Photovoltaic (PV) technologies have shown remarkable progress recently in terms of annual production capacity and life cycle environmental performances, which necessitate timely updates of environmental indicators. Based on PV production data of 2004–2006, this study presents the life-cycle greenhouse gas emissions, criteria pollutant emissions, and heavy metal emissions from four types of major commercial PV systems: multicrystalline silicon, monocrystalline silicon, ribbon silicon, and thin-film cadmium telluride. Life-cycle emissions were determined by employing average electricity mixtures in Europe and the United States during the materials and module production for each PV system. Among the current vintage of PV technologies, thin-film cadmium telluride (CdTe) PV emits the least amount of harmful air emissions as it requires the least amount of energy during the module production. However, the differences in the emissions between different PV technologies are very small in comparison to the emissions from conventional energy technologies that PV could displace. As a part of prospective analysis, the effect of PV breeder was investigated. Overall, all PV technologies generate far less life-cycle air emissions per GWh than conventional fossil-fuel-based electricity generation technologies. At least 89% of air emissions associated with electricity generation could be prevented if electricity from photovoltaics displaces electricity from the grid.
Hans De Keulenaer on 27 Feb 08This paper gives an overview of the opportunities that exist for combining wind power and hydrogen (H2) production in weak grids. It is described how H2 storage can be applied in both isolated and grid-connected systems, and how the produced H2 can be utilized for stationary energy supply and/or as a fuel for transportation. The paper discusses the benefits and limitations of the different H2 storage applications, and presents a logistic simulation model for performance evaluation of wind-H2 plants. A case study simulating the use of excess wind power in a weak distribution grid to produce H2 for vehicles has been presented. It is shown that the penetration of wind power can be significantly increased by introducing electrolytic H2 production as a controllable load. The results also indicate that there are large benefits of using the grid as backup for H2 production in periods with low wind speed, regarding the H2 storage sizing and the electrolyser operating conditions.