Paper III: Informing policymaking

3.3.1 RATIONALE

It is now certain that enforcing climate change mitigation policies will come with environmental costs and benefits, at every scale (Stechow et al. 2015). So-called

“co-benefits” of climate change mitigation encompass all the environmental impact reductions accompanying the application of climate change mitigation policies, for instance the reduction of particulate matter emissions as a result of fossil fuel taxation. Co-benefit analysis is pertinent as the reduction of greenhouse gas emissions, from electricity generation in particular, is a priority on most governments’ agendas. Beyond the challenging task of limiting negative effects of the deployment of low-carbon technological solutions, the question whether we

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should harness this opportunity to kill two (or more) birds with one stone is therefore central. Quantifying these co-benefits has the potential to encourage the implementation of mitigation policies.

Opportunities to address other pollution issues have been identified, quantified from a short-term or regional perspective (Thompson et al. 2014; Cifuentes et al.

2001; Davis 1997), but also from analysing low-carbon electricity deployment on a longer-term horizon (Markandya et al. 2009). These studies do not rely, however, on life cycle data, neither do they cover a wide range of environmental impact or damage; in fact, most of them analyse the co-benefits of climate change mitigation on air quality solely.

Furthermore, covering all available and emerging technologies is essential to comprehend what costs and opportunities arise with low carbon technology development; the panel of technologies assessed in Papers I and II is not complete, and Paper III overcomes this shortcoming by adding biomass and nuclear technologies to the analysis.

3.3.2 OBJECTIVES

This paper aims at adopting a holistic perspective on the environmental performance of stationary electricity generation options in order to quantify the degree of co-benefice of climate change-mitigating energy scenarios, and thus to support policymaking. The main objectives are:

a. To quantify environmental and health impacts of the future global electricity production in a straightforward and consistent fashion, relying on endpoint indicators, easier to interpret than the usual midpoint indicators – which only denote various aspects of the environmental burden of a system on aquatic, terrestrial and atmospheric milieus without offering any insight on actual consequences onto areas of protections,

31 b. To place and show the relevance of these results in the context of

co-benefits analysis, to determine what environmental and health opportunities lie in low-carbon electricity deployment,

c. To integrate a wider panel of technologies by integrating biomass and nuclear technologies.

3.3.3 METHODS

The model developed in Paper I, THEMIS (Gibon et al. 2015) is applied to the set of technologies described in Paper II (Hertwich et al. 2015) extended with biopower technologies, as well as two nuclear power inventories. In addition, endpoint characterisation factors (damage to ecosystem quality and to human health) are included in the framework. For the sake of communicability, midpoint indicators are aggregated into a small set of groups for each endpoint indicator.

Selecting a smaller set of indicators while addressing actual damage instead of stress confers policy-relevance to these results by making them clearer, more readable and interpretable (van Hoof et al. 2013). The introduction of biopower technologies in the set of inventories brings along site-specificity issues. Yield assumptions directly influence land occupation results, yet yield is a highly variable parameter that requires fine hydrological and climate modelling.

3.3.4 RESULTS

Results show an overall bettering of the environmental footprint of electricity by shifting to low-carbon generation. Land occupation, however, remains a concern for biopower, with a sensible variation of land use per kWh produced depending on the feedstock. The variety of biomass systems indeed appear to offer the wider range of performances, due to the difference in feedstocks. Using forest residues as feedstock yields the lowest impacts, even “negative damage” to ecosystem and human health when used with carbon capture and storage. However, short-rotation crop-based biopower could engender the highest impact on ecosystems due to land occupation. Cultivating these crops in the regions with the lowest yields appears to lead to the highest damage on ecosystems per kWh among all variations of all technologies analysed here, but this is merely a consequence of

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using global characterisation factors. The results shown here should be refined by adopting spatially-explicit coefficients.

Figure 8. Future impacts of power generation. Panels A and B: Comparison of electricity producing technologies from two endpoint perspectives: A) damage to human health and B) damage to ecosystem quality. Panel C: Variation of the impact of global electricity production on climate change, land occupation, health impacts, and ecosystem damage according to a baseline and a 2°C energy scenarios (respectively “Baseline” and “BLUE Map” scenarios from the International Energy Agency).

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3.3.5 UNCERTAINTY AND LIMITATIONS

The aggregation of impacts of different nature and scope into one indicator relies on assumptions that are sometimes remote from quantifiable biophysical mechanisms. For example, the disability-adjusted loss of life years (DALY) indicator depends on subjective assumptions such as the “disability weight,” an index that aims at qualifying the degree of gravity of a disability (where 0 is perfect health, 1 is death). One aggregation further in the impact assessment chain therefore introduces substantial subjectivity and uncertainty The characterisation factors used in the midpoint-to-endpoint conversion and aggregation processes rely on regional averages and do not take into account local specificity, let alone time specificity.

3.3.6 POTENTIAL IMPACT OF STUDY

A first conclusion of the work carried out in Paper III can be made at the technology level: with the exception of forest residues-fed gasification plants with carbon dioxide capture and storage, bioenergy for electricity production does not offers a benefit in terms of damage to ecosystems. The ecosystem damage of biomass systems is comparable to conventional fossil fuels, land use being the main issue in these cases. Land use and land use change appear very detrimental to biodiversity. At the power plant project level, biomass deployment should therefore be considered only after a careful environmental assessment of the feedstock supply chain. At the global level, it raises the question of the actual feasibility of planned biomass (with and without CCS) rollout.

Second, the reduction of greenhouse gas emissions from electricity generation is a priority on most governments’ agendas, even more so since the Paris Agreement, to be enforced in June 2016. Opportunities to address non-climate pollution issues have been identified, quantified from a short-term perspective (Davis 1997;

Cifuentes et al. 2001), and more recently from analysing low-carbon electricity deployment on a longer-term horizon (Markandya et al. 2009). Paper III goes one step further by quantifying the actual direct and indirect damage on human health and ecosystems of a low-carbon energy shift. A recurrent remark has been raised

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