• Post Reply Bookmark Topic Watch Topic
  • New Topic
permaculture forums growies critters building homesteading energy monies kitchen purity ungarbage community wilderness fiber arts art permaculture artisans regional education experiences global resources the cider press projects digital market permies.com private forums all forums
this forum made possible by our volunteer staff, including ...
master stewards:
  • Nicole Alderman
  • r ranson
  • Anne Miller
  • paul wheaton
stewards:
  • Mike Jay
  • Jocelyn Campbell
  • Miles Flansburg
garden masters:
  • Dan Boone
  • Dave Burton
  • Steve Thorn
  • Greg Martin
gardeners:
  • Shawn Klassen-Koop
  • Pearl Sutton
  • Mike Barkley

Energy Storage

 
pollinator
Posts: 2385
Location: Massachusetts, Zone:6/7, AHS:4, Rainfall:48in even Soil:SandyLoam pH6 Flat
125
forest garden solar
  • Mark post as helpful
  • send pies
  • Quote
  • Report post to moderator


1. Collects
Energy is gathered from wind, solar, or fossil generators on the grid as electrical energy and sent to Malta’s energy storage system.

2. Converts
The electricity drives a heat pump, which converts electrical energy into thermal energy by creating a temperature difference.

3. Stores
The heat is then stored in molten salt, while the cold is stored in a chilled liquid.

4. Reconverts
The temperature difference is converted back to electrical energy with a heat engine.

5. Distributes
Electricity is sent back to the grid when it is needed.

Malta Inc
 
S Bengi
pollinator
Posts: 2385
Location: Massachusetts, Zone:6/7, AHS:4, Rainfall:48in even Soil:SandyLoam pH6 Flat
125
forest garden solar
  • Mark post as helpful
  • send pies
  • Quote
  • Report post to moderator


They have even built 2,000kWH portable systems. (Hopefully it didn't take up the entire shipping container)
 
pollinator
Posts: 3080
627
books cat chicken duck rabbit transportation trees woodworking
  • Mark post as helpful
  • send pies
  • Quote
  • Report post to moderator
I always thought a compost heating pile, coupled with the cool temperature of the ground, would produce enough of a thermal difference to drive a Sterling Engine. If it did, it would enable a lot of electricity on a homestead.
 
pollinator
Posts: 626
Location: Southern Illinois
114
building cat dog fungi rocket stoves transportation trees woodworking writing
  • Mark post as helpful
  • send pies
  • Quote
  • Report post to moderator
S Bengi,

For high temperature heat storage and heat transfer, molten salts are very hard to beat.  I am curious about the overall efficiency of this system as each step in the process loses a portion of the overall energy so I am intellectually interested in how much energy the system delivers compared to how much it receives.  Also, over time the hot side will cool over time and the cold side will warm.  But over short time spans (such as overnight heat storage, maybe even a couple of days depending on power needs and circumstances) this setup could have real potential.

Extremely cool idea though.  I did my masters research in the history of energy and I am starting to contemplate going for my PhD in the history of energy and by now I have an almost unhealthy fascination with all things energy.  I now see energy everywhere.  I see it in my coffee in the morning, sunshine streaming into my windows in the day, my Christmas tree—EVERYTHING!  I especially like new forms, sources, methods of generating and storing energy.

If I don’t stop now, I will ramble on incessantly so I will conclude by saying again, very cool and you have piqued my interest.

Eric
 
Eric Hanson
pollinator
Posts: 626
Location: Southern Illinois
114
building cat dog fungi rocket stoves transportation trees woodworking writing
  • Mark post as helpful
  • send pies
  • Quote
  • Report post to moderator
Ok , I am officially interested and I can’t stop yet.  Energy is notoriously difficult to store.  By its very nature, energy wants to disperse.  For energy storage, most people automatically think of batteries.  Even with the very best batteries, the electrons just don’t want to pack close to one another (which is why nature is basically electrically neutral over any appreciable timescale,  please correct me if I am wrong).  Thermal batteries want to cool to ambient temperatures even with the very best insulation, and the issue gets worse as the temperature differential grows.  Some power plants use compressed air and hydro electric plants can pump water to higher elevations, but both compressing air and pumping water are energy intensive operations that detract from overall efficiency.

Personally, I have thought of two systems that may work better.  First, electrolyzing water into hydrogen for storage later turned back into energy with a fuel cell might be overall efficient, but today is expensive and cumbersome.

Secondly, I have thought about a version of pumped hydro I call a mass battery.  In the mass battery, excess energy would raise up a heavy mass, say a huge block of cement, using a worm drive to elevate along a shaft.  After the mass is elevated, the worm drive would disengage would detach and a spur gear attached to a generator would generate electricity as the mass lowered back to ground.  The mass battery is my own idea, would only apply to stationary applications, is completely hypothetical/untested, but would not spontaneously lose energy just by sitting.

I still think the molten salts are fascinating and I would be very interested in others’ ideas of good energy storage.

Eric
 
Eric Hanson
pollinator
Posts: 626
Location: Southern Illinois
114
building cat dog fungi rocket stoves transportation trees woodworking writing
  • Likes 1
  • Mark post as helpful
  • send pies
  • Quote
  • Report post to moderator
I’ve gone overboard now.

Making matters worse is the fact that electricity is by far the most flexible form of energy ever discovered but perhaps the very hardest to store.  Almost anything can be powered by electricity (from motors to computers to spacecraft—ion drive).  This makes tempting the notion that all energy should be converted to electricity and back to some other form of energy.  Each energy conversion (say, heat to mechanical work in a car, or heat to steam to spinning a flywheel to electricity—4 steps—in a power plant) loses energy through inevitable inefficiency.  Far better to, say, convert sunlight to heat in a thermal mass only to be re-released back as heat.  The fewer the steps the better.

Eric
 
S Bengi
pollinator
Posts: 2385
Location: Massachusetts, Zone:6/7, AHS:4, Rainfall:48in even Soil:SandyLoam pH6 Flat
125
forest garden solar
  • Mark post as helpful
  • send pies
  • Quote
  • Report post to moderator
Pumped hydro and pumped mass require huge height/mass.
I like pumped air/compressed air. except for the heat lost.
my 2nd post pumps the air and pressurize it store that potential energy but it also stores the heat too and converts that to electricity.

The 1st one stores the heat in liquids vs air.
Like any other battery both system does have energy conversion loss. sadly we have to store solar.
Solar Panels are cheap compared to battery. So if a cheap battery can be made then the money saves can be used to double the amount of solar panels installed.
 
Eric Hanson
pollinator
Posts: 626
Location: Southern Illinois
114
building cat dog fungi rocket stoves transportation trees woodworking writing
  • Mark post as helpful
  • send pies
  • Quote
  • Report post to moderator
S Bengi,

Yep, I agree.  Basically any energy storage has its own energy cost and the fewer energy transformations, the more efficient.  I looked long and hard at pv solar for my house and never considered batteries because of the expense.  In Illinois, we can grid tie and essentially use the grid as the battery.  At least that was the case when I last looked at it.

Energy is a tricky subject and there are some good, practical reasons renewables have not really taken over the market yet.  Not saying renewables are a bad idea in any way, just that there still exist real difficulties in replacing coal (and for the record, I do want to get rid of coal).

Thanks for the intellectually stimulating thread.  I hope it continues.

Eric
 
pollinator
Posts: 836
Location: Virginia USDA 7a/b
143
bee chicken food preservation forest garden hugelkultur hunting
  • Likes 1
  • Mark post as helpful
  • send pies
  • Quote
  • Report post to moderator
There are two ways of dealing with energy storage. One is to avoid it. Living Energy Farms (I haven't been there, just from reading) uses solar when it produces enough to run the equipment. This is tough for planning for sure. If you must store it, you have to decide what density (Wh/kg) you need. High density storage tends to be volatile. Low density storage is of course heavy. I am fascinated with NiFe batteries for long term storage, but they take up the best part of a room, and have to be on ground level (or in some monstrous structure). Your generating source is likely to be somewhere other than in the basement, so there is loss and cost in the transmission. That being said they are a mature technology. For obvious reasons they suck for transportation.

Lead acid is somewhere in the middle, but they need to be maintained. When I was in Cambodia, I saw a bunch of SLA implementations that lasted only a year or two because they were not maintained. That is a giant waste.

Lithium is finicky but the density is awesome! I'm working on a conversion, but it takes a lot of time and unless you are in the industry, learning a lot of information to keep from exploding stuff in the garage. This is probably a couple years' project for me.

All the other storage (mass, thermal, pressure) have very very poor density compared with batteries, and not just from the losses essentially running a generator from storage to electric output. I do like pump storage, there is a large artificial lake in Massachusetts I remember visiting as a child that was recharged in the middle of the night and run as hydro at peak hours. It was coupled with a nuclear plant to use the waste energy.  
 
Travis Johnson
pollinator
Posts: 3080
627
books cat chicken duck rabbit transportation trees woodworking
  • Likes 1
  • Mark post as helpful
  • send pies
  • Quote
  • Report post to moderator

Eric Hanson wrote:Secondly, I have thought about a version of pumped hydro I call a mass battery.  In the mass battery, excess energy would raise up a heavy mass, say a huge block of cement, using a worm drive to elevate along a shaft.  After the mass is elevated, the worm drive would disengage would detach and a spur heat attached to a generator would generate electricity as the mass lowered back to ground.  The mass battery is my own idea, would only apply to stationary applications, is completely hypothetical/untested, but would not spontaneously lose energy just by sitting.



Nope, not at all. I think it is being done in Denmark.

What they are doing is, using automated cranes to hoist concrete blocks to massive heights when the cost of electricity is low (middle of the night), then when peak demand hits, and power is bought from power companies at premium rates, the same crane takes the blocks and lowers them, the weight powering electrical generators that send power to the grid.

One problem was the high cost of concrete, but my suggestion is to use old quarries where depths can reach 1000 feet or more and the weights are simply the granite or marble blocks taken from the quarry.

For off-grid cabins the same thing could be done on a smaller scale.
 
S Bengi
pollinator
Posts: 2385
Location: Massachusetts, Zone:6/7, AHS:4, Rainfall:48in even Soil:SandyLoam pH6 Flat
125
forest garden solar
  • Mark post as helpful
  • send pies
  • Quote
  • Report post to moderator
Don't forget LiFePo4 batteties.
You can extract 80% of the stored energy during each cycle vs just 40% for lead batteries.
Given the 2x battery capacity per cycle. It really cost about the same.
They are safe, and will give you 3000 cycles before they lose 20% of their capacity at 80% DoD
So we now have 6x life aka 18yrs vs just 3yrs for lead.



 
Eric Hanson
pollinator
Posts: 626
Location: Southern Illinois
114
building cat dog fungi rocket stoves transportation trees woodworking writing
  • Mark post as helpful
  • send pies
  • Quote
  • Report post to moderator
TJ,

Lithium batteries have awesome storage potential--for batteries.  There are hypothetical Magnesium and Aluminum batteries that get approaching double and triple the storage capacity (per unit volume) respectively because they have 2 and 3 electrons to give up to Lithium's 1.

On the other hand, chemical storage far surpasses batteries.  A gallon of gasoline has far more potential energy than the best Lithium-ion battery of comparable volume.  If only we could store extra energy by directly making gasoline (or some other fuel) and then run that fuel through a fuel cell, the energy storage capacity would be tremendous.  This is the basis for some hydrogen fuel cell setups.  Sadly, fuel cells have not gone anywhere for almost 20 years.  Around the year 2000, there was some promising developments with positron exchange membrane fuel cells (PEM Fuel Cell), direct methanol fuel cells and a few other types of fuel cells, but sadly these technologies have stagnated for 2 decades as far as I can tell.

I would love for someone to prove me wrong on this last part, but there it is for the mean time.

Eric
 
Eric Hanson
pollinator
Posts: 626
Location: Southern Illinois
114
building cat dog fungi rocket stoves transportation trees woodworking writing
  • Mark post as helpful
  • send pies
  • Quote
  • Report post to moderator
Travis,

Thanks for the input on the "mass battery."  I had no idea that this concept was in fact being put to use.  The strengths that it has is that it does not spontaneously lose energy unless it falls over.  You are probably right about the price of cement and really, any heavy object would do.  Gravel from a huge, deep open pit mine would work just fine.

I did all this research in energy and there I go and find things I did not know before--Thanks Much,

Eric
 
pollinator
Posts: 255
Location: Boston, Massachusetts
56
books building rocket stoves solar ungarbage urban
  • Mark post as helpful
  • send pies
  • Quote
  • Report post to moderator

S Bengi wrote:

1. Collects
Energy is gathered from wind, solar, or fossil generators on the grid as electrical energy and sent to Malta’s energy storage system.

2. Converts
The electricity drives a heat pump, which converts electrical energy into thermal energy by creating a temperature difference.

3. Stores
The heat is then stored in molten salt, while the cold is stored in a chilled liquid.

4. Reconverts
The temperature difference is converted back to electrical energy with a heat engine.

5. Distributes
Electricity is sent back to the grid when it is needed.

Malta Inc



It seems to me there's a line connecting #2 and #4 (generation directly to grid) which is missing. As Eric says, losses at each conversion...

There's heat to be captured everywhere! Compost is one that's free, but think of all the situations where COOLING is also being PAID FOR! Server farms come to mind... All sorts of buildings, offices, hospitals, apartment blocks.
Heat pumps and storage could offer both short term (peak pricing) and long term (seasonal) benefits.
 
Travis Johnson
pollinator
Posts: 3080
627
books cat chicken duck rabbit transportation trees woodworking
  • Mark post as helpful
  • send pies
  • Quote
  • Report post to moderator
This is kind of a neat idea.

I disagree with them that they have a patent on "a proprietary set of gears that makes continuous rotation possible." I have a book, published in 1896 that show that same train of gears. I know what is old is new again, but please, don' say it is patented.

In any case I think it would be possible to scale this to home use.


 
Eric Hanson
pollinator
Posts: 626
Location: Southern Illinois
114
building cat dog fungi rocket stoves transportation trees woodworking writing
  • Mark post as helpful
  • send pies
  • Quote
  • Report post to moderator
TJ,

I am afraid I misread your earlier post regarding using pumped hydro from waste energy from nuclear plants.  This is another area I find fascinating for its complexity and diversity of often conflicting opinions.  

Commercial nuclear power plants are basically designed to run at a specific power output level and while they can change their output, they often can’t respond to rapidly changing power needs.  When they do change power, they do so slowly.  Several tons of uranium still put out a lot of heat even if the reactor gets SCRAMed (Military nuclear plants are a different matter).  Also, when the nuclear reactions are increased, they have to heat a LOT of water which soaks up that energy.  It’s not that a nuke can’t change power settings, but they run best at a constant power output.

So how do they meet an increasingly erratic power demand?  Some reactors run at a more or less constant power output and make up the difference with natural gas fueled gas turbines that adjust to load quickly.  As you pointed out, others run slightly above average load and store the excess either in pumped hydro storage or compressed air in geological storage.  Neither solution is perfect.

Strangely dovetailing with the OP’s comments about molten salts is the molten salt nuclear reactor that used molten salts as both coolant and fuel.  These are experimental reactors that operated in the 50’s and 70’s with a movement to restart them today.  Some hate the idea and some love it, but either way, an important factor in its safety system is that salts are used to capture and store the heat and have an enormous capacity to store that heat without creating associated pressure and the accompanying risk of a steam explosion like at Chernobyl (but not Fukushima—just to be clear, that explosion was NOT a nuclear explosion, it was a hydrogen gas explosion that would also be extremely unlikely as a molten salt reactor uses no cooling water that serves as a source of hydrogen).

Sorry if I rambled again, but I find energy in all its forms a fascinating concept.  I am trying to be neither pro, nor opposed to any energy form in any of my commentary.  I am just trying to describe the relationship we have with it.  I can also barely resist the opportunity to discuss the qualities of molten salts.

Thanks for your patience,

Eric
 
S Bengi
pollinator
Posts: 2385
Location: Massachusetts, Zone:6/7, AHS:4, Rainfall:48in even Soil:SandyLoam pH6 Flat
125
forest garden solar
  • Mark post as helpful
  • send pies
  • Quote
  • Report post to moderator
Kenneth you are correct, the picture omitted the direct connection from 2 to 4.
But like you assumed it is there only the 'extra' energy is stored over for night time.  
 
Travis Johnson
pollinator
Posts: 3080
627
books cat chicken duck rabbit transportation trees woodworking
  • Mark post as helpful
  • send pies
  • Quote
  • Report post to moderator

Eric Hanson wrote:TJ,

I am afraid I misread your earlier post regarding using pumped hydro from waste energy from nuclear plants.  This is another area I find fascinating for its complexity and diversity of often conflicting opinions.  

Commercial nuclear power plants are basically designed to run at a specific power output level and while they can change their output, they often can’t respond to rapidly changing power needs.  When they do change power, they do so slowly.  Several tons of uranium still put out a lot of heat even if the reactor gets SCRAMed (Military nuclear plants are a different matter).  Also, when the nuclear reactions are increased, they have to heat a LOT of water which soaks up that energy.  It’s not that a nuke can’t change power settings, but they run best at a constant power output.

So how do they meet an increasingly erratic power demand?  Some reactors run at a more or less constant power output and make up the difference with natural gas fueled gas turbines that adjust to load quickly.  As you pointed out, others run slightly above average load and store the excess either in pumped hydro storage or compressed air in geological storage.  Neither solution is perfect.

Strangely dovetailing with the OP’s comments about molten salts is the molten salt nuclear reactor that used molten salts as both coolant and fuel.  These are experimental reactors that operated in the 50’s and 70’s with a movement to restart them today.  Some hate the idea and some love it, but either way, an important factor in its safety system is that salts are used to capture and store the heat and have an enormous capacity to store that heat without creating associated pressure and the accompanying risk of a steam explosion like at Chernobyl (but not Fukushima—just to be clear, that explosion was NOT a nuclear explosion, it was a hydrogen gas explosion that would also be extremely unlikely as a molten salt reactor uses no cooling water that serves as a source of hydrogen).

Sorry if I rambled again, but I find energy in all its forms a fascinating concept.  I am trying to be neither pro, nor opposed to any energy form in any of my commentary.  I am just trying to describe the relationship we have with it.  I can also barely resist the opportunity to discuss the qualities of molten salts.

Thanks for your patience,

Eric




This is how many power generating stations, generally anything with a steam turbine whether it is coal, nuclear, natural gas, or biomass that is the heat source, they just cannot be shut down. This is why have diversified power generation is critical for the grid. For instance at peak times, hydro dams can be put on or off line in an instant via remote controlled penstock valves. Sadly in Maine they are ripping them out as fast as they can.

The best battery bank in the world is the tide though. Here in Maine where we share the highest tides in the world with Canada, if we could harness that power, a tremendous amount of power could be generated. They tried back in the 1940's. but then stopped the project. Too bad...
 
Eric Hanson
pollinator
Posts: 626
Location: Southern Illinois
114
building cat dog fungi rocket stoves transportation trees woodworking writing
  • Mark post as helpful
  • send pies
  • Quote
  • Report post to moderator
Travis,

As it turns out, the single most efficient method of generating electricity is a large spinning flywheel, and currently the most efficient way to spin that flywheel (assuming you don’t have falling water) is with steam.  Obviously, to make steam you need heat, be it coal, nuclear, concentrated solar, etc.  

Presently there is some interesting work on supercritical carbon dioxide, that would be CO2 pressurized up to its critical point where it can’t decide if its a liquid or a gas so it tries to be both.  It is about 2/3 the density of water so it is dense stuff, but it expands to fill a container like a gas.  Supercritical CO2 (SCO2) density is extremely sensitive to small changes in temperature and therefore makes a rocking working fluid to spin a turbine.  If the details can be worked out, then SCO2 can really push the limits of efficiency in a power plant.

But then again we are talking about spinning flywheels again.  In theory, an SCO2 system should respond to load better than steam, but we still need something to respond to the need for instantaneous changes in power load.  

I actually do like the OP’s solution being molten salts for overnight storage.  Concentrated solar does something similar.  Let us know if you have any further thoughts on this intriguing discussion.

Eric
 
Posts: 100
9
  • Likes 1
  • Mark post as helpful
  • send pies
  • Quote
  • Report post to moderator
Just thought I’d link to my thread rgdg the new method of storing energy from solar in a molecule that can store the energy for years and release it only when the molecule is exposed to a catalyst: https://permies.com/t/97272/Molecular-Solar-Thermal-Energy-Storage
 
Eric Hanson
pollinator
Posts: 626
Location: Southern Illinois
114
building cat dog fungi rocket stoves transportation trees woodworking writing
  • Mark post as helpful
  • send pies
  • Quote
  • Report post to moderator
James,

Fascinating idea!  230F is not terribly high and a lot of that energy would simply be used to heat the water (which is perfectly fine if you want hot water).  If you want electricity, combined with supercritical carbon dioxide, this has some real potential.  

Thanks for adding this information.

Eric
 
Eric Hanson
pollinator
Posts: 626
Location: Southern Illinois
114
building cat dog fungi rocket stoves transportation trees woodworking writing
  • Mark post as helpful
  • send pies
  • Quote
  • Report post to moderator
A note about supercritical carbon dioxide (SCO2)

I have mentioned SCO2 for energy production a couple of times and I thought I should clarify a couple of points of misunderstanding.  In SCO2 systems, the CO2 is in a closed loop,  CO2 would not be released to the environment like steam from a power plant.  The SCO2 is merely a working fluid (but an awesome one) that would turn a turbine better than steam in a traditional open cycle.  I want to be clear I am not endorsing pumping CO2 into the air in any uncontrollable fashion.

I just thought I would clarify this for anyone not familiar with SCO2.

Eric
 
This. Exactly this. This is what my therapist has been talking about. And now with a tiny ad:
permaculture bootcamp - learn permaculture through a little hard work
https://permies.com/wiki/bootcamp
  • Post Reply Bookmark Topic Watch Topic
  • New Topic
Boost this thread!