Systems and methods for combined thermal and compressed gas energy conversion systems

Abstract

The invention relates to systems and methods including an energy conversion system for storage and recovery of energy using compressed gas, a source of recovered thermal energy, and a heat-exchange subsystem in fluid communication with the energy conversion system and the source of recovered thermal energy.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS[0001]This application claims priority to U.S. Provisional Patent Application Ser. No. 61 / 145,860, filed on Jan. 20, 2009; U.S. Provisional Patent Application Ser. No. 61 / 145,864, filed on Jan. 20, 2009; U.S. Provisional Patent Application Ser. No. 61 / 146,432. filed on Jan. 22, 2009; U.S. Provisional Patent Application Ser. No. 61 / 148,481, filed on Jan. 30, 2009; U.S. Provisional Patent Application Ser. No. 61 / 151,332, filed on Feb. 10, 2009; U.S. Provisional Patent Application Ser. No. 61 / 227,222, filed on Jul. 21, 2009; U.S. Provisional Patent Application Ser. No. 61 / 256,576, filed on Oct. 30, 2009; U.S. Provisional Patent Application Ser. No. 61 / 264,317, filed on Nov. 25, 2009; and U.S. Provisional Patent Application Ser. No. 61 / 266,758, filed on Dec. 4, 2009; the disclosure of each of which is hereby incorporated herein by reference in its entirety.STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH[0002]This invention was made with government...

AI Technical Summary

Benefits of technology

This approach increases the power output and efficiency of compressed-gas energy storage systems, reducing energy costs and environmental impact by leveraging thermal energy recovery, thereby addressing peak demand and renewable energy intermittency.

Problems solved by technology

In certain parts of the United States, inability to meet peak demand has led to inadvertent brownouts and blackouts due to system overload as well as to deliberate “rolling blackouts” of non-essential customers to shunt the excess demand.

However, these units burn expensive fuels, such as natural gas, and have high generation costs when compared with coal-fired systems and other large-scale generators.

Accordingly, supplemental sources have economic drawbacks and, in any case, can provide only a partial solution in a growing economy.

The most obvious solution involves construction of new power plants, which is expensive and has environmental side effects.

In addition, because most power plants operate most efficiently when generating a relatively continuous output, the difference between peak and off-peak demand often leads to wasteful practices during off-peak periods, such as over-lighting of outdoor areas, as power is sold at a lower rate off peak.

As demand for renewable energy increases, the intermittent nature of some renewable energy sources (e.g., wind and solar) places an increasing burden on the electric grid.

However, the need to burn fossil fuel (or apply another energy source, such as electric heating) to compensate for adiabatic expansion substantially defeats the purpose of an emission-free process for storing and recovering energy.

While it is technically possible to attach a heat-exchange subsystem directly to a hydraulic / pneumatic cylinder (an external jacket, for example), such an approach is not particularly effective given the thick walls of the cylinder.

An internalized heat exchange subsystem could conceivably be mounted directly within the cylinder's pneumatic (gas-filled) side; however, size limitations would reduce such a heat exchanger's effectiveness and the task of sealing a cylinder with an added subsystem installed therein would be significant, making the use of a conventional, commercially available component difficult or impossible.

However, the prior art does not disclose systems and methods for increasing efficiency and power density in isothermal compressed-gas-based energy storage systems having heat exchangers by heating or cooling the heat-transfer fluid.

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