Life Cycle Assessment (LCA) of a Concentrating Solar Power (CSP) Plant in Tower Configuration with and without Thermal Energy Storage (TES)

Abstract

Despite the big deployment of concentrating solar power (CSP) plants, their environmental evaluation is still a pending issue. In this paper, a detailed life cycle assessment (LCA) of a CSP tower plant with molten salts storage in a baseload configuration is carried out and compared with a reference CSP plant without storage. Results show that the plant with storage has a lower environmental impact due to the lower operational impact. The dependence on grid electricity in a CSP tower plant without storage increases its operation stage impact. The impact of the manufacturing and disposal stage is similar in both plants. When analyzed in detail, the solar field system and the thermal energy storage (TES) and heat transfer fluid (HTF) systems are the ones with higher impact. Within the storage system, the molten salts are those with higher impact. Therefore, in this study the impact of the origin of the salts is evaluated, showing that when the salts come from mines their impact is lower than when they are synthetized. Results show that storage is a key element for CSP plants not only to ensure dispatchability but also to reduce their environmental impact.

Definition of Key Performance Indicators (KPIs) to Evaluate Innovative Storage Systems in Concentrating Solar Power (CSP) Plants

“…KPIs at thermal energy storage level are useful to compare the different storage technologies, but it is important to consider also the effect of the integration of TES into the CSP plant. Indeed, as demonstrated by Gasa et al (2021), the integration of thermal energy storage highly affects the performance of the whole CSP plant such electric energy consumption that affects directly the CO2 emissions,. In this paper, some relevant KPIs that can be applied to most of the storage technologies were selected at thermal energy storage level and reported as follows (Cabeza et al, 2015;Del Pero et al, 2018;Gasia et al, 2017;Palomba and Frazzica, 2019): KPI 1 -Nominal capacity [MWhth]: amount of energy that can be stored in the storage at nominal conditions.…”

“…Thermal energy storage tanks in CSP plants need special design features to limit mechanical stress resulting from the thermal effects due to their high temperature operation. Cold storage tanks are commonly fabricated with carbon steel (ASTM A-516 Gr.70), while hot storage tanks are fabricated with stainless steel (ASTM A-347H or ASTM A-321H) (Gasa et al, 2021). The thermal energy storage of the CSP plant used to validate the KPIs proposed in this study had a storage capacity in molten salts of 17,5 equivalent hours at nominal conditions, allowing for a 24/7 electric baseload production (Tab.…”

“…In order to offer electricity dispatchability and to adapt the electricity power production to the demand curve, thermal energy storage is an essential component of CSP plants (González-Roubaud et al, 2017). Furthermore, as reported by Gasa et al (2021), the use thermal energy storage has a strong positive effect on the environmental impact during the life-cycle of a CSP plant. Current commercial thermal energy storage systems in CSP plants are steam accumulators and molten salts.…”

Bibliometric Map on Corrosion in Concentrating Solar Power Plants

“…Both commercially used HTF and storage materials, as well as new studied storage materials, are potentially corrosive [5]. Materials used for pipes, tanks, receivers, etc., are mostly carbon steel, stainless steel and/or Ni-based alloys; materials used as HTF or storage are water, synthetic oils, organic solvents, molten metals, and molten salts [5,6]. A significant number of studies show that molten salt corrosion in metal alloys has a fundamental relationship with the anion type, process temperature, HTF impurity content, cover gas atmosphere, flow state and metal alloy composition.…”

Molten salts: Potential candidates for thermal energy storage applications

“…Steam accumulators use the steam released from the NPPs as coolants and store the high‐pressure steam as a saturated liquid 6 . The tanks made to store pressurized steam can store the same at high temperatures and are hence found in abundance in multiple parts of Europe and North America despite the potential hazards due to the high expansion coefficient of water resulting in leakages 7 and the closeness of the freezing and boiling points of water giving low operational temperature range 8 . Hybrid systems of solar and NPPs are also reported to be used to achieve higher thermal efficiencies in which solar heat is transmitted to nuclear steam to increase its temperature, and the required continuous heat is delivered via molten salts‐based TES systems.…”