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A lot of the discussion here is around hydrogen fuel cells for cars and aviation. Which would be cool. But the real reason we need “green” hydrogen now is for m

by habosa 5y ago

A lot of the discussion here is around hydrogen fuel cells for cars and aviation. Which would be cool. But the real reason we need “green” hydrogen now is for making steel and cement: https://www.vox.com/energy-and-environment/2019/10/10/20904213/climate-change-steel-cement-industrial-heat-hydrogen-ccs https://www.vox.com/energy-and-environment/2019/10/10/209042...

ncmncm 5y ago
It's a good point: can any imagined use of hydrogen for cars even begin to compete with all the other demands for it? They might always outbid the car owners. For aviation, LH2 has such fantabulous efficiencies that we can expect to see all serious air transport switched over by 2050 (providing civilization doesn't collapse first).
- mlindner 5y ago
  Aviation won’t be using LH2. The volume required makes it not feasible. Not to mention the cooling requirements. Look at the volumetric energy density of it compared to other fuels.
  - ncmncm 5y ago
    Volume is very cheap on board aircraft, so volumetric energy density doesn't matter. What costs is weight. On weight, LH2 clobbers everything, by a very long way. https://news.ycombinator.com/item?id=29206505 https://news.ycombinator.com/item?id=29206505
twic 5y ago
That article shows a graph of cement cost increases from alternative energy use, and says: > As you can see, every low-carbon alternative raises costs more than 50 percent above baseline. The only ones that don’t raise it more than 100 percent are CCS (of the heat source only), blue hydrogen, or resistive electric in places with extremely cheap and plentiful carbon-free energy. > The alternative that climate hawks would most prefer, the carbon-free option that would work best for most applications, is green hydrogen. But that currently raises costs between 400 and 800 percent. Ouch. Green hydrogen is by far the most expensive option. 3-4 times more expensive than electric heat. That's the direct opposite of "the real reason we need “green” hydrogen now is for making [...] cement". This new work will hopefully make green hydrogen cheaper. But if you're using electricity to make that hydrogen, i don't think it can ever be cheaper than electric heating.
- habosa 5y ago
  Sorry I didn't mean it was more viable for that purpose, I meant it's more essential. We already know how to make good electric cars and power them with green-ish energy. For cement and steel we have barely even started making them "green" and they make a huge amount of our total greenhouse gas input.
dopkew 5y ago
Apart from the humanitarian catastrophe, does anyone else feel vexed, at the enormous resources and man-hours lost because of the bombing campaigns in conflicts? One could argue, that efforts towards achieving inter-national harmony is also vital in reducing humanity's carbon footprint.

by habosa 5y ago

ncmncm 5y ago

It's a good point: can any imagined use of hydrogen for cars even begin to compete with all the other demands for it? They might always outbid the car owners. For aviation, LH2 has such fantabulous efficiencies that we can expect to see all serious air transport switched over by 2050 (providing civilization doesn't collapse first).

mlindner 5y ago
Aviation won’t be using LH2. The volume required makes it not feasible. Not to mention the cooling requirements. Look at the volumetric energy density of it compared to other fuels.
- ncmncm 5y ago
  Volume is very cheap on board aircraft, so volumetric energy density doesn't matter. What costs is weight. On weight, LH2 clobbers everything, by a very long way. https://news.ycombinator.com/item?id=29206505 https://news.ycombinator.com/item?id=29206505

twic 5y ago

That article shows a graph of cement cost increases from alternative energy use, and says: > As you can see, every low-carbon alternative raises costs more than 50 percent above baseline. The only ones that don’t raise it more than 100 percent are CCS (of the heat source only), blue hydrogen, or resistive electric in places with extremely cheap and plentiful carbon-free energy. > The alternative that climate hawks would most prefer, the carbon-free option that would work best for most applications, is green hydrogen. But that currently raises costs between 400 and 800 percent. Ouch. Green hydrogen is by far the most expensive option. 3-4 times more expensive than electric heat. That's the direct opposite of "the real reason we need “green” hydrogen now is for making [...] cement". This new work will hopefully make green hydrogen cheaper. But if you're using electricity to make that hydrogen, i don't think it can ever be cheaper than electric heating.

habosa 5y ago
Sorry I didn't mean it was more viable for that purpose, I meant it's more essential. We already know how to make good electric cars and power them with green-ish energy. For cement and steel we have barely even started making them "green" and they make a huge amount of our total greenhouse gas input.

dopkew 5y ago

Apart from the humanitarian catastrophe, does anyone else feel vexed, at the enormous resources and man-hours lost because of the bombing campaigns in conflicts? One could argue, that efforts towards achieving inter-national harmony is also vital in reducing humanity's carbon footprint.