158 results found
Patrizio P, Sunny N, Mac Dowell N, 2022, Inefficient investments as a key to narrowing regional economic imbalances, ISCIENCE, Vol: 25
Galan-Martin A, Vazquez D, Cobo S, et al., 2021, Delaying carbon dioxide removal in the European Union puts climate targets at risk, NATURE COMMUNICATIONS, Vol: 12
For hydrogen to play a meaningful role in a sustainable energy system, all elements of the value chain must scale coherently. Advocates support electrolytic (green) hydrogen or (blue) hydrogen that relies on methane reformation with carbon capture and storage; however, efforts to definitively choose how to deliver this scaling up are premature. For blue hydrogen, methane emissions must be minimized. Best in class supply chain management in combination with high rates of CO2 capture can deliver a low carbon hydrogen product. In the case of electrolytic hydrogen, the carbon intensity of power needs to be very low for this to be a viable alternative to blue hydrogen. Until the electricity grid is deeply decarbonized, there is an opportunity cost associated with using renewable energy to produce hydrogen, as opposed to integrating this with the power system. To have a realistic chance of success, net zero transition pathways need to be formulated in a way that is coherent with socio-political-economic constraints.
Patrizio P, Fajardy M, Bui M, et al., 2021, CO2 mitigation or removal: The optimal uses of biomass in energy system decarbonization, ISCIENCE, Vol: 24
Danaci D, Bui M, Petit C, et al., 2021, En route to zerio emissions for power and industry with amine-based post-combustion capture, Environmental Science and Technology (Washington), Vol: 55, Pages: 10619-10632, ISSN: 0013-936X
As more countries commit to a net-zero GHG emission target, we need a whole energy and industrial system approach to decarbonization rather than focus on individual emitters. This paper presents a techno-economic analysis of monoethanolamine-based post-combustion capture to explore opportunities over a diverse range of power and industrial applications. The following ranges were investigated: feed gas flow rate between 1–1000 kg ·s–1, gas CO2 concentrations of 2–42%mol, capture rates of 70–99%, and interest rates of 2–20%. The economies of scale are evident when the flue gas flow rate is <20 kg ·s–1 and gas concentration is below 20%mol CO2. In most cases, increasing the capture rate from 90 to 95% has a negligible impact on capture cost, thereby reducing CO2 emissions at virtually no additional cost. The majority of the investigated space has an operating cost fraction above 50%. In these instances, reducing the cost of capital (i.e., interest rate) has a minor impact on the capture cost. Instead, it would be more beneficial to reduce steam requirements. We also provide a surrogate model which can evaluate capture cost from inputs of the gas flow rate, CO2 composition, capture rate, interest rate, steam cost, and electricity cost.
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.
Negri V, Galan-Martin A, Pozo C, et al., 2021, Life cycle optimization of BECCS supply chains in the European Union, APPLIED ENERGY, Vol: 298, ISSN: 0306-2619
Daggash HA, Mac Dowell N, 2021, Delivering low-carbon electricity systems in sub-Saharan Africa: insights from Nigeria, ENERGY & ENVIRONMENTAL SCIENCE, Vol: 14, Pages: 4018-4037, ISSN: 1754-5692
Fajardy M, Morris J, Gurgel A, et al., 2021, The economics of bioenergy with carbon capture and storage (BECCS) deployment in a 1.5 degrees C or 2 degrees C world, GLOBAL ENVIRONMENTAL CHANGE-HUMAN AND POLICY DIMENSIONS, Vol: 68, ISSN: 0959-3780
Bui M, Zhang D, Fajardy M, et al., 2021, Delivering carbon negative electricity, heat and hydrogen with BECCS – Comparing the options, International Journal of Hydrogen Energy, Vol: 46, Pages: 15298-15321, ISSN: 0360-3199
Homan S, Mac Dowell N, Brown S, 2021, Grid frequency volatility in future low inertia scenarios: Challenges and mitigation options, APPLIED ENERGY, Vol: 290, ISSN: 0306-2619
Cuellar-Franca RM, Garcia-Gutierrez P, Hallett JP, et al., 2021, A life cycle approach to solvent design: challenges and opportunities for ionic liquids - application to CO2 capture, REACTION CHEMISTRY & ENGINEERING, Vol: 6, Pages: 258-278, ISSN: 2058-9883
Carbon capture and storage (CCS) will have an essential role in meeting our climate change mitigation targets. CCS technologies are technically mature and will likely be deployed to decarbonise power, industry, heat, and removal of CO2 from the atmosphere. The assumption of a 90% CO2 capture rate has become ubiquitous in the literature, which has led to doubt around whether CO2 capture rates above 90% are even feasible. However, in the context of a 1.5 °C target, going beyond 90% capture will be vital, with residual emissions needing to be indirectly captured via carbon dioxide removal (CDR) technologies. Whilst there will be trade-offs between the cost of increased rates of CO2 capture, and the cost of offsets, understanding where this lies is key to minimising the dependence on CDR. This study quantifies the maximum limit of feasible CO2 capture rate for a range of power and industrial sources of CO2, beyond which abatement becomes uneconomical. In no case, was a capture rate of 90% found to be optimal, with capture rates of up to 98% possible at a relatively low marginal cost. Flue gas composition was found to be a key determinant of the cost of capture, with more dilute streams exhibiting a more pronounced minimum. Indirect capture by deploying complementary CDR is also assessed. The results show that current policy initiatives are unlikely to be sufficient to enable the economically viable deployment of CCS in all but a very few niche sectors of the economy.
Landera A, Mac Dowell N, George A, 2021, Development of robust models for the prediction of Reid vapor pressure (RVP) in fuel blends and their application to oxygenated biofuels using the SAFT-gamma approach, FUEL, Vol: 283, ISSN: 0016-2361
Denbow C, Le Brun N, Dowell NM, et al., 2020, The potential impact of Molten Salt Reactors on the UK electricity grid, Journal of Cleaner Production, Vol: 276, Pages: 1-18, ISSN: 0959-6526
The UK electricity grid is expected to supply a growing electricity demand and also to cope with electricity generation variability as the country pursues a low-carbon future. Molten Salt Reactors (MSRs) could offer a solution to meet this demand thanks to their estimated low capital costs, low operational risk, and promise of reliably dispatchable low-carbon electricity. In the published literature, there is little emphasis placed on estimating or modelling the future impact of MSRs on electricity grids. Previous modelling efforts were limited to quantifying the value of renewable energy sources, energy storage and carbon capture technologies. To date, no study has assessed or modelled MSRs as a competing power generation source for meeting decarbonization targets. Given this gap, the main objective of this paper is to explore the cost benefits for policy makers, consumers, and investors when MSRs are deployed between 2020 and 2050 for electricity generation in the UK. This paper presents results from electricity systems optimization (ESO) modelling of the costs associated with the deployment of 1350 MWe MSRs, from 2025 onwards to 2050, and compares this against a UK grid with no MSR deployment. Results illustrate a minimum economic benefit of £1.25 billion for every reactor installed over this time period. Additionally, an investment benefit occurs for a fleet of these reactors which have a combined net present value (NPV) of £22 billion in 2050 with a payback period of 23 years if electricity is sold competitively to consumers at a price of £60/MWh.
Sunny N, Mac Dowell N, Shah N, 2020, What is needed to deliver carbon-neutral heat using hydrogen and CCS?, ENERGY & ENVIRONMENTAL SCIENCE, Vol: 13, Pages: 4204-4224, ISSN: 1754-5692
CO2 capture, utilization and storage (CCUS) is recognized as a uniquely important option in global efforts to control anthropogenic greenhouse-gas (GHG) emissions. Despite significant progress globally in advancing the maturity of the various component technologies and their assembly into full-chain demonstrations, a gap remains on the path to widespread deployment in many countries. In this paper, we focus on the importance of business models adapted to the unique technical features and sociopolitical drivers in different regions as a necessary component of commercial scale-up and how lessons might be shared across borders. We identify three archetypes for CCUS development-resource recovery, green growth and low-carbon grids-each with different near-term issues that, if addressed, will enhance the prospect of successful commercial deployment. These archetypes provide a framing mechanism that can help to translate experience in one region or context to other locations by clarifying the most important technical issues and policy requirements. Going forward, the archetype framework also provides guidance on how different regions can converge on the most effective use of CCUS as part of global deep-decarbonization efforts over the long term.
Patrizio P, Pratama YW, Mac Dowell N, 2020, Socially equitable energy system transitions, Joule, Vol: 4, Pages: 1700-1713, ISSN: 2542-4351
The European transition to a net-zero economy by 2050 implies a wide range of changes that may adversely affect certain industrial sectors, communities, and regions. However, these impacts are entirely obscured by conventional least-cost analyses. Thus, this work compares the socio-economic impacts of various strategies to decarbonize the energy system by 2050 within the framework of the Sustainable Development Goals (SDGs). We demonstrate that transitions that protect domestic strategic assets and preserve key industrial sectors correspondingly deliver a socially equitable transition. Adopting a technology-agnostic approach to decarbonizing the European electricity system maximizes the associated co-benefits and potentially increases the gross value added (GVA) to the economy by 50% relative to a business as usual scenario. This new way of thinking about the economic transition fundamentally reframes the discussion from one of cost to one of opportunity.
Ganzer C, Mac Dowell N, 2020, A comparative assessment framework for sustainable production of fuels and chemicals explicitly accounting for intermittency, SUSTAINABLE ENERGY & FUELS, Vol: 4, Pages: 3888-3903, ISSN: 2398-4902
Firth AEJ, Mac Dowell N, Fennell PS, et al., 2020, Assessing the economic viability of wetland remediation of wastewater, and the potential for parallel biomass valorisation, Environmental Science: Water Research & Technology, Vol: 6, Pages: 2103-2121, ISSN: 2053-1400
Constructed wetlands have been shown to consistently remove a wide range of pollutants from contaminated water. However, no wide-ranging studies exist on the economic viability of this technology. This paper performs a high-level economic comparison between wetland remediation and conventional water remediation technologies, for a wide range of contaminant inputs, outputs, and flow rates. The cases considered are nutrient removal from wastewater, and remediation of low-pH and circumneutral acid mine drainage (AMD). The first-order P-k-C* model is used for nutrient removal, while a zeroth-order model is used for AMD remediation, with removal rate data taken from the literature. The number of wetland cells employed was found to significantly affect the overall cost of nutrient removal, allowing savings of up to 86% and 42% for biochemical oxygen demand and phosphorus removal, particularly for low concentrations and flow rates. For integrated secondary and tertiary treatment, wetland remediation was economically competitive down to stringent effluent standards. A sensitivity analysis was performed on sizing and costing parameters of nutrient removal wetlands, with required wetland size found to be most strongly correlated with the assumed removal rate, and land costs found to have relatively little effect on overall costs. Wetland remediation of AMD was only found to be economically favourable for less severe conditions and lower flow rates when treating low-pH drainage, and was heavily influenced by the acidity removal rate. However, the majority of site data from literature was found to fall within this range of conditions. For circumneutral AMD, wetland remediation was found to be cheaper for all simulated cases. The feasibility of offsetting wetland remediation costs through biomass valorisation was investigated for a range of products, with area requirements for minimum economic production identified as the principal barrier.
Fajardy M, Mac Dowell N, 2020, Recognizing the value of collaboration in delivering carbon dioxide removal, One Earth, Vol: 3, Pages: 214-225, ISSN: 2590-3322
In delivering the Paris climate target, bioenergy with carbon capture and storage (BECCS) is likely to play an important role, both as a climate mitigation and a carbon dioxide removal technology. However, regional drivers of BECCS sustainability and cost remain broadly unknown and the regional attribution of a global CO2 removal burden remains largely undetermined. This study explores the mechanisms behind cost-optimal BECCS deployment with evolving regional CO2 removal targets and energy sectors to provide insights into the ways in which different regional players will interact as a function of their bio-geophysical endowments and their ability to trade these assets. An important finding is that inter-regional cooperation—in choosing the right burden-sharing principle to establish regional targets—and collaboration—in trading negative emissions credits and biomass—are central to sustainably and affordably meeting these targets. This multilateralism in biomass and carbon credits trading constitutes important value creation opportunities for key providers of CO2 removal.
Pozo C, Galán-Martín Á, Reiner DM, et al., 2020, Equity in allocating carbon dioxide removal quotas, Nature Climate Change, Vol: 10, Pages: 640-646, ISSN: 1758-678X
The first nationally determined contributions to the Paris Agreement include no mention of the carbon dioxide removal (CDR) necessary to reach the Paris targets, leaving open the question of how and by whom CDR will be delivered. Drawing on existing equity frameworks, we allocate CDR quotas globally according to Responsibility, Capability and Equality principles. These quotas are then assessed in the European Union context by accounting for domestic national capacity of a portfolio of CDR options, including bioenergy with carbon capture and storage, reforestation and direct air capture. We find that quotas vary greatly across principles, from 33 to 325 GtCO2 allocated to the European Union, and, due to biophysical limits, only a handful of countries could meet their quotas acting individually. These results support strengthening cross-border cooperation while highlighting the need to urgently deploy CDR options to mitigate the risk of failing to meet the climate targets equitably.
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
Al-Qahtani A, Gonzalez-Garay A, Bernardi A, et al., 2020, Electricity grid decarbonisation or green methanol fuel? A life-cycle modelling and analysis of today's transportation-power nexus, APPLIED ENERGY, Vol: 265, ISSN: 0306-2619
Rúa J, Bui M, Nord LO, et al., 2020, Does CCS reduce power generation flexibility? A dynamic study of combined cycles with post-combustion CO2 capture, International Journal of Greenhouse Gas Control, Vol: 95, Pages: 1-10, ISSN: 1750-5836
To date, the deployment, integration, and utilization of intermittent renewable energy sources, such as wind and solar power, in the global energy system has been the cornerstone of efforts to combat climate change. At the same time, it is recognized that renewable power represents only one element of the portfolio of technologies that will be required to deliver a technically feasible and financially viable energy system. In this context, carbon capture and storage (CCS) is understood to play a uniquely important role, providing significant value through flexible operation. It is therefore of vital importance that CCS technology can operate synergistically with intermittent renewable power sources, and consequently ensuring that CCS does not inhibit the flexible and dispatchable nature of thermal power plants. This work analyses the intrinsic dynamic performance of the power and CO2 capture plants independently and as an integrated system. Since the power plant represents the fast dynamics of the system and the steam extraction is the main point of integration between the CO2 capture and power plants, disturbances with fast dynamics are imposed on the steam extraction valve during steady state and dynamic operation of a natural gas combined cycle (NGCC) to study the effects of the integration on power generation capacity. The results demonstrate that the integration of liquid-absorbent based post-combustion CO2 capture has negligible impact on the power generation dynamics of the NGCC.
Bui M, Flø NE, de Cazenove T, et al., 2020, Demonstrating flexible operation of the Technology Centre Mongstad (TCM) CO2 capture plant, International Journal of Greenhouse Gas Control, Vol: 93, Pages: 1-26, ISSN: 1750-5836
This study demonstrates the feasibility of flexible operation of CO2capture plants with dynamic modelling and experimental testing at the Technology Centre Mongstad (TCM) CO2capture facility in Norway. This paper presents three flexible operation scenarios: (i) effect of steam flow rate, (ii) time-varying solvent regeneration, and (iii) variable ramp rate. The dynamic model of the TCM CO2capture plant developed in gCCS provides further insights into the process dynamics. As the steam flow rate decreases, lean CO2loading increases, thereby reducing CO2capture rate and decreasing absorber temperature. The time-varying solvent regeneration scenario is demonstrated successfully. During “off-peak” mode (periods of low electricity price), solvent is regenerated, reducing lean CO2loading to 0.16molqY:/molMEAand increasing CO2capture rate to 89–97%. The “peak” mode(period of high electricity price) stores CO2within the solvent by reducing the reboiler heat supply and in-creasing solvent flow rate. During peak mode, lean CO2loading increases to 0.48molqY:/molMEA, reducing CO2 capture rate to 14.5%, which in turn decreases the absorber temperature profile. The variable ramp rate scenario demonstrates that different ramp rates can be applied successively to a CO2capture plant. By maintaining constant liquid-to-gas (L/G) ratio during the changes, the CO2capture performance will remain the same, i.e., constant lean CO2loading (0.14–0.16molqY:/molMEA) and CO2capture rate (87–89%). We show that flexible operation in a demonstration scale absorption CO2capture process is technically feasible. The deviation between the gCCS model and dynamic experimental data demonstrates further research is needed to improve existing dynamic modelling software. Continual development in our understanding of process dynamics during flexible operation of CO2capture plants will be essential. This paper provides additional value by presenting a com-prehensive dy
Leeson D, Ramirez A, Mac Dowell N, 2020, Chapter 9: Carbon capture and storage from industrial sources, RSC Energy and Environment Series, Pages: 296-314, ISBN: 9781788014700
The industrial sector is responsible for 21% of all global carbon dioxide emissions, and, as such, emissions mitigation is as important in this sector as in the power generation sector. Individual industries are sufficiently diverse that bespoke capture strategies must be created for them, with different technologies more appropriate for different industries. One major difference between industrial and power carbon capture and storage (CCS) is that industries often have numerous sources of varying sizes and CO2 concentration, requiring some degree of aggregation or multiple capture units in order to capture large proportions of flue gases, implying an important trade-off between capture rate and cost. Within the chemical manufacturing industries, there exist streams of high-purity CO2 which can be used for demonstration CCS schemes at a lower cost than other flue streams, and as a first mover towards wide scale deployment. However, attempting to calculate the cost of industrial CCS is difficult since there are a wide range of reported costs from literature, with little consensus even within technologies for the same industry. Policy challenges remain broadly similar to those encountered in the power industry, though due to the global markets for industrial products, some market mechanism would be required in the event of unilateral decarbonisation in order not to penalise first-mover entities.
Heuberger CF, Mac Dowell N, 2020, Chapter 12: CCS in electricity systems, RSC Energy and Environment Series, Pages: 392-425, ISBN: 9781788014700
This chapter aims at evaluating CCS equipped power generation in a power system context. Initially, the main power system services and mechanisms are reviewed. Decarbonisation poses transformational challenges associated with system reliability and operability to the energy system. New approaches to evaluate power generation and storage technologies in a whole-systems context are discussed and demonstrated. CCS power plants are able to reduce the total system cost and lead to a least-cost decarbonisation of the power sector. Enhanced flexibility in CCS power generation can provide additional value to the system. Research, policies, and markets should aim at explicitly evaluating new technology services to the power system, such as flexibility, low CO2 emissions, or the provision of ancillary services.
Cabral RP, Mac Dowell N, 2020, Chapter 6: Oxy-fuel combustion capture technology, RSC Energy and Environment Series, Pages: 168-188, ISBN: 9781788014700
This chapter discusses oxy-fuel combustion for the capture and subsequent sequestration of carbon dioxide. Technologies for oxygen production based on air separation will be presented and the need to reduce energy consumption of these units will be discussed along with some potential strategies. A pulverized coal-fired power plant and a natural gas combined cycle will be analysed as case studies for oxy-combustion and the benefits of using pure oxygen will be discussed as well as how the changes in the thermodynamic properties affect boiler operation. Purification of carbon dioxide in the resulting flue gas to pipeline transport specifications will end the discussion of this chapter with two examples of gas processing units. The parasitic power consumption of this gas processing unit combined with the air separation unit reduces the net efficiency of the plant even though the thermal efficiency is increased, which emphasises the importance of developing new technologies, such as ion transport membranes for oxygen production. The possibility to reduce the energy consumption of both air separation unit and gas processing unit combined with the increased combustion efficiency by using pure oxygen make this a promising technology for carbon capture and storage.
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