Using "waste cold" from Liquid Air Energy Storage to achieve temperature objectives
Liquid Air Energy Storage (LAES) is a greenhouse gas-free method of storing potential energy for later conversion. Hydropower generated during off-peak hours can be used to liquefy air. Stored air can be used to generate energy by heating it, creating pressurized air that can be run through a turbine. "Waste cold" is generated during the heating process. The energy industry is seeking use cases for economical disposal of this asset. Hydropower dams are frequently located above stretches of river in which fish evolved for cold water, especially anadromous salmonid species, are present during the summer. Regulatory requirements to preserve cold water in these habitats are operationally challenging, and sometimes hydrologically impossible, to meet.
This study seeks to examine the cold water benefits offered by LAES waste cold. Water supply planning models will provide reservoir elevation time series for power modeling, which will be used to estimate availability (off-peak hours). Water temperature models will be used to convert waste cold into cold water within reservoirs and downriver, with fish mortality models being used to quantify temperature impacts. Other uses for the waste cold relevant to Reclamation such as fish hatcheries will also be considered.
California's energy grid has a great deal of demand for energy storage, and LAES may soon be a reliable way of doing so. The same is true throughout the West. In fact, a company called EPSIM has sent Mid-Pacific Central Valley Operations office a proposal to install a pilot LAES plant with a reservoir cooling element. Studies are needed in the short term so that long-term investments can be made with or without the proposed reservoir cooling devices. The economic viability of hydropower may be the main argument for or against LAES, but an analysis of temperature benefits allows for a fish biology argument as well. As hydropower seeks to position itself in a world of green energy sources, this line of argument
Need and Benefit
Delivering cold water benefits to fish is difficult, and a process called Liquid Air Energy Storage (LAES) is likely to be deployed at hydropower plants. For proper planning, it would be useful to know what cold water benefits are available for a given flow and an LAES plant of a given size. LAES and hydropower are a natural fit on the power side because LAES acts as an emissions-free battery, allowing turbines to liquefy air during off-peak hours. During peak hours the liquefied air is depressurized, turning turbines and emitting "waste cold" which could be used to cool reservoir water. This proposal intends to quantify the scope and benefit of "waste cold" for river and reservoir temperature management purposes.
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Bureau of Reclamation Review
The following documents were reviewed by experts in fields relating to this project's study and findings. The results were determined to be achieved using valid means.
Using “waste cold” from Liquid Air Energy Storage to achieve temperature objectives (final, PDF, 1.8MB)
By Michael Wright and James Lu
Report completed on September 30, 2021