2 ms·

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 im

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:/...
  - pfdietz 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. Nowhere did I say or imply that. My argument is actually the complete opposite. What hydrogen does is get a much lower cost per unit of energy storage capacity, at the cost of lower efficiency . The cost per energy capacity of batteries is two orders of magnitude higher than for hydrogen storage. So, hydrogen exploits that for long term storage, it's ok to waste more input energy, if you can get the capital cost down. > Us retail energy costs are about $.13/KWh. Industrial costs are $.07/KWh. The correct figure to look at is wholesale price, which is often below $.03/kWh in US power markets, and lower at off peak times when one would make hydrogen. https://www.eia.gov/todayinenergy/detail.php?id=42456 https://www.eia.gov/todayinenergy/detail.php?id=42456 > For diurnal storage, hydrogen energy storage I explicitly wasn't talking about diurnal storage. That's not the use case for hydrogen. The use case is long term storage. > 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. Hydrogen has a huge advantage in long term storage, because the per-energy capacity cost is so damned low, compared to batteries. Yes, the cost per kWh stored in long term storage is higher than the cost per kWh in short term storage. But they are different use cases and one cannot be substituted for the other. If you optimize the problem of providing a steady output from renewables over the days and years, you will find in most places that a mix of short term and long term storage is optimal. Neither substitutes for the other.

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:/...
- pfdietz 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. Nowhere did I say or imply that. My argument is actually the complete opposite. What hydrogen does is get a much lower cost per unit of energy storage capacity, at the cost of lower efficiency . The cost per energy capacity of batteries is two orders of magnitude higher than for hydrogen storage. So, hydrogen exploits that for long term storage, it's ok to waste more input energy, if you can get the capital cost down. > Us retail energy costs are about $.13/KWh. Industrial costs are $.07/KWh. The correct figure to look at is wholesale price, which is often below $.03/kWh in US power markets, and lower at off peak times when one would make hydrogen. https://www.eia.gov/todayinenergy/detail.php?id=42456 https://www.eia.gov/todayinenergy/detail.php?id=42456 > For diurnal storage, hydrogen energy storage I explicitly wasn't talking about diurnal storage. That's not the use case for hydrogen. The use case is long term storage. > 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. Hydrogen has a huge advantage in long term storage, because the per-energy capacity cost is so damned low, compared to batteries. Yes, the cost per kWh stored in long term storage is higher than the cost per kWh in short term storage. But they are different use cases and one cannot be substituted for the other. If you optimize the problem of providing a steady output from renewables over the days and years, you will find in most places that a mix of short term and long term storage is optimal. Neither substitutes for the other.