By Sean O’Neil
Renewable energy sources are experiencing a period of rapid growth, with the U.S. Energy Information Agency forecasting that they will be the fastest growing source of electricity generation in the near future. However, renewable energy sources such as solar and wind suffer from supply and demand imbalances, because their most productive periods are when electricity demand is lowest, leading to a surplus of unused energy, and they are least productive when electricity demand peaks, leading to energy shortages that must be filled by other means. To address this issue, renewables must be supplemented with other dispatchable energy sources, which can instantaneously adjust output to match shifts in energy demand. One promising option to fulfill this dispatchable energy role is hydrogen energy storage.
Hydrogen energy storage is a process wherein the surplus of energy created by renewables during low energy demand periods is used to power electrolysis, a process in which an electrical current is passed through a chemical solution in order to separate hydrogen. Once hydrogen is created through electrolysis it can be used in stationary fuel cells, for power generation, to provide fuel for fuel cell vehicles, injected into natural gas pipelines to reduce their carbon intensity, or even stored as a compressed gas, cryogenic liquid or wide variety of loosely-bonded hydride compounds for later use. Hydrogen created through electrolysis is showing great promise as an economic fuel choice, with data from the International Energy Agency predicting that hydrogen generated from wind will be cheaper than natural gas by 2030.
While other forms of energy storage such as batteries and pumped water storage facilities can fulfill the same dispatchable energy needs, both have limitations that hydrogen energy storage can overcome. Batteries suffer from storage degradation, and can only store a limited amount of energy, whereas hydrogen fuel can be stored for long periods of time, and in quantities only limited by the size of storage facilities. According to Steve Szymanski, Director of Business Development at FCHEA member Nel Hydrogen, “batteries are best suited to discharge times that are 4 hours or less… [Hydrogen energy storage] can address longer duration needs (say days or even weeks).” Although pumped water storage does not suffer from the same duration and capacity limitations of chemical batteries, it can only be used in limited geographic areas where hills or mountains are present, requires vast areas of land, and can be prohibitively expensive to build.
Hydrogen energy storage has proven its merit beyond the lab through real-world projects. For example, in 2018 Enbridge Gas Distribution and FCHEA member Hydrogenics opened North America's first multi-megawatt power-to-gas facility using renewably-sourced hydrogen, the 2.5 MW Markham Energy Storage Facility in Ontario, Canada. The facility is currently providing grid regulation services under contract to the Independent Electricity System Operator of Ontario.
In Europe many hydrogen energy storage projects have been created, such as the Energiepark Mainz in Germany, a project involving FCHEA member Linde, in partnership with Siemens, the Rhein Main University of Applied Sciences and the Mainzer Stadtwerke. The Energiepark uses excess wind energy to create hydrogen fuel, which is later used to generate energy when wind power cannot match demand.
Orsted, Denmark’s largest energy firm, is planning to use excess energy from its proposed North Sea wind farms to power electrolysis and create renewable hydrogen energy. The proposed wind farms would have a nameplate capacity of 700 MW and be linked directly to the grid. During periods of time where the wind farms oversupplied energy, this excess power would be used to generate hydrogen through electrolysis which would later be sold to large industrial customers.
In the United States, hydrogen energy storage has begun to show promise through ongoing tests, and promising projects. For example, SoCalGas, a natural gas provider based in Southern California, has partnered in hydrogen energy storage projects. With the National Fuel Cell Research Center at the University of California at Irvine, SoCalGas installed an electrolyzer powered by the on-campus solar electric system, which generates renewable hydrogen to be fed into the campus power plant. With the National Renewable Energy Laboratory, SoCalGas constructed a biomethanation reactor system, which uses a water electrolyzer to produce hydrogen from renewable power, through a bioreactor that converts hydrogen and carbon dioxide into methane and water.
Beyond tests, promising full-scale hydrogen energy projects have also been constructed. Mitsubishi Hitachi Power Systems and Magnum Developer are planning to develop a 1,000 MW power facility in Millard County, Utah, which will be used to store renewable hydrogen, while also deploying flow batteries and solid oxide fuel cells at the site. Xcel Energy, a large utility provider, is partnering with the National Renewable Energy Laboratory to create an 110 kW wind-to-hydrogen project which would use excess wind energy to create hydrogen to be stored for later use at the site's hydrogen fueling station or converted back to electricity and fed to the utility grid during peak-demand hours.
As the American energy grid is becoming increasingly fueled by renewable energy sources, it should continue to embrace hydrogen energy storage as a dispatchable energy source to manage the supply and demand imbalances which will come with a renewable energy powered grid.