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The other elephant in the room with hydrogen is the fact that using current production methods, it's a fossil fuel. Direct solar separation will be a game chan

The other elephant in the room with hydrogen is the fact that using current production methods, it's a fossil fuel. Direct solar separation will be a game changer when/if that becomes a thing at scale, but right now almost all hydrogen produced for industry is made by steam reforming natural gas, which releases just as much CO2 as burning it. More, if you account for the extra steps in the process and the energy required to perform them.

nostromo 5y ago
I wouldn't consider that a decision criteria since it's also true for battery tech. (Most Teslas are powered by fossil fuels today via the grid, not renewables. 80% of US energy is still non-renewable and non-nuclear.)
- xxpor 5y ago
  Is that what OP meant by fossil fuel? Fixing the source of electricity is (probably) a lot easier than fixing the source of hydrogen itself.
- Robotbeat 5y ago
  If by “energy” you meant “electricity” (which is the only thing that makes sense given context), that is incorrect. The US electrical grid is about 40% clean (half being renewable and the other nuclear). Coal is 19% and falling. The rest natural gas. But even on natural gas, Teslas are more efficient than conventional cars. This is NOT true for hydrogen. Making electrolytic hydrogen from existing grid energy is not better than a good hybrid in terms of overall efficiency. The “but electric cars still use the grid which has a lot of fossil fuel production” argument is actually compounded for hydrogen cars as they require over twice the electricity input to achieve the same distance traveled as battery electric.
EricE 5y ago
Several companies have demonstrated generating copious amounts of hydrogen from algae - much more efficient than converting sunlight to electricity than performing electrolysis. I've seen even more alternate ways of generating hydrogen over the last 20 years - lots of thought around production; without demand it isn't worth pursuing/refining the processes to do so. Production can be distributed - no need to ship fuel or electricity over vast distances either. Charging batteries isn't without loss either. Most importantly, vehicle refueling speed is on par with liquid chemical energy (i.e. gas or diesel) which is the single biggest problem with batteries. And we haven't had EVs long enough to where people are needing to replace battery packs in volume. That's going to be fun when that day inevitably starts to roll around. I used to be a big hydrogen skeptic - but the more I have looked at it, the more I think we could deploy infrastructure for hydrogen faster than battery tech can improve. There aren't many combinations left to try, or to try to make practical for high volume production and that would be safe enough for universal adoption that will produce any significant gains. Maybe with liquid electrolytes - but those introduce new complexity/safety issues. I'm a huge fan of "liquid batteries" for stationary storage capacity - think Tesla powerwall but on an industrial neighborhood/town scale.
- tigershark 5y ago
  Even with a 100% energy efficiency to create hydrogen you use a huge amount of energy to compress it.
  - MaxBarraclough 5y ago
    Can that energy be utilised?
dumbfoundded 5y ago
With the price of solar so much cheaper than anything else, solar will almost certainly be overbuilt times of solar output exceeding overall demand. This will probably lead to negative energy spot prices at specific times during the day. People will want to figure out a way how to use this energy. Maybe it will be pumped hydro, batteries, compressed air, or hydrogen. Maybe it'll even lead to colocation with aluminum smelting or something like that. The point is something needs to be figured out how to handle the increasingly excess energy supply. Each technology has a different set of tradeoffs. Hydrogen is a potential but if it has any chance of succeeding, the technology has to be built now and quickly. Once a specific solution has momentum, it will be difficult to overcome. Large scale batteries seem to have the lead for now but the weight efficiency has always been an issue. I imagine at least one of the more weight efficient solutions will gain some reasonable % of market share.

nostromo 5y ago

I wouldn't consider that a decision criteria since it's also true for battery tech. (Most Teslas are powered by fossil fuels today via the grid, not renewables. 80% of US energy is still non-renewable and non-nuclear.)

xxpor 5y ago
Is that what OP meant by fossil fuel? Fixing the source of electricity is (probably) a lot easier than fixing the source of hydrogen itself.
Robotbeat 5y ago
If by “energy” you meant “electricity” (which is the only thing that makes sense given context), that is incorrect. The US electrical grid is about 40% clean (half being renewable and the other nuclear). Coal is 19% and falling. The rest natural gas. But even on natural gas, Teslas are more efficient than conventional cars. This is NOT true for hydrogen. Making electrolytic hydrogen from existing grid energy is not better than a good hybrid in terms of overall efficiency. The “but electric cars still use the grid which has a lot of fossil fuel production” argument is actually compounded for hydrogen cars as they require over twice the electricity input to achieve the same distance traveled as battery electric.

EricE 5y ago

Several companies have demonstrated generating copious amounts of hydrogen from algae - much more efficient than converting sunlight to electricity than performing electrolysis. I've seen even more alternate ways of generating hydrogen over the last 20 years - lots of thought around production; without demand it isn't worth pursuing/refining the processes to do so. Production can be distributed - no need to ship fuel or electricity over vast distances either. Charging batteries isn't without loss either. Most importantly, vehicle refueling speed is on par with liquid chemical energy (i.e. gas or diesel) which is the single biggest problem with batteries. And we haven't had EVs long enough to where people are needing to replace battery packs in volume. That's going to be fun when that day inevitably starts to roll around. I used to be a big hydrogen skeptic - but the more I have looked at it, the more I think we could deploy infrastructure for hydrogen faster than battery tech can improve. There aren't many combinations left to try, or to try to make practical for high volume production and that would be safe enough for universal adoption that will produce any significant gains. Maybe with liquid electrolytes - but those introduce new complexity/safety issues. I'm a huge fan of "liquid batteries" for stationary storage capacity - think Tesla powerwall but on an industrial neighborhood/town scale.

tigershark 5y ago
Even with a 100% energy efficiency to create hydrogen you use a huge amount of energy to compress it.
- MaxBarraclough 5y ago
  Can that energy be utilised?

dumbfoundded 5y ago

With the price of solar so much cheaper than anything else, solar will almost certainly be overbuilt times of solar output exceeding overall demand. This will probably lead to negative energy spot prices at specific times during the day. People will want to figure out a way how to use this energy. Maybe it will be pumped hydro, batteries, compressed air, or hydrogen. Maybe it'll even lead to colocation with aluminum smelting or something like that. The point is something needs to be figured out how to handle the increasingly excess energy supply. Each technology has a different set of tradeoffs. Hydrogen is a potential but if it has any chance of succeeding, the technology has to be built now and quickly. Once a specific solution has momentum, it will be difficult to overcome. Large scale batteries seem to have the lead for now but the weight efficiency has always been an issue. I imagine at least one of the more weight efficient solutions will gain some reasonable % of market share.