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Nuclear power is currently the single largest carbon-free source of electricity in the United States. The climate mitigation cost savings of the existing U.S. nuclear fleet is denominated in hundre...

The transportation sector is experiencing a period of unprecedented and disruptive change from the rapid improvement in the performance and cost of battery electric vehicles (BEVs). We quantify the carbon mitigation cost impact from transport electrification with BEVs under policies to limit the Earth surface temperature change to [Formula: see text]C. Our results show that the reduction in carbon mitigation costs from transport electrification is as high as 40%. While BEVs without decarbonization policies merely shift the sources of emissions, aggressive BEV adoption with policies dramatically reduces the cost of addressing climate change because power sector decarbonization costs are capped by a broad range of emission-free power technologies. The decarbonization of electricity caps road transport decarbonization costs with BEVs. Without BEVs, transportation decarbonization costs escalate as the liquid fuel costs rise sharply with carbon penalties on fossil fuels and large-scale biofuels production. Electrification of transport with BEVs transforms a “problem” sector into a major part of the climate solution.

Long-term temperature change and variability are expected to have significant impacts on future electric capacity and investments. This study improves upon past studies by accounting for hourly and monthly dynamics of electricity use, long-term socioeconomic drivers, and interactions of the electric sector with rest of the economy for a comprehensive analysis of temperature change impacts on cooling and heating services and their corresponding impact on electric capacity and investments. Using the United States as an example, here we show that under a scenario consistent with a socioeconomic pathway 2 (SSP2) and representative concentration pathway 8.5 (RCP 8.5), mean temperature changes drive increases in annual electricity demands by 0.5-8% across states in 2100. But more importantly, peak temperature changes drive increases in capital investments by 3-22%. Moreover, temperature-induced capital investments are highly sensitive to both long-term socioeconomic assumptions and spatial heterogeneity of fuel prices and capital stock characteristics, which underscores the importance of a comprehensive approach to inform long-term electric sector planning., Temperature changes as a result of climate change are expected to impact electric capacity and investment. Here, the authors show that in the United States under socioeconomic pathway 2 and RCP 8.5 mean temperature rises will drive increased electricity demand (0.5-8%) by 2100, along increases in capital investments by 3-22%.

Governance measures such as restrictions on groundwater pumping and adjustments to sectoral water pricing have been suggested as response strategies to curtail recent increases in groundwater pumping and enhance sustainable water use. However, little is known about the impacts of such sustainability strategies. We investigate the implications of such measures, with the United States (U.S.) as an example. Using the Global Change Analysis Model (GCAM) with state-level details in the U.S., we find that the combination of these two governance measures can drastically alter agricultural production in the U.S. The Southwest stands to lose upwards of 25% of their total agricultural production, much of which is compensated for by production increases in river basins on the east coast of the U.S. The implementation of future sustainable water governance measures will require additional investments that allow farmers to maximize production while minimizing water withdrawals to avoid potentially detrimental revenue losses.

This paper describes GCAM-USA v5.3_water_dispatch, an open source model that represents key interactions across economic, energy, water, and land systems in a consistent global framework, with subnational detail in the United States. GCAM-USA divides the world into 31 geopolitical regions outside the United States (U.S.) and represents the U.S. economic and energy systems in 51 state-level regions (50 states plus the District of Columbia). The model also includes 235 water basins and 384 land-use regions; 23 of each fall at least partially within the United States. GCAM-USA offers a level of process and temporal resolution rare for models of its class and scope, including detailed subnational representation of U.S. water demands and supplies and sub-annual operations (day/night for each month) in the U.S. electric power sector. GCAM-USA can be used to explore how changes in socioeconomic drivers, technological progress, or policy impact demands for, and production of, energy, water, and crops at a subnational level in the United States, while maintaining consistency with broader national and international conditions. This paper describes GCAM-USA’s structure, inputs, and outputs, with emphasis on new model features. Four illustrative scenarios encompassing varying socioeconomic and energy system futures are used to explore subnational changes in energy, water, and land-use outcomes. We conclude with information about how public users can access the model.

Climate change is projected to increase hydropower generation in some parts of the world and decrease it in others. Here we explore the possible consequences of these impacts for the electricity supply sector at the global scale. Regional hydropower projections are developed by forcing a coupled global hydrological and dam model with downscaled, bias-corrected climate realizations. Consequent impacts on power sector composition and associated emissions and investment costs are explored using the Global Change Assessment Model (GCAM). We find that climate-driven changes in hydropower generation may shift power demands onto and away from carbon intensive technologies. This causes significantly altered power sector CO2 emissions in several hydro-dependent regions, although the net global impact is modest. For drying regions, we estimate a global, cumulative investment need of approximately one trillion dollars (±$500 billion) this century to make up for deteriorated hydropower generation caused by climate change. Total investments avoided are of a similar magnitude across regions projected to experience increased precipitation. Investment risks and opportunities are concentrated in hydro-dependent countries for which significant climate change is expected. Various countries throughout the Balkans, Latin America and Southern Africa are most vulnerable, whilst Norway, Canada, and Bhutan emerge as clear beneficiaries.

Future scenarios and assessment studies used to prepare for long-term energy transitions and develop robust strategies to address climate change are highly dependent on the assessment of technology characteristics and availability. The electric power sector in the United States recently experienced a significant cost escalation: e.g., construction costs for large plants such as nuclear and coal-fired power plants doubled between 2003 and 2007. We assess the main drivers of this escalation. While many factors have affected costs, some of the most significant include cost of materials, particularly the price of metals and to a lesser extent cement, possible increases in labor quantity requirements, the aggressive worldwide competition for power plant design and construction resources, driven by high demand in Asia, market and regulatory changes, and general uncertainty about future regulations and climate policies. We recalibrate power sector technology costs in the Global Change Assessment Model (GCAM) based on an extensive literature review of recent (post-2010) studies and in the process develop a coherent and updated set of current cost and performance assumptions for all major electricity-generating technologies. While current cost and performance assumptions of electricity-generating technologies are key drivers of short-term technology deployment and technology mix in the electricity sector, medium- and long-term deployment pathways are significantly affected by assumed efficiency improvement rates and cost reductions. We develop and demonstrate a method to project efficiency and construction cost of power plants and report a sensitivity analysis to explore the importance of such assumptions in future scenarios generated by GCAM.

Electricity capacity planning requires simultaneous consideration of multi-decadal and sub-annual power sector dynamics along with interactions of the power sector with other economic sectors and uncertain physical conditions. A challenge for long-term multi-sector models is to capture critical structural elements of the power sector without drastically increasing solution complexity. We incorporate sub-annual dynamics in the power sector module of a multi-sector model (GCAM-USA). We combine linearly optimal dispatch modeling for electricity generation with a non-linear method for new capacity investment assuming no foresight. With this approach, we are able to model the impact of future surprises. We demonstrate this capability by modeling the impact of different natural gas price paths on state-level power-sector investment and operation in the U.S. Keywords: Electric sector, Power sector, Investment, Dispatch, Capacity expansion

Water stressed regions rely heavily on the import of water-intensive goods to offset insufficient food production driven by socioeconomic and environmental factors. The water embedded in these traded commodities, virtual water, has received increasing interest in the scientific community. However, comprehensive future projections of virtual water trading remain absent. Here we show, for the first time, changes over the 21st century in the amount of various water types required to meet international agricultural demands. Accounting for evolution in socioeconomic and climatic conditions, we estimate future interregional virtual water trading and find trading of renewable water sources may triple by 2100 while nonrenewable groundwater trading may at least double. Basins in North America, and the La Plata and Nile Rivers are found to contribute extensively to virtual water exports, while much of Africa, India, and the Middle East relies heavily on virtual water imports by the end of the century., Assessments of future virtual water trading are still lacking. Here the authors estimated the global virtual water trade throughout the century and found that virtual green water exports and virtual blue water exports at least triple to more than 3200 bcm and 170 bcm, respectively, by the end of the century.

This study incorporates the energy demands of water abstraction, treatment, distribution, and post-use wastewater treatment into the Global Change Analysis Model, an integrated human-Earth systems model, and analyzes a range of scenarios that estimate the future evolution of this demand of energy. The study complements research on historical and future water-for-energy, and builds on bottom-up estimates of historical energy-for-water (EFW), by integrating EFW into nation-level energy statistics, where EFW is normally categorized with other energy use in the commercial and public services, industrial, agricultural, and/or electric power sectors. This development allows more resolved projections of future energy demands in general, and in this study, allows for assessment of the energy implications of improvements in water access and water quality that are consistent with the sustainable development goals (SDGs). In our baseline scenario, EFW increases by 2.6 times from 2015 to 2050, and in the SDG scenario with enhanced water access, standards for treatment of wastewater, and irrigation, the consequent EFW demands quadruple from 2015 to 2050. The study highlights the value of integrated, multi-sector analysis in quantifying the future impacts of the SDGs and other aspirational targets.

Water is essential for the world’s food supply, for energy production, including bioenergy and hydroelectric power, and for power system cooling. Water is already scarce in many regions of the world and could present a critical constraint as society attempts simultaneously to mitigate climate forcing and adapt to climate change, and to provide for a larger and more prosperous human population. Numerous studies have pointed to growing pressures on the world’s scarce fresh water resources from population and economic growth, and climate change. This study goes further. We use the Global Change Assessment Model to analyze interactions between population, economic growth, energy, land, and water resources simultaneously in a dynamically evolving system where competing claims on water resources from all claimants—energy, land, and economy—are reconciled with water resource availability—from renewable water, non-renewable groundwater and desalinated water sources —across 14 geopolitical regions, 151 agriculture-ecological zones, and 235 major river basins. We find that previous estimates of global water withdrawal projections are overestimated. Model simulations show that it is more economical in some basins to alter agricultural and energy activities rather than utilize non-renewable groundwater or desalinated water. This study highlights the importance of accounting for water as a binding factor in agriculture, energy and land use decisions in integrated assessment models and implications for global responses to water scarcity, particularly in the trade of agricultural commodities and land-use decisions.

Despite significant effort to quantify the interdependence of the water and energy sectors, global requirements of energy for water (E4W) are still poorly understood, which may result in biases in projections and consequently in water and energy management and policy. This study estimates water-related energy consumption by water source, sector, and process for 14 global regions from 1973 to 2012. Globally, E4W amounted to 10.2 EJ of primary energy consumption in 2010, accounting for 1.7%-2.7% of total global primary energy consumption, of which 58% pertains to fresh surface water, 30% to fresh groundwater, and 12% to nonfresh water, assuming median energy intensity levels. The sectoral E4W allocation includes municipal (45%), industrial (30%), and agricultural (25%), and main process-level contributions are from source/conveyance (39%), water purification (27%), water distribution (12%), and wastewater treatment (18%). While the United States was the largest E4W consumer from the 1970s until the 2000s, the largest consumers at present are the Middle East, India, and China, driven by rapid growth in desalination, groundwater-based irrigation, and industrial and municipal water use, respectively. The improved understanding of global E4W will enable enhanced consistency of both water and energy representations in integrated assessment models.

Future changes in climate and socioeconomic systems will drive both the availability and use of water resources, leading to evolutions in scarcity. The contributions of both systems can be quantified individually to understand the impacts around the world, but also combined to explore how the coevolution of energy-water-land systems affects not only the driver behind water scarcity changes, but how human and climate systems interact in tandem to alter water scarcity. Here we investigate the relative contributions of climate and socioeconomic systems on water scarcity under the Shared Socioeconomic Pathways-Representative Concentration Pathways framework. While human systems dominate changes in water scarcity independent of socioeconomic or climate future, the sign of these changes depend particularly on the socioeconomic scenario. Under specific socioeconomic futures, human-driven water scarcity reductions occur in up to 44% of the global land area by the end of the century.

Rapidly growing energy demand from China's transportation sector in the last two decades have raised concerns over national energy security, local air pollution, and carbon dioxide (CO 2 ) emissions, and there is broad consensus that China's transportation sector will continue to grow in the coming decades. This paper explores the future development of China's transportation sector in terms of service demands, final energy consumption, and CO 2 emissions, and their interactions with global climate policy. This study develops a detailed China transportation energy model that is nested in an integrated assessment model—Global Change Assessment Model (GCAM)—to evaluate the long-term energy consumption and CO 2 emissions of China's transportation sector from a global perspective. The analysis suggests that, without major policy intervention, future transportation energy consumption and CO 2 emissions will continue to rapidly increase and the transportation sector will remain heavily reliant on fossil fuels. Although carbon price policies may significantly reduce the sector's energy consumption and CO 2 emissions, the associated changes in service demands and modal split will be modest, particularly in the passenger transport sector. The analysis also suggests that it is more difficult to decarbonize the transportation sector than other sectors of the economy, primarily owing to its heavy reliance on petroleum products.

The electric power sector both affects and is affected by climate change. Numerous studies highlight the potential of the power sector to reduce greenhouse gas emissions. Yet fewer studies have explored the physical impacts of climate change on the power sector. The present analysis examines how projected rising temperatures affect the demand for and supply of electricity. We apply a common set of temperature projections to three well-known electric sector models in the United States: the US version of the Global Change Assessment Model (GCAM-USA), the Regional Electricity Deployment System model (ReEDS), and the Integrated Planning Model (IPM®). Incorporating the effects of rising temperatures from a control scenario without emission mitigation into the models raises electricity demand by 1.6 to 6.5 % in 2050 with similar changes in emissions. The increase in system costs in the reference scenario to meet this additional demand is comparable to the change in system costs associated with decreasing power sector emissions by approximately 50 % in 2050. This result underscores the importance of adequately incorporating the effects of long-run temperature change in climate policy analysis.

With high reliance on light-duty vehicles in the present, the future of global transportation system is also geared towards private modes, which has significant energy and emission implications. Public transportation has been argued as an alternative strategy for meeting the rising transportation demands of the growing world, especially the poor, in a sustainable and energy efficient way. The present study analyzes an important yet under-researched question – what are the long-term energy and emission implications of an electric rail based passenger transportation system for meeting both long and short distance passenter transportation needs? We analyze a suite of electric rail share scenarios with and without climate policy. In the reference scenario, the transportation system will evolve towards dominance of fossil based light-duty vehicles. We find that an electric rail policy is more successful than an economy wide climate policy in reducing transport sector energy demand and emissions. Economy wide emissions however can only be reduced through a broader climate policy, the cost of which can be reduced by hundreds of billions of dollars across the century when implemented in combination with the transport sector focused electric rail policy. Moreover, higher share of electric rail enhances energy security for oil importing nations and reduces vehicular congestion and road infrastructure requirement as well.

Achieving climate policy targets will require large-scale deployment of low-carbon energy technologies, including nuclear power. The small modular reactor (SMR) is viewed as a possible solution to the problems of energy security as well as climate change. In this paper, we use an integrated assessment model (IAM) to investigate the evolution of a global energy portfolio with SMRs under a stringent climate policy. Technology selection in the model is based on costs; we use results from previous expert elicitation studies of SMR costs. We find that the costs of achieving a 2 °C target are lower with SMRs than without. The costs are higher when large reactors do not compete for market share compared to a world in which they can compete freely. When both SMRs and large reactors compete for market share, reduction in mitigation cost is achieved only under advanced assumptions about SMR technology costs and future cost improvements. While the availability of SMRs could lower mitigation costs by a moderate amount, actual realization of these benefits would depend on the rapid up-scaling of SMRs in the near term. Such rapid deployment could be limited by several social, institutional and behavioral obstacles.

Improving the energy efficiency of building stock, commercial equipment, and household appliances can have a major positive impact on energy use, carbon emissions, and building services. Sub-national regions such as the U.S. states wish to increase energy efficiency, reduce carbon emissions, or adapt to climate change. Evaluating sub-national policies to reduce energy use and emissions is difficult because of the large uncertainties in socioeconomic factors, technology performance and cost, and energy and climate policies. Climate change itself may undercut such policies. However, assessing all of the uncertainties of large-scale energy and climate models by performing thousands of model runs can be a significant modeling effort with its accompanying computational burden. By applying fractional–factorial methods to the GCAM-USA 50-state integrated-assessment model in the context of a particular policy question, this paper demonstrates how a decision-focused sensitivity analysis strategy can greatly reduce computational burden in the presence of uncertainty and reveal the important drivers for decisions and more detailed uncertainty analysis.

Objective Because long-term socioeconomic transformation and energy service expansion show large spatial heterogeneity, advanced understanding of climate change impact on buildings energy use at the sub-national level will offer useful insights into climate policy and regional energy system planning. Methods In this study, we present a detailed buildings energy model with U.S. state-level representation, nested in an integrated assessment framework of the Global Change Assessment Model (GCAM). We project state-level buildings energy demand and its spatial pattern through the end of the century, considering the impact of climate change based on the estimates of heating and cooling degree days derived from downscaled USGS CASCaDE temperature data. Results The results indicate that climate change has a large impact on heating and cooling buildings energy and fuel use at the state level and that the 48 U.S. contiguous states exhibit a large spatial heterogeneity (ranges from −10% to +10% for total, −10% to +20% for electricity use and −20% to −5% for oil and gas use in the A2 scenario). Sensitivity analysis explores the potential implications of multiple driving forces, including climate action that would both change the price of energy and reduce climate change, the choice of climate models, and population and GDP growth. In addition, the 50-state building model is compared to a comparable version of the model which represents the entire United States as one region. Conclusions The study clearly demonstrates the spatially varying nature of fuel consumption changes that might occur from a changing climate. Although the study illustrates the importance of incorporating climate change into infrastructure-planning exercises, it also demonstrates that uncertainties about underlying drivers still must weigh heavily on these planning decisions. Finally, the study demonstrates that the 50-state building model provides both insights at the regional level and potentially better national-level estimates. Practice implication The findings from this study will help the climate-based policy decision and energy system, especially utility planning related to the buildings sector at the U.S. state and regional level facing the potential climate change.

In this paper, we assess future water demands for the agricultural (irrigation and livestock), energy (electricity generation, primary energy production and processing), industrial (manufacturing and mining), and municipal sectors, by incorporating water demands into a technologically-detailed global integrated assessment model of energy, agriculture, and climate change � the Global Change Assessment Model (GCAM). Base-year water demands � both gross withdrawals and net consumptive use � are assigned to specific modeled activities in a way that maximizes consistency between bottom-up estimates of water demand intensities of specific technologies and practices, and top-down regional and sectoral estimates of water use. The energy, industrial, and municipal sectors are represented in fourteen geopolitical regions, with the agricultural sector further disaggregated into as many as eighteen agro-ecological zones (AEZs) within each region. We assess future water demands representing six socioeconomic scenarios, with no constraints imposed by future water supplies. The scenarios observe increases in global water withdrawals from 3710 km3 year- 1 in 2005 to 6195�8690 km3 year- 1 in 2050, and to 4869�12,693 km3 year- 1 in 2095. Comparing the projected total regional water withdrawals to the historical supply of renewable freshwater, the Middle East exhibits the highest levels of water scarcity throughout the century, followed by India; water scarcity increases over time in both of these regions. In contrast, water scarcity improves in some regions with large base-year electric sector withdrawals, such as the USA and Canada, due to capital stock turnover and the almost complete phase-out of once-through flow cooling systems. The scenarios indicate that: 1) water is likely a limiting factor in meeting future water demands, 2) many regions can be expected to increase reliance on non-renewable groundwater, water reuse, and desalinated water, but they also highlight an important role for development and deployment of water conservation technologies and practices.

We explore the implications that alternative pathways for human population and economic development have for the role of Asia in reference no-climate-policy scenarios and scenarios in which climate forcing is limited. We consider three different pathways of socioeconomic development, which we refer to as Shared Socio-economic Pathways (SSPs) and four different levels of limitation on climate forcing, which we refer to as Shared Climate Policy Assumptions (SPAs). SSPs are differentiated by population and economic growth assumptions, while SPAs are differentiated on the level of radiative forcing in the year 2100. Regardless of the scenarios we examined Asia plays a central role in shaping the world's future with nearly half of the world's people and more than half of the world's economic activity and energy consumption. The future of Asia and the world are dramatically different across the various combinations of SSPs and SPAs. High population worlds place significant stress on Asian resources and ecosystems. In high population SSPs the poorest members of the population face high energy and food prices and the more stringent the level of emissions mitigation, the more stress poor populations experience, though the more stringent the emissions mitigation, the larger the area of unmanaged ecosystems that are preserved.

Large-scale, dedicated commercial biomass energy systems are a potentially large contributor to meeting global climate policy targets by the end of the century. We use an integrated assessment model of energy and agriculture systems to show that, given a climate policy in which terrestrial carbon is appropriately valued equally with carbon emitted from the energy system, biomass energy has the potential to be a major component of achieving these low concentration targets. A key aspect of the research presented here is that the costs of processing and transporting biomass energy at much larger scales than current experience are explicitly incorporated into the modeling. From the scenario results, 120–160 EJ/year of biomass energy is produced globally by midcentury and 200–250 EJ/year by the end of this century. In the first half of the century, much of this biomass is from agricultural and forest residues, but after 2050 dedicated cellulosic biomass crops become the majority source, along with growing utilization of waste-to-energy. The ability to draw on a diverse set of biomass-based feedstocks helps to reduce the pressure for drastic large-scale changes in land use and the attendant environmental, ecological, and economic consequences those changes would unleash. In terms of the conversion of bioenergy feedstocks into value added energy, this paper demonstrates that biomass is and will continue to be used to generate electricity as well as liquid transportation fuels. A particular focus of this paper is to show how climate policies and technology assumptions – especially the availability of carbon dioxide capture and storage (CCS) technologies – affect the decisions made about where the biomass is used in the energy system. The potential for net-negative electric sector emissions through the use of CCS with biomass feedstocks provides an attractive part of the solution for meeting stringent emissions constraints; we find that at carbon prices above $150/tCO 2 , over 90% of biomass in the energy system is used in combination with CCS. Despite the higher technology costs of CCS, it is a very important tool in controlling the cost of meeting a target, offsetting the venting of CO 2 from sectors of the energy system that may be more expensive to mitigate, such as oil use in transportation. CCS is also used heavily with other fuels such as coal and natural gas, and by 2095 a total of 1530 GtCO 2 has been stored in deep geologic reservoirs. The paper also discusses the role of cellulosic ethanol and Fischer–Tropsch biomass derived transportation fuels as two representative conversion processes and shows that both technologies may be important contributors to liquid fuels production, with unique costs and emissions characteristics.

Plug-in hybrid electric vehicles (PHEVs) have the potential to be an economic means of reducing direct (or tailpipe) carbon dioxide (CO 2 ) emissions from the transportation sector. However, without a climate policy that places a limit on CO 2 emissions from the electric generation sector, the net impact of widespread deployment of PHEVs on overall U.S. CO 2 emissions is not as clear. A comprehensive analysis must consider jointly the transportation and electricity sectors, along with feedbacks to the rest of the energy system. In this paper, we use the Pacific Northwest National Laboratory's MiniCAM model to perform an integrated economic analysis of the penetration of PHEVs and the resulting impact on total U.S. CO 2 emissions. In MiniCAM, the deployment of PHEVs (or any technology) is determined based on its relative economics compared to all other methods of providing fuels and energy carriers to serve passenger transportation demands. Under the assumptions used in this analysis where PHEVs obtain 50–60% of the market for passenger automobiles and light-duty trucks, the ability to deploy PHEVs under the two climate policies modelled here results in over 400 million tons (MT) CO 2 per year of additional cost-effective emissions reductions from the U.S. economy by 2050. In addition to investments in nuclear and renewables, one of the key technology options for mitigating emissions in the electric sector is CO 2 capture and storage (CCS). The additional demand for geologic CO 2 storage created by the introduction of the PHEVs is relatively modest: approximately equal to the cumulative geologic CO 2 storage demanded by two to three large 1000 megawatt (MW) coal-fired power plants using CCS over a 50-year period. The introduction of PHEVs into the U.S. transportation sector, coupled with climate policies such as those examined here, could also reduce U.S. demand for oil by 20–30% by 2050 compared to today's levels.

The EMF22 Transition Scenario subgroup explores the implications of delayed accession on limiting climate change to various radiative forcing levels. This paper focuses on the cost of limiting radiative forcing and the role that industrial leakage plays in scenarios of delayed accession. We find that delayed participation shifts the cost burden toward regions that take early action and away from regions that undertake mitigation later. However, the inefficiencies introduced by delay are so great that present discounted costs are higher in the delayed scenario for regions that delay as well as for regions taking early actions. An important element of these inefficiencies is industrial emissions leakage, that is non-participating regions increase their emissions relative to the reference case. In aggregate, industrial leakage rates are less than 10% if all regions of the world begin emissions mitigation by 2050—higher in carbon-intensive sectors and lower in low-carbon-intensity sectors. Additionally, we consider the implication of technology on carbon prices, the feasibility of limiting radiative forcing to low levels, and the incentives to overshoot the radiative forcing limit.

This paper, a contribution to the EMF 22 subgroup on Transition Scenarios, examines the relationship between technology evolution over the next 40 years and the cost, energy, and greenhouse gas emissions consequences of possible U.S. mitigation goals. The paper explores these issues within the context of cumulative emissions targets based on linear reductions in CO 2 -e emissions of 50% and 80% below 1990 levels by 2050. Six technology futures were constructed within the MiniCAM integrated assessment model and then applied to the emissions targets. The paper explores the influence of technology availability and expectations of future technology availability on the economic consequences of emissions mitigation, on the time path of emissions mitigation, and on the evolution of the U.S. energy system over time. One of the strongest themes to emerge from the scenarios in this study is that near-term decision-making depends on the availability of technology decades into the future, when deep emissions reductions are required to meet the cumulative emissions goals. In the scenarios in this paper, it is the expectations about future technology that have the most dramatic effect on greenhouse gas emissions prices and emissions reductions in 2020, as opposed to near-term technology availability. Moreover, it is the nature of technology 20, 30, and 40 years out, rather than availability and deployment of technology in the next decade, that will largely determine the character of the mid-century energy system.

The EMF 22 subgroup on Transition Scenarios explores a rich suite of potential future worlds in which climate change is limited to a variety of alternative radiative forcing levels. This paper focuses primarily on the requirements to limit radiative forcing from Kyoto gases to 2.6 W/m2. Given that we estimate year 2005 radiative forcing to be 2.4 W/m2, the 2.6 W/m2 limit creates a non-trivial constraint. Allowing radiative forcing to exceed the long-term target level provides greater latitude in achieving the goal, but implies major changes to both global energy and land-use systems in the near term as well as the long term. In addition, delay on the part of major emitting parties creates potential “leakage” in both energy and land use. We estimate the challenging near-term and long-term deployment of new wind power, nuclear power and CO2 capture and storage associated with the 2.6 W/m2 limit.

Plug-in hybrid electric vehicles (PHEVs) have the potential to be an economic means of reducing direct (or tailpipe) carbon dioxide (CO 2 ) emissions from the transportation sector. However, without a climate policy that places a limit on CO 2 emissions from the electric generation sector, the net impact of widespread deployment of PHEVs on overall US CO 2 emissions is not as clear. A comprehensive analysis must consider jointly the transportation and electricity sectors, along with feedbacks to the rest of the energy system. In this paper, we use the Pacific Northwest National Laboratory MiniCAM model to perform an integrated economic analysis of the penetration of PHEVs and the resulting impact on total US CO 2 emissions. Under the assumptions used in this analysis where PHEVs obtain 50–60% of the market for passenger and light-duty trucks, the ability to deploy PHEVs under the two climate policies modeled here results in 6000–7300 Mt CO 2 of additional cost -effective emissions reductions from the US economy over the period 2005–2050. The additional demand for geologic CO 2 storage created by the introduction of the PHEVs is approximately equal to the cumulative geologic CO 2 storage demanded by two to three large 1000 MW IGCC+CCS power plants over a 50 -year period. The introduction of PHEVs into the US transportation sector, coupled with climate policies such as those examined here, can also reduce US demand for oil by 20–30% by 2050 compared to today’s levels.

We examine the potential role of several energy technologies, including carbon capture and dispose (CC and D), hydrogen and advanced transportation systems, on the cost of stabilizing CO2 concentrations. While not currently deployed at scale, CC and D, hydrogen energy systems, and biotechnology have the potential to be major components of the global energy system by the middle of the 21st century. Other technologies, such as renewables, nuclear power and energy efficiency also play critical roles in addressing climate change. The development of advanced technologies in the absence of limitations on the concentration of carbon dioxide need not lead to CO2 stabilization.

Models of the global energy system can help shed light on the competition and complementarities among technologies and energy systems both in the presence and absence of actions to affect the concentration of greenhouse gases. This paper explores the role of modeling in the analysis of technology deployment in addressing climate change. It examines the competition among technologies in a variety of markets, and explores conditions under which new markets, such as for hydrogen and carbon disposal, or modern commercial biomass, could emerge. Carbon capture and disposal technologies are shown to have the potential to play a central role in controlling the cost of stabilizing the concentration of greenhouse gases, the goal of the UN Framework Convention on Climate Change.

In this analysis, we explore the role of solar energy, specifically utility-scale photovoltaic (PV) technology, in supplying the world's growing demand for energy while limiting the impact of climate change by reducing carbon dioxide emissions. We present a range of cost paths for the technology and examine the role of solar energy in the global energy system under these paths and a reference scenario. We also assess the impacts of these cost paths on the role of solar power under carbon constraint scenarios designed to stabilize the concentration of atmospheric carbon dioxide over the next century. Our analysis shows that solar energy can play a significant role in the future global energy system, and that the benefit of the solar energy option increases as the limitation on carbon emissions becomes more stringent. But, lowering the cost of power production to the point at which solar is competitive with other options is critical if solar power is to become a core generation technology. Aggressively lowering the cost of solar energy in the next few decades will ensure that solar energy technologies are a prominent part of any global energy system, so the potential value of research in solar energy is great. Copyright © 2000 John Wiley & Sons, Ltd.

Using the Indian module of the Second Generation Model (SGM), we explore a reference case and three scenarios in which greenhouse gas emissions were controlled. Two alternative policy instruments (carbon taxes and tradable permits) were analyzed to determine comparative costs of stabilizing emissions at (1) 1990 levels (the 1X case), (2) two times the 1990 levels (the 2X case), and (3) three times the 1990 levels (the 3X case). The analysis takes into account India's rapidly growing population and the abundance of coal and biomass relative to other fuels. We also explore the impacts of a global tradable permits market to stabilize global carbon emissions on the Indian economy under the following two emissions allowance allocation methods. 1. 1. Grandfathered emissions: emissions allowances are allocated based on 1990 emissions. 2. 2. Equal per capita emissions: emissions allowances are allocated based on share of global population. Tradable permits represent a lower-cost method to stabilize Indian emissions than carbon taxes, i.e. global action would benefit India more than independent actions.

Nuclear energy is an important part of our current global energy system, and contributes to supplying the significant demand for electricity for many nations around the world. There are 433 commercial nuclear power reactors operating in 30 countries with an installed capacity of 367 GWe as of October 2011 (IAEA PRIS, 2011). Nuclear electricity generation totaled 2630 TWh in 2010 representing 14% the world’s electricity generation. The top five countries of total installed nuclear capacity are the US, France, Japan, Russia and South Korea at 102, 63, 45, 24, and 21 GWe, respectively (WNA, 2012a). The nuclear capacity of these five countries represents more than half, 68%, of the total global nuclear capacity. The role of nuclear power in the global energy system today has been motivated by several factors including the growing demand for electric power, the regional availability of fossil resources and energy security concerns, and the relative competitiveness of nuclear power as a source of base-load electricity. There is additional motivation for the use of nuclear power because it does not produce greenhouse gas (GHG) emissions or local air pollutants during its operation and contributes to low levels of emissions throughout the lifecycle of the nuclear energymore » system (Beerten, J. et. al., 2009). Energy from nuclear fission primarily in the form of electric power and potentially as a source of industrial heat could play a greater role for meeting the long-term growing demand for energy worldwide while addressing the concern for climate change from rising GHG emissions. However, the nature of nuclear fission as a tremendously compact and dense form of energy production with associated high concentrations of radioactive materials has particular and unique challenges as well as benefits. These challenges include not only the safety and cost of nuclear reactors, but proliferation concerns, safeguard and storage of nuclear materials associated with nuclear fuel cycles. In March of 2011, an unprecedented earthquake of 9 magnitude and ensuing tsunami off the east coast of Japan caused a severe nuclear accident in Fukushima, Japan (Prime Minister of Japan and His Cabinet, 2011). The severity of the nuclear accident in Japan has brought about a reinvestigation of nuclear energy policy and deployment activities for many nations around the world, most notably in Japan and Germany (BBC, 2011; Reuter, 2011). The response to the accident has been mixed and its full impact may not be realized for many years to come. The nuclear accident in Fukushima, Japan has not directly affected the significant on-going nuclear deployment activities in many countries. China, Russia, India, and South Korea, as well as others, are continuing with their deployment plans. As of October 2011, China had the most reactors under construction at 27, while Russia, India, and South Korea had 11, 6, and 5 reactors under construction, respectively (IAEA PRIS, 2011). Ten other nations have one or two reactors currently under construction. Many more reactors are planned for future deployment in China, Russia, and India, as well as in the US. Based on the World Nuclear Association’s data, the realization of China’s deployment plan implies that China will surpass the US in total nuclear capacity some time in the future.« less

This chapter discusses scenarios of potential future anthropogenic developments that could affect the concentrations of greenhouse gases, aerosols, and short-lived species and thereby the climate. Scenarios of this type have been published for more than a quarter of a century. The earliest work on this problem focused on fossil fuel and industrial CO2 emissions and employed timetrend extrapolations of fossil fuel resource utilization (Rotty 1977, 1978). This work was followed by the development of models that employed economic principles and considered energy markets explicitly in the development of scenarios that explored emissions and concentrations of CO2 in the absence of policies to limit anthropogenic emissions. See, for example, Nordhaus (1979), JASON (1979), Niehaus and Williams (1979), Hafele (1981), Nordhaus and Yohe (1983), and Edmonds and Reilly (1983, 1985). This literature evolved with other climate sciences and was extended to include land use change emissions of CO2, non-CO2 greenhouse gases, aerosols, and short-lived species, as well as a wide range of potential climate policy regimes. The range of global CO2 emissions reported in the literature by Nakicenovic et al. (2000) is shown in Figure 3.1. This broad literature is summarized in a variety of reviews and assessments, including Leggett et al. (1992), Edmonds et al. (1994), Weyant et al. (1996), Special Report on Emissions Scenarios (SRES) (Nakicenovic et al. 2000), Fisher et al. (2007), van Vuuren et al. (2008), and van Vuuren and Riahi (2011).

We present here a detailed, service-based model of China's building energy use, nested in the GCAM (Global Change Assessment Model) integrated assessment framework. Using the model, we explore long-term pathways of China's building energy use and identify opportunities of reducing greenhouse gas emissions. The inclusion of a structural model of building energy demands within an integrated assessment framework represents a major methodological advance. It allows for a structural understanding of the drivers of building energy consumption while simultaneously considering the other human and natural system interactions that influence changes in the global energy system and climate. We also explore a range of different scenarios to gain insights into how China's building sector might evolve and what the implications might be for improved building energy technology and carbon policies. The analysis suggests that China's building energy growth will not wane anytime soon, although technology improvement will put downward pressure on this growth. Also, regardless of the scenarios represented, the growth will involve the continued, rapid electrification of the buildings sector throughout the century, and this transition will be accelerated by the implementation of carbon policy.

This entry discusses the role of integrated assessment models (IAMs) in climate change research. IAMs are an interdisciplinary research platform, which constitutes a consistent scientific framework in which the large-scale interactions between human and natural Earth systems can be examined.

Leakage occurs whenever actions to mitigate greenhouse gas emissions in one part of the world unleash countervailing forces elsewhere in the world so that reductions in global emissions are less than emissions mitigation in the mitigating region. While many researchers have examined the concept of industrial leakage, land-use policies can also result in leakage. We show that land-use leakage is potentially as large as or larger than industrial leakage. We identify two potential land-use leakage drivers, land-use policies and bioenergy. We distinguish between these two pathways and run numerical experiments for each. We also show that the land-use policy environment exerts a powerful influence on leakage and that under some policy designs leakage can be negative. International “offsets” are a potential mechanism to communicate emissions mitigation beyond the borders of emissions mitigating regions, but in a stabilization regime designed to limit radiative forcing to 3.7 2/m2, this also implies greater emissions mitigation commitments on the part of mitigating regions.

High-field spectroscopic studies at 5.88 tesla (T) indicate significant T2* shortening of water in suspensions of powdered bone, interpreted to be a result of magnetic susceptibility differences between bone particles and water. The authors investigated the effects of magnetic susceptibility differences between trabecular bone and water on magnetic resonance (MR) images at 0.6 T. The phantom was constructed of macerated intact trabecular human bone immersed in water. Although susceptibility-induced magnetic field inhomogeneities were detected by spectral line broadening by using an asymmetric spin-echo technique, the results show only a modest T2* shortening at this field strength. As expected, no T1 effect of trabecular bone was observed. Although susceptibility effects of trabecular bone may have a small impact on the signal intensity of MR images of bone marrow at midfield strength, the observed field strength dependence of these effects would predict significant susceptibility effects on clinical images at higher field strength.

This report documents a scenario analysis exploring the value of advanced technologies in the U.S. buildings, industrial, and transportation sectors in stabilizing atmospheric greenhouse gas concentrations. The analysis was conducted by staff members of Pacific Northwest National Laboratory (PNNL), working at the Joint Global Change Research Institute (JGCRI) in support of the strategic planning process of the U.S. Department of Energy (U.S. DOE) Office of Energy Efficiency and Renewable Energy (EERE). The conceptual framework for the analysis is an integration of detailed buildings, industrial, and transportation modules into MiniCAM, a global integrated assessment model. The analysis is based on three technology scenarios, which differ in their assumed rates of deployment of new or presently available energy-saving technologies in the end-use sectors. These technology scenarios are explored with no carbon policy, and under two CO2 stabilization policies, in which an economic price on carbon is applied such that emissions follow prescribed trajectories leading to long-term stabilization of CO2 at roughly 450 and 550 parts per million by volume (ppmv). The costs of meeting the emissions targets prescribed by these policies are examined, and compared between technology scenarios. Relative to the reference technology scenario, advanced technologies in all three sectors reduce costsmore » by 50% and 85% for the 450 and 550 ppmv policies, respectively. The 450 ppmv policy is more stringent and imposes higher costs than the 550 ppmv policy; as a result, the magnitude of the economic value of energy efficiency is four times greater for the 450 ppmv policy than the 550 ppmv policy. While they substantially reduce the costs of meeting emissions requirements, advanced end-use technologies do not lead to greenhouse gas stabilization without a carbon policy. This is due mostly to the effects of increasing service demands over time, the high consumption of fossil fuels in the electricity sector, and the use of unconventional feedstocks in the liquid fuel refining sector. Of the three end-use sectors, advanced transportation technologies have the greatest potential to reduce costs of meeting carbon policy requirements. Services in the buildings and industrial sectors can often be supplied by technologies that consume low-emissions fuels such as biomass or, in policy cases, electricity. Passenger transportation, in contrast, is especially unresponsive to climate policies, as the fuel costs are small compared to the time value of transportation and vehicle capital and operating costs. Delaying the transition from reference to advanced technologies by 15 years increases the costs of meeting 450 ppmv stabilization emissions requirements by 21%, but the costs are still 39% lower than the costs assuming reference technology. The report provides a detailed description of the end-use technology scenarios and provides a thorough analysis of the results. Assumptions are documented in the Appendix.« less

The response to climate change and the stabilization of atmospheric greenhouse gas concentrations has major implications for the global energy system. Stabilization of atmospheric carbon dioxide (CO2) concentrations requires a peak and an indefinite decline of global CO2 emissions. Nuclear energy, along with other technologies, has the potential to contribute to the growing demand for energy without emitting CO2. Nuclear energy is of particular interest because of its global prevalence and its current significant contribution, nearly 20%, to the world’s electricity supply. We have investigated the value of nuclear energy in addressing climate change, and have explored the potential challenges for the rapid and large-scale expansion of nuclear energy as a response to climate change. The scope of this study is long-term and the modeling time frame extends out a century because the nature of nuclear energy and climate change dictate that perspective. Our results indicate that the value of the nuclear technology option for addressing climate change is denominated in trillions of dollars. Several-fold increases to the value of the nuclear option can be expected if there is limited availability of competing carbon-free technologies, particularly fossil-fuel based technologies that can capture and sequester carbon. Challenges for the expanded globalmore » use of nuclear energy include the global capacity for nuclear construction, proliferation, uranium availability, and waste disposal. While the economic costs of nuclear fuel and power are important, non-economic issues transcend the issues of costs. In this regard, advanced nuclear technologies and new vision for the global use of nuclear energy are important considerations for the future of nuclear power and climate change.« less

Technology is a critically important determinant of the cost of meeting any environmental objective. In this paper we examine the role of a particular technology, carbon dioxide capture and storage (CCS), in the stabilization of the concentration of atmospheric carbon dioxide (CO2). While CCS is not presently deployed at scale, it has the potential to deploy extensively during the course of the 21st century if concentrations of atmospheric CO2 are to be stabilized. The existing research literature has focused largely on the cost of capturing CO2, with the implicit assumption that storage options would be relatively cheap, plentiful and located in close proximity to future CO2 point sources. However, CO2 capture and storage will take place at the local and regional scale and will compete with other mitigation options that also exhibit local or regional differences. This paper provides an initial examination of the implications of regionally disaggregated demand for and supply of CO2 storage reservoirs within the context of a globally disaggregated, long-term analysis of both the geology and economics of CCS. This analysis suggests that some regions will see their ability to deploy CCS systems constrained by a lack of quality target reservoirs relative to the demand formore » storage placed upon these candidate geologic storage reservoirs by large stationary CO2 point sources within the region. Other regions appear to have sufficient storage capacity to easily carry them into the 22nd century. We examined the regional and global economic implications of the distribution of these sources and sinks in meeting various potential limits to atmospheric CO2 concentrations. This analysis confirms that CCS is an important potential response to climate change throughout the 21st century and a technology that can play a key role in controlling the cost of addressing climate change.« less