Green hydrogen could efficiently power heavy-duty transportation, according to new U-M study

A study published today by University of Michigan (U-M) researchers asserts that green hydrogen could be used strategically to fuel heavy-duty road, rail, aviation, and marine transportation where electric alternatives are limited.

While the researchers say that renewable electricity sources in the United States can't sufficiently support hydrogen production for light-duty vehicles, they say green hydrogen is a viable alternative when electric power can't support the necessary load or range.

Their results are published in Joule, a peer-reviewed publication that spotlights "outstanding and insightful research, analysis and ideas addressing a global challenge: the need for more sustainable energy." 

"The window to avoid greater devastating impacts of climate change is closing, and dramatic greenhouse gas emission reductions must be achieved in the next few years," says Greg Keoleian, a senior author of the paper and co-director of U-M’s MI Hydrogen initiative. "Transportation – road, rail, water, and air – accounts for 22% of global and 37% of U.S. fossil fuel carbon dioxide emissions." 

The researchers examined factors such as the cost, fueling time, range, and safety of using green hydrogen as a transportation source. They determined the total system energy efficiency (the energy used to drive a vehicle, relative to the total renewable electrical energy invested) of using green hydrogen to power planes, trains, automobiles, and ships. 

Keoleian, who is also a professor of sustainable systems, explains that most hydrogen today is produced from natural gas. The resulting “grey hydrogen” is a problem because it generates greenhouse gas emissions. Green hydrogen is produced using renewable electricity from sources such as wind or solar that create essentially zero or low emissions. This clean electricity is then used to split water into hydrogen and oxygen. It can be used directly, or in synthetic fuels, to decarbonize road, rail, marine, and air transportation.

"All sources of energy have an impact on the environment," Keoleian says. "This is true for wind and solar, but the impacts are dramatically reduced compared to electricity from fossil sources such as coal and natural gas. Our study informed where it is best strategically to deploy green hydrogen."

The study, which can be found in the online edition of Joule, was conducted as part of U-M’s MI Hydrogen initiative, a collaborative team of U-M researchers, community groups, and government and industry partners seeking hydrogen solutions to speed up clean energy transitions. The initiative includes scientists from U-M's Center for Sustainable Systems, Department of Aerospace Engineering, and Department of Naval Architecture and Marine Engineering. A series of seminars and workshops with industry leaders and experts from national labs also informed their results.

"Navigating the clean energy transition is challenging and complex," Keoleian says. "Our work at MI Hydrogen, the Center for Sustainable Systems, and the School for Environment and Sustainability seeks to find solutions that align the technologies, economics, policies, and behaviors needed to accelerate this transition."  

Jaishree Drepaul is a writer and editor based in Ann Arbor. She can be reached at jaishreeedit@gmail.com.