Challenges in the Thermal Energy Storage for Solar Power Plants

The need for renewable and sustainable energy is clear. Concentrated Solar Power (CSP) is one means of power generation that is becoming economically viable to meet those needs. CSP however, does have limitations due to it's reliance on direct sunlight as a means of energy input. Thermal energy storage (TES) can overcome these limitations and can improve a plant's economic viability by allowing power production during peak demand periods that occur during non-daylight hours. The Solana project designed by Abener North America, near Gila Bend, AZ utilizes molten nitrate salt thermal energy storage to capture these benefits. Thermal energy storage has long been considered by the solar industry; and the Abengoa companies have endeavored to design and build the world's largest thermal energy storage system attached to a CSP plant. A variety of technical considerations must be made when designing a nitrate salt thermal energy storage system. Just a few of these design considerations include salt melting operations, the high temperature molten salt storage tank and tank foundation designs, TES heat exchangers, nitrogen blanketing, and the salt freeze protection design. The test facility designed and built by the Abengoa companies in 2009 in Sanlucar La Mayor Spain has provided much insight and experience necessary to answer many of these design issues. This paper will present in detail the technologies associated with, and the challenges in designing the world's largest nitrate salt thermal energy storage system by a world leader in renewable energy solutions.