Life Cycle Assessment and Environomic Optimization of Concentrating Solar Thermal Power Plants

摘要

The number of Concentrating Solar Power(CSP)plants in operation and under planning is currently growing.The assessment and the optimization of their performances are required both at the economic level and at the environmental level.Life Cycle Assessment(LCA)has been proven to be suitable for the environmental assessment of renewable energy technologies,since it accounts for the impacts generated over the full life cycle.This paper presents first a comparative LCA of four different CSP plants using data of recently built power plants: parabolic trough(Andasol),tower(Gemasolar),Fresnel(PE2)and dishes(Maricopa).The Impact2002+method is used to assess their impacts on human health,ecosystem quality,climate change and resources.A sensitivity analysis on the key design parameters of CSP plants is as well performed.Subsequently,a multi-objective environomic optimization is run with selected decision variables to minimize simultaneously the levelized cost of electricity and the environmental impacts.The hybridization with natural gas is considered.The issue of the optimal value of the C02 tax ensuring the competitiveness of CSP over its fossil competitors is as well addressed.The results of the LCA demonstrate that more than 86％of the impact is due to the construction phase.In general,the solar field construction has the highest contribution to the impact.In addition,the storage system and the heat transfer fluid(HTF)may have as well a significant impact,in particular for trough plants.However,when compared with its fossil competitors,CSP has a much lower impact for most of the impact categories.The optimization highlights the trade-off between the investment costs of the CSP plant and its environmental impacts.The optimal range for the hybridization ratio is between 70％and 20％.The breakeven value of the C02 tax favoring CSP over coal or natural gas is between 54 and 174 $/ton of C02-eq,depending on the CSP technology and the hybridization ratio.