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Interesting concept. Sort of a terribly written article. Things the author should have talked about: 1) comparison between life expectancy of a lithium ion batt

Interesting concept. Sort of a terribly written article. Things the author should have talked about: 1) comparison between life expectancy of a lithium ion battery vs a sand battery 2) environmental impact of lithium ion battery waste, vs sand battery. 3) ethics of lithium mining. 4) how lithium ion batteries perform poorly at colder temperatures (eg Finland) There are a lot of strong arguments for these batteries the author seemed to just skip over, and instead focused on costs, which they don’t know the answer to.

metalrain 1y ago
I don't think lithium ion is even the right comparison in this case. This could more comparable in spirit, although 900 times bigger in capacity and not yet finished. https://www.vantaanenergia.fi/en/about-us/projects/varanto-the-cavern-thermal-energy-storage/ https://www.vantaanenergia.fi/en/about-us/projects/varanto-t... If you try gauge the price from that cavern storage (estimated 200 million euros) then lets say it has some economies of scale, maybe this sand battery costs like 500k-1M euros. If you just heat the storage on cheap hours and output at high prices. You could in theory cycle (24*365/2) hours at 1 MW so 4,4 GWh of energy per year. So how could be the project profitable? In 10 year period with full utilization price differential would need to be 22.8 €/MWh to break even with 1M investment, then add operating costs, loan interest, etc. With more realistic utilization it would need to even higher. Maybe you amortize costs over 20, 30 years. But its's even more uncertain what cost of electricity will be. I think it only makes sense if this storage allows them to electrify heat production replacing much more expensive current production.
- lrasinen 1y ago
  22.8 €/MWh is just 2.28 c/kWh and that's a very low bar to clear. Just yesterday we had 6 hours of negative prices, followed shortly after by one hour at 2.66 c/kWh and four more over 3 c. Friday had swings from 0.4 c to 13 c. (All prices with VAT included) And this is in summer when energy consumption is low, the swings will intensify when the heating season starts.
  - metalrain 1y ago
    Yes, very easy for most days to find some hours of that price differential. However my calculation needs it to happen all the time for 10 years in row. Alternatively: 6 hours with 45 €/MWh differential, 3 hours with 90 €/MWh differential or one hour with 270 €/MWh differential. There are several days when some of these happen, but I don't think its every day for ten years straight. There are lots of days when price moves in tight range or even if there is some movement there isn't enough of it.
    - lrasinen 1y ago
      I took the electricity spot prices for the first three months of this year (so that it covers the cold period), and ran a simple simulation on it. The simulation model assumes we're charging during the 12 cheapest hours, and discharging during the most expensive 12 h, and then calculated the average price differential per day. This is of course suboptimal, since the day-ahead prices are available. The mean differential in the data is 56.5 €/MWh, and on 64% of the days the differential is over 22.8 €/MWh. 10%, 50% and 90% percentiles are 3, 54 and 119. So at least during the winter time (when consumption is greatest) you'd expect to hit the price goal more often than not. Adding the rest of the year up to now drops the mean to 52 €/MWh and the median down to 38 €/MWh. Still pretty good. (As for cherry-picking the data: this year was easily available and didn't dig too hard for older data, but it was one of the mildest winters in recent years.)
foxglacier 1y ago
That and the downsides to the sand battery. We don't need more biased new stories trying to promote everything as miraculously pure-good. Environmental concerns hardly matter for utility energy generation because if it's not cheaper, it will will either completely fail or be a tax on everyone if the government mandates it. The obvious problem is it can only really be used for heating, not electricity. But heating is still a fine use when available.
- bodiekane 1y ago
  Surely the environmental concerns are the larger "tax on everyone". Fossil fuels appear cheap specifically because the benefits accumulate to the corporation extracting and selling them, while a substantial portion of the costs get unevenly distributed to random people who's homes get destroyed by hurricanes or wildfires as well as everyone having to run their air conditioners more.

metalrain 1y ago

I don't think lithium ion is even the right comparison in this case. This could more comparable in spirit, although 900 times bigger in capacity and not yet finished. https://www.vantaanenergia.fi/en/about-us/projects/varanto-the-cavern-thermal-energy-storage/ https://www.vantaanenergia.fi/en/about-us/projects/varanto-t... If you try gauge the price from that cavern storage (estimated 200 million euros) then lets say it has some economies of scale, maybe this sand battery costs like 500k-1M euros. If you just heat the storage on cheap hours and output at high prices. You could in theory cycle (24*365/2) hours at 1 MW so 4,4 GWh of energy per year. So how could be the project profitable? In 10 year period with full utilization price differential would need to be 22.8 €/MWh to break even with 1M investment, then add operating costs, loan interest, etc. With more realistic utilization it would need to even higher. Maybe you amortize costs over 20, 30 years. But its's even more uncertain what cost of electricity will be. I think it only makes sense if this storage allows them to electrify heat production replacing much more expensive current production.

lrasinen 1y ago
22.8 €/MWh is just 2.28 c/kWh and that's a very low bar to clear. Just yesterday we had 6 hours of negative prices, followed shortly after by one hour at 2.66 c/kWh and four more over 3 c. Friday had swings from 0.4 c to 13 c. (All prices with VAT included) And this is in summer when energy consumption is low, the swings will intensify when the heating season starts.
- metalrain 1y ago
  Yes, very easy for most days to find some hours of that price differential. However my calculation needs it to happen all the time for 10 years in row. Alternatively: 6 hours with 45 €/MWh differential, 3 hours with 90 €/MWh differential or one hour with 270 €/MWh differential. There are several days when some of these happen, but I don't think its every day for ten years straight. There are lots of days when price moves in tight range or even if there is some movement there isn't enough of it.
  - lrasinen 1y ago
    I took the electricity spot prices for the first three months of this year (so that it covers the cold period), and ran a simple simulation on it. The simulation model assumes we're charging during the 12 cheapest hours, and discharging during the most expensive 12 h, and then calculated the average price differential per day. This is of course suboptimal, since the day-ahead prices are available. The mean differential in the data is 56.5 €/MWh, and on 64% of the days the differential is over 22.8 €/MWh. 10%, 50% and 90% percentiles are 3, 54 and 119. So at least during the winter time (when consumption is greatest) you'd expect to hit the price goal more often than not. Adding the rest of the year up to now drops the mean to 52 €/MWh and the median down to 38 €/MWh. Still pretty good. (As for cherry-picking the data: this year was easily available and didn't dig too hard for older data, but it was one of the mildest winters in recent years.)

foxglacier 1y ago

That and the downsides to the sand battery. We don't need more biased new stories trying to promote everything as miraculously pure-good. Environmental concerns hardly matter for utility energy generation because if it's not cheaper, it will will either completely fail or be a tax on everyone if the government mandates it. The obvious problem is it can only really be used for heating, not electricity. But heating is still a fine use when available.

bodiekane 1y ago
Surely the environmental concerns are the larger "tax on everyone". Fossil fuels appear cheap specifically because the benefits accumulate to the corporation extracting and selling them, while a substantial portion of the costs get unevenly distributed to random people who's homes get destroyed by hurricanes or wildfires as well as everyone having to run their air conditioners more.