4 ms·

Gravitational storage is hard. For perspective: if the U.S. loaded up all 1.5 million of its rail freight cars to 30-ton capacity and sent them 4km up to the t

Gravitational storage is hard. For perspective: if the U.S. loaded up all 1.5 million of its rail freight cars to 30-ton capacity and sent them 4km up to the top of Mt. Rainier, that would store 494 GWh of energy. That's just over an hour's worth of our average electricity usage. Gravitational storage is hard.

dragontamer 10y ago
We don't need to store everything. We just need to store enough to make load-shifting environmentally (and commercially) available. The 30 Gigawatt Hour Bath County Station gets there (https://en.wikipedia.org/wiki/Bath_County_Pumped_Storage_Station https://en.wikipedia.org/wiki/Bath_County_Pumped_Storage_Sta...), but even the "smaller" Tesla 50MWhr projects do too. Compressed Air is hitting 300MW-hr designs (https://www.greentechmedia.com/articles/read/texas-calls-for-317mw-of-compressed-air-energy-storage2 https://www.greentechmedia.com/articles/read/texas-calls-for...). That's enough for a metropolitan solar community to loadshift the 12:00 noon sun to the 5:00 dusk peak-energy period. (Average home: 30kwhr per day. 300MW-hr design would serve over 10,000 homes easily, and doesn't need to actually hold the electric usage for the whole day. It'd realistically only need to hold 1/10th the energy or so, to load-shift a few hours here and there). ARES seems to be in the 12MW-hr to 100MW-hr design size. This is smaller than Pumped Hydro but still useful. Smaller, cheaper projects that partially solve the problem is still a good thing. It seems like a perfectly good solution to the problem. Buying up cheap energy from night (or noon-power solar arrays), and selling it during the 3pm to 7pm peak-energy time. As long as there's at least a 20% differential in peak pricing somewhere in the day, "small" 1MW-hr to 300MW-hr plants will be profitable. ---------- In any case: Wind continues to work at night. Nuclear works throughout the day. Hydro works throughout the day. We don't need to store EVERYTHING, we just need to store the excess from Solar from noon, and then load-shift it to 5pm to 8pm, while the sun is setting and solar arrays generate less electricity.
- Retric 10y ago
  Using hydro 24/7 is fairly wasteful, dam fed hydro is awesome for peaking power.
  - pm24601 10y ago
    except in a drought... when we have no water
- rando18423 10y ago
  To finance this, a bank will want to see they've managed to hedge their business and are in the business of capturing those spreads rather than speculating on the widening of that spread (only to have it contract). Interestingly, this may be exceedingly hard to do on the open market and may require setting up an expensive structured product with the trading group of some bank, where they pay you a fixed price each day and take on the daily/monthly (and particularly in power markets, term) risk. That won't be cheap, especially if these aren't located to one of the major grid nodes where there are liquid markets available. Basically, I'm just wondering how hedging costs affect your numbers.
  - dragontamer 10y ago
    > To finance this, a bank will want to see they've managed to hedge their business and are in the business of capturing those spreads rather than speculating on the widening of that spread (only to have it contract) The spread is grossly positive. Pumped-Hydro provides a location for baseline power plants (nuclear, coal, and even Wind / Solar) to continue to pump energy into the grid without getting shut down. Coal, Wind, and Nuclear plants, in particular, are typically very difficult to start back up again. So it is profitable for these plants to continue to generate power, even when the plants pay money for the privilege for someone to "waste" it somewhere. Then of course, later in the day, the "batteries" (ARES, Pumped Hydro, CAES, and what-not) sell the energy back to the grid when peak-energy occurs (usually around 5:00, when businesses still have the factories running but people have also begun to return home and turned on their air conditioning again).
jhallenworld 10y ago
The other way to look at this is to consider how much chemical energy there is in the diesel fuel tank of a train. Or that a single AAA battery has enough energy to raise a garage door (but slowly).
kposehn 10y ago
Correction here: the grand majority of cars (bulk manifest, hopper, etc.) have a carrying capacity of 100-120 tons. That's 3-4x. That said, curious where you got your calculations from.
- cheeko1234 10y ago
  Potential energy= mgh: 1.5 million * 30000 * 9.8 * 4000 / 3600 = 490 GW-hr

dragontamer 10y ago

We don't need to store everything. We just need to store enough to make load-shifting environmentally (and commercially) available. The 30 Gigawatt Hour Bath County Station gets there (https://en.wikipedia.org/wiki/Bath_County_Pumped_Storage_Station https://en.wikipedia.org/wiki/Bath_County_Pumped_Storage_Sta...), but even the "smaller" Tesla 50MWhr projects do too. Compressed Air is hitting 300MW-hr designs (https://www.greentechmedia.com/articles/read/texas-calls-for-317mw-of-compressed-air-energy-storage2 https://www.greentechmedia.com/articles/read/texas-calls-for...). That's enough for a metropolitan solar community to loadshift the 12:00 noon sun to the 5:00 dusk peak-energy period. (Average home: 30kwhr per day. 300MW-hr design would serve over 10,000 homes easily, and doesn't need to actually hold the electric usage for the whole day. It'd realistically only need to hold 1/10th the energy or so, to load-shift a few hours here and there). ARES seems to be in the 12MW-hr to 100MW-hr design size. This is smaller than Pumped Hydro but still useful. Smaller, cheaper projects that partially solve the problem is still a good thing. It seems like a perfectly good solution to the problem. Buying up cheap energy from night (or noon-power solar arrays), and selling it during the 3pm to 7pm peak-energy time. As long as there's at least a 20% differential in peak pricing somewhere in the day, "small" 1MW-hr to 300MW-hr plants will be profitable. ---------- In any case: Wind continues to work at night. Nuclear works throughout the day. Hydro works throughout the day. We don't need to store EVERYTHING, we just need to store the excess from Solar from noon, and then load-shift it to 5pm to 8pm, while the sun is setting and solar arrays generate less electricity.

Retric 10y ago
Using hydro 24/7 is fairly wasteful, dam fed hydro is awesome for peaking power.
- pm24601 10y ago
  except in a drought... when we have no water
rando18423 10y ago
To finance this, a bank will want to see they've managed to hedge their business and are in the business of capturing those spreads rather than speculating on the widening of that spread (only to have it contract). Interestingly, this may be exceedingly hard to do on the open market and may require setting up an expensive structured product with the trading group of some bank, where they pay you a fixed price each day and take on the daily/monthly (and particularly in power markets, term) risk. That won't be cheap, especially if these aren't located to one of the major grid nodes where there are liquid markets available. Basically, I'm just wondering how hedging costs affect your numbers.
- dragontamer 10y ago
  > To finance this, a bank will want to see they've managed to hedge their business and are in the business of capturing those spreads rather than speculating on the widening of that spread (only to have it contract) The spread is grossly positive. Pumped-Hydro provides a location for baseline power plants (nuclear, coal, and even Wind / Solar) to continue to pump energy into the grid without getting shut down. Coal, Wind, and Nuclear plants, in particular, are typically very difficult to start back up again. So it is profitable for these plants to continue to generate power, even when the plants pay money for the privilege for someone to "waste" it somewhere. Then of course, later in the day, the "batteries" (ARES, Pumped Hydro, CAES, and what-not) sell the energy back to the grid when peak-energy occurs (usually around 5:00, when businesses still have the factories running but people have also begun to return home and turned on their air conditioning again).

jhallenworld 10y ago

The other way to look at this is to consider how much chemical energy there is in the diesel fuel tank of a train. Or that a single AAA battery has enough energy to raise a garage door (but slowly).

kposehn 10y ago

Correction here: the grand majority of cars (bulk manifest, hopper, etc.) have a carrying capacity of 100-120 tons. That's 3-4x. That said, curious where you got your calculations from.

cheeko1234 10y ago
Potential energy= mgh: 1.5 million * 30000 * 9.8 * 4000 / 3600 = 490 GW-hr