The majority of spinning reserves in the U.S. are natural gas turbines. The decreasing price of natural gas that the U.S. has experienced in the last few years has made combined-cycle gas turbines the prime producer of choice. However, 25-30% of the gas feeding these turbines goes into compressing air in an effort to meet air quality standards mandated by the government. If the utilities using these turbines had a source of air on hand to offset the air produced by the turbine’s compressors, 100% of their fuel could be used to produce electricity. Having pressurized or liquid air onsite meets this need, giving years of service to the turbines and adding value to the plant, while offsetting the need to add new turbines to meet demands.
It is common to decommission natural gas fired turbines when they fail to meet gas-related safety requirement standards and the costs of turbine reconditioning are no longer justifiable. Since there are no combustion issues with using a pressurized or liquid air system to spin these machines, and they are already connected to the power grid, using air as fuel would extend their service life and realize considerable savings to the industry.

Another utility incentive is to use liquid air for converting low-grade waste heat such as that generated in an existing power plant into power. Liquid air can accomplish this with very high levels of efficiency because of its low starting temperature (-196oC). Other waste heat recovery technologies’ maximum theoretical yields are usually limited to about 20% because they begin at 100°C. The abundant cold that comes from the re-gas process of the liquid air could be used to offset the air conditioning needs of the power plant, while the excess power plant heat could be used to re-gas.

Liquid air as stored energy would be well suited for grid reliability. The PUC’s (Public Utility Commissions) of most states will allow energy storage to be a grid reliability device rather than a generating asset. A storage technology that is integrated into the grid architecture and used for reliability can be utility owned. Peaking and firming can be easily done with air due to its almost instant demand time. Liquid air could phase in for firm capacity as fossil fuel systems age.

Most states actually have legal mandates that require IOU’s (investor owned utilities) to use the least expensive source of electricity available. Fossil fuel historically has been the least expensive, but liquid air could soon out-bid it.

(Technology)

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