SBIR Phase II: Advanced Molten Salt for Solar Thermal Power Generation with Supercritical Steam Turbines

This Small Business Innovation Research (SBIR) Phase II project proposes to develop a novel molten salt for solar thermal power generation with supercritical steam turbines. Solar thermal technology developers must increase the operating temperature of their plants to lower their levelized cost of electricity and reduce the cost of thermal storage. Building upon a successful Phase I program, the project team has developed a prototype salt mixture that could enable this trend. It is low cost, exhibits a melting point below 240 deg. C, and has a high maximum temperature of 700 deg. C, a broad operating range currently unavailable elsewhere. The project will conduct a high throughput R & D program to rapidly screen up to thousands of unique mixtures of inorganic salts to optimize the physical properties of the prototype fluid. The project will apply combinatorial chemistry techniques, originally developed for pharmaceutical applications, to this new field. After screening many candidates, the project will evaluate the materials compatibility of a few promising mixtures with common steel and nickel-based alloys. Corrosion mitigation techniques will be developed and evaluated. The project will conduct flow testing in a lab-scale test loop capable of 700 deg. C operation. The broader impact/commercial potential of this project will be the enabling of low-cost electricity from the sun. It is imperative that society reduce its usage of fossil fuels (oil, natural gas, coal) to address pressing concerns - climate change and environmental degradation, energy security, and price volatility. Solar thermal power, a compelling source of renewable electricity at large scale, is the most promising solution to reduce fossil fuel use. However, electricity from solar thermal power currently costs too much to be directly competitive with fossil fuels. Furthermore, solar thermal plants need a cheap way to store heat in order to produce power after sundown or when utilities demand it. This project focuses on the material at the heart of these plants - the heat transfer fluid - and thermal storage system. The market for thermal storage is projected to reach $3.7 billion by 2015. Thermal storage is growing increasingly valuable as utilities realize the need for solar power that can deliver smooth, reliable output regardless of weather conditions. The development of the proposed innovation would both reduce the cost of solar thermal power and enable economical thermal storage, bringing the nation significantly closer to eliminating the use of coal.