spasmodicus wrote:The newspaper article seems to suggest that it is somehow a new idea to drill for hydrogen. It’s no surprise that hydrogen effuses from the Earth given that the Universe is alleged to consist of about 73% hydrogen. Soviet geologists long argued that many oil and gas fields were sourced from hydrogen which percolated up from the Earth’s mantle and interacted with organic rich deposits in sedimentary deposits to form oil. The AAPG (American Association of Petroleum Geologists) still considers this a heresy (i.e. the “not invented here” syndrome) and asserts that oil and gas are solely produced by the action of heat and pressure on sedimentary deposits. Some oil and gas fields contain significant amounts of hydrogen and natural gas can also be found in rocks of non-sedimentary origin, which indicates that maybe one should keep an open mind about this. Nevertheless, the gas industry grew to its present size and importance on methane, not hydrogen.
It ain't rocket science, they say, to indicate that something is technologically simple. Proponents of hydrogen technologies, as a solution for greening our energy use, point to its wondrous property viz that burning it just produces water vapour and, they say, it has a high energy density in terms of Joules/kg.
What they do not emphasise are the difficulties in producing and handling the stuff. Theoretically, you could pipe it down the existing network that supplies millions of gas boilers in the UK, tweak the boiler combustion a bit and Bob's yer uncle. However although the chemical energy stored per unit weight of hydrogen (in liquid or gaseous form) is higher than that for methane, the volumetric energy density of hydrogen is significantly lower. This means you have to run the pipe network at a higher pressure to transport the same amount of energy as for methane. This exacerbates the problem that molecules of hydrogen are much smaller than those of methane, or coal gas, so they leak much more readily.
Rocket scientists know all about this. Hydrogen seems like the best chemical fuel for rockets, from the point of view of the specific impulse of a liquid hydrogen/liquid oxygen (hydrolox) rocket being higher than almost any other chemical combination that could safely (that word is relative in this context) be employed. The first (and only) human landing on the Moon in 1969 used a Saturn rocket booster (kerolox i.e. kerosene and liquid oxygen) with a hydrolox (liquid hydrogen and oxygen) second stage. Look what fun they had designing it here
https://en.wikipedia.org/wiki/S-IIThe space Shuttle also used hydrolox for its three RS-25 main engines and because of the very large volume of the liquid hydrogen required, it had to have a huge external fuel tank. Right next to it, two solid fuel boosters were attached and when one of them started leaking high temperature gases which impinged on this tank, it caused the tragic loss of the Challenger shuttle. The tank had to be insulated to slow down the hydrogen boil-off, which would otherwise have caused massive amounts of ice to form on the outside of the tank. Later, a chunk of this insulation broke off on takeoff of the Columbia shuttle, which damaged one wing, causing it to burn up on re-entry.
The inherent problems of handling hydrogen were recognised by Elon Musk when designing his Starship/Super Heavy rocket, with ambitions to create a re-usable rocket which could potentially go to Mars and beyond. Having successfully achieved re-usability (an amazing achievement in itself) with Spacex's Falcon rockets powered by kerolox Merlin engines, he embarked on an engineering project to create the Raptor liquid methane/liquid oxygen (methalox) engine for the Starship programme. Liquid methane has a number of advantages over liquid hydrogen, even though methalox has a lower specific impulse than hydrolox (are you still with me?)
1) It's volumetric energy density is higher, meaning smaller fuel tankage. Hydrogen is hard to handle and it leaks much more readily than methane, due to its smaller molecules.
2) The boiling point of liquid methane is a lot higher that that of liquid hydrogen, reducing the insulation requirements for tankage. It is less prone to boil away on a long duration space flight.
3) Most importantly, there is a chance that methane could be synthesised in situ on Mars, or the Moon, from the carbon dioxide and water which are though to exist there. One can imagine a Martian economy based on a carbon dioxide, oxygen, methane and water cycle, e.g. CO2 and 2xH20 --> CH4 and O2 --> CO2 and 2xH20 which is, after all, roughly how things work on Earth.
Other rocket designers have started to wake up to the advantages of methalox, e.g. European Space agency (Prometheus) etc. etc.
Earth has even better facilities that Mars for an economy based on a Carbon/Hydrogen cycle. In fact our own biological life cycle involves both methane and hydrogen. see these articles about farts.
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1378885/https://heatable.co.uk/boiler-advice/fart-powered-homesIt seems that the relative hydrogen and methane contents of your farts depends very much on your diet. So maybe the idea of using a mixture of methane and hydrogen to power our gas boilers is not so silly.
There is already a well established LNG (Liquid Natural Gas) industry on Earth. Typically, LNG is 85 to 95-plus percent methane, along with a few percent ethane, even less propane and butane, and trace amounts of nitrogen. The system is well adapted to transporting 100% methane.
What we really need to learn how to do is to fuse that damn H2 stuff into Helium.
S