NET ENERGY ANALYSIS FOR CONCENTRATED SOLAR POWER PLANTS IN CHILE

The Chilean Energy Policy calls for 15 percent of new power generation capacity to come from renewable energy Sources from 2006 to 2010, and then a 5% of electric energy generated from renewable energy sources with gradual increases in order to reach 10% by 2024. Concentrated solar power is an interesting alternative to help achieving those objectives, as it is estimated that northern Chile has high radiation levels, coupled with high values of the local clearness index and availability of flat terrain. The present report investigates the net energy attributes of parabolic trough plants installed in the Atacama Desert. Monthly means of solar radiation are used in order to estimate the solar fraction for a 100 MW plant at three different locations. Our analysis considers three cases: operation during sunlight hours only, with and without fossil fuel back-up, and continuous operation during 24 hours a day. The net energy analysis for concentrated solar power (CSP) plants is then performed, considering the energy costs of manufacturing, transport, installation, operation and decommissioning. The results indicate that the CSP plants are a net energy source when operating in sunlight-only mode and that the energy payback time is a linear function of the total operation time when utilizing fossil fuel back-up. In the continuous operation mode, the CSP plants become fossil fuel plants with solar assistance, and therefore all locations display negative net energy. Based on this result, the back-Lip fraction required for the plants to be net energy sources is estimated from the EROEI as function of the back-up fraction. It is estimated that the net energy analysis is a useful tool for determining under which conditions a CSP plant becomes a net energy Source, and thus can be utilized in order to define geographical locations and operation conditions where they can be considered renewable energy sources.