real time. Advanced variablevalve timing (VVT) is a promising feature that allows piston machines not only to be operated bothas reversible compression and expansion devices, but also to maintain high efficiencies over a widerange of operating conditions, thanks to the possibility of adjusting the built-in volume ratio of a par-ticular machine. With enhanced part-load performance, such disruptive piston machines offer greatpotential for round-trip efficiency enhancement and cost minimisation of PTES storage plants. In thiswork, a cost-benefit analysis of innovative VVT-fitted reciprocating-piston technology is performedusing: (i) comprehensive dynamic reduced-order models to predict the compressor-expander perfor-mance for design optimisation, and (ii) Schumann-style one-dimensional models for simulating heatand mass transf
This data is extracted from the Web of Science and reproduced under a licence from Thomson Reuters. You may not copy or re-distribute this data in whole or in part without the written consent of the Science business of Thomson Reuters.