Imperial College London

Dr Ajay Gambhir

Faculty of Natural SciencesThe Grantham Institute for Climate Change

Senior Research Fellow
 
 
 
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Contact

 

+44 (0)20 7594 6363a.gambhir

 
 
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Location

 

Electrical EngineeringSouth Kensington Campus

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Summary

 

Publications

Publication Type
Year
to

73 results found

Gambhir A, Green R, Grubb M, Heptonstall P, Wilson C, Gross Ret al., 2021, How are future energy technology costs estimated? can we do better?, International Review of Environmental and Resource Economics, Vol: 15, Pages: 1-48, ISSN: 1932-1465

Making informed estimates of future energy technology costs is central to understanding the cost of the low-carbon transition. A number of methods have been used to make such estimates: extrapolating empirically derived learning rates; use of expert elicitations; and engineering assessments which analyse future developments for technology components’ cost and performance parameters. In addition, there is a rich literature on different energy technology innovation systems analysis frameworks, which identify and analyse the many processes that drive technologies’ development, including those that make them increasingly cost-competitive and commercially ready. However, there is a surprising lack of linkage between the fields of technology cost projections and technology innovation systems analysis. There is a clear opportunity to better relate these two fields, such that the detailed processes included in technology innovation systems frameworks can be fully considered when estimating future energy technology costs.Here we demonstrate how this can be done. We identify that learning curve, expert elicitation and engineering assessment methods already either implicitly or explicitly incorporate some elements of technology innovation systems frameworks, most commonly those relating to R&D and deployment-related drivers. Yet they could more explicitly encompass a broader range of innovation processes. For example, future cost developments could be considered in light of the extent to which there is a well-functioning energy technological innovation system (TIS), including support for the direction of technology research, industry experimentation and development, market formation including by demand-pull policies and technology legitimation. We suggest that failure to fully encompass such processes may have contributed to overestimates of nuclear cost reductions and under-estimates of offshore wind cost reductions in the last decade.

Journal article

Stevenson S, Collins A, Jennings N, Köberle AC, Laumann F, Laverty AA, Vineis P, Woods J, Gambhir Aet al., 2021, Correction to: A hybrid approach to identifying and assessing interactions between climate action (SDG13) policies and a range of SDGs in a UK context, Discover Sustainability, Vol: 2

Journal article

Köberle AC, Vandyck T, Guivarch C, Macaluso N, Bosetti V, Gambhir A, Tavoni M, Rogelj Jet al., 2021, Publisher Correction: The cost of mitigation revisited, Nature Climate Change, ISSN: 1758-678X

Journal article

Sognnaes I, Gambhir A, van de Ven D-J, Nikas A, Anger-Kraavi A, Bui H, Campagnolo L, Delpiazzo E, Doukas H, Giarola S, Grant N, Hawkes A, Köberle AC, Kolpakov A, Mittal S, Moreno J, Perdana S, Rogelj J, Vielle M, Peters GPet al., 2021, A multi-model analysis of long-term emissions and warming implications of current mitigation efforts, Nature Climate Change, ISSN: 1758-678X

Journal article

Koberle AC, Vandyck T, Guivarch C, Macaluso N, Bosetti V, Gambhir A, Tavoni M, Rogelj Jet al., 2021, The cost of mitigation revisited, NATURE CLIMATE CHANGE, ISSN: 1758-678X

Journal article

Pearce D, Pearce A, Gambhir A, Nelson J, Gilbert A, Rhodes A, Bhugobaun Ret al., 2021, Research pathways for net-zero transport

The future is uncertain and there are many different pathways ahead for technology and society. Some, but not all, ofthese pathways will deliver the required amount of decarbonisation to comply with the Paris Agreement. Whilst wecannot know for certain which of these pathways will be chosen, research allows us both to identify the patterns andtrends that can help shape the pathways, and ultimately our future, and to develop the technologies and approachesthat can assist decarbonisation

Report

Stevenson S, Collins A, Jennings N, Koberle A, Laumann F, Laverty A, Vineis P, Woods J, Gambhir Aet al., 2021, A hybrid approach to identifying and assessing interactions between climate action (SDG13) policies and a range of SDGs in a UK context, Discover Sustainability, Vol: 2, ISSN: 2662-9984

In 2015 the United Nations drafted the Paris Agreement and established the Sustainable Development Goals (SDGs) for all nations. A question of increasing relevance is the extent to which the pursuit of climate action (SDG 13) interacts both positively and negatively with other SDGs. We tackle this question through a two-pronged approach: a novel, automated keyword search to identify linkages between SDGs and UK climate-relevant policies; and a detailed expert survey to evaluate these linkages through specific examples. We consider a particular subset of SDGs relating to health, economic growth, affordable and clean energy and sustainable cities and communities. Overall, we find that of the 89 UK climate-relevant policies assessed, most are particularly interlinked with the delivery of SDG 7 (Affordable and Clean Energy) and SDG 11 (Sustainable Cities and Communities) and that certain UK policies, like the Industrial Strategy and 25-Year Environment Plan, interlink with a wide range of SDGs. Focusing on these climate-relevant policies is therefore likely to deliver a wide range of synergies across SDGs 3 (Good Health and Well-being), 7, 8 (Decent Work and Economic Growth), 9 (Industry, Innovation and Infrastructure), 11, 14 (Life Below Water) and 15 (Life on Land). The expert survey demonstrates that in addition to the range of mostly synergistic interlinkages identified in the keyword search, there are also important potential trade-offs to consider. Our analysis provides an important new toolkit for the research and policy communities to consider interactions between SDGs, which can be employed across a range of national and international contexts.

Journal article

Grant N, Hawkes A, Mittal S, Gambhir Aet al., 2021, The policy implications of an uncertain carbon dioxide removal potential, Joule, Vol: 5, Pages: 2593-2605, ISSN: 2542-4351

Many low-carbon scenarios rely on carbon dioxide removal (CDR) to meet decarbonization goals. The feasibility of large-scale CDR deployment is highly uncertain, and existing scenarios have been criticized for overreliance on CDR. We conduct an expert survey on the feasible potential for CDR via bioenergy with carbon capture and storage, direct air capture and afforestation. We use the survey results to represent uncertainty in future CDR availability and explore the implications in an integrated assessment model. Stochastic optimization demonstrates that uncertainty in future CDR availability provides a strong rationale to increase near-term rates of decarbonization. In scenarios with high CDR uncertainty, emissions are reduced by an additional 10 GtCO2e in 2030 compared with scenarios with no consideration of CDR uncertainty. This highlights the urgent need to increase ambition contained in nationally determined contributions (NDCs) for 2030, to get the world on track to deliver 1.5°C and to hedge against an uncertain future CDR potential.

Journal article

vandeVen D, Westphal M, GonzálezEguino M, Gambhir A, Peters G, Sognnaes I, McJeon H, Hultman N, Kennedy K, Cyrs T, Clarke Let al., 2021, The impact of U.S. re‐engagement in climate on the Paris targets, Earth's Future, Vol: 9, Pages: 1-7, ISSN: 2328-4277

The Paris Agreement seeks to combine international efforts to keep global temperature increase to well-below 2°C. Whilst current ambitions in many signatories are insufficient to achieve this goal, optimism prevailed in the second half of 2020. Not only did several major emitters announce net-zero mitigation targets around mid-century, but the new Biden Administration immediately announced the U.S.’s re-entry into Paris and a net-zero goal for 2050. U.S. federal re-engagement in climate action could have a considerable impact on its national greenhouse gas emissions pathway, by significantly augmenting existing state-level actions. Combined with U.S. re-entry in the Paris Agreement, this could also serve as a stimulus to enhance ambitions in other countries. A critical question then becomes what such U.S. re-engagement, through both national and international channels, would have on the global picture. This commentary explores precisely this question, by using an integrated assessment model to assess U.S. national emissions, global emissions, and end-of-century temperatures in five scenarios combining different climate ambition levels in both the U.S. and the rest of the world. Our analyses finds that ambitious climate leadership by the Biden Administration on top of enhanced climate commitments by other the major economies could potentially be the trigger for the world to fulfill the temperature goal of the Paris Agreement.

Journal article

Giarola S, Mittal S, Vielle M, Perdana S, Campagnolo L, Delpiazzo E, Bui H, Anger Kraavi A, Kolpakov A, Sognnaes I, Peters G, Hawkes A, Koberle A, Grant N, Gambhir A, Nikas A, Doukas H, Moreno J, van de Ven D-Jet al., 2021, Challenges in the harmonisation of global integrated assessment models: a comprehensive methodology to reduce model response heterogeneity, Science of the Total Environment, Vol: 783, ISSN: 0048-9697

Harmonisation sets the ground to a solid inter-comparison of integrated assessment models. A clear and transparent harmonisation process promotes a consistent interpretation of the modelling outcomes divergences and, reducing the model variance, is instrumental to the use of integrated assessment models to support policy decision-making. Despite its crucial role for climate economic policies, the definition of a comprehensive harmonisation methodology for integrated assessment modelling remains an open challenge for the scientific community.This paper proposes a framework for a harmonisation methodology with the definition of indispensable steps and recommendations to overcome stumbling blocks in order to reduce the variance of the outcomes which depends on controllable modelling assumptions. The harmonisation approach of the PARIS REINFORCE project is presented here to layout such a framework. A decomposition analysis of the harmonisation process is shown through 6 integrated assessment models (GCAM, ICES-XPS, MUSE, E3ME, GEMINI-E3, and TIAM). Results prove the potentials of the proposed framework to reduce the model variance and present a powerful diagnostic tool to feedback on the quality of the harmonisation itself.

Journal article

Beath H, Hauser M, Sandwell P, Gambhir A, Few S, Chambon CL, Nelson Jet al., 2021, The cost and emissions advantages of incorporating anchor loads into solar mini-grids in India, Renewable and Sustainable Energy Transition, Vol: 1, Pages: 1-14, ISSN: 2667-095X

Renewables-based mini-grids have the potential to improve electricity access with lower emissions and better reliability than national grids. However, these systems have a challenging cost to revenue ratio, hindering their implementation. Combining residential loads with an anchor load, a relatively large non-domestic user, can help to improve mini-grid economics. Using measured electricity demand data from India and energy modelling, we assess the cost and emissions advantages of integrating health clinics as anchor loads within domestic solar mini-grids. For comparison, we also assess the ability of the national grid to meet our demand scenarios using monitored grid data. We apply a scenario-based approach, using separate domestic and anchor load demand profiles, and both in combination; we test meeting two levels of energy demand, 95% and 100%; and compare systems using PV and batteries, diesel, and hybrid generation. We find that the national grid has poor availability, at just over 50% at the most comparable monitoring site; and that it would meet a lower fraction of energy demand for our anchor load scenarios than the domestic only ones. For the off-grid systems, we find substantial cost and emissions reductions with anchor loads relative to demand scenarios without anchor loads. At 95% of demand met, we find PV and battery systems are 14-22% cheaper than diesel-only systems, with 10 times lower carbon intensity. Our findings illustrate the role off-grid systems can play in the provision of reliable low-carbon electricity and highlight the advantages of incorporating anchor loads like health centres into such systems.

Journal article

Grant N, Hawkes A, Mittal S, Gambhir Aet al., 2021, Confronting mitigation deterrence in low-carbon scenarios, Environmental Research Letters, Vol: 16, ISSN: 1748-9326

Carbon dioxide removal (CDR) features heavily in low-carbon scenarios, where it often substitutes for emission reductions in both the near-term and long-term, enabling temperature targets to be met at lower cost. There are major concerns around the scale of CDR deployment in many low-carbon scenarios, and the risk that anticipated future CDR could dilute incentives to reduce emissions now, a phenomenon known as mitigation deterrence. Here we conduct an in-depth analysis into the relationship between emissions reduction and emissions removal in a global integrated assessment model. We explore the impact of CDR on low-carbon scenarios, illustrating how the pathway for the 2020s is highly sensitive to assumptions around CDR availability. Using stochastic optimisation, we demonstrate that accounting for uncertainty in future CDR deployment provides a strong rationale to increase rates of mitigation in the 2020s. A 20% chance of CDR deployment failure requires additional emissions reduction in 2030 of 3–17 GtCO2. Finally, we introduce new scenarios which demonstrate the risks of mitigation deterrence and the benefits of formally separating CDR and emissions reduction as climate strategies. Continual mitigation deterrence across the time-horizon leads to the temperature goals being breached by 0.2–0.3 °C. If CDR is treated as additional to emissions reduction, up to an additional 700–800 GtCO2 can be removed from the atmosphere by 2100, reducing end-of-century warming by up to 0.5 °C. This could put sub-1.5 °C targets within reach but requires that CDR is additional to, rather than replaces, emission reductions.

Journal article

Nikas A, Elia A, Boitier B, Koasidis K, Doukas H, Cassetti G, Anger-Kraavi A, Bui H, Campagnolo L, De Miglio R, Delpiazzo E, Fougeyrollas A, Gambhir A, Gargiulo M, Giarola S, Grant N, Hawkes A, Herbst A, Köberle AC, Kolpakov A, Le Mouël P, McWilliams B, Mittal S, Moreno J, Neuner F, Perdana S, Peters GP, Plötz P, Rogelj J, Sognnæs I, Van de Ven D-J, Vielle M, Zachmann G, Zagamé P, Chiodi Aet al., 2021, Where is the EU headed given its current climate policy? A stakeholder-driven model inter-comparison., Science of the Total Environment, Vol: 793, Pages: 148549-148549, ISSN: 0048-9697

Recent calls to do climate policy research with, rather than for, stakeholders have been answered in non-modelling science. Notwithstanding progress in modelling literature, however, very little of the scenario space traces back to what stakeholders are ultimately concerned about. With a suite of eleven integrated assessment, energy system and sectoral models, we carry out a model inter-comparison for the EU, the scenario logic and research questions of which have been formulated based on stakeholders' concerns. The output of this process is a scenario framework exploring where the region is headed rather than how to achieve its goals, extrapolating its current policy efforts into the future. We find that Europe is currently on track to overperforming its pre-2020 40% target yet far from its newest ambition of 55% emissions cuts by 2030, as well as looking at a 1.0-2.35 GtCO2 emissions range in 2050. Aside from the importance of transport electrification, deployment levels of carbon capture and storage are found intertwined with deeper emissions cuts and with hydrogen diffusion, with most hydrogen produced post-2040 being blue. Finally, the multi-model exercise has highlighted benefits from deeper decarbonisation in terms of energy security and jobs, and moderate to high renewables-dominated investment needs.

Journal article

Ortega-Arriaga P, Babacan O, Nelson J, Gambhir Aet al., 2021, Grid versus off-grid electricity access options: A review on the economic and environmental impacts, Renewable and Sustainable Energy Reviews, Vol: 143, Pages: 1-17, ISSN: 1364-0321

This research reviews the economic and environmental impacts of grid-extension and off-grid systems, to inform the appropriate electrification strategy for the current population without electricity access. The principal technologies reviewed are centralised conventional fossil-fuel grid-extension and off-grid systems mainly based on solar PV and batteries. It finds that relatively few studies explicitly compare grid-extension electricity costs against off-grid systems costs and that there is a lack of consistency in the methodologies used to determine the least-cost solution. Nevertheless, the studies reviewed show a range of around $0.2–1.4/kWh for off-grid electricity access, compared to a range of below $0.1/kWh to more than $8/kWh for grid access, pointing to a number of cases in which off-grid access may already be the more cost-effective option. Existing literature on the environmental impacts primarily focuses on greenhouse gas emissions from electricity generation, with off-grid (solar PV and storage) systems’ emissions in the range of 50–130 gCO2-eq/kWh and grid generation from close to 0 gCO2-eq/kWh (for renewables and nuclear sources) to over 1,000 gCO2-eq/kWh (for coal). Emissions impacts stemming from transmission and distribution grids suggest a range of 0–30 gCO2-eq/kWh. Assessments of other environmental impacts such as water use, land use, biodiversity and e-waste are often absent in studies, whilst few studies explicitly compare the environmental impacts of grid versus off-grid systems. Further research should focus on comparing the costs of electricity access options using consistent metrics, expanding the scope of environmental impacts analysis, and integrating environmental and economic impacts into a comprehensive sustainability assessment of different options.

Journal article

Vallejo L, Mazur C, Strapasson A, Cockerill T, Gambhir A, Hills T, Jennings M, Jones O, Kalas N, Keirstead J, Khor C, Napp T, Tong D, Woods J, Shah Net al., 2021, Halving Global CO2 Emissions by 2050: Technologies and Costs, International Energy Journal, Vol: 21, Pages: 147-158, ISSN: 1513-718X

This study provides a whole-systems simulation on how to halve global CO2 emissions by 2050, compared to 2010, with an emphasis on technologies and costs, in order to avoid a dangerous increase in the global mean surface temperature by end the of this century. There still remains uncertainty as to how much a low-carbon energy system costs compared to a high-carbon system. Integrated assessment models (IAMs) show a large range of costs of mitigation towards the 2°C target, with up to an order of magnitude difference between the highest and lowest cost, depending on a number of factors including model structure, technology availability and costs, and the degree of feedback with the wider macro-economy. A simpler analysis potentially serves to highlight where costs fall and to what degree. Here we show that the additional cost of a low-carbon energy system is less than 1% of global GDP more than a system resulting from low mitigation effort. The proposed approach aligns with some previous IAMs and other projections discussed in the paper, whilst also providing a clearer and more detailed view of the world. Achieving this system by 2050, with CO2 emissions of about 15GtCO2, depends heavily on decarbonisation of the electricity sector to around 100gCO2/kWh, as well as on maximising energy efficiency potential across all sectors. This scenario would require a major mitigation effort in all the assessed world regions. However, in order to keep the global mean surface temperature increase below 1.5°C, it would be necessary to achieve net-zero emission by 2050, requiring a much further mitigation effort.

Journal article

Wood SLR, Luers A, Garard J, Gambhir A, Chaudhari K, Ivanova M, Cronin Cet al., 2021, Collective foresight and intelligence for sustainability, Global Sustainability, Vol: 4, Pages: 1-7, ISSN: 2059-4798

Non-technical summaryCharting robust pathways towards more sustainable futures that ‘leave no one behind’ requires that diverse communities engage in collective foresight and intelligence exercises to better understand global systemic challenges, anticipate the emerging risks and opportunities that disruptions present, and share perspectives on how to respond and inform decision-making. We report on the recent use of an international rapid foresight survey to assess expected societal trends over the next 3 years following the COVID-19 crisis. The results illustrate the power of collective foresight approaches to provide timely, nuanced insights for decision-making across sectors and scales, particularly in times of uncertainty.Technical summaryWe present the findings of a rapid foresight survey launched in spring 2020 to draw on the collective intelligence of the global community on where the world is headed post-COVID-19. Respondents were asked to (i) assess five key societal trends in the coming 3 years, (ii) provide news headlines they both expect and hope to see, and (iii) assess the role of digital technologies during crises. Analysis of over 2000 responses from more than 90 countries revealed important regional differences in expected societal trends related to sustainability. More respondents in the Global South expected shifts towards less inequality while more respondents in the Global North expected shifts towards a smaller ecological footprint. Qualitative analysis of proposed news headlines revealed four broad themes of focus (environment, equity, health, and economy), and yielded insights into perspectives on critical drivers of change. Finally, the survey report found that the vast majority of respondents were not opposed to digital surveillance in crises. In presenting these results, we explore the value of collective foresight and intelligence exercises in providing pluralistic inputs to decision-making and in complementing more prevalent

Journal article

Nikas A, Gambhir A, Trutnevyte E, Koasidis K, Lund H, Thellufsen JZ, Mayer D, Zachmann G, Miguel LJ, Ferreras-Alonso N, Sognnaes I, Peters GP, Colombo E, Howells M, Hawkes A, van den Broek M, Van de Ven DJ, Gonzalez-Eguino M, Flamos A, Doukas Het al., 2021, Perspective of comprehensive and comprehensible multi-model energy and climate science in Europe, Energy, Vol: 215, Pages: 1-8, ISSN: 0360-5442

Europe’s capacity to explore the envisaged pathways that achieve its near- and long-term energy and climate objectives needs to be significantly enhanced. In this perspective, we discuss how this capacity is supported by energy and climate-economy models, and how international modelling teams are organised within structured communication channels and consortia as well as coordinate multi-model analyses to provide robust scientific evidence. Noting the lack of such a dedicated channel for the highly active yet currently fragmented European modelling landscape, we highlight the importance of transparency of modelling capabilities and processes, harmonisation of modelling parameters, disclosure of input and output datasets, interlinkages among models of different geographic granularity, and employment of models that transcend the highly harmonised core of tools used in model inter-comparisons. Finally, drawing from the COVID-19 pandemic, we discuss the need to expand the modelling comfort zone, by exploring extreme scenarios, disruptive innovations, and questions that transcend the energy and climate goals across the sustainability spectrum. A comprehensive and comprehensible multi-model framework offers a real example of “collective” science diplomacy, as an instrument to further support the ambitious goals of the EU Green Deal, in compliance with the EU claim to responsible research.

Journal article

Nikas A, Lieu J, Sorman A, Gambhir A, Turhan E, Baptista BV, Doukas Het al., 2020, The desirability of transitions in demand: Incorporating behavioural and societal transformations into energy modelling, Energy Research and Social Science, Vol: 70, ISSN: 2214-6296

Quantitative systems modelling in support of climate policy has tended to focus more on the supply side in assessing interactions among technology, economy, environment, policy and society. By contrast, the demand side is usually underrepresented, often emphasising technological options for energy efficiency improvements. In this perspective, we argue that scientific support to climate action is not only about exploring capacity of "what", in terms of policy and outcome, but also about assessing feasibility and desirability, in terms of "when", "where" and especially for "whom". Without the necessary behavioural and societal transformations, the world faces an inadequate response to the climate crisis challenge. This could result from poor uptake of low-carbon technologies, continued high-carbon intensive lifestyles, or economy-wide rebound effects. For this reason, we propose a framing for a holistic and transdisciplinary perspective on the role of human choices and behaviours in influencing the low-carbon transition, starting from the desires of individuals and communities, and analysing how these interact with the energy and economic landscape, leading to systemic change at the macro-level. In making a case for a political ecology agenda, we expand our scope, from comprehending the role of societal acceptance and uptake of end-use technologies, to co-developing knowledge with citizens from non-mainstream and marginalised communities, and to defining the modelling requirements to assess the decarbonisation potential of shifting lifestyle patterns in climate change and action.

Journal article

Pye S, Broad O, Bataille C, Brockway P, Daly HE, Freeman R, Gambhir A, Geden O, Rogan F, Sanghvi S, Tomei J, Vorushylo I, Watson Jet al., 2020, Modelling net-zero emissions energy systems requires a change in approach, Climate Policy, Vol: 21, Pages: 222-231, ISSN: 1469-3062

Energy modelling can assist national decision makers in determining strategies that achieve net-zero greenhouse gas (GHG) emissions. However, three key challenges for the modelling community are emerging under this radical climate target that needs to be recognized and addressed. A first challenge is the need to represent new mitigation options not currently represented in many energy models. We emphasize here the under representation of end-use sector demand-side options due to the traditional supply side focus of many energy models, along with issues surrounding robustness in deploying carbon dioxide removal (CDR) options. A second challenge concerns the types of models used. We highlight doubts about whether current models provide sufficient relevant insights on system feasibility, actor behaviour, and policy effectiveness. A third challenge concerns how models are applied for policy analyses. Priorities include the need for expanding scenario thinking to incorporate a wider range of uncertainty factors, providing insights on target setting, alignment with broader policy objectives, and improving engagement and transparency of approaches. There is a significant risk that without reconsidering energy modelling approaches, the role that the modelling community can play in providing effective decision support may be reduced. Such support is critical, as countries seek to develop new Nationally Determined Contributions and longer-term strategies over the next few years.

Journal article

Koasidis K, Nikas A, Neofytou H, Karamaneas A, Gambhir A, Wachsmuth J, Doukas Het al., 2020, The UK and German low-carbon industry transitions from a sectoral innovation and system failures perspective, Energies, Vol: 13, ISSN: 1996-1073

Industrial processes are associated with high amounts of energy consumed and greenhouse gases emitted, stressing the urgent need for low-carbon sectoral transitions. This research reviews the energy-intensive iron and steel, cement and chemicals industries of Germany and the United Kingdom, two major emitting countries with significant activity, yet with different recent orientation. Our socio-technical analysis, based on the Sectoral Innovation Systems and the Systems Failure framework, aims to capture existing and potential drivers of or barriers to diffusion of sustainable industrial technologies and extract implications for policy. Results indicate that actor structures and inconsistent policies have limited low-carbon innovation. A critical factor for the successful decarbonisation of German industry lies in overcoming lobbying and resistance to technological innovation caused by strong networks. By contrast, a key to UK industrial decarbonisation is to drive innovation and investment in the context of an industry in decline and in light of Brexit-related uncertainty.

Journal article

Babacan O, De Causmaecker S, Gambhir A, Fajardy M, Rutherford AW, Fantuzzi A, Nelson Jet al., 2020, Assessing the feasibility of carbon dioxide mitigation options in terms of energy usage, Nature Energy, Vol: 5, Pages: 720-728, ISSN: 2058-7546

Measures to mitigate the emissions of carbon dioxide (CO2) can vary substantially in terms of the energy required. Some proposed CO2 mitigation options involve energy-intensive processes that compromise their viability as routes to mitigation, especially if deployed at a global scale. Here we provide an assessment of different mitigation options in terms of their energy usage. We assess the relative effectiveness of several CO2 mitigation routes by calculating the energy cost of carbon abatement (kilowatt-hour spent per kilogram CO2-equivalent, or kWh kgCO2e–1) mitigated. We consider energy efficiency measures, decarbonizing electricity, heat, chemicals and fuels, and also capturing CO2 from air. Among the routes considered, switching to renewable energy technologies (0.05–0.53 kWh kgCO2e–1 mitigated) offer more energy-effective mitigation than carbon embedding or carbon removal approaches, which are more energy intensive (0.99–10.03 kWh kgCO2e–1 and 0.78–2.93 kWh kgCO2e–1 mitigated, respectively), whereas energy efficiency measures, such as improving building lighting, can offer the most energy-effective mitigation.

Journal article

Butnar I, Li P-H, Strachan N, Portugal Pereira J, Gambhir A, Smith Pet al., 2020, A deep dive into the modelling assumptions for biomass with carbon capture and storage (BECCS): a transparency exercise, Environmental Research Letters, Vol: 15, ISSN: 1748-9326

Bioenergy with carbon capture and storage (BECCS) is envisaged as a critical element of most deep decarbonisation pathways compatible with the Paris Agreement. Such a transformational upscaling—to 3–7 Gt CO2/yr by 2050—requires an unprecedented technological, economic, socio-cultural and political effort, along with, crucially, transparent communication between all stakeholders. Integrated Assessment Models (IAMs) that underpin the 1.5 °C scenarios assessed by IPCC have played a critical role in building and assessing deep decarbonisation narratives. However, their high-level aggregation and their complexity can cause them to be perceived as non-transparent by stakeholders outside of the IAM community. This paper bridges this gap by offering a comprehensive assessment of BECCS assumptions as used in IAMs so as to open them to a wider audience. We focus on key assumptions that underpin five aspects of BECCS: biomass availability, BECCS technologies, CO2 transport and storage infrastructure, BECCS costs, and wider system conditions which favour the deployment of BECCS. Through a structured review, we find that all IAMs communicate wider system assumptions and major cost assumptions transparently. This quality however fades as we dig deeper into modelling details. This is particularly true for sets of technological elements such as CO2 transport and storage infrastructure, for which we found the least transparent assumptions. We also found that IAMs are less transparent on the completeness of their treatment of the five BECCS aspects we investigated, and not transparent regarding the inclusion and treatment of socio-cultural and institutional-regulatory dimensions of feasibility which are key BECCS elements as suggested by the IPCC. We conclude with a practical discussion around ways of increasing IAM transparency as a bridge between this community and stakeholders from other disciplines, policy decision makers, financiers, and the public.

Journal article

Realmonte G, Drouet L, Gambhir A, Glynn J, Hawkes A, Koberle AC, Tavoni Met al., 2020, Reply to "High energy and materials requirement for direct air capture calls for further analysis and R&D", NATURE COMMUNICATIONS, Vol: 11, ISSN: 2041-1723

Journal article

Grant N, Hawkes A, Napp T, Gambhir Aet al., 2020, The appropriate use of reference scenarios in mitigation analysis, Nature Climate Change, Vol: 10, Pages: 605-610, ISSN: 1758-678X

Comparing emissions scenarios is an essential part of mitigation analysis, as climate targets can be met in various ways with different economic, energy system and co-benefit implications. Typically, a central ‘reference scenario’ acts as a point of comparison, and often this has been a no policy baseline with no explicit mitigative action taken. The use of such baselines is under increasing scrutiny, raising a wider question around the appropriate use of reference scenarios in mitigation analysis. In this Perspective, we assess three critical issues relevant to the use of reference scenarios, demonstrating how different policy contexts merit the use of different scenarios. We provide recommendations to the modelling community on best practice in the creation, use and communication of reference scenarios.

Journal article

Allan J, Donovan C, Ekins P, Gambhir A, Hepburn C, Reay D, Robins N, Shuckburgh E, Zenghelis Det al., 2020, A net-zero emissions economic recovery from COVID-19, A net-zero emissions economic recovery from COVID-19, www.imperial.ac.uk/Grantham, Publisher: COP26 Universities Network, 1

This briefing identifies key recovery policies that the UK government could introduce to both respond to the crisis of COVID-19, and support the country in meeting its commitment to reaching net-zero emissions by 2050.

Report

Le Varlet T, Schmidt O, Gambhir A, Few S, Staffell Iet al., 2020, Comparative life cycle assessment of lithium-ion battery chemistries for residential storage, Journal of Energy Storage, Vol: 28, ISSN: 2352-152X

Residential storage deployment is expected to grow dramatically over the coming decade. Several lithium-ion chemistries are employed, but the relative environmental impacts of manufacturing them is poorly understood. This study presents a cradle-to-gate life cycle assessment to quantify the environmental impact of five prominent lithium-ion chemistries, based on the specifications of 73 commercially-available battery modules used for residential applications. Three impact categories (global warming potential, cumulative energy demand and mineral resource scarcity) are analysed across two functional units (storage capacity and lifetime energy delivered). Most chemistries have embodied carbon footprints of around 200 kg CO2e per kWh of useable storage capacity, which corresponds to 43–84 g CO2e per kWh of lifetime energy delivered with daily cycling operation. Energy delivered on energy invested is also calculated at values of 2–4, which falls to 0.54–0.66 with the energy for charging included (cf. a round-trip efficiency of 82–89%). Environmental impact depends more on cycling frequency than chemistry choice, and none of the battery chemistries convincingly outperforms the others. Cells only constitute a third to a half of the environmental impact, which is comparable to the inverter. Routes to making residential lithium-ion battery systems more environmentally benign include reducing the reliance on cobalt, nickel and copper, increasing the specific useable energy, developing comprehensive recycling initiatives, and maximising the utilisation (cycle frequency) once in operation.

Journal article

McCollum DL, Gambhir A, Rogelj J, Wilson Cet al., 2020, Energy modellers should explore extremes more systematically in scenarios, Nature Energy, Vol: 5, Pages: 104-107, ISSN: 2058-7546

Journal article

Gambhir A, Tavoni M, 2019, Direct Air Carbon Capture and Sequestration: How It Works and How It Could Contribute to Climate-Change Mitigation, One Earth, Vol: 1, Pages: 405-409, ISSN: 2590-3322

Owing to the small quantity of carbon dioxide (CO2) that can be emitted before we exceed the 1.5°C–2°C target of the Paris Agreement on climate change, we are increasingly likely to require ways of removing significant CO2 from the atmosphere. In addition to the biological options considered to date such as afforestation and bioenergy with CO2 capture, direct air carbon capture and sequestration (DACCS) is emerging as a potentially important synthetic CO2 removal technology. Here, we explain how DACCS works, focusing on two major processes that have been developed into large-scale pilot plants. We discuss cost estimates and operational energy requirements, as well as ecological and ethical considerations. We highlight the role of DACCS in the low-carbon transition by discussing its benefits, while also noting potential trade-offs and uncertainties that deserve further investigation.

Journal article

Gambhir A, Cronin C, Matsumae E, Rogelj J, Workman Met al., 2019, Using futures analysis to develop resilient climate change mitigation strategies, Grantham Briefing Paper, Publisher: Imperial College London, 33

Report

Green F, Gambhir A, 2019, Transitional assistance policies for just, equitable and smooth low-carbon transitions: who, what and how?, Climate Policy, Vol: 20, Pages: 902-921, ISSN: 1469-3062

While the decarbonization of the global economy will bring immense benefits in the aggregate and to many individuals, it will also be disruptive and costly for some, at least in the short term. As these disruptions and costs have become increasingly salient in recent years, there has been an explosion of interest in the climate policy community about how low-carbon transitions can be implemented justly, equitably, and politically smoothly. A key part of what is needed in responding to this growing interest is a better understanding of the suite of ‘transitional assistance policies’ and strategies that can be deployed, alongside or as part of climate change mitigation policies and processes. Responding to this need, we survey a wide, multi-disciplinary literature to answer the ‘who’, ‘what’ and ‘how’ of transitional assistance policy: who is likely to be adversely affected by the low-carbon transition, and in what ways? What substantive strategies and policy instruments are available to governments to mitigate the burdens of low-carbon transitions? And how can governments implement such strategies and policies successfully? In the course of answering the first two of these questions, we develop a novel typology of transitional assistance policies, in which multiple policies are parsimoniously classified according to one of four coherent policy strategies, and one of five kinds of beneficiaries. In answering the third question, we emphasize the importance of certain ‘state capacities’ for shaping transition processes and managing vested interests.

Journal article

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