We could generate hydrogen from rocks while storing CO2 in them

We desperately need clean hydrogen for processes that cannot be powered by renewable electricity – and it might be possible to generate vast quantities from rocks deep underground while locking away carbon dioxide at the same time. Researchers at the University of Texas at Austin have shown that this process works for one common rock type in lab studies. They now want to work with companies on field trials.

“We hope to demonstrate that we will be able to generate hydrogen economically while sequestering CO2,” says team member Orsolya Gelencsér . It might even be possible to generate geothermal energy at the same time, she says. Burning hydrogen produces only water, so doesn’t cause global warming. Hydrogen could therefore play a major part in achieving net zero , for instance by helping to decarbonise industrial processes such as fertiliser production and steel-making . The problem is that almost all hydrogen is currently made from fossil fuels, meaning lots of CO2 is emitted during its production. One way to avoid these emissions is to use wind or solar power to split water, yielding hydrogen and oxygen. This is starting to be done, but hydrogen made this way is more expensive for now. Producing it at scale would also require vast amounts of renewable energy, which means less of this green energy would be available for other purposes, such as replacing coal-fired power plants. Hence, the recent surge of interest in natural or geological hydrogen. Several processes can generate hydrogen in rocks, and in the right conditions, the gas can accumulate and be extracted in similar ways to natural gas. This could be clean and cheap, but no one yet knows just how much natural hydrogen is there for the taking. While some researchers think there could be vast amounts waiting to be tapped , others – including Gelencsér – believe natural hydrogen resources may be limited .

Key points

• “We hope to demonstrate that we will be able to generate hydrogen economically while sequestering CO2,” says team member Orsolya Gelencsér .
• It might even be possible to generate geothermal energy at the same time, she says.
• Burning hydrogen produces only water, so doesn’t cause global warming.
• Hydrogen could therefore play a major part in achieving net zero , for instance by helping to decarbonise industrial processes such as fertiliser production and steel-making .
• The problem is that almost all hydrogen is currently made from fossil fuels, meaning lots of CO2 is emitted during its production.