Concentrated solar power : plant optimization for energy return on investment and deployment analysis for OECD Europe : a dynamic function for the EROI of CSP

A model of energy balance demonstrates that the solar technology owns the highest potential of evolution due to the future numerous installations and improvements of the technology. The Concentrated Solar Power (CSP) technology, producing electricity from direct irradiation, in the opposite of photovoltaic which produces power from diffuse light, is studied in details. The CSP perspectives in the future mix are analyzed. It appears that CSP towers, among the others CSP technologies, will have the lead of the future deployment. A model computing the Energy Return on Investment (EROI) is used to evaluate the net energy return of the CSP technology. The EROI allows to assess the net potential that the technology is able to deliver to the society and enables the comparison of different energy sources. This dimensionless factor is used to analyze the integration of the CSP technology as an actor of the energy transition for OECD Europe. The model, based on solar data from the NASA, simulates the hourly comportment of a CSP tower plant, during a year, for a given location. A study of life cycle assessments (LCA) allows to attribute energy cost to the defined plant, depending on its configuration. Then, the parameters impacts are analyzed. It appears that three main parameters, defining the plant configuration, critically impact the results given by the model. These parameters are: the capacity of the storage ratio, the power designed of the turbine and the size of the mirrors field. From there, a static analysis of the EROI is performed and the optimal configuration in terms of EROI is computed. The optimal plant for Sevilla (Spain), one of the best region in Europe for CSP applications, has a 49 MW designed power, 20 hours of storage capacity at full load and a solar multiplicator of 2.84. The tests demonstrated that the optimal configuration depends on the location. Afterwards, a dynamic analysis is performed. A program simulates the installation of these optimal plants in all OECD Europe. Sites are ranked by their level of direct irradiation. The availability, in terms of area, is defined for each site, and the program fills the sites with optimal CSP plants (with a configuration suited to the location, maximizing the EROI) until the site is full. Moreover, the evolution of technology is considered. With an optimistic evolution of the technology, the study demonstrates a low net energy gain and question a sustainable deployment of CSP in OECD Europe. To complete the Advanced Energy Scenario of Greenpeace (430 TWh of electricity production in 2050), the model installed 80.5 GW, with 1807 plants, spread over Southern Europe. For this scenario, the mean fossil primary equivalent EROI decreases from 25 in 2015, to 15 in 2050. The electric equivalent EROI is constant at a value around 10. These results confirm the low net energy return of CSP technology for a deployment over OECD Europe, though the technological improvement was optimistic. Indeed, with a value found around 10 for the electric equivalent EROI, the energy sector scale would need to more that double, as the value of the current energy mix for the electric equivalent EROI is much higher than 10. Therefore, operating an energy transition in OECD Europe, with CSP technology as the main pillar, would change the way in which the energy is allocated in society, since the energy sector would need more energy to produce the same quantity than currently. On the other hand, the results for North-Africa countries, due to the high lands availability, considering an optimistic evolution of the technology, show a rise of the electric equivalent EROI. Its value increases from 11 in 2015, to more than 15 in 2050, for a CSP installed capacity able to produce more than 2000 TWh per year in 2050. These results proved that a CSP delployment in North-Africa is interesting in terms of net energy gain