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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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... Of interest to the modeling community, which works on designing and improving such systems, are multiple scales, from micro to macro, and the associated applications ( Fig. 1 ). For example, on the macro scale, we study energy use within the whole economy ( McCollum et al., 2018 ;Pehl et al., 2017 ), as well as continent-wide or multi-region power systems ( Galán- Martín et al., 2018 ;Tröndle et al., 2020 ). On the meso scale, we assess regional multi-sector energy systems ( Baumgärtner et al., 2021 ) or optimize regional fuel supply chains ( De-León Almaraz et al., 2014 ;Ehrenstein et al., 2020 ). ...
... Particularly the provision of low-carbon technologies, e.g. solar photovoltaic, is currently carbon-intensive -due to the electricity mix used in the production -and carbon intensities for energy generation are thus pro-jected to change significantly ( Pehl et al., 2017 ). There are thus issues around the timeliness and trustworthiness of the data. ...
Energy systems analysis supports in designing and operating reliable and cost-effective energy solutions to a range of sectors, including power, heating, mobility, and industry. Notwithstanding the wellbeing and prosperity implications for current generations, it becomes increasingly clear that our current global energy system has profound impacts on our planet, potentially breaching the safe operating space for humanity. Life cycle assessments are broadly used to account for environmental aspects, however, this traditional approach may fall short of designing truly sustainable alternatives. Here, we review the concept of absolute sustainability and how it can be incorporated into energy systems modeling and optimization. Besides providing background, guidance, and perspective, we also discuss remaining challenges related to environmental and computational aspects. Although much work is still required, the absolute environmental sustainability concept can already be used in energy systems modeling and would contribute to achieving a green energy transition within planetary boundaries, ensuring wellbeing and prosperity for future generations.
... The UN SDG 7 target 2 recommends increasing the use of renewable energy as part of the strategies for reducing the carbon intensity of economic output. According to Pehl et al. (2017), solar, wind, and other renewable energy sources create an insignificant carbon footprint compared to traditional fossil fuels (oil, coal, and gas). Also, natural resource utilization in African economies has been accompanied by high energy and material intensities, as well as waste generation (UN, 2016). ...
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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.
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