Hydrogen gas is pumped into the anode of the fuel cell where it makes contact with a catalyst, usually a metal like platinum. This splits a hydrogen atom’s positively and negatively charged particles apart. Its proton, a positive ion, is able to pass through the electrolyte—a polymer membrane known as the proton exchange membrane (PEM)—to reach the cathode. Its electron, with a negative charge, is unable to take this route and instead travels through a circuit, where ultimately it becomes electricity that is transferred through a load like a lightbulb or a motor.
Oxygen from the atmosphere is pumped into the cathode, set on the opposite side of the PEM from the anode. The hydrogen electrons eventually find their way to this section, reuniting with protons and bonding with oxygen atoms. Electricity is produced; the only by-products are pure water and heat. But, despite the completely pollution-free process inside the fuel cell, the make-or-break classification for hydrogen as a clean form of energy comes down to how hydrogen gas is made.
Hydrogen is the most abundant element on the planet, but it's rarely found in isolation. It's usually part of a compound, like water (H2O) or methane (CH4). Pure hydrogen is derived only by separating it from other elements, which requires substantial amounts of energy.
The bulk of hydrogen produced today—about 95 percent of it—is made using fossil fuels. Processes like steam methane reforming and gasification use natural gas and coal, contributing about 830 million tonnes of carbon dioxide (CO2) into the atmosphere annually. This amount is equal to the total annual CO2 emissions of the United Kingdom and Indonesia combined. Thirty percent of all hydrogen on the market is made using oil. The petrochemical industry accounts for 70 percent of all pure hydrogen production, where it’s used to make ammonia and added to heavier oil for transport fuel production.
But green hydrogen is possible, thanks to a process known as electrolysis, where hydrogen is extracted from water molecules using electricity—a lot of electricity. And it’s that power demand that has made green hydrogen too cost-prohibitive in past decades when it comes to scaling up the technology. For example, an electrolyzer, the machine used for electrolysis, running on photovoltaic energy can cost six times as much as steam methane reforming using natural gas. Overcoming that price point is critical to expanding clean hydrogen’s reach. Yet it’s a surmountable barrier: Electricity alone accounts for 60 percent of the total cost of electrolysis, which means that the declining price of wind and solar energy is good news for green hydrogen. The cheaper renewables become, the more feasible green hydrogen becomes.
New research is finding how organic waste, a major contributor to greenhouse gas, can be kept out of landfills and processed to extract hydrogen. Known as “gasification” or “gasifying biomass,” it’s a key strategy for extracting hydrogen fuel cited in an August 2020 report published by the Lawrence Livermore National Laboratory (Getting to Neutral: Options for Negative Carbon Emissions in California).
Researchers at RIT’s Golisano Institute for Sustainability (GIS) are exploring how gasification could be applied to common forms of biomass waste from agriculture and manufacturing, like crop residues, woody biomass, and cardboard. One product of this method would be syngas (synthetic gas). They are investigating how different fuel-cell designs could make use of this biomass-derived syngas, such as solid oxide fuel cells (SOFCs), which operate at a much higher temperature than the PEM fuel-cell design described in the previous section. Running at 800–1000 degrees Celsius, SOFCs are “fuel flexible,” which means they can utilize a wide range of compound gases, including natural gas, and aren’t dependent solely on pure hydrogen. Another technology focus at GIS is high-temperature PEM (HT-PEM) fuel cells. These use a different membrane material than the conventional PEM described above, which allows them to operate at temperatures reaching 200 degrees Celsius. At such a high heat, fuel-purity requirements become less stringent and other primary hydrogen sources like propane and biomass can be used.
Last August, the world's first fossil-free hydrogen-powered steel plant began operations in Sweden under the company HYBRIT is exploring use of fossil-free, bio-oil pellets as the hydrogen source. Its progress will be closely watched as a model for decarbonizing heavy industries like steel production. It is just one project of many that have launched as the green hydrogen economy gains fresh momentum.
The green hydrogen economy
In September 2020, the financial magazine Barron’s reported that Goldman Sachs saw the green hydrogen market as a “once-in-a-lifetime opportunity” for investors, predicting that it could be worth $12 trillion by 2050. Policymakers at the European Union wrote in August 2020 that a tipping point had been reached for green hydrogen. They cited that the projected power output for planned electrolyzers—essential to making green hydrogen—by 2030 worldwide had increased from 3.2 to 8.2 GigaWatts (GW) in just a few months (November 2019 to March 2020). A surge in investment and construction across the globe backs these observations.
Germany is set to invest over nine billion euros into clean hydrogen electrolysis in a bid to become the world’s leading exporter of the pure element. This comes as the European Union commits to put 180–470 billion euros into the sector. The International Hydrogen Council’s membership has grown from 13 to 81 since 2017. The U.S. firm Air Products and Chemicals announced last July its plans to build a 5 billion-dollar green hydrogen plant in Saudi Arabia. It’s slated to be the world’s biggest yet, using 4 GW of energy to produce 650 tons of clean hydrogen fuel daily. The largest municipal utility authority in the U.S., the Los Angeles Department of Water and Power, is set to spend $1.9 billion to convert a power plant in Utah from coal to a mix of natural gas and green hydrogen. It plans to shift it entirely to clean hydrogen within two decades. This move comes as the U.S. Department of Energy announced in July 2020 that it will invest $64 million into 18 projects to advance its signature hydrogen program, H2@Scale, though it’s not exclusively focused on green hydrogen. In March 2020, a 10-MegaWatt (MW) electrolyzer project was launched in Japan and a 20-MW operation began construction in Canada.
Once fully commercialized, green hydrogen could help alleviate the growing reliance on natural gas in places like Germany and California, where it is increasingly used by peaker plants to compensate for the intermittency and limited storage of wind and solar power. Hydrogen is a highly complementary technology. It can be used as a pure fuel, an alternative method to batteries for storing renewable energy, and an additive to natural gas for lowering its emissions.
Learn more about hydrogen energy and our work in this field.