Hydrogen is becoming more viable as a microgrid fuel source, although few hydrogen microgrids exist yet and cost remains a challenge, industry members say.
One example is a housing complex in Sweden where six public buildings run on electricity and heat from a microgrid that combines solar, batteries, heat pumps, hydrogen production and storage plus hydrogen fuel cells.
There are two ways of using hydrogen, explained Scott Kessler, head of U.S. microgrid sales and strategy, Siemens. In the first, a fuel cell creates electricity from hydrogen. “You have a stream of hydrogen coming in, and end up with electricity,” he said.
A second option is using an electrolyzer to create hydrogen, he said. Electrolysis involves using electricity to split water into hydrogen and oxygen. Electrolizers can be small units, the size of household appliances, or large central facilities tied to renewable or other clean forms of electricity production, according to the US Department of Energy.
“One is hydrogen to power, the other is power to hydrogen,” Kessler said.
Stores easily
A major advantage of hydrogen is its ability to be stored for long periods and to provide power in the winter or at night, he said. That means hydrogen can be used to address California’s duck curve, for example, by providing power when the sun goes down. Unlike lithium ion, hydrogen has no capacity issues.
“You can create compressed gas and store it over long periods of time. You could be 100 percent renewable in summer and have a deficit in winter. Hydrogen is an opportunity to push some of that production into winter months,” said Kessler.
Renewable and flexible
Also on the plus side, hydrogen is renewable, and hydrogen-based generating plants can provide grid services.
What’s more, hydrogen electrolyzers are controllable loads that enhance the overall flexibility of the microgrid, added. Rob Hovsapian, research advisor at the National Renewable Energy Laboratory (NREL).
“It only makes sense to do it with a cheap source of electricity.” — Scott Kessler, Siemens
On the negative side, high costs are an issue. As the price of electricity drops, the cost of hydrogen produced by electrolyzers will drop, said Kessler. Right now, hydrogen from electrolyzers can only compete with natural gas if the electricity used to make the hydrogen is 2 to 6 cents/kWh. “It only makes sense to do it with a cheap source of electricity,” said Kessler.
However, one company, Enapter, has found that hydrogen microgrids can be less expensive than diesel microgrids.
“The continuous reductions in capital cost and improvements in efficiency of the electrolyser now make hydrogen cost-competitive,” said Tanai Potisat, business analyst, Enapter.
On the downside, hydrogen can ignite more easily than gasoline or natural gas, which can be dangerous, according to the U.S. Department of Energy.
For Siemens, the benefits are many. The company now has some hydrogen power plants connected to the grid and they could theoretically island, said Kessler.
For example, Siemens helped develop a hydrogen power plant that provides grid services to the Austrian Power Grid.
Hydrogen can also be included in solar microgrids, adding reliability and security to the microgrids, said Thomas Chrometzka, head of strategy, Enapter.
Waste as feedstock
Jean-Louis Kindler, CEO of Ways2H, said his company takes a unique approach to hydrogen. Ways2H uses waste as a feedstock from which to extract hydrogen. The hydrogen can be fed into a fuel cell that will generate power and sent to a microgrid. Or, the fuel cell can power a vehicle.
“The core of our concept is to be able to process waste where it is being produced and produce hydrogen where it will be consumed,” he said.
The company is considering a hospital application that would use medical waste. The hydrogen produced from waste would be put into a fuel cell at the hospital so the hospital could directly use the power generated by the fuel cell, he said. A microgrid that can island could take advantage of the fuel cell in this instance.
One byproduct of creating the hydrogen from waste is carbon dioxide, said Kindler. That can be captured by injecting the carbon dioxide into a salt cave or by using other carbon sequestration strategies.
When carbon dioxide is sequestered in this way, the project becomes carbon negative, he said.
Price competitive in California
As for cost, in some regions of the country — especially California, where electricity prices are high — Ways2H can produce hydrogen that matches electricity prices on the grid.
“In southern California or northern California, the price ranges from 8 to 30 cents/kWh. We can produce power between 8 to 10 cents per kWh using waste,” he said.
With hydrogen’s ability to provide clean energy, supply services to the grid and allow for long-term storage, we can expect to see it used more often in microgrids in the near future.
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