The Technology Assessment group conducts interdisciplinary research in order to support the decision-making processes of its clients as well as all stakeholders involved in the public debate on energy supply options and the requirements of a sustainable development. In order to achieve a comprehensive assessment of both current and future energy systems and scenario mixes, the Technology Assessment group has five main areas of research
- Life Cycle Assessment
- Environmental Impact and External Cost Assessment
- Risk Assessment
- Electric Sector Simulation
- Sustainability Assessment

Life Cycle Assessment (LCA)
LCA deals with the full spectrum of ways that the fabrication of a product or the delivery of a service affects the environment. The Life cycle inventories account for all material and energy flows occurring during production, operation and decommissioning over the lifetime of every activity. The Technology Assessment group focuses on the assessment of present and future energy systems, including fossil, nuclear and renewable resources. The full energy chain for each system is analyzed, from raw materials extraction through processing, transport, energy conversion, and waste management. This accounts for both direct and indirect burdens to the environment such as emissions to air, water and soil as well as resource and land use. The cumulative results of the inventories allow fair comparison of the wide spectrum of environmental burdens associated with each unit of energy. The environmental inventories are also used in the estimation of impacts and associated external costs. The environmental profiles are an essential input to the group’s implementation of Multi-Criteria Decision Analysis (MCDA).
Life Cycle Assessment: Overview of selected projects, main results, and key publications

Environmental Impact and External Cost Assessment
Polluting activities can cause damage to people, goods, and/or nature. These burdens are often imposed on society and not fully born by the polluter. From the polluter‘s viewpoint, the damages are „external“. In general, an effect on a group of people or the environment that is caused by another group but not fully accounted for by those causing it, is called an externality. Negative externalities are called external costs, and positive externalities are called external benefits. The Impact Pathway Approach (IPA) consists of four steps: 1. Estimation of emissions. 2. Estimation of changes of pollutant concentrations. 3. Estimation of impacts on receptors like humans, animals, plants etc. 4. Valuation. The external cost method uses money in order to value the impacts.
Environmental Impact and External Cost Assessment : Overview of selected projects, main results, and key publications

Risk Assessment
Severe accidents are a very controversial topic in public perception and energy politics. The database ENSAD (Energy-related Severe Accident Database) at PSI concentrates on comprehensively covering severe, energy-related accidents and their technical aspects. Complete energy chains are considered because accidents can occur in every stage of the chain. The results based on ENSAD show that energy-related risks in the industrialized countries of the OECD are significantly lower than in the medium or less developed non-OECD countries. This is due to differences in the technologies used, safety standards and the general safety culture. The most accident-prone areas in non-OECD countries are the upstream stages of the fossil energy chains and hydro power. Expected fatality rates are lowest for western hydropower and nuclear power plants; however the maximum credible consequences can be very large.
Risk Assessment: Overview of selected projects, main results, and key publications

Electric Sector Simulation (ESS)
The cumulative impacts of the electrical power system depend upon how the system evolves over time in its physical composition, and also very importantly upon how we choose to operate the system. The ESS method analyzes many specific scenarios over time, optimizing the operation of existing and future plants. Each scenario is uses a fixed strategy composed of available options (e.g. new generation technologies, fuel choices, or efficiency programs), combined with uncontrollable uncertainties (e.g. demand growth, fuel prices, or regulatory changes). Electric sector strategies concern multiple stakeholders, so no one strategy for expansion and operation is ever optimum because stakeholders disagree on how to balance conflicting objectives. For this reason, the ESS method may analyze (simulate) several thousand scenarios, calculating many different indicators for multi-criteria assessment. If multi-criteria tradeoff analysis is not adequate to assist stakeholders in selecting their preferred strategies, then the ESS group can use multi-criteria decision analysis methods to assist stakeholders in their choices. The ESS method is therefore complementary to the Energy Economic Modeling performed by the EEM group within LEA, which models the full energy sector, optimizing system expansion strategies using a single, least-cost criterion for a limited number of future scenarios. In both cases, the key results used by other Technology Assessment efforts (like LCA) are the total annual generation by each technology.
Electric Sector Simulation: Overview of selected projects, main results, and key publications

Sustainability Assessment
The sustainability of current and future power-supply technologies can be analyzed by comprehensive, interdisciplinary assessment. The evaluation may use the total-cost approach, and/or Multi-Criteria Decision Analysis (MCDA), taking into account ecological, economic and social aspects. Total costs can be controversial, but they do include the economic and environmental effects of the various energy options. Internalization of external costs increases the relative competitiveness of renewables and nuclear. Renewable technologies have the highest potential for technological improvements and thus cost reductions. Nuclear power has the lowest total costs both now and in 2030. Total costs lead to a clear ranking of technologies, but provide a limited representation of social aspects whose broader consideration may affect ranking of nuclear. Social factors are better represented in Multi-Criteria Decision Analysis. Depending on stakeholder preferences, MCDA can lead to a different technology ranking than total cost, and is therefore used to provide an alternate aggregate sustainability indicator.
Sustainability Assessment: Overview of selected projects, main results, and key publications