Many recent headlines have touted the benefits of green hydrogen, an energy-dense fuel made from the most abundant element in the universe, as a tool to combat climate change. What exactly is green hydrogen? Is it truly the fuel of the future as advocates claim? To answer these questions, one must explore how hydrogen fuel is created and the current limitations of renewable energy in supporting certain industries.
Hydrogen fuel is created when electrolysis (sending an electric current through water) is used to split two hydrogen atoms from the oxygen atom within water (H2O) molecules. The most common source of energy used to power the electrolysis is fossil fuels, and the resulting fuel is known as gray hydrogen. Blue hydrogen uses the same method but incorporates technology to capture the majority of the carbon emissions. Green hydrogen is created when renewable energy is used to power the electrolysis.
Renewable energy sources such as solar and wind cannot currently meet the demands of certain energy-intensive industries such as steel manufacturing. We also cannot store enough renewable energy in batteries to power machines like an airplane or ocean liner. Though battery technology is developing rapidly, any batteries that could store enough energy to fly a plane would be prohibitively heavy with current technology.
Advocates say green hydrogen could step in to meet these unfulfilled needs. Start-up companies, like ZeroAvia and Airbus, are working to develop zero-emissions airplanes that run on hydrogen fuel cells. Fuel cells operate similar to a battery – a catalyst pulls negative electrons from the hydrogen atoms. The electrolyte membrane between the cathode and anode allows only protons to reach the cathode. The electrons travel through an external circuit to create electricity. However, fuel cells have an advantage over batteries because they do not degrade over time since there is no need to recharge. [i]
There are still limitations that stop hydrogen from being a one-size-fits-all solution to climate change. Today’s hydrogen electrolysis plants are inefficient and expensive to run. According to the Columbia Climate School, hydrogen costs three times as much as natural gas in the United States. In August 2020, a gallon of gas in California was $3.18 versus $8 a pound for hydrogen fuel. Hydrogen fuel cells are highly expensive due to the platinum that is commonly used as the catalyst between the anode and cathode. Hydrogen gas is difficult to transport and store – it is highly flammable and far lighter than gasoline or natural gas. Therefore, the gas has to be liquified or cooled to -253 C in order to be transported. This would require a massive infrastructure investment – hydrogen gas cannot be sent through existing natural gas pipelines because it could cause the pipelines to become brittle and crack.[ii]
There is also debate regarding whether hydrogen fuel is an improvement over fossil fuels. Environmental groups like Friends of the Earth Scotland argue that renewable energy should be used for direct electrification of vehicles and homes, not diverted to create hydrogen fuel. A study published August 2021 in Energy Science and Engineering concluded that blue hydrogen has a larger greenhouse gas footprint than some fossil fuels – 20% higher than natural gas or coal and 60% higher than diesel oil. Only green hydrogen is a truly climate-friendly energy source as the only byproduct is water.
There is no silver bullet to meet our global society’s growing energy demands while mitigating climate change. In the near future, green hydrogen could be one of the arrows in the renewable energy quiver. For that to happen, further investments are needed to bring costs down. In the United States, California is leading the way by investing $230 million in hydrogen projects by 2023. Hyundai, Capacity Trucks, El Dorado National, Golden Gate Zero Emission Marine, Plug Power, the Protium Company and Ballard Power Systems founded the Western States Hydrogen Alliance (WSHA) in 2020. Their goal is to facilitate increased development and implementation of fuel cell technologies across commercial sectors in 13 Western states.[iii]
Imagine a future where your next car’s emissions are only water! Where you could travel the globe using the captured energy of the Sun, energy that has traveled over 92,000,000 miles to reach us. If more states and companies invest in green hydrogen, that future could become a reality.