3 ms·

Then what's the alternative? Kinetic storage is geographically limited. Th Sabatier process has end to end efficiency of ~30% not to mention it needs an externa

Then what's the alternative? Kinetic storage is geographically limited. Th Sabatier process has end to end efficiency of ~30% not to mention it needs an external source of carbon dioxide. The remaining proposals are at the experimental stage (thermal storage, hydrogen storage).

pfdietz 6y ago
Underground hydrogen storage is a demonstrated technology, not experimental. All that's required is scaling it up, and there's plenty of room to do that. The only real missing piece was sufficiently cheap electrolysers for use with intermittently available power, but that's coming along very fast now too, with rumors of costs as low as $200/kW in China (and a recent contract win of $350/kW from a European maker of alkaline electrolysis systems). This is more than adequate for hydrogen storage.
- manfredo 6y ago
  Underground hydrogen storage had the same issue as kinetic storage: it's geographically limited. It's not just a matter of scaling it up, it's also matter to implementing it in places without empty salt mines handy. And as you point out, generating this hydrogen is nowhere near cost efficient. To put this in perspective, energy costs in the US average about $.10-$.20 per KWh [1]. You're literally talking about a 1,000x increase in the cost of electricity for hydrogen storage even if the rumors of "cheap" $200/KWh hydrogen production turn out to be true. 1. https://www.electricchoice.com/electricity-prices-by-state/ https://www.electricchoice.com/electricity-prices-by-state/ This thread is being rate limited, reply in edit: > You are pointing to RETAIL electricity costs. Rookie error, man. Elaborate on what you mean by emphasizing retail energy costs. That is the cost that customers pay for the electricity that is delivered to them. Some of this is subsidized, but this subsidy is not large. The US provides $3-5 subsidy per MWh of electricity. [2] Half a cent per KWh. Even if we ignore subsidies, hundreds of dollars per kilowatt hour of hydrogen storage is still a factor of a thousand more expensive. 2. https://spectrum.ieee.org/energywise/energy/policy/how-much-does-the-us-government-subsidize-electricity-generating-technologies https://spectrum.ieee.org/energywise/energy/policy/how-much-...
  - the8472 6y ago
    My understanding is that salt domes previously used for natural gas storage can be retooled to store hydrogen. Those have enormous capacities, months worth. At least in europe and north america they're hardly georaphically limited in the sense that pumped hydro is.
  - pfdietz 6y ago
    You are pointing to RETAIL electricity costs. Rookie error, man. Hydrogen would be produced at wholesale, especially with cut rate power when renewables are overproducing. In some places this number becomes negative.
  - pfdietz 6y ago
    > Elaborate on what you mean by emphasizing retail energy costs. That is the cost that customers pay for the electricity that is delivered to them. It's what a residential customer would pay. It's not what an industrial customer would pay, and it's certainly not the internal cost the utility to pay for their own production of hydrogen. In particular, it includes the cost of supporting the distribution network. None of the power being sent to the electrolysers will be sent over the thousands of miles of residential distribution lines. It also doesn't take into account that the wholesale price of electricity in power markets varies with time. The residential fixed price is derived from some average of that (plus charges for all the overhead), but the electrolysers could be operated when the wholesale price is low. > hundreds of dollars per kilowatt hour of hydrogen storage is still a factor of a thousand more expensive. The capital cost of storing hydrogen in underground cavities is estimated to be $1 per kWh of capacity, and perhaps much less.
    - manfredo 6y ago
      You seem to be under the impression that the cost of hydrogen storage comes almost exclusively from the cost of electricity used for electrolysis of water. This is not the case. Even if we assume zero electricity costs, th cost of storing hydrogen amounts to over a thousand dollars per KWh. Current estimates place this at $1,400 per KWh per year for the average case assuming that the electricity provided is free [1]. That works out to $3.80 per day per kilowatt hour of storage. Even for the optimistic estimated provided by this study, it's still $800/KWh/year - still over $2.00 per day. And again, this is assuming that free excess wind generation is used to get generate hydrogen. Us retail energy costs are about $.13/KWh. Industrial costs are $.07/KWh. For diurnal storage, hydrogen energy storage represents a 20x cost increase even in the best case estimates for the storage cost and assuming that excess wind generation will pick up th slack. And for non-diurnal storage the costs are even higher per KWh because a smaller amount of delivered electricity needs to pay off the same amount of capacity cost. Also, before you point at figure 16, know that this graph includes "capacity credits" - it's not the actual cost. 1. https://www.google.com/url?sa=t&source=web&rct=j&url=https://prod-ng.sandia.gov/techlib-noauth/access-control.cgi/2011/114845.pdf&ved=2ahUKEwiOnYj9wLbqAhVXJzQIHZLrDSYQFjAGegQIBBAB&usg=AOvVaw3nNskLLKaSysr_Dltygx1B https://www.google.com/url?sa=t&source=web&rct=j&url=https:/...
alexitorg 6y ago
Cool, I was looking for the efficiency of the Sabatier process. If people are prepared to use electrolosis with a end to end efficiency of ~ 40%. Using the Sabatier process to produce methane begins to look good to me. Just as green as the methane is produced from carbon dioxide and water. And it is much cheaper to produce pipes and tanks for methane and it should be able to be used in all the current natural gas infrastructure (compared to only 20% of the gas in these lines being able to be replaced with hydrogen). It seems to me anywhere where the gas has to be stored or moved the Sabatier process would win economically.

pfdietz 6y ago

Underground hydrogen storage is a demonstrated technology, not experimental. All that's required is scaling it up, and there's plenty of room to do that. The only real missing piece was sufficiently cheap electrolysers for use with intermittently available power, but that's coming along very fast now too, with rumors of costs as low as $200/kW in China (and a recent contract win of $350/kW from a European maker of alkaline electrolysis systems). This is more than adequate for hydrogen storage.

manfredo 6y ago
Underground hydrogen storage had the same issue as kinetic storage: it's geographically limited. It's not just a matter of scaling it up, it's also matter to implementing it in places without empty salt mines handy. And as you point out, generating this hydrogen is nowhere near cost efficient. To put this in perspective, energy costs in the US average about $.10-$.20 per KWh [1]. You're literally talking about a 1,000x increase in the cost of electricity for hydrogen storage even if the rumors of "cheap" $200/KWh hydrogen production turn out to be true. 1. https://www.electricchoice.com/electricity-prices-by-state/ https://www.electricchoice.com/electricity-prices-by-state/ This thread is being rate limited, reply in edit: > You are pointing to RETAIL electricity costs. Rookie error, man. Elaborate on what you mean by emphasizing retail energy costs. That is the cost that customers pay for the electricity that is delivered to them. Some of this is subsidized, but this subsidy is not large. The US provides $3-5 subsidy per MWh of electricity. [2] Half a cent per KWh. Even if we ignore subsidies, hundreds of dollars per kilowatt hour of hydrogen storage is still a factor of a thousand more expensive. 2. https://spectrum.ieee.org/energywise/energy/policy/how-much-does-the-us-government-subsidize-electricity-generating-technologies https://spectrum.ieee.org/energywise/energy/policy/how-much-...
- the8472 6y ago
  My understanding is that salt domes previously used for natural gas storage can be retooled to store hydrogen. Those have enormous capacities, months worth. At least in europe and north america they're hardly georaphically limited in the sense that pumped hydro is.
- pfdietz 6y ago
  You are pointing to RETAIL electricity costs. Rookie error, man. Hydrogen would be produced at wholesale, especially with cut rate power when renewables are overproducing. In some places this number becomes negative.
- pfdietz 6y ago
  > Elaborate on what you mean by emphasizing retail energy costs. That is the cost that customers pay for the electricity that is delivered to them. It's what a residential customer would pay. It's not what an industrial customer would pay, and it's certainly not the internal cost the utility to pay for their own production of hydrogen. In particular, it includes the cost of supporting the distribution network. None of the power being sent to the electrolysers will be sent over the thousands of miles of residential distribution lines. It also doesn't take into account that the wholesale price of electricity in power markets varies with time. The residential fixed price is derived from some average of that (plus charges for all the overhead), but the electrolysers could be operated when the wholesale price is low. > hundreds of dollars per kilowatt hour of hydrogen storage is still a factor of a thousand more expensive. The capital cost of storing hydrogen in underground cavities is estimated to be $1 per kWh of capacity, and perhaps much less.
  - manfredo 6y ago
    You seem to be under the impression that the cost of hydrogen storage comes almost exclusively from the cost of electricity used for electrolysis of water. This is not the case. Even if we assume zero electricity costs, th cost of storing hydrogen amounts to over a thousand dollars per KWh. Current estimates place this at $1,400 per KWh per year for the average case assuming that the electricity provided is free [1]. That works out to $3.80 per day per kilowatt hour of storage. Even for the optimistic estimated provided by this study, it's still $800/KWh/year - still over $2.00 per day. And again, this is assuming that free excess wind generation is used to get generate hydrogen. Us retail energy costs are about $.13/KWh. Industrial costs are $.07/KWh. For diurnal storage, hydrogen energy storage represents a 20x cost increase even in the best case estimates for the storage cost and assuming that excess wind generation will pick up th slack. And for non-diurnal storage the costs are even higher per KWh because a smaller amount of delivered electricity needs to pay off the same amount of capacity cost. Also, before you point at figure 16, know that this graph includes "capacity credits" - it's not the actual cost. 1. https://www.google.com/url?sa=t&source=web&rct=j&url=https://prod-ng.sandia.gov/techlib-noauth/access-control.cgi/2011/114845.pdf&ved=2ahUKEwiOnYj9wLbqAhVXJzQIHZLrDSYQFjAGegQIBBAB&usg=AOvVaw3nNskLLKaSysr_Dltygx1B https://www.google.com/url?sa=t&source=web&rct=j&url=https:/...

alexitorg 6y ago

Cool, I was looking for the efficiency of the Sabatier process. If people are prepared to use electrolosis with a end to end efficiency of ~ 40%. Using the Sabatier process to produce methane begins to look good to me. Just as green as the methane is produced from carbon dioxide and water. And it is much cheaper to produce pipes and tanks for methane and it should be able to be used in all the current natural gas infrastructure (compared to only 20% of the gas in these lines being able to be replaced with hydrogen). It seems to me anywhere where the gas has to be stored or moved the Sabatier process would win economically.