A fraction of the underground hydrogen would give us energy for 200 years

Dec. 27 () –

Only a fraction of the hydrogen contained beneath the Earth’s surface could ending energy dependence on fossil fuels for 200 years.

New research suggests that the planet contains about 6.2 trillion tons (5.6 trillion metric tons) of hydrogen in rocks and underground deposits. That’s about 26 times the amount of oil known to remain underground (1.6 trillion barrels, each weighing about 0.15 tons), but it is still unknown where these hydrogen reserves are located.

Most of the hydrogen is likely too deep or too far offshore to access, and some of the reserves are probably too small to extract in a way that makes economic sense. However, the results indicate that there is more than enough hydrogen to go around, even with those limitations, told LiveScience.com Geoffrey Ellis, a petroleum geochemist with the US Geological Survey (USGS) and lead author of the new study.

Hydrogen is a clean energy source that can power vehicles, power industrial processes and generate electricity. Only 2% of the hydrogen reserves found in the study, equivalent to 124 billion tons (112 billion metric tons) of gas, “would supply all the hydrogen we need to reach zero net carbon emissions for a couple of years.” hundreds of years,” Ellis said.

The energy released by that amount of hydrogen is about twice the energy stored in all known reserves of natural gas on Earth, according to the new study. published in the journal Science Advances.

To estimate the amount of hydrogen inside Earth, the researchers used a model that took into account the rate at which the gas is produced underground, the amount likely to be trapped in reservoirs, and the amount lost through various processes. , like the filtration of rocks and the atmosphere.

Hydrogen is created through chemical reactions in rocks, the simplest being a reaction that splits water into hydrogen and oxygen, Ellis said. “Actually, There are dozens of natural processes that are capable of generating hydrogenbut most of them generate very small amounts,” he said.

Until recently, researchers did not realize that hydrogen accumulates beneath the Earth’s surface. “The paradigm throughout my entire career was that hydrogen is out there, it happens, but it is a very small molecule, so it easily escapes through small pores, cracks and rocks“Ellis explained.

But when scientists discovered a huge hydrogen deposit in West Africa, and then another in an Albanian chrome mine, that paradigm changed. It’s now clear that hydrogen accumulates in Earth’s reservoirs, and the new study suggests that some of those accumulations could be considerable.

“I was surprised that the results were greater than I thought.“Ellis said. “The bottom line is there’s a lot down there.”

But it’s important to note that there is enormous uncertainty around these results, he said, as the model showed there could be between one billion and 10 trillion tons of hydrogen in the subsurface. (The most likely value, based on model assumptions, was 6.2 billion tons.)

Hydrogen is expected to represent up to 30% of future energy supply in some sectors, and global demand is expected to quintuple by 2050. The gas is produced artificially through water electrolysis, where water molecules are broken down with electrical currents. When renewable energy is used, the product is called “green hydrogen” and when fossil fuels are used, it is known as “blue hydrogen.”

The benefits of taking advantage of natural hydrogen are that does not require an energy source to produce it and underground reservoirs can hold the gas until needed. “We don’t have to worry about storage, which is something that happens with blue hydrogen or green hydrogen: you want to produce it when electricity is cheap and then you have to store it somewhere,” Ellis said. With natural hydrogen, “You could just open a valve and close it when you needed to.”