A unified ecological assessment of a solar concentrating plant based on an integrated approach joining cosmic exergy analysis with ecological indicators

A unified ecological assessment is carried out for the 1.5 MW Dahan solar tower power plant in Beijing, by means a thermodynamic approach based on exergy. This study for the first time inventoried a most detailed list of the renewable and nonrenewable inputs of a pilot solar concentrating plant, which are traced to a sufficient detail to be matched with the macro economic statistics. Ecological indices are calculated for an objective assessment of the renewability and sustainability of the solar electricity system. The results reveal that the total resource inputs exceed the electricity output in a thermodynamic measure, suggesting that the solar plant with a designed life of twenty years is ecologically unfriendly. The purchased inputs account for more than 99% of the total resource inputs. It is found that the system needs to be operating for no less than 28 years before achieving ecological benefits. The ecological performance of the pilot solar concentrating plant is also compared with other forms of electricity generation systems. The findings quantitively support existing arguments doubting the renewability and sustainability of solar plants and provide a benchmark for unified evaluation of renewable-based electricity systems.