So-called "White Hydrogen" has been proposed as a carbon-neutral fuel source.
In the short term, the lack of carbon is a feature, but I'd argue over geological timeframes, it's a huge bug.
CO2 vs O2 at least has a cycle for replenishment. If we just burn H2 and use up an O, i can imagine we would reduce the O and we could only use processes like electrolysis to get it back.
It might seem like photosynthesis is a counter-argument to this, that plants "make oxygen" and so we'd be OK for that reason. My counter-argument would be that geological history is important to understand. The earth once had a CO2 atmosphere at about 25 atmospheres today, and the cyanobacteria converted all that CO2 into oxygen and sugar. That led to the biggest extinction event in the history of the planet, called the oxygen catastrophe. The carbon cycle takes that oxygen that was produced and recombines it with carbon to release energy, which then ends up getting split up again. The oxygen released is part of that cycle. It was part of the sugars produced, and it remains in that cycle. The carbon cycle has functioned for billions of years because it is cyclical -- the oxygen is released, consumed and returned to CO2, then released again.
As I said, photosynthesis does convert water and CO2 into sugars and O2, but the O2 is tied to the carbon cycle, and that same carbon cycle can use up the O2 just as quickly. We've actually seen that during the period where humans have been using lots of old sugars from fossil fuels, and the amount of oxygen in the atmosphere has dropped slightly (but at least it'll be returned because of the carbon cycle)
Contrasting that with burning hydrogen on its own, the hydrogen combines with atmospheric oxygen, and does not get released directly through any similar cycles. The fact that the carbon cycle releases O2 doesn't change that, because the carbon cycle was what released that O2 in the first place, and if you burn away O2, it doesn't get replaced by the carbon cycle, it just stops being available. It isn't a problem today, but it chips away at the planetary resources without any way to actually replenish them on geological scales.
There's no reason to believe that the carbon cycle would be able to produce enough oxygen to support all life on earth and all combustion and also a magical excess for billions of kilograms of hydrogen soaking up oxygen every year. It doesn't fit, it's not cyclic at all. In fact, we should have way more oxygen on earth in the sense that much more was produced through the process of photosynthesis in that original thick CO2 atmosphere was eaten up by other processes such as rusting iron or burning of combustible minerals
We'd end up in a century or two right back where we are today, stuck requiring massive public works projects to figure out how to release more elemental oxygen in the O2 form before we all suffocate. It's something way scarier than releasing too much carbon into the atmosphere, because at least nature has a way to deal with too much carbon!
In the short term, the lack of carbon is a feature, but I'd argue over geological timeframes, it's a huge bug.
CO2 vs O2 at least has a cycle for replenishment. If we just burn H2 and use up an O, i can imagine we would reduce the O and we could only use processes like electrolysis to get it back.
It might seem like photosynthesis is a counter-argument to this, that plants "make oxygen" and so we'd be OK for that reason. My counter-argument would be that geological history is important to understand. The earth once had a CO2 atmosphere at about 25 atmospheres today, and the cyanobacteria converted all that CO2 into oxygen and sugar. That led to the biggest extinction event in the history of the planet, called the oxygen catastrophe. The carbon cycle takes that oxygen that was produced and recombines it with carbon to release energy, which then ends up getting split up again. The oxygen released is part of that cycle. It was part of the sugars produced, and it remains in that cycle. The carbon cycle has functioned for billions of years because it is cyclical -- the oxygen is released, consumed and returned to CO2, then released again.
As I said, photosynthesis does convert water and CO2 into sugars and O2, but the O2 is tied to the carbon cycle, and that same carbon cycle can use up the O2 just as quickly. We've actually seen that during the period where humans have been using lots of old sugars from fossil fuels, and the amount of oxygen in the atmosphere has dropped slightly (but at least it'll be returned because of the carbon cycle)
Contrasting that with burning hydrogen on its own, the hydrogen combines with atmospheric oxygen, and does not get released directly through any similar cycles. The fact that the carbon cycle releases O2 doesn't change that, because the carbon cycle was what released that O2 in the first place, and if you burn away O2, it doesn't get replaced by the carbon cycle, it just stops being available. It isn't a problem today, but it chips away at the planetary resources without any way to actually replenish them on geological scales.
There's no reason to believe that the carbon cycle would be able to produce enough oxygen to support all life on earth and all combustion and also a magical excess for billions of kilograms of hydrogen soaking up oxygen every year. It doesn't fit, it's not cyclic at all. In fact, we should have way more oxygen on earth in the sense that much more was produced through the process of photosynthesis in that original thick CO2 atmosphere was eaten up by other processes such as rusting iron or burning of combustible minerals
We'd end up in a century or two right back where we are today, stuck requiring massive public works projects to figure out how to release more elemental oxygen in the O2 form before we all suffocate. It's something way scarier than releasing too much carbon into the atmosphere, because at least nature has a way to deal with too much carbon!
@sj_zero You should run the numbers to see if natural hydrogen would even be capable of soaking up that much oxygen (it's not like there's much CO2 in the atmosphere), but I don't see it being a threat to life on earth this side of a total world government.
Because it's just not a practical replacement for liquid fossil fuels, and is subpar for natural gas (CH4 which is hydrogen dominant anyway, thus its use in providing them to fix nitrogen into ammonia, NH3). It's just not dense stuff for the former, and see second link, but...
...I wonder, surely it's too expensive to completely remove it from drilled natural gas, and was especially so back when networks were being made? I don't know enough about this, but I do know we've have to keep our residential natural gas systems or replace them or a lot of them, with stuff suitable for hydrogen or $$$ electricity as is already currently being done perforce in NY state and north of it.
There was a paper recently that suggested there could be enough white hydrogen in the earth's crust to power human civilization for 100,000 years. That's where this idea came from, that if we were to power civilization by burning large amounts of hydrogen over long enough timeframes, we start having to worry about oxygen depletion.
Geological or even long human timeframes really mess things up -- even stuff like planting trees doesn't matter because the trees die and rot and forests become deserts when the tectonic plates shift. On the other hand, microscopic organisms like diatoms dying over time can cause overwhelming geological changes -- such things are how we ended up with most forms of sedimentary rock for example.
Geological or even long human timeframes really mess things up -- even stuff like planting trees doesn't matter because the trees die and rot and forests become deserts when the tectonic plates shift. On the other hand, microscopic organisms like diatoms dying over time can cause overwhelming geological changes -- such things are how we ended up with most forms of sedimentary rock for example.
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