Electricity from the Sun: is it attractive for Latvia? Life-cycle assessment of photovoltaic systems

Minimizing greenhouse gas emissions (GGE) may prove to be the most significant technical and political challenge facing energy decision-makers today. The Latvian electric industry contributes over 18% of domestic emissions and is arguably one of the most important components for effective GGE mitigation. This paper uses Life-Cycle Assessment (LCA) to better understand the energy and environmental performance of electricity generating systems. The results of the LCA are employed to provide an effective and accurate means for evaluating GGE reduction strategies for the Latvian electricity generation. The LCA has been performed for an 8 kW building-integrated photovoltaic (PV) system. Consideration of life-cycle energy requirements significantly reduces the PV system's net energy performance. This reduction is important when evaluated over the life cycle of such a PV system. The LCA results show that the PV system has low - but not zero - life-cycle GGE rate of 36 tonnes CO2-equivalent per GWhe (36 t CO2/Gwhe). This value is higher than that for the hydro- and renewable systems studied by other authors, including data for hydropower system 18 t CO2/ GWhe, for wind system 12 t CO2/GWhe, and others. However the PV emission rate is more than 10 times less than that for a natural-gas-fuelled plant emission rate (469 t CO2/GWhe) or coal-fuelled plant emission rate (974 t CO2/GWhe). Concerning the effective climate change policy, in addition to reducing the emissions it must also address the growing demand for electricity. This demand will likely be met with diverse energy sources, including peat, coal, gas, and multiple renewable technologies. The total GGE impact from any combined electricity system is difficult to evaluate, as it requires the assimilation of emission factors and generation from each technology. For the evaluation a ternary method is developed that provides a simple means for comparison of GGE reduction alternatives.With the ternary method two GGE mitigation alternatives are evaluated: - fuel switching from peat to natural gas for Kyoto-based compliance, - fuel switching from peat to hydro/renewable for Kyoto-based compliance. In a moderate consumption growth scenario, fuel switching from peat to natural gas fails to meet a Kyoto-based emission target, while fuel switching to hydro/renewable meets the emission objective by reducing peat generated electricity 1-2 % below the 2002 level. (authors)