Paper I: Framework development

3.1.1 RATIONALE

If successfully followed, climate change mitigation roadmaps will lead to profound changes in the way our global economy affects the environment, beyond the reduction of greenhouse gas emissions. Not only are direct emissions of greenhouse gases of products and services expected to decrease, but also indirect emissions. These indirect emissions are highly dependent on the carbon content of the economy in which they are provided, and more particularly of the energy system supplying said economy. It is therefore crucial to be able to assess environmental impacts (including non-climate impacts) in a context accounting for a changing economic and technological background.

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Implementing scenarios to a hybrid life cycle assessment framework allows for the long-term prospective assessment of a range of systems. In this exercise, we chose to hybridise electricity generation system inventories with a life cycle inventory database and a multiregional input-output background. By reflecting changes in technological efficiency, electricity mixes, and pollutant emission policies, the model becomes appropriate for assessing an existing or emerging technology under climate change mitigation scenarios.

3.1.2 OBJECTIVES

This study describes the method behind the setup of THEMIS⁶, the “technology hybridised environmental-economic model with integrated scenarios.” The main goals can be summed up in three points:

a. To lay down the methodological tools to set up a prospective, multiregional, hybridised life cycle assessment model,

b. To single out methodological challenges, such as double-counting, fully integrating energy technologies, or harmonising a heterogeneous set of data sources,

c. To exemplify the use of this new hybrid model by applying the assessment to an emerging electricity generating technology.

3.1.3 METHODS

Integrated hybrid LCA is at the core of the methods used in this paper. The principles followed for the model setup as well as the main methodological challenges encountered (data harmonisation and implementation of scenarios) are described hereafter.

Given the quantity and heterogeneity of the various sources considered, a primary challenge to overcome is to streamline the data. Discrepancies in time,

6 In Ancient Greek mythology, Themis (Θέμις) was a Titaness, daughter of Ouranos (the Heavens) and Gaia (the Earth). She personified custom, tradition, divine justice, and civilised existence. She could foresee the future, hence the model’s namesake.

23 technological, or geographical representativeness are indeed recurrent barriers for LCA practitioners. As the energy scenarios drive the whole model, we chose to align the geographical and time resolution to nine main regions of the globe and the 2010–2050 period, respectively.

Three main changes were brought to the databases to represent future years:

technological efficiency, energy mix, and emissions regulations. The first change was mainly based on the “New Energy Externalities Developments for Sustainability” or NEEDS, a four-year EU FP6 project aiming at evaluating the

“full costs and benefits of energy policies and of future energy systems” (ESU and IFEU 2008). NEEDS’ “realistic-optimistic” assumptions were used to modify industrial processes in ecoinvent 2.2. The energy mix scenarios modifications were based on the IEA’s two Energy Technology Perspective (ETP) scenarios for nine world regions to 2050. Finally, the global atmospheric emissions of major pollutants were assumed to follow the historic trend of 1990-2011 in the European Union (European Environment Agency 2013). Inherently, making these choices assumes that technological efficiency and emissions restrictions improvements up to 2050 are similar for Europe and the world alike.

3.1.4 RESULTS

The main outcome of this paper is a fully functional hybrid life cycle framework able to compute the environmental impacts of various systems from 2010 to 2050, in nine various global regions, and according to two scenarios. The model using this framework, THEMIS, supports both tiered and integrated hybrid life cycle assessments.

To illustrate the use and interest of THEMIS, the prospective analysis of a concentrated solar power plant is carried out. In 2010 and according to the regional context, life-cycle greenhouse gas emissions for CSP range from 33 to 95 g CO² eq./kWh, and falls to 30-87 g CO² eq./kWh in 2050. Using regional life cycle data yields insightful results: climate, regional technology, or energy mix

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Figure 7. Impacts of concentrated solar power. Comparison of the life cycle environmental impacts of 1 kWh of electricity from a concentrated solar power tower plant in 2010 and 2050 with the impacts of the 2010 global grid.

3.1.5 UNCERTAINTY AND LIMITATIONS

Limitations of this study exist at different levels. First, the compounding uncertainties arising at various stages of the LCA: background data adaptation, life cycle inventory of the foreground system, life cycle impact assessment… are a phenomenon typical to LCA studies (Finnveden et al. 2009). In this study, this is accentuated by the combination of heterogeneous data sources. The results variability is reflected by quantifying the environmental impacts by region and by year, in both scenarios.

The assumptions that the global future economy will undergo the same changes as in Europe have been made for technological efficiency and emissions regulations. Using Europe as a proxy in most of the scenario integration process – which reflects the lack of detailed data for non-European regions – is an assumption that should be kept in mind when analysing and interpreting the results of prospective analyses made with THEMIS.

Beyond the various data sources, we have relied on expert judgment to estimate the penetration of various systems in the future energy markets. These assumptions are not based on actual measurements or scientifically sound

25 predictions, but rather on the informed judgment of the co-authors. Further research should focus on documenting more accurately the deployment of specific systems, based on relevant parameters, such as prices, demand, and proper resource assessment, and if possible rely on dynamic features.

3.1.6 POTENTIAL IMPACT OF STUDY

This novel attempt at combining methods, databases, and scenarios into a single framework reveals both the challenges of and the need for such exercises. Where most previous LCAs are snapshots of a system in a certain time and regional context, the presented framework accounts for all regions and all years considered by default. Especially in the context of informing climate change mitigation, an integrated framework like THEMIS can deliver precious insights – most importantly the regional variability of the implementation of a mix of technologies and environmental consequences of global energy policies. It is worth noting that the THEMIS structure is completely independent from the data that the model relies on. Paper I stresses on the links between potential data sources, their degree of complementarity and the issues associated with the various possible combinations. The use of this framework was illustrated with an electricity-producing technology, yet THEMIS can support the assessment of any kind of technology; as a matter of fact, the same structure has been used to assess the environmental consequences of end-use electricity demand efficiency policies in the context of climate change mitigation (Beucker et al. 2015; Bergesen et al. 2016).

The framework has also been tested with other databases, such as CEDA (Bergesen et al. 2014), further showing its flexibility. It was also used to analyse the effects of renewable energy penetrating the European market, by Berrill et al. (2016). Papers II-IV, as well as the two UNEP IRP reports on the trade-offs of climate change mitigation (United Nations Environment Programme 2016; Potočnik and Khosla 2016), use THEMIS extensively. It is therefore our hope that similar structures be used in future large-scale hybrid LCA studies.

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