Proceedings of ASME 2011 5th International Conference on Energy Sustainability & 9th Fuel Cell Science, Engineering and Technology Conference · 2011

Enhancing the Economics of Wind-Based Compressed Air Energy Storage by Waste Heat Recovery

Hossein Safaei Mohamadabadi, Ronald J. Hugo, and David W. Keith

Large scale penetration of the renewable energy sources such as wind and solar into the electric grid is complicated by their substantial hourly, daily, and seasonal fluctuations. Energy storage systems can mitigate these fluctuations by storing excess off-peak energy for use at peak-demand times. Compressed Air Energy Storage (CAES) is one of the most promising storage technologies due to the large amount of energy that can be stored at an economical cost. Although conventional CAES systems are operational, they do suffer from low overall efficiency due to the significant amount of energy lost during the air-compression process in the form of waste heat. The Adiabatic CAES design has been introduced to improve the economics of the conventional CAES systems by storing the heat of compression to heat the compressed air prior to the expansion process and electricity generation. However, this design is challenged by the technical complexity of the heat storage system due to the higher pressures and temperatures of the compressed air. We have analyzed the feasibility of improving the economics of a conventional CAES plant by strategically siting the plant to sell the heat of compression as a by-product. We have modeled a system composed of a variable electric and heat load, wind farm, CAES plant, and heat recovery system in Alberta, Canada at an hourly resolution and evaluated the economic gains of selling waste heat. The size of each component was optimized to minimize the cost of electricity generation and maximize revenues from heat sale. Furthermore, a sensitivity analysis on the price of natural gas, carbon tax, and geological constrains for underground storage of compressed air was performed.

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