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Understanding future emissions from low-carbon power systems by integration of life-cycle assessment and integrated energy modelling

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Both fossil-fuel and non-fossil-fuel power technologies induce life-cycle greenhouse gas emissions, mainly due to their embodied energy requirements for construction and operation, and upstream CH4 emissions. Here, we integrate prospective life-cycle assessment with global integrated energy-economy-land-use-climate modelling to explore life-cycle emissions of future low-carbon power supply systems and implications for technology choice. Future per-unit life-cycle emissions differ substantially across technologies. For a climate protection scenario, we project life-cycle emissions from fossil fuel carbon capture and sequestration plants of 78-110 gCO2eq kWh⁻¹, compared with 3.5-12 gCO2eq kWh⁻¹ for nuclear, wind and solar power for 2050. Life-cycle emissions from hydropower and bioenergy are substantial (~100 gCO2eq kWh⁻¹), but highly uncertain. We find that cumulative emissions attributable to upscaling low-carbon power other than hydropower are small compared with direct sectoral fossil fuel emissions and the total carbon budget. Fully considering life-cycle greenhouse gas emissions has only modest effects on the scale and structure of power production in cost-optimal mitigation scenarios.
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© 2017 Macmillan Publishers Limited, part of Springer Nature. All rights reserved. © 2017 Macmillan Publishers Limited, part of Springer Nature. All rights reserved.
1Potsdam Institute of Climate Impact Research, PO Box 60 12 03 Potsdam, Germany, . 2Industrial Ecology Programme and Department of Energy and
Process Engineering, Norwegian University of Science and Technology (NTNU), Trondheim, Norway. 3Center for Industrial Ecology, Yale School for Forestry
and Environmental Studies, New Haven, CT, USA. *e-mail:;
The Paris Agreement of COP21 confirmed the goal of limiting
global temperature increase well below 2 °C and acknowledged
the need to achieve net greenhouse gas neutrality during the
second half of the century1. Previous research based on integrated
energy–economy–climate models has shown that achieving these
targets cost-effectively requires a rapid, almost full-scale decarbon-
ization of the electricity system by mid-century2,3. In electricity pro-
duction, ample low-carbon alternatives are available4 and electricity
is a potential substitute for fossil-based fuels in all economic sectors,
which leads to final energy electricity shares of 25–45% in stringent
mitigation scenarios2.
The life-cycle assessment (LCA) literature illustrates that all
energy transformation technologies are associated with upstream
energy demands and corresponding indirect (that is, not caused by
fuel-burning on site) greenhouse gas (GHG) emissions47. Concerns
have been voiced that these can impair the emission reduction
potential of low-carbon technologies6,8,9. However, LCA studies of
electricity mostly focus on impacts on a per-kilowatt-hour basis
in static settings, typically neglecting technology improvements in
electricity generation technologies, as well as the effects of concur-
rent decarbonization measures in other sectors of the energy system
and the economy6,10,11.
Integrated energy–economy–climate modelling approaches
estimate cost-optimal long-term strategies to meet the emissions
constraints implied by climate targets3. Whereas direct combustion
emissions as well as CH4 from fossil fuel extraction and indirect
land-use change emissions are accounted for by many state-of-the-
art modelling systems, other indirect emissions, in particular those
related to energy required for the construction of power plants
and the production and transportation of fuels and other inputs
(defined here as embodied energy use, EEU), are not considered in
the optimization. We investigate to what extent this omission leads
to incomplete internalization of externalities.
A previous study by Hertwich et al.5 used prospective LCA to
compare similar scenarios in terms of environmental impacts,
but relied on exogenous scenarios for technology deployment,
and focused on non-climate environmental impacts to assess co-
benefits and trade-offs of climate change mitigation. Daly et al.9 and
Scott et al.12 investigated the influence of national climate policy on
domestic and non-domestic indirect GHG emissions and found
them to have a large potential for carbon leakage, as the ratio of
emissions caused domestically and overseas shifts to the latter due
to imports of goods and services. However, their analysis consid-
ered only the United Kingdom, based carbon intensities on aggre-
gate input–output relationships rather than process detail, and did
not account for policy-induced non-domestic emission reductions
in the context of coordinated international climate change mitiga-
tion efforts. Portugal-Pereira et al.13 included LCA emission coef-
ficients in an integrated assessment model (IAM) and studied the
effect of taxing indirect emissions on the electricity mix. However,
they considered only the Brazilian electricity system and used static
LCA coefficients.
In this study, we present consistent and detailed modelling of
EEU and indirect GHG emissions for global scenarios of future
electricity systems. By linking an IAM with EEU coefficients from a
prospective LCA model, we can provide a holistic and detailed per-
spective on future life-cycle greenhouse gas emissions of low-carbon
technologies and power systems in the context of a universal climate
change mitigation regime, thus closing an important research gap1416
by quantifying these emissions and their effect on the choice of low-
carbon technologies in mitigation scenarios. This study combines
results from the REMIND model17,18, which details energy use and
Understanding future emissions from low-carbon
power systems by integration of life-cycle
assessment and integrated energy modelling
Michaja Pehl 1*, Anders Arvesen 2, Florian Humpenöder1, Alexander Popp1, Edgar G. Hertwich 3
and Gunnar Luderer1*
Both fossil-fuel and non-fossil-fuel power technologies induce life-cycle greenhouse gas emissions, mainly due to their embod-
ied energy requirements for construction and operation, and upstream CH4 emissions. Here, we integrate prospective life-
cycle assessment with global integrated energy–economy–land-use–climate modelling to explore life-cycle emissions of future
low-carbon power supply systems and implications for technology choice. Future per-unit life-cycle emissions differ substan-
tially across technologies. For a climate protection scenario, we project life-cycle emissions from fossil fuel carbon capture and
sequestration plants of 78–110gCO2eq kWh1, compared with 3.5–12gCO2eq kWh1 for nuclear, wind and solar power for 2050.
Life-cycle emissions from hydropower and bioenergy are substantial ( 100gCO2eq kWh1), but highly uncertain. We find
that cumulative emissions attributable to upscaling low-carbon power other than hydropower are small compared with direct
sectoral fossil fuel emissions and the total carbon budget. Fully considering life-cycle greenhouse gas emissions has only
modest effects on the scale and structure of power production in cost-optimal mitigation scenarios.
NATURE ENERGY | VOL 2 | DECEMBER 2017 | 939–945 | 939
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... demand changes, is considered in the foreground systems and the supply chains involved in supplying those products and services are considered in the background systems. Studies applying a prospective lifecycle assessment framework generally either mapp integrated assessment modeling results for future decarbonization scenarios to lifecycle inventory databases 22,23 , or combine results from integrated assessment models (IAMs) with lifecycle inventories and additional analytical tools to understand the deployment of new technologies, such as Morfeldt et al. 24 for electric cars or Pehl et al. 25 for power systems. ...
... Adjustments have been made to account for transmission and distribution losses. Upstream emissions from maintenance in power generation plants and fuel production are estimated for each technology based on global averages for each of the two global decarbonization pathways 25 . ...
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National emission reduction targets under the Paris Agreement have a territorial focus, incentivizing mitigation actions domestically. Here we examine the theoretical basis for adopting complementary consumption-based net-zero emission targets and assess the consequences of adopting such proposed targets for Sweden. We apply scenario analyses based on a prospective lifecycle assessment framework. The framework is a hybrid of bottom-up simulations for passenger travel, construction and housing, and food, and top-down analyses for remaining consumption. In this work, we show how consumption-based climate targets may accentuate the need for new demand-side climate policies that contribute to reducing emissions along supply chains of products and services. Our scenario analysis suggests that combining advanced mitigation technologies with behavioral changes could reduce emissions from 9.8 tons of carbon dioxide equivalents per capita in 2019 to between 2.7 and 4.8 tons by 2045 for Swedish residents, depending on global decarbonization pathways.
... 6 Mt per year in 2021 24 , its growth has been evident in recent years, with the number of demonstration projects under development or operation worldwide growing from 43 in 2018 to 136 in 2021 24,25 . This is reflected in the considered IPCC scenarios, with almost all integrated assessment model (IAM) scenarios incorporating CCUS under limiting global warming to 1.5°C or 2°C relative to preindustrial levels 26,27 , as the CCUS option generally yields lower costs in reducing carbon emissions than nuclear and renewable options under these scenarios 13,22,28 and provides a viable solution for carbon lock-in of fossil fuel energy infrastructure 7,29,30 , stranded assets, and industry employment losses 31,32 , although previous research has considered IAM-specific modeling assumptions (e.g., the application of general equilibrium theory-based IAMs) 33 . Therefore, it is important to quantify the carbon emission reduction effectiveness of the high-renewable power system combined with abated fossil fuel power generation involving CCUS via a comparison to the 100% renewable power system, especially from system reliability and resilience perspectives. ...
... To evaluate the economics of the power system, we calculated the costs of the overall power system and its components under all scenarios and selected the optimal scenario characterized by the lowest total cost and total power shortage lower than 0.1% (i.e., ensuring a general level of the electricity supply reliability of 99.9% in Chinese cities). The total cost of the power system includes the cost of nonfossil fuel power generation, the cost of abated fossil fuel power generation with CCUS, the cost of short-term energy storage, the cost of hydrogen energy, and the cost of power transmission (all costs in this study were adjusted to 2020 constant prices), as expressed in Eq. (27). ...
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Decarbonized power systems are critical to mitigate climate change, yet methods to achieve a reliable and resilient near-zero power system are still under exploration. This study develops an hourly power system simulation model considering high-resolution geological constraints for carbon-capture-utilization-and-storage to explore the optimal solution for a reliable and resilient near-zero power system. This is applied to 31 provinces in China by simulating 10,450 scenarios combining different electricity storage durations and interprovincial transmission capacities, with various shares of abated fossil power with carbon-capture-utilization-and-storage. Here, we show that allowing up to 20% abated fossil fuel power generation in the power system could reduce the national total power shortage rate by up to 9.0 percentages in 2050 compared with a zero fossil fuel system. A lowest-cost scenario with 16% abated fossil fuel power generation in the system even causes 2.5% lower investment costs in the network (or $16.8 billion), and also increases system resilience by reducing power shortage during extreme climatic events.
... They cover upstream emissions and the emissions of the construction of new power plants throughout their lifetimes as a function of the electricity generated. Using a conservative approach, no reduction in these factors for future years is included, even though the ongoing decarbonization of industry will reduce the emissions of renewable power plant manufacturing (Pehl et al., 2017). As the IPCC's life-cycle GHG emission factors for electricity-generation technologies do not include land use change emissions, the value for biomass-based electricity production is adjusted to 230 g CO 2 eq. ...
Technical Report
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Reaching Indonesia’s target of net-zero greenhouse gas (GHG) emissions by 2060 or sooner will depend in part on the decarbonization of the transportation sector, which today is responsible for about 15% of the country’s GHG emissions. Indonesia is considering a range of measures, including shifting from gasoline and diesel internal combustion engine vehicles (ICEVs) to hybrid electric vehicles (HEVs), plug-in hybrid electric vehicles (PHEVs), battery electric vehicles (BEVs), and hydrogen fuel cell electric vehicles (FCEVs), and increasing the use of biofuels. This report presents a life-cycle assessment (LCA) of the GHG emissions of passenger cars and two-wheelers with different power trains in Indonesia. It assesses vehicles sold in 2023 and hypothetical vehicles sold in 2030, and encompasses emissions from fuel combustion, fuel and electricity production, vehicle maintenance, and vehicle and battery manufacturing. The assessment finds that BEVs offer the lowest life-cycle emissions across all segments and can bring significant emissions reduction in line with the net-zero goal. Importantly, as the electricity mix is expected to decarbonize over time, the GHG emission benefit continuously increases for future BEVs, as illustrated in the figure below. HEVs and PHEVs, meanwhile, do not offer a deep reduction in emissions from the passenger car and two-wheeler fleets in Indonesia, as they remain largely dependent on the combustion of fossil fuels. The findings reflect the same trends observed in previous ICCT analyses of vehicles in China, Europe, India, and the United States. This report is a valuable resource for policymakers in Indonesia, as reducing transport emissions while the vehicle fleet is likely to expand due to economic growth requires a resolute shift to low-carbon technologies. The authors highlight that with a vehicle lifetime of more than 18 years, a transition to a fully electric fleet by 2060 thus requires that from around 2040, no new combustion engine cars, HEVs, or PHEVs are sold in Indonesia. Beyond GHG emissions, increasing the share of electric vehicles will help mitigate the public health and environmental consequences of air pollution in Indonesian cities, reduce Indonesia’s dependence on oil imports, and reduce public spending on fuel subsidies. As Indonesia is the world’s largest supplier of nickel and has rich reserves of other key battery materials, creating a domestic battery and electric vehicle manufacturing industry is expected to create jobs and grow the economy. The report explores policy options to continuously increase the electric vehicle share in Indonesia and support the development of a domestic battery and electric vehicle supply chain.
... Strengths. Compared with traditional and other renewables, solar energy has a far less long-term carbon impact (Pehl et al., 2017). (Gillingham and Stock, 2018;Tiwari and Tiwari, 2016) agree that switching to solar energy is a great way to help the planet and the economy. ...
Utilizing natural resources may assists India in overcoming its prevailing energy crises. However, the instability of natural resources hinders its capacity to overcome these crises. To overcome this research gap, this study uses "Porter's Five Forces Model" to investigate the sustainability of natural resources. We use a hybrid approach for data compilation and empirical investigation. First, we introduce a new value chain model of Indian solar industry. Second, we conduct semi-structured interviews with industry experts on various sustainability and natural resources management-related issues. Third, we critically evaluate official statistics, national policy structure, and regulatory studies using the Five Forces Model. Research findings indicate India's present condition of natural resources, existing barriers, competitive landscape, and future projections. Results further disclose that the Indian government has announced various proposals to promote natural resources but few have been implemented. The government policies that require modification include the solar Bidding Scheme, National Tariff Policy, and Generation Based Incentive (GBI). Based on research findings, policy recommendations are suggested for improving the sustainability of natural resources, including the role of the government, innovative workers, regional and international collaboration, awareness programs, and the transition to domestic manufacturing through integrated and coherent efforts.
... These dangers are exemplified by accidents such as those that occurred at Chernobyl in 1986 and Fukushima Daiichi in 2011, which led to substantial radioactive releases into the environment. The risk reduction side of the narrative is more mature and well established (Fell et al., 2022;Pye et al., 2017), mainly due to the abundance of available data and research on decarbonisation and the advantages of nuclear power (Fell et al., 2022;Kharecha and Hansen, 2013;Sornette et al., 2018;Pehl et al., 2017). In contrast, the evaluation of nuclear risks presents a unique challenge due to the exceptionally rare occurrence of nuclear accidents. ...
The opposition in some countries to including nuclear power in future sustainable energy portfolios—in part due to “nuclear dread”—often has limited quantitative scientific foundation of the real benefits and risks. This has been amplified by the lack of sound estimates of operational risk due to the scarcity of the relevant empirical data. In order to address this gap, we use the largest open database on accident precursors along with our in-house generic probabilistic safety assessment models to conduct a comprehensive statistical study of operational risks in the civil nuclear sector. We find that the distribution of precursor severities follows a Pareto distribution, and we observe a runaway Dragon Kings regime for the most significant events. Based on our findings, we have determined that exogenous factors account for 95% of the risk associated with nuclear power. By addressing these factors in new reactor designs, we estimate that the frequency of accidents similar to the Fukushima Daiichi level can be reduced to about one every 300 years for the global fleet. Finally, our study highlights the importance and need for international cooperation focused on constructing comprehensive blockchains of accident precursors.
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Factors such as climate change, economic development, population growth, pandemics, and geopolitical instability threaten water, energy, and food (WEF) security, which consequently put sustainability at risk. However, studies that simultaneously consider WEF security and sustainability aspects still need improvement. This research aimed to build a sustainable WEF nexus framework and analyze the interrelationships among water consumption, electricity demand, food production, and ecological footprint, considering the Environmental Kuznets curve (EKC) hypothesis and external factors of the WEF nexus. For the empirical analysis, this study employed the three-stage least squares method to identify synergies and trade-offs in the sustainable WEF nexus in South Korea using panel data from 2005 to 2019. The results indicated that rice production causes excessive use of agricultural water, thereby deteriorating water availability and quality. This phenomenon leads to scarce water resources and environmental degradation, which negatively impact energy production and sustainability. Although increased agricultural productivity through automation “improves food security,” it can pose a threat to energy security by increasing electricity demand and energy imports. The EKC hypothesis test revealed that environmental problems cannot be solved through economic development. However, the indicators related to WEF security influence environmental sustainability rather than economic growth. These results indicate that WEF security and sustainability can be improved simultaneously by maximizing synergies and minimizing trade-offs within a sustainable WEF nexus. Therefore, this research provides a roadmap for policymakers regarding efficient ways to improve environmental quality and WEF security.
The sustainability of air transport is increasingly studied in relation to climate issues. The objective of this paper is to provide the key elements for assessing whether a given transition scenario for aviation could be considered as sustainable in the context of the Paris Agreement. Addressing this question relies on a broad range of concepts which are reviewed. First, ethical considerations related to effort-sharing mitigation principles and physical considerations on climate impacts of aviation are introduced. Then, the technological levers of action for mitigating CO2 and non-CO2 effects are detailed. Concerning CO2 emissions, low-carbon alternative energy carriers represent the main lever, with a wide range of solutions with varying degrees of maturity and decarbonization potentials. Other significant CO2 levers include improving aircraft architecture efficiency and accelerating fleet renewal. Concerning non-CO2 effects, contrail effect mitigation through operational strategies is one of the most promising lever. Aviation transition scenarios are then reviewed, with a particular focus on scenario simulation and sustainability assessment methodologies. Prospective scenarios are a useful framework for assessing the impacts of technological levers on the achievement of climate objectives. This review leads to the conclusion that technological levers have an important role to play in making aviation sustainable; however, significant uncertainties weigh on their feasibility, particularly for the most ambitious scenarios which rely on strong technological and political trade-off assumptions. The paper ends by raising the question about the meaning of sustainable aviation, which must be based on technological but also, for instance, social, economic and ethical considerations.
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Some advanced countries’ rapid population, economic growth, and energy consumption expansion contribute significantly to global CO2 emissions. And while developed countries have achieved 100% universal access to electricity, mainly from non-renewable sources, many developing countries still lack it. This presents challenges and opportunities for achieving the United Nations’ Sustainable Development Goals (SDGs) 7 and 13 of generating all energy from cleaner or low-carbon sources to reduce CO2 emissions in all countries and combating climate change consequences. Renewable energies have been widely acknowledged to greatly advance this endeavour, resulting in many studies and about 30 countries already with over 70% of their national electricity mix from RE. It has birthed a new paradigm and an emerging field of 100% RE for all purposes, recently receiving much attention from academia and in public discourse. The major challenge with this idea is that achieving such a feat requires a more diverse approach. This study emphasises the need to meet technical and non-technical requirements for working towards a 100% RE for all purposes. Therefore, our work introduces six methodological or evaluation mechanisms (herein, identified as 100% RE evaluation metrics) suitable for existing and future 100% renewable energy analysis. It then reviews energy modelling tools to identify their applicability to 100% RE analysis. The review and perspectives presented in this study will be valuable in developing a common integrated methodology and modelling tool for analysing full renewable energy adoption in countries or regions with best trade-offs, using performance indices that have not been previously used. It will also help with proper national and regional energy resources and system planning for new energy projects and installations, contributing to sustainable development.
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Most prior studies have found that substituting biofuels for gasoline will reduce greenhouse gases because biofuels sequester carbon through the growth of the feedstock. These analyses have failed to count the carbon emissions that occur as farmers worldwide respond to higher prices and convert forest and grassland to new cropland to replace the grain (or cropland) diverted to biofuels. By using a worldwide agricultural model to estimate emissions from land-use change, we found that corn-based ethanol, instead of producing a 20% savings, nearly doubles greenhouse emissions over 30 years and increases greenhouse gases for 167 years. Biofuels from switchgrass, if grown on U.S. corn lands, increase emissions by 50%. This result raises concerns about large biofuel mandates and highlights the value of using waste products.
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The greenhouse gases (GHG) emissions from land-use change are of particular concern for land-based biofuels. Emissions avoided by substituting fossil fuels with biofuels may be offset by emissions from direct and indirect land-use changes (LUC). There is an urgent need to investigate what impact land-use change emissions may have on the expansion of bioenergy and biofuels, in the context of EU mitigation policies. This paper focuses on Ireland, which faces a number of challenges in delivering its renewable energy and GHG reduction targets. The Irish TIMES energy systems model was used to assess the impact of a range of land-use change emissions’ levels on the evolution of Ireland’s low-carbon energy system. A reference scenario was developed where LUC is ignored and Ireland achieves a least-cost low-carbon energy system by 2050. If high indirect land-use change (ILUC) emissions are included, this results in a decrease by 30 % in bioenergy and a 68 % increase in marginal abatement costs by 2050. Hydrogen is used instead of bioenergy in the freight sector in this scenario, while private cars are fuelled by renewable electricity. If GHG emissions from ILUC were considered less severe, indigenous grass biomethane becomes the key biofuel representing 31 % of total bioenergy consumption. This is in line with recent research in Ireland of the key role that grass biomethane can play. The full article is available from:
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Rapid cuts in greenhouse gas emissions require an almost complete transformation of the energy system to low carbon energy sources. Little consideration has been given to the potential adverse carbon consequences associated with the technology transition. This paper considers the embodied emissions that will occur to replace the UK’s fossil fuel-reliant energy supply with low carbon sources. The analysis generates a number of representative scenarios where emissions embodied in energy systems are integrated within current national climate and energy policy objectives. The embodied emissions associated with a new low carbon energy system are lower than the emissions reduction associated with the low carbon energy sources, confirming that there is a carbon return on investment. However, even if the UK reaches its 2050 territorial climate target, it is estimated that by 2050 an additional 200 Mt CO2 emissions are generated overseas (compared to 128 Mt generated within the UK) in the production of imported fuels and infrastructure components. The cost-optimal model results suggest that more electrification would need to occur, supported by nuclear energy, mainly in replacement of natural gas to mitigate these emissions. However, due to a number of deployment barriers, other policy interventions along the energy supply chain are likely needed, which are discussed alongside the model results. There could be more emphasis on an absolute reduction in energy demand to reduce the scale of change needed in supplying energy; new business models oriented towards performance and not sales; and existing trade schemes and international effort-sharing frameworks could be extended.
The fields of life cycle assessment (LCA) and integrated assessment (IA) modelling today have similar interests in assessing macro-level transformation pathways with a broad view of environmental concerns. Prevailing IA models lack a life cycle perspective, while LCA has traditionally been static- and micro-oriented. We develop a general method for deriving coefficients from detailed, bottom-up LCA suitable for application in IA models, thus allowing IA analysts to explore the life cycle impacts of technology and scenario alternatives. The method decomposes LCA coefficients into life cycle phases and energy carrier use by industries, thus facilitating attribution of life cycle effects to appropriate years, and consistent and comprehensive use of IA model-specific scenario data when the LCA coefficients are applied in IA scenario modelling. We demonstrate the application of the method for global electricity supply to 2050 and provide numerical results (as supplementary material) for future use by IA analysts.
In this paper we study the impact of alternative metrics on short- and long-term multi-gas emission reduction strategies and the associated global and regional economic costs and emissions budgets. We compare global warming potentials with three different time horizons (20, 100, 500 years), global temperature change potential and global cost potentials with and without temperature overshoot. We find that the choice of metric has a relatively small impact on the CO 2 budget compatible with the 2° target and therefore on global costs. However it substantially influences mid-term emission levels of CH 4 , which may either rise or decline in the next decades as compared to today’s levels. Though CO 2 budgets are not affected much, we find changes in CO 2 prices which substantially affect regional costs. Lower CO 2 prices lead to more fossil fuel use and therefore higher resource prices on the global market. This increases profits of fossil-fuel exporters. Due to the different weights of non-CO 2 emissions associated with different metrics, there are large differences in nominal CO 2 equivalent budgets, which do not necessarily imply large differences in the budgets of the single gases. This may induce large shifts in emission permit trade, especially in regions where agriculture with its high associated CH 4 emissions plays an important role. Furthermore it makes it important to determine CO 2 equivalence budgets with respect to the chosen metric. Our results suggest that for limiting warming to 2 °C in 2100, the currently used GWP100 performs well in terms of global mitigation costs despite its conceptual simplicity. Copyright Springer Science+Business Media Dordrecht 2014
Understanding which energy future configurations provide publicly acceptable levels of energy security, affordability, and environmental protection is critical for institutional decision-making. However, little is known about how scenarios influence energy preferences. Here we present nationally representative UK data on public preferences for energy futures using the my2050 scenario-building tool that encourages engagement with the holistic complexities of system change. Engagement with the tool strengthened existing preferences for renewable energy and intentions to take personal action. Importantly, patterns of energy preferences were influenced by exemplar scenarios, which served as reference points that anchored choices. Carbon capture and storage, nuclear power, biofuels, and changes to heating and travel were particularly impacted by scenarios indicating uncertainty and ambivalence regarding these options. Scenarios (and scenario-building tools) are valuable for engaging citizens about future energy systems. However, care is required in their design and interpretation to reach robust conclusions about underlying preferences and acceptance.
Technology-rich integrated assessment models (IAMs) address possible technology mixes and future costs of climate change mitigation by generating scenarios for the future industrial system. Industrial ecology (IE) focuses on the empirical analysis of this system. We conduct an in-depth review of five major IAMs from an IE perspective and reveal differences between the two fields regarding the modelling of linkages in the industrial system, focussing on AIM/CGE, GCAM, IMAGE, MESSAGE, and REMIND. IAMs ignore material cycles and recycling, incoherently describe the life-cycle impacts of technology, and miss linkages regarding buildings and infrastructure. Adding IE system linkages to IAMs adds new constraints and allows for studying new mitigation options, both of which may lead to more robust and policy-relevant mitigation scenarios. © 2017 Macmillan Publishers Limited, part of Springer Nature. All rights reserved.
This work evaluates implications of incorporating LCA-GHG (life cycle assessment of GHG emissions) into the optimisation of the power generation mix of Brazil through 2050, under baseline and low-carbon scenarios. Furthermore, this work assesses the impacts of enacting a tax on LCA-GHG emissions as a strategy to mitigate climate change. To this end, a model that integrates regional life cycle data with optimised energy scenarios was developed using the MESSAGE-Brazil integrated model. Following a baseline trend, the power sector in Brazil would increasingly rely on conventional coal technologies. GHG emissions from the power sector in 2050 are expected to increase 15-fold. When enacting a tax on direct-carbon emissions, advanced coal and onshore wind technologies become competitive. GHG emissions peak at 2025 and decrease afterwards, reaching an emission level 40% lower in 2050 than that of 2010. However, if impacts were evaluated through the entire life cycle of power supply systems, LCA-GHG emissions would be 50% higher in 2050 than in 2010. This is due to loads associated with the construction of plant infrastructures and extraction and processing of fossil fuel resources. Thus, taxes might not be as effective in tackling GHG emissions as shown by past studies, if they are only applied to direct emissions.
Land-use change, mainly the conversion of tropical forests to agricultural land, is a massive source of carbon emissions and contributes substantially to global warming. Therefore, mechanisms that aim to reduce carbon emissions from deforestation are widely discussed. A central challenge is the avoidance of international carbon leakage if forest conservation is not implemented globally. Here, we show that forest conservation schemes, even if implemented globally, could lead to another type of carbon leakage by driving cropland expansion in non-forested areas that are not subject to forest conservation schemes (non-forest leakage). These areas have a smaller, but still considerable potential to store carbon. We show that a global forest policy could reduce carbon emissions by 77 Gt CO 2, but would still allow for decreases in carbon stocks of non-forest land by 96 Gt CO 2 until 2100 due to non-forest leakage effects. Furthermore, abandonment of agricultural land and associated carbon uptake through vegetation regrowth is hampered. Effective mitigation measures thus require financing structures and conservation investments that cover the full range of carbon-rich ecosystems. However, our analysis indicates that greater agricultural productivity increases would be needed to compensate for such restrictions on agricultural expansion.