Roberto Dones

Life‐cycle assessment of photovoltaic systems: results of Swiss studies on energy chains

The methodology used and results obtained for grid-connected photovoltaic (PV) plants in recent Swiss life-cycle assessment (LCA) studies on current and future energy systems are discussed. Mono- and polycrystalline silicon cell technologies utilized in current panels as well as monocrystalline and amorphous cells for future applications were analysed for Swiss conditions. The environmental inventories of slanted-roof solar panels and large plants are presented. Greenhouse gas emissions from present and future electricity systems are compared. The high electricity requirements for manufacturing determine most of the environmental burdens associated with current photovoltaics. However, due to increasing efficiency of production processes and cells, the environmental performance of PV systems is likely to improve substantially in the future.

Life Cycle Assessment of Photovoltaics; Update of the ecoinvent Database

Recently, the data for photovoltaics in the ecoinvent database have been updated on behalf of the European Photovoltaics Industry Association and the Swiss Federal Authority for Energy. Data have been collected in this project directly from manufacturers and were provided by other research projects. LCA studies from different authors are considered for the assessment. The information is used to elaborate a life cycle inventory from cradle to grave for the PV electricity production in 3kWp plants in the year 2005. The inventories cover mono- and polycrystalline cells, amorphous and ribbon-silicon, CdTe and CIS thin film cells. Environmental impacts due to the infrastructure for all production stages and the effluents from wafer production are also considered. The ecoinvent database is used as background database. Results from the LCA study are presented, comparing different types of cells and analysing also the electricity production in a range of different countries. It is also discussed how the environmental impacts of photovoltaics have been reduced over the last 15 years, using the CED indicator. The consistent and coherent LCI datasets for basic processes make it easier to perform LCA studies, and increase the credibility and acceptance of the life cycle results. The content of the PV LCI datasets is made publicly available via the website www.ecoinvent.org for ecoinvent members.

Life Cycle Assessment of Future Fossil Technologies with and without Carbon Capture and Storage

The NEEDS project of the European Commission (2004-2008) continues the ExternE series, aiming at improving and integrating external cost assessment, LCA, and energy-economy modeling, using multi-criteria decision analysis for technology roadmap up to year 2050. The LCA covers power systems suitable for Europe. The paper presents environmental inventories and cumulative results for selected representative evolutionary hard coal and lignite power technologies, namely the Ultra-Supercritical Pulverized Combustion (USC-PC) and Integrated Gasification Combined Cycle (IGCC) technologies. The power units are modeled with and without Carbon Capture and Storage (CCS). The three main technology paths for CO 2 capture are represented, namely pre-combustion, post-combustion, and oxy-fuel combustion. Pipeline transport and storage in geological formations like saline aquifers and depleted gas reservoirs, which are the most likely solutions to be implemented in Europe, are modeled for assumed average conditions. The entire energy chains from fuel extraction through, when applicable, the ultimate sequestration of CO2, are assessed, using ecoinvent as background LCA database. The results show that adding CCS to fossil power plants, although resulting in a large net decrease of the CO 2 effluents to the atmosphere per unit of electricity, is likely to produce substantially more GHG than claimed by near-zero emission power plant promoters when the entire energy chain is accounted for, especially for post-combustion capture technologies and hard coal as a fuel. Besides, the lower net power plant efficiencies lead to higher consumption rate of non-renewable fossil fuel. Furthermore, consideration of the full spectrum of environmental burdens besides greenhouse gas (GHG) results in a less definite picture of the energy chain with CCS than obtained by just focusing on GHG reduction.

Sustainability aspects of current and future electricity supply systems

Approaches to comprehensive and consistent evaluation of sustainability of electricity supply systems including fossil, nuclear and renewable technologies are described. Sustainability can be assessed in a comparative manner using a comprehensive set of indicators derived using a variety of methods. Examples of indicators are provided for a variety of current systems. Some trends for future systems are briefly described. Finally, conclusions are drawn on performance of the various technologies with respect to economic, ecologic and social criteria.

Comparison and Integration of CETP Tasks

The CETP project has approached the problem of Shandong’s electricity future in a way that has integrated the use of many different and complex methodologies within specific tasks and task interactions. These integration activities were conducted on different levels with varying degrees of implementation, and have included the following:

An Integrated Decision-Support Tool for Sustainable Energy Supply

Within the China Energy Technology Program (CETP), sponsored by ABB in conjunction with the Alliance for Global Sustainability (AGS), PSI, together with American (MIT), numerous Chinese, Japanese (Tokyo University) and Swiss (ETHZ and EPFL) partners, investigated how the future electricity supply in China could be made more sustainable. Most detailed analyses were carried out for the Shandong province though a wide spectrum of results was obtained for whole China. Representatives of major Chinese stakeholders participated in the program.