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Carbon dioxide removal technologies, such as bioenergy with carbon capture and direct air capture, are valuable for stringent climate targets. Previous work has examined implications of carbon removal, primarily bioenergy-based technologies using integrated assessment models, but not investigated the effects of a portfolio of removal options on power systems in detail. Here, we explore impacts of carbon removal technologies on electric sector investments, costs, and emissions using a detailed capacity planning and dispatch model with hourly resolution. We show that adding carbon removal to a mix of low-carbon generation technologies lowers the costs of deep decarbonization. Changes to system costs and investments from including carbon removal are larger as policy ambition increases, reducing the dependence on technologies like advanced nuclear and long-duration storage. Bioenergy with carbon capture is selected for net-zero electric sector emissions targets, but direct air capture deployment increases as biomass supply costs rise., Carbon dioxide removal technologies such as bioenergy with carbon capture and direct air can influence power sector planning and operations. Here the authors show how carbon removal options lower costs of deep decarbonization and alter electric sector investments.

Policymakers, planners, and other stakeholders are increasingly interested in net-zero emissions energy systems as countries and companies adopt net-zero goals. The power sector will play an important function in deeply decarbonized energy systems to lower emissions in other sectors through electrification and electricity-derived fuels. This article summarizes insights from the literature on the role and characteristics of the electric power sector as part of net-zero emissions energy systems. The power sector generally has very low or negative emissions at the point where economy-wide net-zero emissions is reached, highlighting the importance of electricity decarbonization and the value of carbon removal in limiting costs of net-zero targets. End-use electrification can alter load shapes and impact electric sector planning and operations, but the scale of these changes in net-zero systems is uncertain. Variable renewables, firm low-carbon resources, energy storage technologies, transmission/trade, and more active demand-side management are expected to have larger roles than today, though the extent of deployment depends on uncertainties about future technologies, markets, and policies.

The emergence of variable renewable energy and battery storage technologies have fundamentally transformed the electric power sector and generated demand for analysis to understand their roles in future energy systems. Although unique characteristics of these resources are well-recognized and require more sophisticated methodologies to capture effectively, guidance is limited on best practices and research gaps. This paper selectively reviews recent literature and draws upon our collective modeling experience to offer recommendations to analysts and consumers of model outputs on approaches for modeling variable renewable energy and storage in long-term electric sector models. We focus on regional- and national-scale models with technological, temporal, and spatial detail given their prevalence in planning and policy analysis, though insights are applicable in other settings. The review highlights how the research frontier has advanced in representing renewables and energy storage over the past decade; however, given the many considerations involved with appropriately capturing salient economic and operational characteristics of renewables, there is a gap between commonly used models and state-of-the-art methods. Model simplifications can materially impact policy analysis associated with power sector decarbonization and high renewables deployment, and improving model representations of variable renewables can enhance insights for policymakers and other stakeholders. This review can point the way for improved methods for established models and designs for emerging ones.

The existing literature has shown the important role of electrification in deep decarbonization pathways, increasing electricity demand as end uses decarbonize. However, studies have not focused on the effects of electrification on aggregate load shapes and peak demand, which influence power sector investments, operations, and costs. Here we investigate potential impacts of deep decarbonization on regional load shapes and peak electricity demand using a detailed end-use simulation model linked to an electric sector capacity planning model. Scenario results suggest that electrification may contribute to peak load increases and shifts from summer peaks to winter ones, especially in cooler climates due to space heating electrification. We illustrate how net-zero emissions goals can amplify electrification and may entail 120%–165% increases in electric system capacity by 2050 due to a combination of electrification and high renewables deployment. The intensity and frequency of peak demand can be limited by load flexibility (providing incentives for electric end uses to shift away from periods of high demand, e.g. through deferrable electric vehicle charging), alternate end-use technology configurations (deploying higher efficiency end-use equipment to lower electricity consumption during peaks or using dual-fuel systems such as heat pumps paired with gas furnaces), and carbon removal (displacing higher marginal abatement cost electrification while reaching an equivalent emissions cap). This analysis is a first step toward systematically exploring load curves for electrified and decarbonized energy systems, and the results highlight opportunities for future research to better understand load shape impacts and flexibility.

The Paris Climate Agreement sets out an aggressive goal of limiting global average warming to well below 2 °C. As a first step, virtually all countries have put forth greenhouse gas emission reduction pledges in the form of nationally determined contributions, or NDCs, for the 2030 timeframe. Our analysis looks beyond the NDCs to explore potential post-2030 regional emissions reduction participation and ambition. For each scenario, we examine the implications for global emissions and long-term temperature. We then evaluate the regional consequences for energy systems and ensuing costs. We conclude by reflecting on the additional global abatement costs of tightening temperature goals. Overall, this study provides a multidimensional characterization of the scale of regional effort supporting climate outcomes, details important to decision-makers as they consider mid-century emissions targets, and long-run climate objectives.

Power sector decarbonization is an important pillar of climate mitigation efforts, but perspectives differ about the relative competitiveness of generation technologies and how limited portfolio approaches (e.g., where non-renewable generation options are prohibited) could alter the costs and likelihoods of reaching emissions reduction goals. The existing literature on impacts of technological availability and cost on electric sector planning typically use models that do not have sufficient technological, spatial, and temporal detail to adequately resolve the economic competitiveness of variable renewable energy vis-a-vis dispatchable generators. Using a state-of-the-art energy-economic model, this work examines impacts of technological availability and advanced generation technologies on U.S. electricity market outcomes across a range of regional, market, and policy contexts. We show that decarbonization costs are 11%–76% higher as technological options are removed from consideration (incremental compliance costs for a 95% CO2 reduction below 2005 levels are roughly twice as high when new nuclear, carbon-capture-equipped units, and transmission are not allowed). However, the economic and technical implications of limited portfolios depend on the market and policy contexts (e.g., costs are higher with stringent targets, more extensive end-use electrification, and lower gas prices) and the costs and capabilities of the remaining options. The analysis demonstrates how lower temporal and spatial resolution models likely understate the value of technology by omitting key economic and technical features of high variable renewable pathways. Additionally, the analysis quantifies how technological change can lower costs of emissions reductions by 7%–73% and how low-cost battery storage can provide a hedge against higher costs when technological portfolios are limited.

The spatial and temporal variability of renewable generation has important economic implications for electric sector investments and system operations. This study describes a method for selecting representative hours to preserve key distributional requirements for regional load, wind, and solar time series with a two-orders-of-magnitude reduction in dimensionality. We describe the implementation of this procedure in the US-REGEN model and compare impacts on energy system decisions with more common approaches. The results demonstrate how power sector modeling and capacity planning decisions are sensitive to the representation of intra-annual variation and how our proposed approach outperforms simple heuristic selection procedures with lower resolution. The representative hour approach preserves key properties of the joint underlying hourly distributions, whereas seasonal average approaches over-value wind and solar at higher penetration levels and under-value investment in dispatchable capacity by inaccurately capturing the corresponding residual load duration curves.

The economics of climate change involves a vast array of uncertainties, complicating our understanding of climate change. This study explores uncertainty in baseline trajectories using mult...

The prospects for the European power sector indicate that it has to almost fully decarbonize in order to reach the economy-wide target of CO2-emission reduction. We apply the EU-REGEN model to explain the penetration of RES from an economic perspective, their spatial distribution, and the complementary role of conventional generation technologies. Furthermore, we identify economic consequences of national energy and climate targets. Our study shows that onshore wind power will be the most crucial generation technology for the future European power sector. Its geographic distribution is driven by resource quality. Gas power will be the major conventional generation technology for backing-up wind power. Moreover, a complete phase out of coal power proves to be not economically optimal. The paper demonstrates that existing national targets have a negative impact, especially on the German region with higher prices and lower revenues. The remaining regions profit are hardly affected. 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This paper synthesizes results of the multi-model Energy Modeling Forum 27 (EMF27) with a focus on climate policy scenarios. The study included two harmonized long-term climate targets of 450 ppm CO2-e (enforced in 2100) and 550 pm CO2-e (not-to-exceed) as well as two more fragmented policies based on national and regional emissions targets. Stabilizing atmospheric GHG concentrations at 450 and 550 ppm CO2-e requires a dramatic reduction of carbon emissions compared to baseline levels. Mitigation pathways for the 450 CO2-e target are largely overlapping with the 550 CO2-e pathways in the first half of the century, and the lower level is achieved through rapid reductions in atmospheric concentrations in the second half of the century aided by negative anthropogenic carbon flows. A fragmented scenario designed to extrapolate current levels of ambition into the future falls short of the emissions reductions required under the harmonized targets. In a more aggressive scenario intended to capture a break from observed levels of stringency, emissions are still somewhat higher in the second half due to unabated emissions from non-participating countries, emphasizing that a phase-out of global emissions in the long term can only be reached with full global participation. A key finding is that a large range of energy-related CO2 emissions can be compatible with a given long-term target, depending on assumptions about carbon cycle response, non-CO2 and land use CO2 emissions abatement, partly explaining the spread in mitigation costs.

Jacobson et al. (1) aim to demonstrate that an all-renewable energy system is technically feasible. Not only are the study’s conclusions based on strong assumptions and key methodological oversights, but its framing also omits the essential notion of trade-offs. A far more relevant question is how renewable energy technologies relate to the broader set of options for meeting long-term societal goals like managing climate change. Even if the goal were to maximize the deployment of renewable energy (and not decarbonization more generally), Jacobson et al. still fail to provide a satisfactory analysis by glossing over fundamental implications of the technical and economic dimensions of intermittency. We briefly highlight two prominent examples, and then …

The economics of climate change involves a vast array of uncertainties, complicating both the analysis and development of climate policy. This study presents the results of the first comprehensive study of uncertainty in climate change using multiple integrated assessment models. The study looks at model and parametric uncertainties for population, total factor productivity, and climate sensitivity. It estimates the pdfs of key output variables, including CO2 concentrations, temperature, damages, and the social cost of carbon (SCC). One key finding is that parametric uncertainty is more important than uncertainty in model structure. Our resulting pdfs also provide insights on tail events.

Results from four integrated assessment models show countries’ efforts to cut emissions fall towards the lower end of the social cost of carbon distribution, suggesting insufficient levels of ambition to meet the Paris Agreement goals. The Paris Agreement culminates a six-year transition towards an international climate policy architecture based on parties submitting national pledges every five years1. An important policy task will be to assess and compare these contributions2,3. We use four integrated assessment models to produce metrics of Paris Agreement pledges, and show differentiated effort across countries: wealthier countries pledge to undertake greater emission reductions with higher costs. The pledges fall in the lower end of the distributions of the social cost of carbon and the cost-minimizing path to limiting warming to 2 °C, suggesting insufficient global ambition in light of leaders’ climate goals. Countries’ marginal abatement costs vary by two orders of magnitude, illustrating that large efficiency gains are available through joint mitigation efforts and/or carbon price coordination. Marginal costs rise almost proportionally with income, but full policy costs reveal more complex regional patterns due to terms of trade effects.

In 2010, Asia accounted for 60% of global population, 39% of Gross World Product, 44% of global energy consumption and nearly half of the world's energy system CO2 emissions. Thus, Asia is an important region to consider in any discussion of climate change or climate change mitigation. This paper explores the role of Asia in mitigating climate change, by comparing the results of 23 energy-economy and integrated assessment models. We focus our analysis on seven key areas: base year data, future energy use and emissions absent climate policy, the effect of urban and rural development on future energy us and emissions, the role of technology in emissions mitigation, regional emissions mitigation, and national climate policies.

The Copenhagen Consensus, conducted at four-year intervals, is an explicit attempt to prioritise solutions to many of the world’s most pressing problems. In its 2008 exercise (CC08) (Lomborg, 2009), a panel of eminent scholars, on the basis of the input of a larger number of field experts, ranked proposed solutions to ten leading problems (see Table 1). Although we are pleased that one of the proposed solutions to climate change was raised from the bottom of the list in the 2004 exercise (Lomborg, 2004)) to the middle of the current list, we have several problems with the study design and the manner in which its results are being interpreted. As authors of the paper on climate change evaluated by the CC08 panel (Yohe et al., 2009), we are concerned that the

No abstract received.

The analysis presented here follows the design specified by the Energy Modeling Forum (EMF) Transition Scenarios study on achieving climate stabilization goals with delayed participation by developing countries. We use the MERGE model to evaluate the core EMF scenarios for both the international and the US-specific studies. Our results indicate that a radiative forcing target equivalent to 450 ppmv CO2-e cannot be met even allowing for full participation and overshoot during the entire 21st century. With delayed participation of developing countries, a target of 550 ppmv CO2-e is only attainable with pessimistic assumptions about economic growth, and even then only at very high cost. A target of 650 ppmv CO2-e can be met with delayed participation for a more affordable cost. We highlight sensitivities to the core scenarios in two key dimensions: (i) the effect of the unfolding global financial crisis on the rate of economic growth and (ii) the willingness of initially non-participating countries to agree at the beginning of the next commitment period (i.e. 2012) to join the coalition at a pre-specified date in the future. We find that while the recession does not fundamentally change the crucial role of developing country involvement, advance agreement on their part to future targets could substantially reduce costs for all countries.

In the current political environment, it is highly unlikely that all countries will agree to take on immediate commitments to reduce their greenhouse gas emissions. In particular, developing countries will look to their wealthier neighbors to be the “first movers.” In this paper, we assume that developing countries will eventually accede to an international emission reductions regime under two alternative scenarios. In the first, the decision on the part of developing countries to join the coalition is not made until just before accession. There is no planning to reconfigure their capital stock in advance of joining the coalition. In the second, we assume that developing countries commit to prespecified reductions beginning at an agreed upon date in the future; that is, they anticipate accession. We find that with an agreement now to future reductions, developing countries will modify their technology investment decisions in advance of accession to avoid being saddled with costly stranded assets, substantially reducing their GDP losses. Developed countries also benefit from not having to make as drastic reductions in the near-term to preserve the feasibility of stringent stabilization goals.

The economic costs of stabilizing greenhouse gas concentrations over the coming century depend critically on the development of new technologies in the energy sector. Our research and development (R&D) investment strategy is the control variable for technology availability. This paper proposes an analytic framework for determining optimal R&D investment allocation and presents some numerical results to demonstrate the implementation of the methodology. The value of technological advance in three targeted areas–fossil-based generation, renewables, and carbon capture and storage–is represented by the increase in expected welfare in the presence of an emissions policy constraint of initially uncertain stringency. R&D expenditure increases the probability of advance. Optimal investment is determined by its relationship with success probability, which is assumed to exhibit decreasing returns to scale, relative to the value of success. While the numerical results are speculative, the paper offers insights into the nature of an optimal technology strategy for addressing climate change.

In response to the challenge of managing the risks of a changing climate, there is no single optimal transition path for energy technology due to uncertainty in several dimensions. In this paper, we use the MERGE model, a long-term optimization model of the global energy and climate systems with regional and technological detail, enhanced in this paper with a more detailed representation of investment and dispatch detail in Europe’s electric sector, to explore a wide range of possible technology futures under alternative emissions reduction goals. We find that, based on the revised modeling approach, wind energy is attractive for Europe in all scenarios, but to a varying extent ranging from under 15% to over 75%. One of its key disadvantages is to impose lower capacity factors on other technologies, an effect that can be partially mitigated with flexible operations such as joint production of hydrogen and electricity via gasification with CCS. Solar PV is almost never attractive for Europe as a whole, unless CCS and other technologies are significantly limited.

The social cost of carbon (SCC) is a monetary estimate of global climate change damages to society from an additional unit of carbon dioxide (CO2) emissions. SCCs are used to estimate the benefits of CO2 reductions from policies. However, little is known about the modeling underlying the values or the implied societal risks, making SCC estimates difficult to interpret and assess. This study performs the first in-depth examination of SCC modeling using controlled diagnostic experiments that yield detailed intermediate results, allow for direct comparison of individual components of the models, and facilitate evaluation of the individual model SCCs. Specifically, we analyze DICE, FUND, and PAGE and the multimodel approach used by the US Government. Through our component assessments, we trace SCC differences back to intermediate variables and specific features. We find significant variation in component-level behavior between models driven by model-specific structural and implementation elements, some resulting in artificial differences in results. These elements combine to produce model-specific tendencies in climate and damage responses that contribute to differences observed in SCC outcomes — producing PAGE SCC distributions with longer and fatter right tails and higher averages, followed by DICE with more compact distributions and lower averages, and FUND with distributions that include net benefits and the lowest averages. Overall, our analyses reveal fundamental model behavior relevant to many disciplines of climate research, and identify issues with the models, as well as the overall multimodel approach, that need further consideration. With the growing prominence of SCCs in decision-making, ranging from the local-level to international, improved transparency and technical understanding is essential for informed decisions.

This paper analyzes the projected development of energy systems in the Asia region in the hypothetical absence of future carbon policies. Baseline scenarios prepared by participating teams in the Asia Modeling Exercise are used to generate a comprehensive assessment of the key drivers of CO2 emissions for the next several decades, especially for China and India. We find a very wide range of projected emissions paths across the models and identify per capita income and energy intensity as the two major factors responsible for the variation. While the range of assumptions for growth in the former is roughly consistent with historical experience in other Asian economies, models foresee faster reductions in the latter with respect to those observed in neighboring countries at similar stages of economic development. On the other hand, there is a considerable agreement on the evolution of the energy technology mix, which is assumed to continue to be dominated by fossil fuels in the foreseeable future.

Recent growth in carbon dioxide emissions from China’s energy sector has exceeded expectations. In a major US government study of future emissions released in 2007 (1), participating models appear to have substantially underestimated the near-term rate of increase in China’s emissions. We present a recalibration of one of those models to be consistent with both current observations and historical development patterns. The implications of the new specification for the feasibility of commonly discussed stabilization targets, particularly when considering incomplete global participation, are profound. Unless China’s emissions begin to depart soon from their (newly projected) business-as-usual path, stringent stabilization goals may be unattainable. The current round of global policy negotiations must engage China and other developing countries, not to the exclusion of emissions reductions in the developed world and possibly with the help of significant financial incentives, if such goals are to be achieved. It is in all nations’ interests to work cooperatively to limit our interference with the global climate.

This paper builds upon recent work by the US Climate Change Science Program (CCSP). Among its products, the CCSP developed new emission projections for the major man-made greenhouse gases, explored the effects of emission limits on the energy system, and calculated the costs of various stabilization constraints to the economy. This paper applies one of the models used for that analysis to explore the sensitivity of the results to three potentially critical factors: the stabilization level, the policy design, and the availability and costs of low- to zero-emitting technologies. The major determinant of costs is likely to be something over which we have little control - Mother Nature. The choice of stabilization level will reflect our understanding of the science of global climate change. We have little control over many of the key bio-geophysical processes which, to a major extent, will determine what constitutes dangerous anthropogenic interference with the climate system. We consider two limits on radiative forcing, corresponding to stabilizing CO2 concentrations at approximately 450 ppmv and 550 ppmv. These levels have been chosen because of the fundamentally different nature of the challenge posed by each. In the case of the lower concentration limit, emission reductions will be required virtually immediately and annual GDP losses to the US could approach 5%. With the higher concentration limit, the pressure for a sharp reduction in near-term emissions is not as great. This offers some potential to reduce GDP losses. Indeed, we find that depending upon the concentration limit, implementing market mechanisms which take advantage of where and when flexibility can markedly reduce GDP losses, perhaps by as much as an order of magnitude. However, for a variety of reasons, our ability to realize such savings may be compromised. One possible impediment relates to the proximity to the target. If the limit is imminent, flexibility will be greatly reduced. The nature of the coalition and our willingness to permit borrowing emission rights from the future will also affect the magnitude of the potential savings. As a result, the reduction in GDP losses from where and when flexibility may turn out to be only a small fraction of what has been previously estimated. Fortunately, the biggest opportunity for managing costs may come from something over which we do have considerable control. We find that investments in climate friendly technologies can reduce GDP losses to the US by a factor of two or more. At present, we have insufficient economically competitive substitutes for high carbon emitting technologies. The development of low- to zero-emitting alternatives will require both a sustained commitment on the part of the public sector upstream in the R&D chain and incentives for the private sector to bring the necessary technologies to the marketplace. Aside from helping to assure that environmental goals are met in an economically efficient manner, climate policy can also serve as an enabler of new technologies. By recognizing the acute shortage of low-cost substitutes, the long lead times required for development and deployment, and the market failures that impede technological progress, climate policy can play an important role in reducing the long-term costs of the transition.

This paper uses the MERGE integrated assessment model to identify the least-cost mitigation strategy for achieving a range of climate policies. Mitigation is measured in terms of GDP foregone. This is not a benefit-cost analysis. No attempt is made to calculate the reduction in damages brought about by a particular policy. Assumptions are varied regarding the availability of energy-producing and energy-using technologies. We find pathways with substantial reductions in temperature change, with the cost of reductions varying significantly, depending on policy and technology assumptions. The set of scenarios elucidates the potential energy system transformation demands that could be placed on society. We find that policy that allows for “overshoot” of a radiative forcing target during the century results in lower costs, but also a higher temperature at the end of the century. We explore the implications of the costs and availability of key mitigation technologies, including carbon capture and storage (CCS), bioenergy, and their combination, known as BECS, as well as nuclear and energy efficiency. The role of “negative emissions” via BECS in particular is examined. Finally, we demonstrate the implications of nationally adopted emissions timetables based on articulated goals as a counterpoint to a global stabilization approach.