Compressed Natural Gas Energy Storage

One of the keys to achieving high levels of renewable energy on the grid is the ability to store electricity and use it later. Renewable energy generation from wind and solar may not coincide with peak power demand hours. Power companies can cover this demand with natural gas peaking plants, which only operate during high demand hours. This option underutilizes capital dollars invested in energy generation. Battery storage is another option, but it has a high capital cost, can only provide power for short durations, and requires a large supply of rare earth metals.

ISTC’s energy storage researchers propose compressed natural gas energy storage (CNGES) as an alternative energy storage solution. Natural gas is compressed (increase pressure) to transport and storage in pipelines. When it is time to use the natural gas, the pressure is reduced. The energy used to compress the natural gas is not usually recovered at the time of use. However, if energy from renewable sources is used to compress natural gas and recovered at time of use, then renewable energy could be stored in the compressed natural gas. Expander generators installed where the gas is prepared for delivery to customers can be used to harness the stored the renewable energy. In this instance, the natural gas pipeline and compression infrastructure already exist. The additional cost is to add the expander generators, which makes this an attractive low-cost energy storage option.

Abbott Power Plant Demonstration Project

Phase 1

ISTC performed a conceptual (Phase I) study at the University of Illinois Urbana-Champaign’s (UIUC) Abbott Power Plant to integrate natural gas-based energy storage into its operations. The goal of the project was to demonstrate the technical and economic feasibility of integrating CNGES technology with an existing co-generation fossil fuel power plant and establishing the path for its maturation and commercialization.

A techno-economic analysis of the cost of energy storage at Abbott showed that CNGES has about an 89% less capital investment when compared to lithium-ion battery storage for the same amount of energy stored. The levelized cost of electricity was about 60% lower for CNGES. Calculated capital costs per kilowatt hour of energy are reduced even more when CNGES is scaled up to commercial size. The conceptual study showed that installing CNGES at Abbott could be well integrated and would be a cost-effective way to store renewable energy.

Funding for the Phase 1 project was provided by the U.S. Department of Energy, National Energy Technology Laboratory, Office of Fossil Fuels (DE-FE 0032018).

Phase II

The team plans to submit a proposal to continue the project. Phase II will include additional team members from external consulting firms. The researchers will create an engineering, procurement, and construction plan; project timeline; detailed cost estimates; and complete the necessary paperwork to build and test the pilot CNGES in phase III.