Imperial College London

Professor Niall Mac Dowell FIChemE FRSC

Faculty of Natural SciencesCentre for Environmental Policy

Professor of Future Energy Systems
 
 
 
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Contact

 

+44 (0)20 7594 9298niall Website

 
 
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Location

 

16 Prince's GardensSouth Kensington Campus

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Summary

 

Publications

Publication Type
Year
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152 results found

Negri V, Galan-Martin A, Pozo C, Fajardy M, Reiner DM, Mac Dowell N, Guillen-Gosalbez Get al., 2021, Life cycle optimization of BECCS supply chains in the European Union, APPLIED ENERGY, Vol: 298, ISSN: 0306-2619

Journal article

Danaci D, Bui M, Petit C, Mac Dowell Net al., 2021, En Route to Zero Emissions for Power and Industry with Amine-Based Post-combustion Capture, ENVIRONMENTAL SCIENCE & TECHNOLOGY, Vol: 55, Pages: 10619-10632, ISSN: 0013-936X

Journal article

Patrizio P, Fajardy M, Bui M, Mac Dowell Net al., 2021, CO2 mitigation or removal: The optimal uses of biomass in energy system decarbonization, ISCIENCE, Vol: 24

Journal article

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

Journal article

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

Journal article

Fajardy M, Morris J, Gurgel A, Herzog H, Mac Dowell N, Paltsev Set 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

Journal article

Bui M, Zhang D, Fajardy M, Mac Dowell Net 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

Journal article

Cuellar-Franca RM, Garcia-Gutierrez P, Hallett JP, Mac Dowell Net 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

Journal article

Brandl P, Bui M, Hallett JP, Mac Dowell Net al., 2021, Beyond 90% capture: Possible, but at what cost?, International Journal of Greenhouse Gas Control, Vol: 105, Pages: 1-16, ISSN: 1750-5836

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.

Journal article

Denbow C, Le Brun N, Dowell NM, Shah N, Markides CNet 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.

Journal article

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

Journal article

Ku AY, Cook PJ, Hao P, Li X, Lemmon JP, Lockwood T, Dowell NM, Singh SP, Wei N, Xu Wet al., 2020, Cross-regional drivers for CCUS deployment, Clean Energy, Vol: 4, Pages: 202-232, ISSN: 2515-4230

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.

Journal article

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.

Journal article

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

Journal article

Firth AEJ, Mac Dowell N, Fennell PS, Hallett JPet 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.

Journal article

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.

Journal article

Pozo C, Galán-Martín Á, Reiner DM, Mac Dowell N, Guillén-Gosálbez Get 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.

Journal article

Olympios A, Hoisenpoori P, Mersch M, Pantaleo A, Simpson M, Sapin P, Mac Dowell N, Markides Cet 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

Conference paper

Al-Qahtani A, Gonzalez-Garay A, Bernardi A, Galan-Martin A, Pozo C, Mac Dowell N, Chachuat B, Guillen-Gosalbez Get 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

Journal article

Rúa J, Bui M, Nord LO, Mac Dowell Net 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.

Journal article

Bui M, Flø NE, de Cazenove T, Mac Dowell Net 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

Journal article

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.

Book chapter

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.

Book chapter

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.

Book chapter

Algunaibet IM, Pozo C, Galan-Martin A, Huijbregts MAJ, Mac Dowell N, Guillen-Gosalbez Get al., 2020, Reply to the 'Comment on "Powering sustainable development within planetary boundaries"' by Y. Yang, Energy Environ. Sci., 2020, 13, DOI: 10.1039/C9EE01176E, Energy and Environmental Science, Vol: 13, Pages: 313-316, ISSN: 1754-5692

In our recently published work, we incorporated planetary boundaries in the optimization of the United States (US) power sector in 2030. Yang claims there is a double-counting error in our results and encourages us to minimize direct emissions instead of life cycle emissions in our model. Here, we argue that Yang's main criticism based on the risk of double-counting emissions when multiple sectors are simultaneously optimized does not apply to our case study, in which only one sector – the power sector – is analyzed. To assess the implications of Yang's suggestion to minimize direct emissions, we repeated the calculations optimizing direct emissions instead of life cycle emissions. We found that this approach is unable to discriminate effectively between electricity production technologies and, consequently, leads to a suboptimal mix with impacts on climate change, ocean acidification and freshwater use 102, 33 and 1.5 times the limits, respectively, whereas our original solution meets all planetary boundaries concurrently. Our findings imply that Yang's suggestion of optimizing direct emissions in energy systems models might not the best way forward in single-sector studies like ours.

Journal article

Heuberger CF, Bains PK, Mac Dowell N, 2020, The EV-olution of the power system: a spatio-temporal optimisation model to investigate the impact of electric vehicle deployment, Applied Energy, Vol: 257, Pages: 1-18, ISSN: 0306-2619

Power system models have become an essential part of strategic planning and decision-making in the energy transition. While techniques are becoming increasingly sophisticated and manifold, the ability to incorporate high resolution in space and time with long-term planning is limited. We introduce ESONE, the Spatially granular Electricity Systems Optimisation model. ESONE is a mixed-integer linear program, determining investment in power system generation and transmission infrastructure while simultaneously optimising operational schedule and optimal power flow on an hourly basis. Unique data clustering combined with model decomposition and an iterative solution procedure enable computational tractability. We showcase the capabilities of the ESONE model by applying it to the power system of Great Britain under CO2 emissions reduction targets. We investigate the effects of a spatially distributed large-scale roll-out of electric vehicles (EVs). We find EV demand profiles correlate well with offshore and onshore wind power production, reducing curtailment and boosting generation. Time-of-use-tariffs for EV charging can further reduce power supply and transmission infrastructure requirements. In general, Great Britain’s electricity system absorbs additional demand from ambitious deployment of EVs without substantial changes to system design.

Journal article

Danaci D, Bui M, Mac Dowell N, Petit Cet al., 2020, Exploring the limits of adsorption-based CO2 capture using MOFs with PVSA – from molecular design to process economics, Molecular Systems Design and Engineering, Vol: 5, Pages: 212-231, ISSN: 2058-9689

Metal-organic frameworks (MOFs) have taken the materials science world by storm, with potentials of near infinite possibilities and the panacea for adsorption-based carbon capture. Yet, no pilot-scale (or larger-scale) study exists on MOFs for carbon capture. Beyond material scalability issues, this clear gap between the scientific and engineering literature relates to the absence of suitable and accessible assessment of MOFs in an adsorption process. Here, we have developed a simple adsorbent screening tool with process economics to evaluate adsorbents for post-combustion capture, while also considering factors relevant to industry. Specifically, we have assessed the 25 adsorbents (22 MOFs, 2 zeolites, 1 activated carbon) against performance constraints – i.e. CO2 purity and recovery – and cost. We have considered four different CO2 capture scenarios to represent a range of CO2 inlet concentrations. The cost is compared to that of amine-based solvents for which a corresponding model was developed. Using the model developed, we have conceptually assessed the materials properties and process parameters influencing the purity, recovery and cost in order to design the ‘best’ adsorbent. We have also set-up a tool for readers to screen their own adsorbent. In this contribution, we show that minimal N2 adsorption and moderate enthalpies of adsorption are key in obtaining good process performance and reducing cost. This stands in contrast to the popular approaches of maximizing CO2 capacity or surface area. Of the 22 MOFs evaluated, UTSA-16 shows the best performance and lowest cost for post-combustion capture, having performance in-line with the benchmark, zeolite 13X. Mg-MOF-74 performs poorly. The cost of using the adsorbents remains overall higher than that of an amine-based absorption process. Ultimately, this study provides specific directions for material scientists to design adsorbents and assess their performance at the process scale. This

Journal article

Bui M, Mac Dowell N, 2020, Chapter 1: Introduction-Carbon capture and storage, RSC Energy and Environment Series, Pages: 1-7, ISBN: 9781788014700

CO2 capture and storage (CCS) and greenhouse gas removal (GGR) are considered vital to meeting global climate change targets. However, despite their technical maturity, their deployment consistently lags behind what is known to be required. This introductory chapter explores why, and suggests some possible paths forward.

Book chapter

Daggash HA, Fajardy M, Mac Dowell N, 2020, Chapter 14: Negative emissions technologies, RSC Energy and Environment Series, Pages: 447-511, ISBN: 9781788014700

The Paris Agreement signalled global consensus to keep average temperature rise "well below" 2 °C by the end of the century. Results from integrated assessment models have made it increasingly evident that negative emissions (removing CO2 from the atmosphere) are crucial to achieving this. Consequently, negative emissions technologies (NETs) have come to the forefront of mitigation discussions. NETs must however overcome challenges if they are to be realised at scale. Uncertainties around the large-scale biomass supply have fuelled a debate on whether negative emissions from bio-energy with carbon capture and storage (BECCS) are sustainably achievable, if at all. Reliable carbon accounting frameworks and policy incentives are needed to improve investment prospects. The direct extraction of CO2 from air, or direct air capture (DAC), has since been demonstrated as a source of negative emissions. The large energy and economic costs associated with extracting CO2 from air are proving prohibitive to achieving commercial viability of DAC technology. Without dedicated policy support for technological innovation, and further interdisciplinary research to constrain a variety of uncertainties, the world risks foregoing a portfolio of technologies that add much-needed flexibility in the mitigation toolbox. This chapter details the evidence for negative emissions, proposed means of achieving them and their barriers to commercial effectiveness.

Book chapter

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