Most Americans know hydrogen as being a key ingredient in water, H2O. Of the many chemical elements on the periodic table, hydrogen is the lightest element, while it’s also estimated to comprise up to 90 percent of the visible universe. With its simplicity and unfathomable abundance, might hydrogen be an overlooked key to some of our greatest challenges? On the issue of energy, the answer may be yes.
This colorless, odorless, and non-toxic gas does not occur naturally on Earth (rather in compounds), but can be produced from other sources of energy. The simplicity of hydrogen’s chemical makeup and its capacity as an energy carrier – a substance that contains energy imbued by another system – make it a promising source of energy storage. This is in addition to its use as a highly combustible gas, which is already attracting significant investment, research, and development from governments and the private sector.
In the U.S., hydrogen comes from a plethora of sources including natural gas, biomass, nuclear power, and renewable energy sources like wind and solar power. Extracting hydrogen from natural gas is the most common method in the U.S. through a process called natural gas reforming. Utilizing already-in-place natural gas infrastructure, steam reforming takes three steps. Firstly, methane present in the natural gas is exposed to steam that is heated between 700 and 1,000 degrees Celsius with 3-25 bars of pressure and in the presence of a catalyst. This reaction produces hydrogen, carbon monoxide, and carbon dioxide. Next, the existing carbon monoxide and steam react with another catalyst to produce more hydrogen and carbon dioxide. Finally, the carbon dioxide and other impurities are removed from the gas stream, leaving pure hydrogen as the final product.
When pure hydrogen is produced it can be used to power fuel cell electric vehicles (FCEVs). Hydrogen’s energy density is similar to that for gasoline. In fact, one kilogram of hydrogen gas contains about the same amount of energy as 2.8 kilograms of gasoline. Hydrogen fuel cells have provided a potential way to decarbonize the transportation sector which was responsible for 29 percent of the total carbon emissions in the U.S. in 2019. Fuel cells convert present fuel, in this case hydrogen, into electricity and heat with zero emissions.
A fuel cell is made up of two electrodes (also called conductors) that are between an electrolyte. In order to generate electricity, hydrogen is fed into the negative electrode, while air is fed into the positive electrode. Inside the negative electrode, a catalyst separates the hydrogen molecules into protons and electrons, which take different paths to the positive electrode, generating electricity externally. At the end of this process, the only byproducts generated are water and heat.
Hydrogen fuel cells can be scaled up or down to fit many different energy needs. In 2020, there were 161 operating fuel cells at 108 energy plants in the U.S. These facilities have a total of 250 megawatts (Mw) of electric generation capacity. While hydrogen’s potential for electricity generation for the grid is already established, the FCEV industry is still in development. Recent innovation in the fuel cell industry now means that a single fuel cell can be up to two to three times more efficient than an internal combustion engine running on gasoline. Projections from the U.S. Department of Energy show how light-duty highway vehicles could have their emissions cut by 50 to 90 percent, specialty vehicles currently running on diesel fuel could cut emissions by 35 percent, and 1.5 times higher fuel economies greater than current diesel powered transit buses.
The main challenge that restricts hydrogen fuel cells and hydrogen gas from being utilized widely as an energy source is cost and infrastructure related. In order for fuel cells to be widely used commercially, fuel cells must be cost-competitive with other traditional fuels and energy storage technology. California provides large tax incentives to encourage hydrogen fuel cell car purchases, but the average $60,000 price tag for a single vehicle is still expensive compared to gasoline and electric vehicles. However, projections from the California Energy Commission on future costs have hydrogen fuel cells being as cheap as gas in five years.
The cost-competitiveness of hydrogen fuel cells is also linked with infrastructure. The production of hydrogen-fueled cars is limited currently due to the limited or nonexistence of hydrogen recharging stations across the U.S. Consumers ultimately will not purchase a vehicle that they believe will be cumbersome to refuel, which limits companies ability to build stations due to the lack of hydrogen vehicles on the road. Nearly all hydrogen recharging stations are located in California currently, so major infrastructure investment is needed to bring hydrogen energy to the forefront of America’s energy mix.
Written by Roy Mathews, Public Policy Associate
The Alliance for Innovation and Infrastructure (Aii) is an independent, national research and educational organization. An innovative think tank, Aii explores the intersection of economics, law, and public policy in the areas of climate, damage prevention, energy, infrastructure, innovation, technology, and transportation.