Is Power-to-Gas the Future of the Gas Utility?
by Bob Shively, Enerdynamics President and Lead Instructor
"Power-to-gas is a compelling concept that converges the existing siloed value chains of the gas and electricity sector into one energy system able to meet the challenges of a mostly renewables-based energy supply system." ~ European PowertoGas Whitepaper
Renewable electricity production is growing rapidly in many regions, both in the U.S. and globally. This is creating opportunities for flexible generation and storage on electricity grids as excess generation during times of high wind or high sun often exceeds system needs but then drops before the hours of peak demand. Many see this as a good opportunity for natural gas utilities serving gas power plants, as flexible gas units provide the perfect match for variable renewable output. But this doesn’t take care of the overgeneration situation when renewable output is robust. And in some regions the same environmental concerns that pushed development of renewable electricity are also leading to questions about further growth of natural gas since use of gas contributes to greenhouse gas (GHG) emissions.
An alternative to flexible generation is to store the renewable electricity and return it to the grid at a later time. This has lead to growth of electric storage projects, but storage becomes costly when power output may need to be shifted across multiple days or even seasons. Another way to deal with the issue is to use renewable electricity to create clean sources of gas that could then be used in gas powerplants without creating harmful emissions. One way is through a process called electrolysis, which, using a device called an electrolyzer, applies electricity to water to split the water into oxygen and hydrogen molecules. The hydrogen can then be used as a clean fuel and can be stored in pipes or underground until needed:
Source: SoCalGas website
At some time in the future, this may result in gas pipeline systems being converted to hydrogen and our gas appliances being modified to burn this clean fuel.
In the meantime, an additional step can be used to convert the hydrogen to renewable natural gas:
Source: SoCalGas website
Feasibility of both processes has been demonstrated at multiple locations including projects at University of California – Irvine, the National Renewable Energy Lab in Colorado, and numerous spots in Europe. A recent whitepaper by the European Power to Gas Platform concluded that power-to-gas coupled with fuel cells and/or high-efficiency combined-cycle gas turbines is a promising multi-purpose tool to provide services including:
- Electric system balancing
- Seasonal energy storage
- Feedstock for decarbonizing chemical and processing industries
- Clean transport fuel
Use of power-to-gas may provide such benefits at a lower cost than investing in electric infrastructure. It is well worth watching the development of the current pilot projects as power-to-gas may provide a future alternative business model for gas utilities in regions where environmental pressures continue to grow.
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