US natural hydrogen explorer Koloma — which has already attracted investment from billionaire Bill Gates — has raised nearly a quarter of a billion dollars in its second funding call, according to reports.

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Denver-based Koloma raised $245 million in Series B funding (the second round of investment for start-ups) from investors such as Amazon’s climate fund and the venture capital arm of US aviation giant, United Airlines, US website Axios reported.

The firm, which is reportedly already exploring the American Midwest for natural deposits of H2, raised $91m in its first funding round, from five investors including Breakthrough Energy, founded by Microsoft billionaire Bill Gates in 2015.

The news comes just days after Koloma’s lab at Ohio State University (where Koloma co-founder Tom Darrah is a professor of Earth sciences) was awarded $900,000 in funding from the US government’s $20m programme to improve natural hydrogen exploration and production.

Koloma was one of ten to win a grant under the Topic G of the Department of Energy’s (DOE) funding stream, to develop technology to “stimulate hydrogen production from mineral deposits found in the subsurface, including developing our understanding of hydrogen-producing geochemical reactions and how to enhance or control the rate of hydrogen”.

According to the DOE, Koloma Labs is developing “geochemical and microbial models” in order to understand the processes that form hydrogen in rock systems, with the ultimate aim of forcing mineral deposits to produce hydrogen that can then be extracted.

“A combination of geochemical, geo-mechanical, and fluid transport models paired with an investigation of naturally occurring microbiology in hydrogen reservoirs seeks to reveal the feasibility of the widespread stimulation of geologic hydrogen in different rock systems,” the department said in its award description.

Also granted $900,000 in the same funding stream was Massachusetts-based Eden Geopower, which was also awarded a second grant of $500,000 in Topic H, to improve hydrogen production methods.

The company wants to run tests in Oman, where mineral deposits in the Hajar Mountains can produce hydrogen-rich fluids for extraction (see panel below).

The Massachusetts Institute of Technology (MIT) was also awarded $1.3m to develop an artificial intelligence-powered reactor to model stimulated hydrogen production.

“The [winners] will work toward improvements in subsurface transport methods and engineered containment, reservoir monitoring and/or modelling during production and extraction, as well as assessing the risk of hydrogen reservoir development,” the DOE said.

United Airlines Ventures’ (UAV) Sustainable Flight Fund, launched last year with the aim of investing in sustainable aviation fuels (SAFs), has been capitalised with $200m from the airline and a further $450,000 from its customers.

The UAV fund is an investor in electrolyser start-up Electric Hydrogen, also backed by Breakthrough Energy.

Hydrogen Insight reached out to Koloma for further details, but the company had not responded at the time of publication.

Key natural hydrogen production processes, environments and locations

There are six known ways in which hydrogen is produced naturally:

Serpentinisation

In which the mineral olivine located in mid-ocean ridges or ophiolites (a geological formation where sections of the Earth’s mantle rise above sea level) is weathered to form hydrogen-rich fluids. This has been seen in the Semail ophiolite, in the Hajar Mountains of Oman. Under pressure and high tempertures, water can react with these iron-rich rocks to produce H2.

Radiolysis of water

Radioactive elements in the Earth’s crust — for example in crystalline basement rocks with high content of uranium, thorium or potassium — decompose water molecules trapped in causing a hydrogen pocket, as happened in South Australia.

Deep degassing

In which “primary” hydrogen (a single hydrogen atom attached to a single carbon atom) escapes from deep within the Earth’s crust. This has been seen in Nebraska, in the US.

Iron reduction and sulphur oxidation

Ferric iron in a black smoker (a subsea hydrothermal vent formed from iron sulphide deposits) is reduced to ferrous iron and hydrogen sulphides.

Thermal decomposition of organic matter

In which ammonium compounds located in deep sendiments decompose under high temperatures to form hydrogen and nitrogen, for example in hydrogen-nitrogen gas seeps in Oman.

Biological activity

Hydrogen is produced by microbes living in the Earth’s crusts, usually co-existing with hydrogen-consuming microbes and found via sediment or aquifers. This has been observed in the coal beds of the Powder River Basin in Montana, US.

Source: Rystad Energy