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Cogeneration

ICAES can store unneeded energy from fossil plants, allowing them to operate at their peak efficiency and avoid the damage caused by repeated cycling. With its patented cogeneration capability, ICAES can utilize low-grade waste heat to substantially boost its performance in hybrid fossil applications.

Cycling of baseload fossil plants is inefficient and shortens lifetime

In the 1960s through the 1980s, the United States saw rapid development of pumped-storage hydropower to balance the output of baseload nuclear plants. Utilizing this early application for grid-scale storage, a nuclear plant could maintain operation at its most efficient power level by storing excess electricity as potential energy in a pumped-storage facility’s upper reservoir. As today’s grid seeks to integrate a growing quantity of variable generation, baseload plants are being forced to cycle their output during periods of rapid change in variable generation. SustainX storage installed at a conventional power plant will convert excess power to energy stored as compressed air. ICAES’s rapid ramp rate and multi-hour storage capabilities allow fossil assets to remain at peak efficiency and avoid the costs, wear, and emissions associated with repeated cycling. At times when higher electric output is needed, such as peak-demand periods, the SustainX system can release energy from storage. A conventional plant enhanced with SustainX storage can thus serve as a low-cost “virtual peaker,” supplying extra electricity at high efficiency during periods of high demand—a service usually provided by costly, dedicated peaker plants burning natural gas. Higher power-plant efficiency means less pollution and lower cost for each unit of electricity produced.

Cogeneration boosts ICAES performance

In a hybrid fossil application, the ICAES system can realize a substantial boost in performance through cogeneration. Cogeneration is the production of electricity using energy left over from some other process. For example, a conventional power plant discards heat not intense enough to make steam, wasting about 60 percent of the energy released from its fuel. SustainX storage technology can turn a portion of this waste heat into electricity, supplying a storage function and a cogeneration function at the same time. It is the only utility-scale energy storage option that can harvest additional electricity from low-grade heat.

A SustainX isothermal (constant-temperature) energy-storage system can cogenerate because it removes heat from air being compressed for storage and adds heat to air being expanded. The heat added during air expansion, when the system is generating electricity, can come from any source—including a conventional power plant. Within limits, the more heat is added, the more extra electricity is produced.