Life Cycle Assessment of a Power Tower Concentrating Solar Plant and the Impacts of Key Design Alternatives

Abstract

A hybrid life cycle assessment (LCA) is used to evaluate four sustainability metrics over the life cycle of a power tower concentrating solar power (CSP) facility: greenhouse gas (GHG) emissions, water consumption, cumulative energy demand (CED), and energy payback time (EPBT). The reference design is for a dry-cooled, 106 MW(net) power tower facility located near Tucson, AZ that uses a mixture of mined nitrate salts as the heat transfer fluid and storage medium, a two-tank thermal energy storage system designed for six hours of full load-equivalent storage, and receives auxiliary power from the local electric grid. A thermocline-based storage system, synthetically derived salts, and natural gas auxiliary power are evaluated as design alternatives. Over its life cycle, the reference plant is estimated to have GHG emissions of 37 g CO2eq/kWh, consume 1.4 L/kWh of water and 0.49 MJ/kWh of energy, and have an EPBT of 15 months. Using synthetic salts is estimated to increase GHG emissions by 12%, CED by 7%, and water consumption by 4% compared to mined salts. Natural gas auxiliary power results in greater than 10% decreases in GHG emissions, water consumption, and CED. The thermocline design is most advantageous when coupled with the use of synthetic salts.

Life Cycle Assessment of a HYSOL Concentrated Solar Power Plant: Analyzing the Effect of Geographic Location

“…Life Cycle Assessment (LCA) is an appropriate methodology to evaluate the environmental performance of renewable technologies, as has been proven in scientific literature [7][8][9]. The environmental impacts of conventional CSP plants have been previously evaluated by the scientific community [10][11][12][13][14][15][16][17][18][19][20]. These analyses are all based on LCA methodology, and evaluate the environmental performance of CSP plants of varying capacity, operating with different technologies (parabolic trough/Fresnel reflectors, central tower, Stirling dish), including specific component characteristics (air/wet cooling, thermal storage technology) and hybridization with different fuels.…”

Embodied energy in thermal energy storage (TES) systems for high temperature applications

“…[2] presented a summary of different technologies used in solar power plants with TES systems existing in the world with more than 25 case studies. Recently, Whitaker et al [3] compared a power tower CSP with a two-tank storage system versus a thermocline design. Moreover, Gil et al [4] created a list of the materials used in high temperature TES applications divided into sensible heat, phase change (PCM), and chemical heat materials and as well as an own new classification of the storage systems dividing it in active and passive storages.…”

“…In high temperature applications, Oró et al [6] studied, also using LCA methodology, different hypothetical scenarios to point out the differences between three TES systems for CSP showing that the system based on solid media presents the lowest environmental impact per kW h stored of all the systems compared. Whitaker et al [3] accounted the GHG emissions, water consumption and cumulative energy demand (CED) for a power tower CSP plant with seven design alternatives. The same parameters are analysed by Burkhardt et al [7] in a parabolic trough CSP plant varying four design alternatives.…”

Análisis de sostenibilidad del ciclo de vida de una configuración innovadora de tecnología termosolar

“…El impacto ambiental potencial obtenido para una planta termosolar de torre en modo solo solar es algo inferior a los dos estudios similares publicados (Weinrebe et al 1998, Whitaker et al 2013. Por ejemplo, los resultados publicados para la categoría de cambio climático se encuentran en un rango de 23 -42 kg CO2/MWh, mientras que el resultado obtenido en este estudio para la termosolar de torre es 18,5 kg CO2/MWh.…”

“…Como aproximación a los materiales presentes en la torre central (no fueron suministrados por la empresa), se ha utilizado de referencia las cantidades proporcionadas por Whitaker et al (2013), usando la altura de la torre como factor de escala (203 m de torre, respecto a 172 m de la torre de Whitaker et al). El inventario relativo a tuberías, válvulas y conectores fue adaptado con el factor de escala 1,6 (de 50 MW a 100 MW).…”