Is the optimal decarbonization pathway influenced by indirect emissions? Incorporating indirect life-cycle carbon dioxide emissions into a European TIMES model

Abstract

This paper first reviews previous relevant efforts to bring energy system models and life-cycle assessments together. In section 3, we set out the method we have used, including the details of the EEIO model, the TIMES model, the procedures for linking them, and the scenarios examined. Section 4 then provides results relating to each of the research questions, while section 5 draws key conclusions. The paper is accompanied by a supplementary file that includes considerable further detail on the modelling approach, the data used, and the results. 2 Literature review Bottom-up ESOMs (such as MARKAL [Loulou et al. 2004] and TIMES [Loulou et al. 2004]) and MESSAGE (Messner and Schrattenholzer 2000)) provide a detailed depiction of the energy system, with explicit representation of primary extraction of energy resources, processing and conversion, delivery to consumers, and end-use (DeCarolis et al. 2017). Such models account for some emissions associated with upstream extraction (flaring, for example), and they account for the efficiency losses and energy inputs associated with conversion and processing (e.g. in refineries and power stations), with transmission and distribution (losses in electricity transmission lines, energy use in fuel distribution, etc.), and efficiency losses in end use devices. Many sources of fossil fuel chain indirect emissions are thus already included in the default setup of TIMES (see the supplementary file for further details). ESOMs are "demand-driven" in the sense that the energy service demands across the economy are a key exogenous input into the models. Energy service demands associated with

Integrating Energy System Models in Life Cycle Management

“…ETSAP's reviews include over 250 references to articles using TIMES models in peer-reviewed journals. Studies deriving life cycle emissions from environmentally extended input-output (EEIO) data are included, despite having a different level of technological detail [8][9][10]. Only works published in peer-reviewed journals were considered.…”

“…Several studies use market mixes from TIMES for prospective assessments, improving temporal representativeness [3,4,12], while others integrate life cycle emissions in TIMES models [7][8][9][10][11]. Limiting the boundaries to a particular sector reduces the number of technologies that need to be mapped, but it could result in a loss of completeness, questioning the suitability of the system boundary.…”

“…Refs. [7][8][9][10][11] added life cycle emissions to several processes of a MARKAL/TIMES model to internalise environmental emissions. It was a first step towards the integration of externalities, but incomplete mapping may be problematic as it may induce a bias against the mapped technologies (see Sect.…”

“…Constructing more "circular" RES in TIMES models is challenging, as the models need to be calibrated using national statistics, and these do not necessarily have a high level of detail of material flows leaving each sector. Studies linking TIMES with EEIO data have more thoughtfully addressed double counting, erasing manually repeated areas of the inventory [8][9][10]. Reference [10] used fixed input-output coefficients to adjust the exogenously defined demands (e.g.…”

“…The use of energy system optimisation models (ESOM) together with life cycle thinking has the potential to underpin comprehensive understanding of the energy supply chain and its influence on sustainable production. There is a small but increasing number of studies combining life cycle assessment (LCA) and ESOM [3][4][5][6][7][8][9][10][11][12], ESOM best practices start to include LCM practices, such as goal and scope definition or the use of data quality indicators as a way to quantify epistemic uncertainty (i.e. the uncertainty associated with data quality) [13].…”