Hydrogen isn’t just used to power fuel cells in futuristic vehicles. It could also have a very bright future as a storage medium for electricity. In a process called power-to-gas (P2G), wind or solar power is used to run electrolysis equipment that transforms water (H2O) into hydrogen (H2) which is stored in underground tanks. From there it can be:
combined with captured carbon dioxide (CO2) to produce green methane (CH2), which is chemically identical to natural gas
injected directly into the gas network in controlled quantities because hydrogen’s combustion properties are similar to those of natural gas
piped to nearby industrial enterprises and used in the production of ammonia, methanol, steel, semiconductors, and other products.
P2G produces green hydrogen, which is almost zero-carbon. Not only that, it can help balance out fluctuations in renewables output. On particularly windy and sunny days the grid can become so congested with renewable energy that some wind and solar farms have to be taken offline. If they’re connected to P2G plants, however, they can continue operating and produce green hydrogen for later use. This will enable countries to harness more of their renewable wind and solar resource.
Today, however, nearly all of the world’s hydrogen is grey. It’s produced in an energy-intensive thermal process that breaks down methane (CH4) into hydrogen (H2). This process results in significant carbon emissions. Gradually replacing grey hydrogen with green will help decarbonize a wide range of industries.
“Oil of tomorrow”
On March 20, 2020, the EU Commission unveiled its new Industrial Strategy to enable Europe to be a global pacesetter in climate neutrality and digitization. The strategy includes a Clean Hydrogen Alliance whose purpose is to accelerate the decarbonization of European industry. The establishment of a hydrogen economy enjoys broad political support. Germany’s Economics Minister Peter Altmaier, for example, has called hydrogen the “oil of tomorrow.”
The world’s largest P2G plant is planned for the port of Hamburg, Germany. The project has suffered from delays and is, according to Lower Saxony Economics Minister Bernd Althusmann, “at a crucial turning point.” The plant would will cost €150 million to build and have a capacity of 100 megawatts (MW), ten times more than the biggest existing P2G plants. It will use surplus wind power to produce, according to turbine manufacturer Siemens, about 2 metric tons, or 22,000 cubic meters, of hydrogen per hour. The hydrogen will fuel gas-fired power plants to generate electricity for nearby industrial enterprises that produce copper, steel, and aluminum.
From grey to green
If the Hamburg project remains stalled, the world’s largest electrolysis plant will be built in Bad Lauchstädt, a town of about 5,000 people located 40 kilometers west of Leipzig, Germany. Plans call for the installation of a 40 MW facility that will be used to study the production, transport, storage, and use of green hydrogen on an industrial scale. The project consortium includes energy provider Uniper (which funds Debate.Energy). “If industrial-scale green hydrogen proves viable, we’ll have found a crucial component of tomorrow’s secure and sustainable energy supply,” the company says.
The hydrogen will be stored in a repurposed salt cavern more than 700 meters underground. The cavern can hold up to 3,800 metric tons of hydrogen. If used to fuel power plants, this amount of hydrogen could supply 40,000 households with electricity. But it will actually be piped directly to chemicals companies in the nearby towns of Leuna, Buna, and Bitterfeld. Being supplied with green hydrogen instead of grey will substantially reduce their climate impact. The EU’s Clean Hydrogen Alliance hopes for many more similar projects around Europe.