6 ms·

Everyone seems a bit obsessed by batteries as a storage method, when we have more traditional methods: - Pumped-storage hydroelectricity - https://en.wikipedia

Everyone seems a bit obsessed by batteries as a storage method, when we have more traditional methods: - Pumped-storage hydroelectricity - https://en.wikipedia.org/wiki/Pumped-storage_hydroelectricity https://en.wikipedia.org/wiki/Pumped-storage_hydroelectricit.... Sure it's not suitable everywhere. - There's always Molten Salt as well - http://www.solarreserve.com/en/technology/molten-salt-energy-storage http://www.solarreserve.com/en/technology/molten-salt-energy.... Also, solar isn't the be all and end all of renewable energy generation. Wind, Solar, Hydro, and Geothermal all have different strengths and weaknesses, and flexibility of generation is important. But above all, I think security of supply is probably the number 1 requirement (unless you're a big fan of load shedding - https://en.wikipedia.org/wiki/Rolling_blackout https://en.wikipedia.org/wiki/Rolling_blackout), and therefore, we'll still need energy sources that are reliable. I predict a move away from coal towards natural gas. Sure it's not perfect, but it's not the worst either.

dredmorbius 10y ago
No idea why the hivemind is downvoting you, but you're absolutely correct. A couple of additions and caveats. Friend of mine at ORNL has been talking up compressed air energy storage (CAES). I'm somewhat dubious due to the Boyles law heating/cooling problem (gasses heat when compressed, cool when expanded, and the resulting heat flows affect both efficiency and equipment function -- gas turbines don't spin well when iced solid). Pumped-hydro is the most efficient storage solution bar none, but is painfully restricted by siting opportunities. Being able to use oceans as a lower baisin might address this, though salt-water engineering is a significant concern (corrosion and other issues). Interesting to see molten salt as at large scale that pencils out a viable for even, say, a two week total energy replacement solution for the US. You'd need tankage (insulated) roughly corresponding to current Oaklahoma oil transshipment storage facilities. Electricity-to-fuel is another option, with Sabatier and Fischer-Tropsch cycles both proven. Carbon source from seawater appears somewhat promising, though my concern is that there's been 50 years of research without a large-scale demonstration project, making me suspect deeper issues. I actually am a fan of load-shedding, and suspect that the concept of dispatchable load as opposed to supply may be part of the future way of thinking. Coal => gas is a no-brainer, though also not a total solution, by a long shot. Geothermal is highly underrated, especially if currently protected areas are opened for consideration. The Yellowstone caldera could possibly supply up to 15% of total US electrical demand.
- jasonwatkinspdx 10y ago
  > Carbon source from seawater appears somewhat promising, though my concern is that there's been 50 years of research without a large-scale demonstration project, making me suspect deeper issues. I haven't seen anything about it recently, but the Navy was/is funding a demonstration plant in Hawaii. I really hope it works out as I'm skeptical that the developing world will shift to electric vehicles anytime soon.
  - dredmorbius 10y ago
    History & paper to 1964: https://www.reddit.com/r/dredmorbius/comments/28nqoz/electrical_fuel_synthesis_from_seawater_older/ https://www.reddit.com/r/dredmorbius/comments/28nqoz/electri...
- Someone 10y ago
  "Being able to use oceans as a lower baisin might address this" There also are ideas to use the ocean as the higher basin. See https://trustyetverify.wordpress.com/2014/12/11/energy-from-an-island/ https://trustyetverify.wordpress.com/2014/12/11/energy-from-..., https://www.technologyreview.com/s/510806/a-manmade-island-to-store-wind-energy/ https://www.technologyreview.com/s/510806/a-manmade-island-t...
  - dredmorbius 10y ago
    Interesting. Japan's done a lower baisin trial.
erikpukinskis 10y ago
Batteries have some advantages that can offset the cost a little: 1) You can move them around, as in an electric car. That's useful if you want to do mobile stuff like driving. Or if you just flat-out want to move the facility somewhere it will be more useful. 2) They can be efficiently decentralized, which benefits reliability, and decreases transmission loss. But anyway, the solution is to use any and all technologies, right? Batteries make sense some places, gravity storage elsewhere.
- amazon_not 10y ago
  > Or if you just flat-out want to move the facility somewhere it will be more useful. While an interesting theory, I can't think of a single scenario where this would be economically justified. > 2) They can be efficiently decentralized, which benefits reliability, and decreases transmission loss. Transmission losses are about 6%, so not really any economic gain.
  - erikpukinskis 10y ago
    Wouldn't that be a 6% economic gain?
    - amazon_not 10y ago
      Only if your local generation plus battery system is equivalent or cheaper at providing power than the grid. Most battery systems aren't profitable even if power is free. So, no.
- ZeroGravitas 10y ago
  Batteries have a variety of uses on the grid. If you're clever enough to use them for several of these at the same time, it makes it easier to pay their way: http://www.rmi.org/electricity_battery_value http://www.rmi.org/electricity_battery_value
artr 10y ago
This is what Danielle Fong at Lightsail has been doing since 2009. They've had investment from Bill Gates and Peter Thiel. They've developed a way to compress and decompress air efficiently by heating/cooling the air. by using a carbon fibre air canister they are able to store air at a much higher pressure than previously possible. Her Ted Talk[1] and their website[2] explains it much better than I do. [1] https://www.youtube.com/watch?v=hZiaTV6uvFQ https://www.youtube.com/watch?v=hZiaTV6uvFQ [2] http://www.lightsail.com/ http://www.lightsail.com/
- extrapickles 10y ago
  Compressed air storage rings of a scam to me. They never mention how efficient it is to compress the air and turn the air back into electricity. It's always how efficient their storage tank is, which on paper gives batteries a run for their money. When sizing an industrial air system a rule of thumb is to budget 7-8hp of compressor for 1 hp of air motor. That is 12% efficiency, or only worth it if you had no other source of power. I'll give them the benefit of the doubt and assume a tightly integrated system you could do 3x better, but it still doesn't come close to batteries. If someone has plug-plug numbers that are better, let me know.
  - dredmorbius 10y ago
    My understanding is that the grid-scale stuff will be using natural geological reservoirs -- basically re-filling old gas wells with air. My understanding isn't particularly deep, and I'd like to run numbers on storage, volume, pressure, etc. But I suspect this'll have to be big enough that constructing cans really isn't viable.
    - evgen 10y ago
      Doesn't this run into insulating problems for the resevoir? How do you prevent the pressure from being lost as heat?
      - dredmorbius 10y ago
Gustomaximus 10y ago
Similar to pumped water storage I wonder if we could do a household version with weight. Something like the gravity light (gravitylight.org) but on larger scale. I wonder if we could see a resurgence of chimneys on houses except now instead of letting smoke out they contain a XY ton weights that gets pushed up by excess solar capacity during the day, and then drops by evening powering the house. I have no idea if that's realistic. Does someone know what the weight/distance to power output would be limited at...
- rm445 10y ago
  The potential energy of a mass m at height h is mgh. Play with this and you'll immediately see it doesn't seem useful. e.g. storing a 50-tonne weight at 10m gives you less than 1.5 kWh of energy.
  - Gustomaximus 10y ago
    So probably needs in excess of 750 ton. And more likely twice as a house would more likely have a 5m 'chimney'. Clearly not viable. Thanks.
- swombat 10y ago
  A much better and denser option for storing energy mechanically is flywheels. I haven't researched what happened to this option since but when I was looking into it 15 years ago it seemed like a good option that needed more R&D into frictionless axles and vacuum chambers.
  - dredmorbius 10y ago
    Excellent rapid response, second only to capacitors. But pretty poor densities, and hugely significant engineering challenges. Flywheels that don't become fly-apart wheels is one problem. Containment of fly-apart wheels another. Buried concrete pipes are usually what you're looking at. You need mass to contain these things. The per-kg energy densities just aren't all that high. If you want reactive load to soak up very short-term demand / supply fluctuations, you can get that. And you've got crazy charge-discharge cycles. Bearings are mostly solvable with magnets, as I understand. But you still lose a given percentage of storage over short time -- ~1% per hour or so, within a few powers of 2. Enough that long-term storage isn't viable. And the thing that really screws you over is that the Earth moves. Geometric precession of your flywheel is something you've got to deal with. There's a place, but I don't think it's large-scale, long-term grid storage.
Gustomaximus 10y ago
And considering this, a big question is will the market move away from centralized power systems. Will it be more viable to have a local/household level power generation and storage or will scale continue to give cost savings. This will likely have the biggest effect on storage/generation methods used. Possibly hybrid with distributed for suburb/rural and consolidated for urban/commercial? Or locally generated with grid peak power? Interesting times.
dangravell 10y ago
PCM being used for domestic hot water now, see companies like http://sunamp.co.uk/products/sunamppv/ http://sunamp.co.uk/products/sunamppv/ . Much better than water - higher energy capacity means smaller units and higher performing insulation making losses much lower. Heat loss is a bit problem in stored water DHW scenarios and will get even more of a problem if we begin building houses properly (which surely has to happen at some point).
olau 10y ago
Wind pioneer and former CTO of Siemens Wind Power is currently working on energy storage using rocks instead of a molten salt - he's blogging about it in the Danish engineering news site ing.dk. Molten salt is efficient because of the phase change, but also much more difficult and expensive to handle than a big (well enormous) bunch of hot rocks. Last thing I heard, he's currently trying to get demonstration plant up and running - it sounded like they'd already done some experiments at Siemens before he left. Anyway, nowhere near ready, but just to show that there are still low-tech options out there being examined. Another low-tech option is biomass, either wood chips/pills or other stuff processed into methane. Yeah, it's not as cheap as coal, but with good grid connections we need less storage than people seem to think, at least according to the research papers I've seen.
- kaybe 10y ago
  We had research show that you can offset storage with capacity to some degree. [0] Some numbers: 100% renewable energy with a capacity of 340% would require 8% storage just for Germany, 3.8% for Europe (due to larger area which means more diverse weather). Also 8% for Europe using no solar and more wind instead. The 340% capacity is needed to get to the 100% coverage since there is more downtime compared to old energy which had 180% in 2007. If we go to 390% capacity (which corresponds to 170 GW additional production as calculated for Germany) we only need 0.9% storage. Depending on the relative pricing of additional capacity and storage, the price for building the whole infrastructure can go down by half. (The upper limit given in numbers is of the same order of magnitude as Europe's GDP in 2009, 12·10^12 €) [0] (German) http://onlinelibrary.wiley.com/doi/10.1002/piuz.201201301/abstract;jsessionid=6DA58A33516AF34DC77811097ABDA1C8.f04t03 http://onlinelibrary.wiley.com/doi/10.1002/piuz.201201301/ab...
xbmcuser 10y ago
Batteries are the best bet for going off grid not for utilities based solar. Now that in more cities and states of US the utilities are getting net metering banned for home solar.

dredmorbius 10y ago

No idea why the hivemind is downvoting you, but you're absolutely correct. A couple of additions and caveats. Friend of mine at ORNL has been talking up compressed air energy storage (CAES). I'm somewhat dubious due to the Boyles law heating/cooling problem (gasses heat when compressed, cool when expanded, and the resulting heat flows affect both efficiency and equipment function -- gas turbines don't spin well when iced solid). Pumped-hydro is the most efficient storage solution bar none, but is painfully restricted by siting opportunities. Being able to use oceans as a lower baisin might address this, though salt-water engineering is a significant concern (corrosion and other issues). Interesting to see molten salt as at large scale that pencils out a viable for even, say, a two week total energy replacement solution for the US. You'd need tankage (insulated) roughly corresponding to current Oaklahoma oil transshipment storage facilities. Electricity-to-fuel is another option, with Sabatier and Fischer-Tropsch cycles both proven. Carbon source from seawater appears somewhat promising, though my concern is that there's been 50 years of research without a large-scale demonstration project, making me suspect deeper issues. I actually am a fan of load-shedding, and suspect that the concept of dispatchable load as opposed to supply may be part of the future way of thinking. Coal => gas is a no-brainer, though also not a total solution, by a long shot. Geothermal is highly underrated, especially if currently protected areas are opened for consideration. The Yellowstone caldera could possibly supply up to 15% of total US electrical demand.

jasonwatkinspdx 10y ago
> Carbon source from seawater appears somewhat promising, though my concern is that there's been 50 years of research without a large-scale demonstration project, making me suspect deeper issues. I haven't seen anything about it recently, but the Navy was/is funding a demonstration plant in Hawaii. I really hope it works out as I'm skeptical that the developing world will shift to electric vehicles anytime soon.
- dredmorbius 10y ago
  History & paper to 1964: https://www.reddit.com/r/dredmorbius/comments/28nqoz/electrical_fuel_synthesis_from_seawater_older/ https://www.reddit.com/r/dredmorbius/comments/28nqoz/electri...
Someone 10y ago
"Being able to use oceans as a lower baisin might address this" There also are ideas to use the ocean as the higher basin. See https://trustyetverify.wordpress.com/2014/12/11/energy-from-an-island/ https://trustyetverify.wordpress.com/2014/12/11/energy-from-..., https://www.technologyreview.com/s/510806/a-manmade-island-to-store-wind-energy/ https://www.technologyreview.com/s/510806/a-manmade-island-t...
- dredmorbius 10y ago
  Interesting. Japan's done a lower baisin trial.

erikpukinskis 10y ago

Batteries have some advantages that can offset the cost a little: 1) You can move them around, as in an electric car. That's useful if you want to do mobile stuff like driving. Or if you just flat-out want to move the facility somewhere it will be more useful. 2) They can be efficiently decentralized, which benefits reliability, and decreases transmission loss. But anyway, the solution is to use any and all technologies, right? Batteries make sense some places, gravity storage elsewhere.

amazon_not 10y ago
> Or if you just flat-out want to move the facility somewhere it will be more useful. While an interesting theory, I can't think of a single scenario where this would be economically justified. > 2) They can be efficiently decentralized, which benefits reliability, and decreases transmission loss. Transmission losses are about 6%, so not really any economic gain.
- erikpukinskis 10y ago
  Wouldn't that be a 6% economic gain?
  - amazon_not 10y ago
    Only if your local generation plus battery system is equivalent or cheaper at providing power than the grid. Most battery systems aren't profitable even if power is free. So, no.
ZeroGravitas 10y ago
Batteries have a variety of uses on the grid. If you're clever enough to use them for several of these at the same time, it makes it easier to pay their way: http://www.rmi.org/electricity_battery_value http://www.rmi.org/electricity_battery_value

artr 10y ago

This is what Danielle Fong at Lightsail has been doing since 2009. They've had investment from Bill Gates and Peter Thiel. They've developed a way to compress and decompress air efficiently by heating/cooling the air. by using a carbon fibre air canister they are able to store air at a much higher pressure than previously possible. Her Ted Talk[1] and their website[2] explains it much better than I do. [1] https://www.youtube.com/watch?v=hZiaTV6uvFQ https://www.youtube.com/watch?v=hZiaTV6uvFQ [2] http://www.lightsail.com/ http://www.lightsail.com/

extrapickles 10y ago
Compressed air storage rings of a scam to me. They never mention how efficient it is to compress the air and turn the air back into electricity. It's always how efficient their storage tank is, which on paper gives batteries a run for their money. When sizing an industrial air system a rule of thumb is to budget 7-8hp of compressor for 1 hp of air motor. That is 12% efficiency, or only worth it if you had no other source of power. I'll give them the benefit of the doubt and assume a tightly integrated system you could do 3x better, but it still doesn't come close to batteries. If someone has plug-plug numbers that are better, let me know.
- dredmorbius 10y ago
  My understanding is that the grid-scale stuff will be using natural geological reservoirs -- basically re-filling old gas wells with air. My understanding isn't particularly deep, and I'd like to run numbers on storage, volume, pressure, etc. But I suspect this'll have to be big enough that constructing cans really isn't viable.
  - evgen 10y ago
    Doesn't this run into insulating problems for the resevoir? How do you prevent the pressure from being lost as heat?
    - dredmorbius 10y ago

Gustomaximus 10y ago

Similar to pumped water storage I wonder if we could do a household version with weight. Something like the gravity light (gravitylight.org) but on larger scale. I wonder if we could see a resurgence of chimneys on houses except now instead of letting smoke out they contain a XY ton weights that gets pushed up by excess solar capacity during the day, and then drops by evening powering the house. I have no idea if that's realistic. Does someone know what the weight/distance to power output would be limited at...

rm445 10y ago
The potential energy of a mass m at height h is mgh. Play with this and you'll immediately see it doesn't seem useful. e.g. storing a 50-tonne weight at 10m gives you less than 1.5 kWh of energy.
- Gustomaximus 10y ago
  So probably needs in excess of 750 ton. And more likely twice as a house would more likely have a 5m 'chimney'. Clearly not viable. Thanks.
swombat 10y ago
A much better and denser option for storing energy mechanically is flywheels. I haven't researched what happened to this option since but when I was looking into it 15 years ago it seemed like a good option that needed more R&D into frictionless axles and vacuum chambers.
- dredmorbius 10y ago
  Excellent rapid response, second only to capacitors. But pretty poor densities, and hugely significant engineering challenges. Flywheels that don't become fly-apart wheels is one problem. Containment of fly-apart wheels another. Buried concrete pipes are usually what you're looking at. You need mass to contain these things. The per-kg energy densities just aren't all that high. If you want reactive load to soak up very short-term demand / supply fluctuations, you can get that. And you've got crazy charge-discharge cycles. Bearings are mostly solvable with magnets, as I understand. But you still lose a given percentage of storage over short time -- ~1% per hour or so, within a few powers of 2. Enough that long-term storage isn't viable. And the thing that really screws you over is that the Earth moves. Geometric precession of your flywheel is something you've got to deal with. There's a place, but I don't think it's large-scale, long-term grid storage.

Gustomaximus 10y ago

And considering this, a big question is will the market move away from centralized power systems. Will it be more viable to have a local/household level power generation and storage or will scale continue to give cost savings. This will likely have the biggest effect on storage/generation methods used. Possibly hybrid with distributed for suburb/rural and consolidated for urban/commercial? Or locally generated with grid peak power? Interesting times.

dangravell 10y ago

PCM being used for domestic hot water now, see companies like http://sunamp.co.uk/products/sunamppv/ http://sunamp.co.uk/products/sunamppv/ . Much better than water - higher energy capacity means smaller units and higher performing insulation making losses much lower. Heat loss is a bit problem in stored water DHW scenarios and will get even more of a problem if we begin building houses properly (which surely has to happen at some point).

olau 10y ago

Wind pioneer and former CTO of Siemens Wind Power is currently working on energy storage using rocks instead of a molten salt - he's blogging about it in the Danish engineering news site ing.dk. Molten salt is efficient because of the phase change, but also much more difficult and expensive to handle than a big (well enormous) bunch of hot rocks. Last thing I heard, he's currently trying to get demonstration plant up and running - it sounded like they'd already done some experiments at Siemens before he left. Anyway, nowhere near ready, but just to show that there are still low-tech options out there being examined. Another low-tech option is biomass, either wood chips/pills or other stuff processed into methane. Yeah, it's not as cheap as coal, but with good grid connections we need less storage than people seem to think, at least according to the research papers I've seen.

kaybe 10y ago
We had research show that you can offset storage with capacity to some degree. [0] Some numbers: 100% renewable energy with a capacity of 340% would require 8% storage just for Germany, 3.8% for Europe (due to larger area which means more diverse weather). Also 8% for Europe using no solar and more wind instead. The 340% capacity is needed to get to the 100% coverage since there is more downtime compared to old energy which had 180% in 2007. If we go to 390% capacity (which corresponds to 170 GW additional production as calculated for Germany) we only need 0.9% storage. Depending on the relative pricing of additional capacity and storage, the price for building the whole infrastructure can go down by half. (The upper limit given in numbers is of the same order of magnitude as Europe's GDP in 2009, 12·10^12 €) [0] (German) http://onlinelibrary.wiley.com/doi/10.1002/piuz.201201301/abstract;jsessionid=6DA58A33516AF34DC77811097ABDA1C8.f04t03 http://onlinelibrary.wiley.com/doi/10.1002/piuz.201201301/ab...

xbmcuser 10y ago

Batteries are the best bet for going off grid not for utilities based solar. Now that in more cities and states of US the utilities are getting net metering banned for home solar.