62 Sustainability of Current Electricity Supply Technologies: A Comparative Evaluation (PSAM-0395)

The present study provides a framework for systematic comparative evaluation of sustainability of energy systems. Existing, representative evaluation criteria and indicators, recently proposed by competent international organisations were reviewed. Based on this survey and own experience from various evaluation studies, a set of criteria and indicators for use in the present project was established. The main effort went into generation of quantitative technology-specific economic, environmental and social indicators. The indicators cover also risks of accidents. The evaluation addressed fossil energy carriers (lignite, hard coal, oil, natural gas), nuclear and renewables (hydro, wind, solar photovoltaic). Apart from power plants the associated fuel cycles were fully included. The methodology was applied to technologies currently operating in Germany.

A number of methods were employed for this purpose including Life Cycle Assessment (LCA), Risk Assessment (RA) and Impact Pathway Approach (IPA). Some new methodological advancements were implemented, in particular improved link between LCA and impact estimation, and enhanced treatment of site-dependent effects in the estimation of impacts and corresponding external costs. Severe accident risks were addressed based on the examination of historical experience world-wide and by employing Probabilistic Safety Assessment (PSA) techniques. In this context a highly comprehensive database ENSAD (Energy-relatedSevere AccidentDatabase) has been established.

Two methods of indicator aggregation were employed, i.e. estimation of total (internal and external) costs and Multi-criteria Decision Analysis (MCDA). Use of MCDA is motivated by acknowledgement of the role of value judgements in decision-making. In terms of total costs nuclear power shows top performance, under German conditions superior to other currently implemented technologies. Evaluations employing a variety of sustainability criteria result in a differentiated picture of the merits and drawbacks of the currently available electricity supply options. No single system exhibits a superior performance on all criteria. MCDA ranking based on the three pillars of sustainability, i.e. economy, ecology and social, is relatively robust when these pillars are considered equally important and the weighting of lower level criteria (e.g. financial requirements or employment effects) is subject to variation. Putting emphasis on economy penalizes renewables; emphasis on environment penalizes fossil systems and on societal aspects nuclear. Refinements of the methodology and specific indicators are feasible. Options for future applications include direct involvement of stakeholders, and evaluations of future technologies and of supply scenarios combining the various candidate technologies. Tools supporting such analyses have been developed by the Paul Scherrer Institut (PSI) and can be adjusted to the needs of country-specific applications.