UC Irvine

Renewable resources, such as wind and solar, exhibit variability which require the electricity grid to be more flexible in order to accommodate their integration into the system. In addition, events can occur where renewable generation exceeds the electricity demand at a given time and must be curtailed to maintain the balance between load and generation, representing a waste of valuable renewable generation. Power-to-Gas (P2G) refers to a class of technologies which can provide the functions of dispatchable loads and/or energy storage to the electricity system. In particular, power (P) is used to produce hydrogen gas (G) from water through electrolysis. The hydrogen can then be stored, transported (e.g., through natural gas pipelines), and eventually used as a transportation fuel and the generation of renewable electricity to meet load demands.

This work analyzes the economic potential and CO2 emission associated with installation of different P2G use cases: pure hydrogen or hydrogen converted into methane injection into the natural gas pipeline system to offset natural gas; hydrogen fuel for fuel cell vehicles; storage of hydrogen to be used in a fuel cell to provide renewable electricity generation back to the electricity system. It is found that hydrogen fuel use case results in the largest CO2 emission reduction since it offsets high CO2 emitting gasoline vehicles. The economics, due to dependency on many factors such as capacity factor, operational parameters, as well as the price of electricity, do not result in a clear use case of best values.