If you have a lot of very cheap energy in the summer efficiency is not central. The storage costs for the energy become more important. I have the impression that storing liquid gas is vastly cheaper than storing energy in gravity batteries.
Efficiency is still pretty central in that the summer stored energy is worth at least what it would return in the winter, and often more. Methane synthesis is still pretty expensive and definitely not very efficient, so a better alternative would be to run particularly energy-hungry industries at full capacity in the summer and slow down in the winter. This wouldn’t be any more wasteful of capacity than having a major methane-producing industry that runs at full capacity in the summer and not at all the rest of the year.
If methane synthesis was substantially cheaper, then it could be useful to provide methane as a feedstock to various other chemical processes, which would also be more valuable than just burning it.
Holding energy in methane is cheap, as is holding energy in towers of dirt-cheap blocks or dams full of water. What’s expensive—for all of these processes—is the equipment to transfer the energy into stored form. On the large scale there isn’t really any known way to put a gigawatt-season of electrical energy into storage more cheaply than just building the capacity to produce an extra gigawatt in the winter. Methane doesn’t come close. Gravity storage doesn’t come close. Pumped hydro doesn’t either, and nor does hydrogen.
That’s why grid-scale energy storage systems focus on the short term: typically up to a few hours, with more speculative projects looking at a week or so.
Probably depends where you are. in NZ, we already HAVE a bunch of hydro dams, so tweaking things to storage is probably more practical. In a country which were say… substantially dryer or flatter, Synthetic Gas might be the way to go.
On a country level I would imagine there are not that big of spikes in demand. Maybe in winter you have 3 to 4 times more flow than without storage configurations. I have trouble imagining what kind of use case would call to throttle between no water level loss to thousandfold flow.
Gravity batteries can be pretty large, and have up to about 90% efficiency. They require infrastructure, but so does SNG.
If you have a lot of very cheap energy in the summer efficiency is not central. The storage costs for the energy become more important. I have the impression that storing liquid gas is vastly cheaper than storing energy in gravity batteries.
Efficiency is still pretty central in that the summer stored energy is worth at least what it would return in the winter, and often more. Methane synthesis is still pretty expensive and definitely not very efficient, so a better alternative would be to run particularly energy-hungry industries at full capacity in the summer and slow down in the winter. This wouldn’t be any more wasteful of capacity than having a major methane-producing industry that runs at full capacity in the summer and not at all the rest of the year.
If methane synthesis was substantially cheaper, then it could be useful to provide methane as a feedstock to various other chemical processes, which would also be more valuable than just burning it.
Holding energy in methane is cheap, as is holding energy in towers of dirt-cheap blocks or dams full of water. What’s expensive—for all of these processes—is the equipment to transfer the energy into stored form. On the large scale there isn’t really any known way to put a gigawatt-season of electrical energy into storage more cheaply than just building the capacity to produce an extra gigawatt in the winter. Methane doesn’t come close. Gravity storage doesn’t come close. Pumped hydro doesn’t either, and nor does hydrogen.
That’s why grid-scale energy storage systems focus on the short term: typically up to a few hours, with more speculative projects looking at a week or so.
Probably depends where you are. in NZ, we already HAVE a bunch of hydro dams, so tweaking things to storage is probably more practical. In a country which were say… substantially dryer or flatter, Synthetic Gas might be the way to go.
You can’t just release most of the water stored in a hydro dam whenever you want. If you would do that you would flood the land after the dam.
On a country level I would imagine there are not that big of spikes in demand. Maybe in winter you have 3 to 4 times more flow than without storage configurations. I have trouble imagining what kind of use case would call to throttle between no water level loss to thousandfold flow.