With only water vapor exiting the tailpipe of hydrogen-consuming vehicles, the fuel type has risen as an Earth-friendly alternative to fossil fuels. However, the full picture of hydrogen fuel's lifecycle raises questions about its true carbon footprint.
A city with a long history of air pollution has moved to a cleaner source of energy: hydrogen. London’s double-decker buses will now run on hydrogen fuel, only emitting water vapor in the process, Quartz reported. These buses are part of a reemerging emphasis on hydrogen fuel, often referred to as the fuel of the future. However, the current hydrogen fuel market is not perfect, and it isn’t even carbon neutral. London’s buses run on hydrogen produced using natural gas; however, proponents of hydrogen remain hopeful for a massive shift towards clean hydrogen.
Hydrogen can power cars and homes and provide clean fuel for technologies where electrification isn't feasible. In conjunction with renewable energy, hydrogen could aid in the shift away from fossil fuels and has already earned a reputation as a low-carbon solution for personal transportation and large-scale industry that is fuel-intensive.
The clean energy shift heavily relies on electrification. However, there are some instances where electrification is very difficult. Nearly all of our technology and tools run on electricity or fuel. An air conditioner runs on electricity, while heaters often run on fuel. A computer uses electricity; an internal combustion vehicle uses fuel. Renewable energy can easily power everything currently run on electricity, but everything not easily electrified is left out.
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Supporters of hydrogen fuel state that hydrogen can substitute fossil fuels in applications where fuel is necessary, like aviation and heavy industry; however, others state that hydrogen fuel is too costly and inefficient to transition the global economy off fossil fuels quickly.
Producing large quantities of hydrogen is necessary to create hydrogen fuel, stored as fuel, then burned for energy. There are two main ways to produce hydrogen for fuel: fossil-fuel reforming and electrolysis.
Methods of Hydrogen Production
Steam-methane reforming is the most common method of hydrogen production for human use. This process uses high-temperature steam and methane to produce hydrogen. Steam-methane reformation is how most of the hydrogen in the U.S. is produced. Steam-methane reforming produces hydrogen and carbon dioxide as a byproduct, which means the process relies on fossil fuels and emits carbon. Producing hydrogen from natural gas still relies on fossil fuels, but according to the U.S. Department of Energy, it can cut vehicular greenhouse gas emissions in half.
The second process to create hydrogen is through electrolysis by using electricity to separate water molecules into oxygen and hydrogen. There is no byproduct in this process, but it requires electricity to start the reaction. If the fossil-fuel-dependent conventional grid powers the electrolysis, the hydrogen produced would not be carbon neutral. However, renewable energy can be used to power electrolysis, producing hydrogen with no greenhouse gas emissions.
When comparing the emissions of hydrogen fuel to conventional fuel, we have to trace back to the energy source that powered the hydrogen production. If steam-methane reforming or electrolysis powered by fossil fuels creates the hydrogen fuel, then greenhouse gas emissions still result.
Wind and solar power don't emit carbon, but they are subject to wind and sun patterns. Yet, hydrogen production from electrolysis powered by renewable energy can work together to form a steady supply of zero-emission energy. Because of their intermittent energy, some people look to hydrogen to bolster energy portfolio reliability.
The electrical grid being predominantly fossil-fuel-based means hydrogen production through electrolysis is still carbon-intensive.
State of the Industry
Hydrogen was once touted as the fuel of the future but has recently fallen behind electric vehicles and solar panels in the clean energy discussion. There are fuel cell electric vehicles available on the market, and some energy plants are producing hydrogen fuel. Nonetheless, the state of clean hydrogen fuel is nowhere near market saturation.
Toyota, Honda and Hyundai all offer hydrogen fuel cell vehicles, but there are relatively few on the road. A handful of governments, from California to Saudi Arabia, are investing in hydrogen fueling stations to help the industry's growth. Kelley Blue Book states the annual fuel costs for hydrogen vehicles are three to four times that of a gas-powered vehicle. However, in California, it costs about $5 to $6 per gallon-equivalent of hydrogen fuel.
Hydrogen fuel is potent: it is the fuel source for rockets. It is a promising fuel alternative for energy-intensive industries like steel, shipping and aviation. However, hydrogen production is not nearly high enough to replace fossil fuels in every sector. Some private companies like dCarbonX and Electric Hydrogen are working to produce better storage options for hydrogen fuel.
Benefits of Hydrogen
When used as a fuel, hydrogen does not emit carbon dioxide, only water vapor, which is itself a greenhouse gas, though the global warming potential is the subject of debate. It can be used for industry sectors that cannot be easily electrified, like manufacturing and shipping, and can power personal vehicles with the hydrogen stored in a fuel cell.
For personal transportation, hydrogen-fueled cars have many advantages over electric ones. Fuel cell electric vehicles (FCEVs) can run on hydrogen and only produce water vapor as an emission. Fuel cell electric vehicles don’t require long charging periods; they can be filled as easily with hydrogen as a traditional gas-powered car. FCEVs have longer ranges than electric vehicles. The Toyota Mirai can travel 317 miles on a full tank, and it has one of the shortest ranges on the market, whereas the Tesla Model 3 can only go 220 miles on a single charge.
Paul Ronney, an engineering professor at the University of Southern California, stated that existing fossil fuel infrastructure could be reworked for hydrogen fuel. Hydrogen could be pumped into buildings and retrofitted internal combustion cars. However, a lack of policy initiatives and capital investment to transition to hydrogen dampens its near-term future potential.
Outlook for Hydrogen as a Renewable Fuel
The main criticism of hydrogen fuel is that it doesn’t efficiently replace fossil fuels at this time. Either fossil fuels are burnt to create hydrogen, or in using hydrogen fuel, we would use more energy than if we used traditional fossil fuels. Currently, there is no economic incentive to drive hydrogen cars as they are less common and expensive. Fuel cells that can convert chemical energy to power, necessary for hydrogen-fueled vehicles, require expensive materials.
A study from the Potsdam Institute for Climate Impact Research (PIK) in Germany found that using hydrogen fuel for a home gas boiler would use six to fourteen times the electricity than a traditional heat pump, The Guardian reported. They also found that a car running on hydrogen fuel would require five times the electricity as a standard battery-powered electric vehicle. This research assumes that hydrogen fuel would be produced using fossil fuels, leading to increased greenhouse gas emissions. However, if the technical capability to make that much hydrogen using renewable energy existed, associated greenhouse gas emissions would diminish.
In the high-energy industrial sector, hydrogen has some negatives compared to methane. Hydrogen has a lower heating value than methane. By volume, it takes three times the hydrogen to provide the same heat as burning methane. Operating a gas turbine on hydrogen would require a system capable of handling a higher flow rate and a large amount of hydrogen. Hydrogen has a higher flame speed than methane, so combustion systems configured for methane would have to be replaced with combustion systems configured for hydrogen. Hydrogen is also more flammable than methane, which could cause safety issues.
Perhaps one of the biggest hurdles is cost efficiency, said Derek Warnick, CFO of Electric Hydrogen. For infrastructure and industry, the cost is the main factor in adopting new technology, so making hydrogen more affordable is the main priority.
Hydrogen could be a suitable replacement for industries that rely on large quantities of fossil fuel. However, the amount of hydrogen capable of being produced using only renewable energy is limited. In ramping up research and production of hydrogen fuel, it’s imperative to ensure that renewable energy is used in production; otherwise, the clean power of the future won’t be so clean.
Doing so also implies an increase in renewable energy production. Transitioning entire industries, like shipping and steel manufacturing, to hydrogen fuel requires enough renewable energy to produce hydrogen fuel for those industries. Currently, the capacity is lacking.
Powering the world on hydrogen instead of fossil fuels would entail significant investments into fuel cell electric vehicles, hydrogen fuel infrastructure, and even more investment into renewable energy. Without a simultaneous shift to renewable energy, hydrogen fuel won't live up to its potential.
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