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Hydrogen: Does Earth hold vast stores of a renewable, carbon-free fuel?

science.org

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Re: Hydrogen: Does Earth hold vast stores of a renewable, carbon-free fuel?

#31

Post by credit_guy »

barathr wrote: post #18

I was hoping to see in the article -- but didn't -- an analysis of the CO2e per KJ produced from natural hydrogen. Water vapor is a greenhouse gas and it'd be important to do the math to see how much better it is vs. other alternative fuels. (I expect it to be better, but how much is the question.)

> Water vapor is a greenhouse gas

No. Or rather, yes, water vapor is a greenhouse gas, but it has a halflife measured in days, compared to CO2, which has a halflife measured in decades. So, for all practical purposes, water vapor can be deglected when talking about global warming.

Re: Hydrogen: Does Earth hold vast stores of a renewable, carbon-free fuel?

#32

Post by zopa »

greenthrow wrote: post #23

This is a very poor quality article. Mining the earth for fuel when wind and solar are already the cheapest form of power is really stupid.

Wind and solar are a great source of electricity, but not everything is easy to electrify right now.

Also —- we have massive amounts of human and physical capital invested in digging flammable stuff out of the ground. If we can redirect some of that away from breaking the planet and into hydrogen, that’s a huge win, even if it’s not what we’d go after if we were designing our energy mix from scratch.

Re: Hydrogen: Does Earth hold vast stores of a renewable, carbon-free fuel?

#33

Post by pwg »

barathr wrote: post #18

I was hoping to see in the article -- but didn't -- an analysis of the CO2e per KJ produced from natural hydrogen. Water vapor is a greenhouse gas and it'd be important to do the math to see how much better it is vs. other alternative fuels. (I expect it to be better, but how much is the question.)

> Water vapor is a greenhouse gas and it'd be important to do the math to see how much better it is vs. other alternative fuels.

With about 71% of the earth's surface covered by water, which constantly emits water vapor due to evaporation, the amount of water vapor added by also burning green hydrogen would likely be minuscule compared to the amount from natural surface evaporation.

The huge advantage would be no carbon dioxide emissions from burning green hydrogen.

Re: Hydrogen: Does Earth hold vast stores of a renewable, carbon-free fuel?

#34

Post by DennisP »

Rimintil wrote: post #27

I think this is important to note about hydrogen as a 'clean' fuel source: > Today’s hydrogen is “gray,” made by reacting methane with steam at high pressures or using fossil fuels in other ways. Those processes emit some 900 million tons of carbon dioxide every year, almost as much as global aviation. In principle, that carbon could be captured and sequestered underground, yielding “blue” hydrogen. But most hopes re…

That has very little to do with the article, which is about actual hydrogen retrievable from underground deposits. It wouldn't be made from anything, just piped out of the ground.

Re: Hydrogen: Does Earth hold vast stores of a renewable, carbon-free fuel?

#35

Post by pfdietz »

phkahler wrote: post #30
sp332 wrote: post #20

Earlier quoted context omitted.

The main engine of natural hydrogen production is now thought to be a set of high-temperature reactions between water and iron-rich minerals such as olivine, which dominate Earth’s mantle. One common reaction is called serpentinization, because it converts olivine into another kind of mineral called serpentinite. In the process, the iron oxidizes, grabbing oxygen atoms from water molecules and releasing hydrogen. So…

But then we burn all that hydrogen and use up all our oxygen. CO2 may be a greenhouse gas, but plants pull the oxygen back off and return it to the air.

Indeed. The amount of ferrous iron in the Earth far exceeds the capacity of the atmosphere's oxygen to oxidize. The Earth is mostly reduced, with a very thin layer of oxidation on top.

Re: Hydrogen: Does Earth hold vast stores of a renewable, carbon-free fuel?

#36

Post by gilleain »

phkahler wrote: post #30
sp332 wrote: post #20

Earlier quoted context omitted.

The main engine of natural hydrogen production is now thought to be a set of high-temperature reactions between water and iron-rich minerals such as olivine, which dominate Earth’s mantle. One common reaction is called serpentinization, because it converts olivine into another kind of mineral called serpentinite. In the process, the iron oxidizes, grabbing oxygen atoms from water molecules and releasing hydrogen. So…

But then we burn all that hydrogen and use up all our oxygen. CO2 may be a greenhouse gas, but plants pull the oxygen back off and return it to the air.

I think that the 21% of the air that is oxygen is unlikely to be used up any time soon? Maybe i'm wrong...

Re: Hydrogen: Does Earth hold vast stores of a renewable, carbon-free fuel?

#37

Post by zopa »

panick21_ wrote: post #8

Why this is interesting, we already have such a fuel, we found it 80 years ago and its called Thorium. And Uranium isn't bad either. And we don't have to find it, every rare earth mine thorws out absurd amounts of it. We have to much of it without even trying. We just to dumb and lazy to anything with it.

So many people here cheering for their preferred carbon-free energy source like it’s a sports team. It’s bizarre.

We’re going to need to do lots of different things. There’s no need to fight about it; everybody’s favorite will have a chance.

Re: Hydrogen: Does Earth hold vast stores of a renewable, carbon-free fuel?

#38

Post by DennisP »

phkahler wrote: post #30
sp332 wrote: post #20

Earlier quoted context omitted.

The main engine of natural hydrogen production is now thought to be a set of high-temperature reactions between water and iron-rich minerals such as olivine, which dominate Earth’s mantle. One common reaction is called serpentinization, because it converts olivine into another kind of mineral called serpentinite. In the process, the iron oxidizes, grabbing oxygen atoms from water molecules and releasing hydrogen. So…

But then we burn all that hydrogen and use up all our oxygen. CO2 may be a greenhouse gas, but plants pull the oxygen back off and return it to the air.

Plants aren't doing that job all that effectively, or the CO2 levels wouldn't be going up.

The entire history of industrial civilization has added 140 parts per million of CO2 to the atmosphere. For CO2, that's too much. But Oxygen is 21% of the atmosphere, or 210,000 parts per million. I think we'll be ok for a while.

Re: Hydrogen: Does Earth hold vast stores of a renewable, carbon-free fuel?

#39

Post by rgmerk »

mytailorisrich wrote: post #15
bloppe wrote: post #9

Is hydrogen really more renewable though? It releases energy when combined with Oxygen to make water, and it requires energy to split it from water (electrolysis). In this sense, it's not fundamentally different from fuel, which releases energy and carbon when burned, but requires energy (sunlight) and carbon (CO2) to re-create via photosynthesis. The involvement of carbon is a difference, but either way it's a 2-way…

The story is about natural hydrogen produced through water-rock reactions. This means it can be extracted 'for free' like natural gas and is naturally continually renewed.

Water reservoirs are naturally renewed. You’re still rate limited, as most irrigation zones around the world have found out.

Re: Hydrogen: Does Earth hold vast stores of a renewable, carbon-free fuel?

#40

Post by DennisP »

notorandit wrote: post #17

Carbon free is not renewable, isn't it? Wasn't the plan for renewables?

Does it have to be? Climate change is getting pretty urgent. Maybe we should fix that first, and then worry about the ideal solution for the next ten thousand years.

However, from the article:

> natural hydrogen may be not only clean, but also renewable. It takes millions of years for buried and compressed organic deposits to turn into oil and gas. By contrast, natural hydrogen is always being made afresh, when underground water reacts with iron minerals at elevated temperatures and pressures. In the decade since boreholes began to tap hydrogen in Mali, flows have not diminished

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