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Renewables have currently very difficult problems to solve with storage. As far as I know the only sufficiently scalable energy storage method is pumped hydro.

Renewables have currently very difficult problems to solve with storage. As far as I know the only sufficiently scalable energy storage method is pumped hydro. Storing enough energy to deal with the intermittency of renewables at the scale required involves essentially digging a very large number of very large reservoirs. This is a huge civil engineering undertaking with massive environmental issues of its own. I've not seen anyone in any government really talking about investing in that much storage. Batteries do not seem to be realistic for the near and medium term (and also come with massive environmental problems), pumped air works where you have appropriate geology, everything else is essentially a meme. Renewables are great as long as you ignore the storage problem, just as coal is great as long as you ignore the waste problem.

dmurray 3y ago
> everything else is essentially a meme. I don't think this is fair: even if something like hydrogen storage isn't practical or economic now, it might be if generation cost falls 3x or 10x. Which is plausible for renewables in the medium to long term.
hannob 3y ago
> Renewables have currently very difficult problems to solve with storage. And fusion does nothing to solve these problems. Even in an optimistic scenario, what you'd end up with fusion is a very expensive power plant that can generate large amounts of energy. Running that as a peaker plant to complement renewables is unlikely to be economically viable. So your only bet really is to have fusion running as baseload power. However there won't be baseload power in the future, because we'll have times where renewables will provide more than 100% of the energy needed. I really don't see how fusion fits into any of this. SUre, intermittency problems of renewables need to be solved. But Fusion ain't the solution. Look at hydrogen-fired power plants, advanced geothermal, or heat storage, those are promising options.
- mirzap 3y ago
  Fusion doesn't have those problems. With fusion, you generate electricity 24h/day. Storage is needed for solar and wind for obvious reasons.
  - hannob 3y ago
    That's under the assumption you'll have a fusion only grid. But fusion won't exist in a vacuum. It will exist within the energy system in 20+ years. That will in all likelyhood be dominated by wind and solar, yet with another 20+ years of improvement.
rgmerk 3y ago
Battery storage works just fine for intraday use. And you don't even need batteries for industrial heat, which is a very substantial fraction of total energy demand. You can heat up a box of rocks/bricks/sand/graphite with resistive wires and run water through pipes to get the heat out again. And you don't need to dig out massive reservoirs for pumped hydro in much of the world. You just need a decent-size mountain range somewhere convenient to your electricity grid. Much of the time you can repurpose conventional hydroelectric dams for the job. Another alternative to storage is interruptible demand. If you're making hydrogen with electrolysis (another potential alternative energy storage medium) you can just turn the electrolysers off when electricity prices are high. There are lots of studies and while the more time you're using your electrolyser the better, the economics of running them intermittently are likely to be quite reasonable. Finally, it's worth pointing out that most people in the developed world seem likely they will have several day's worth of home electricity usage parked in their driveways by 2035 or so. Tapping just a small amount of that will make a huge dent in dunkelflautes.
- michaelt 3y ago
  As a Brit with solar panels, in June I get 15x the kWh output that I get in December. Which is the month with the highest demand for natural gas, for heating. So I think we need more than just intraday storage.
  - rgmerk 3y ago
    Yes, solar power has a huge amount of seasonal variation in the UK and the rest of northern Europe. And obviously, batteries on their own won't cut it to deal with this seasonal variation. But northern Europe, particularly the UK, has a lot less solar and a lot more wind in its grids than Spain, California, or Australia, for that very reason. Beyond that, there are quite a few other current or near-term technologies you can use to deal with the seasonality of supply and demand. First, insulating its houses properly to reduce the winter demand peak. Second, switching to heat pumps is another. Third, expanding biogas production and using it specifically for the winter peak. In the long term, producing hydrogen in the summer and storing it for the winter seems like the most likely solution for 100 or near-100% renewable grids in northern Europe at this point.
anovikov 3y ago
Battery storage is very cheap already with LiFePo batteries being at about $70/kwh with 80% cycle life of 3000 cycles. That's ~2.6 cents per kwh of energy stored. With invertors, grid connections, buildings etc. (that don't wear out nearly as quickly), it will capitalise to maybe about 6 cents per kwh for multiple hour storage. Because only a small fraction of energy needs to go through storage, it will make a really small impact on overall electricity cost.

dmurray 3y ago

> everything else is essentially a meme. I don't think this is fair: even if something like hydrogen storage isn't practical or economic now, it might be if generation cost falls 3x or 10x. Which is plausible for renewables in the medium to long term.

hannob 3y ago

> Renewables have currently very difficult problems to solve with storage. And fusion does nothing to solve these problems. Even in an optimistic scenario, what you'd end up with fusion is a very expensive power plant that can generate large amounts of energy. Running that as a peaker plant to complement renewables is unlikely to be economically viable. So your only bet really is to have fusion running as baseload power. However there won't be baseload power in the future, because we'll have times where renewables will provide more than 100% of the energy needed. I really don't see how fusion fits into any of this. SUre, intermittency problems of renewables need to be solved. But Fusion ain't the solution. Look at hydrogen-fired power plants, advanced geothermal, or heat storage, those are promising options.

mirzap 3y ago
Fusion doesn't have those problems. With fusion, you generate electricity 24h/day. Storage is needed for solar and wind for obvious reasons.
- hannob 3y ago
  That's under the assumption you'll have a fusion only grid. But fusion won't exist in a vacuum. It will exist within the energy system in 20+ years. That will in all likelyhood be dominated by wind and solar, yet with another 20+ years of improvement.

rgmerk 3y ago

Battery storage works just fine for intraday use. And you don't even need batteries for industrial heat, which is a very substantial fraction of total energy demand. You can heat up a box of rocks/bricks/sand/graphite with resistive wires and run water through pipes to get the heat out again. And you don't need to dig out massive reservoirs for pumped hydro in much of the world. You just need a decent-size mountain range somewhere convenient to your electricity grid. Much of the time you can repurpose conventional hydroelectric dams for the job. Another alternative to storage is interruptible demand. If you're making hydrogen with electrolysis (another potential alternative energy storage medium) you can just turn the electrolysers off when electricity prices are high. There are lots of studies and while the more time you're using your electrolyser the better, the economics of running them intermittently are likely to be quite reasonable. Finally, it's worth pointing out that most people in the developed world seem likely they will have several day's worth of home electricity usage parked in their driveways by 2035 or so. Tapping just a small amount of that will make a huge dent in dunkelflautes.

michaelt 3y ago
As a Brit with solar panels, in June I get 15x the kWh output that I get in December. Which is the month with the highest demand for natural gas, for heating. So I think we need more than just intraday storage.
- rgmerk 3y ago
  Yes, solar power has a huge amount of seasonal variation in the UK and the rest of northern Europe. And obviously, batteries on their own won't cut it to deal with this seasonal variation. But northern Europe, particularly the UK, has a lot less solar and a lot more wind in its grids than Spain, California, or Australia, for that very reason. Beyond that, there are quite a few other current or near-term technologies you can use to deal with the seasonality of supply and demand. First, insulating its houses properly to reduce the winter demand peak. Second, switching to heat pumps is another. Third, expanding biogas production and using it specifically for the winter peak. In the long term, producing hydrogen in the summer and storing it for the winter seems like the most likely solution for 100 or near-100% renewable grids in northern Europe at this point.

anovikov 3y ago

Battery storage is very cheap already with LiFePo batteries being at about $70/kwh with 80% cycle life of 3000 cycles. That's ~2.6 cents per kwh of energy stored. With invertors, grid connections, buildings etc. (that don't wear out nearly as quickly), it will capitalise to maybe about 6 cents per kwh for multiple hour storage. Because only a small fraction of energy needs to go through storage, it will make a really small impact on overall electricity cost.