Best large scale energy storage device?

[AngryAmish]

As I see it the main problem with wind/solar is the fact that the sun goes down and sometimes the wind does not blow. In order to deal with that problem a separate and parallel system of on demand electricity must be made and maintained. This obvious increases the cost of a solar/wind system.

The way around this problem is if we can store electricity. Right now it really is not practical. I read an article about sodium/sulfur (I think) batteries that operate at high temps but are very efficient. I have also heard of compressed air.

Are any of these devices practical? What are the engineering obstacles?

[phantom power]

1. Sheer scale is the biggest obstacle.

If you really want to run a grid on solar and wind, you have to store multiple terawatt hours of electricity, and be able to dump it back into the grid at the rate of multiple gigawatts.

The added cost and environmental impact that represents are enormous. Trillions of dollars. On top of the trillions requiered to deploy the power generation hardware itself.

[Ezlivin]

2. I've seen solutions that involve pumping water to a raised reservoir

However the energy is not wholly recaptured when the water is released.

http://en.wikipedia.org/wiki/Hydroelectric_energy_storage

[Trillo]

3. Too bad the whole earth can't have a "super grid"

(electric grid) constructed. A portion of the earth is always in daylight, somewhere.

[bigmonkey]

5. You're correct. Bucky Fuller pointed this out decades ago.

Part of his demonstration that our problems with energy and so forth are essentially _political_ problems, in the sense that there is a technically feasible solution, if only politics could be overcome.

[Xithras]

9. Line loss kills that.

It's a nice theory, but it doesn't hold up to the practicalities of real world electrical transmission. Electrical lines tend to suffer substantial power losses when electricity is sent even a few hundred miles from the point of generation, and sending any appreciable amount of power more than a few thousand miles really isn't practical. You could generate all the power you wanted at high noon on the sunny side of the planet, but by the time that power completes its 12,000 mile trip to power someones reading light on the opposite side of the world, there will be so little power left that the original environmental "savings" would be dwarfed by the destruction required to string the cables and mine the copper worldwide. It would be an energy negative project.

And what do you do when it's noon over the Pacific, and there are no sizeable landmasses on which to place large PV arrays?

[bigmonkey]

11. Of course it does.

Fuller wasn't presenting a finished plan, his point was that there are huge unused synergies that are blocked mainly by ossified thinking. To make such a plan practical, of course the points you raise would have to be addressed. Nowadays, one would think that more decentralized plans, using mutiple sources, combined with conservation, would be a better bet.

[NNadir]

14. Um, well, uh...there is the matter of loss of energy for electrical transmission...

It is very unlikely that a brazillion solar cells of the size needed to supply the world's electrical demand could be manufactured without a vast environmental impact.

The external cost of solar energy largely escapes notice because in fact, less than a single gas plant's worth of solar PV cells are manufactured on the entire planet in a typical year.

I assure you that this would be a very different matter if solar electricity ever got to 5% of the world's electrical demand, something that will not happen in the lifetime of any one now living.

[phildo]

4. Need to start with defining what you mean by large . . .

If you are talking about power plant sized large . . .

http://en.wikipedia.org/wiki/Ludington_Pumped_Storage_Power_Plant

Those methods are quite practical and functional.

But stepping back towards your premise . . . you are prescribing the need for this storage based on the nighttime demand for power? (i.e., when the sun is not shining)

Might want to review that topic, as well? The daily cycle of power demand is such that daytime is the primary time when power is being used. Works that way all around the world. At night, the demand drops so low that power plants just idle or are shut down -- depending on the type of plant.

All new generation is needed only for daytime peak loads.

While batteries are needful things for some applications -- such as remote locations, underwater craft, . . . the chemical mess they carry (Lead, and/or Sulfur and/or Sodium, etc.) have some major downsides to do in large volume.

additional note on compressed air -- to store much energy in compressed air takes either VERY large volumes (think underground cavern sizes) or VERY high pressure. As air is compressed, it heats up (combined gas law) and when it cools, the pressure drops -- losing a chunk of the energy being stored.

[AngryAmish]

6. Ludington is kinda unique geographically

I don't think it is practicle to run Miami for example (really flat around there).

That said it is a nice local solution.

Something much larger is necessary.

[phildo]

17. Much larger storage . . . for what?

The reason none exists is because there is no need.

Miami, like most Southern US cities, has a primary heavy load from electrically driven Air Conditioning. That is mostly a daytime event. Time of day works out the same as solar thermal, so there is no storage needed. A typical solar thermal plant keeps running some hours after sundown just working off the residual heat. Again the same hours as the Air Conditioning.

But stepping back and looking at the "problem" first (heavy daytime consumption for A/C) instead of trying to fit a solution first would give that the Air Conditioning does not even have to be primarily electrical driven. Solar (again thermal -- not PV) driven AC can run it more cheaply and just use electric/freon based system for dehumidification.

[IDemo]

7. V2G may be the most promising thing here

http://www.udel.edu/V2G/

[Warpy]

8. How about solar powered electrolysis?

Once the sun goes down, the power comes from fuel cells using the hydrogen and oxygen. End product: the water that got split into hydrogen and oxygen during the previous day.

[frogcycle]

10. Water water water

Water in a reservoir is superb. Hydroelectric dams crank out electricity 24x7, and it is solar energy, after all, that lifts the water via evaporation/rainfall to recharge the system.

Using electricity from solar/wind to break seawater down into H and O; then distributing the H via pipeline and/or tanks to be used in combustion chambers is a good possibility for large scale. You "store" energy by breaking the h2o molecule into its constituents; it gives it back via energy of combustion.

Water can also store energy by being a heat sink. Rather than raise it to a higher elevation, raise its temperature, then scavenge the energy back with a heat exchanger. This is more of a point-solution use, like a building's cooling plant for example

moving water in the oceans due to tides is not a storage system per se, but is an attribute of the gravitational interaction between earth and moon, so in a way you could say we are sitting in the middle of a giant untapped storage system

On smaller scale, flywheels are good, various batteries are ok - capacitors are ok. The electric grid itself can function as a load-balancing system - if a solar cell or windmill is operating, it feeds the grid; if not, well, one somewhere else may be.

[madokie]

12. here in oklahoma we have a pumped back lake that is around two hundred feet

above lake hudson that grda uses as a giant battery, during the overnight hours when the demand for electricity is lower they pump water up into this lake which I think is around a 750+ acre or so that is close to 200 feet deep. its a money saver for them bigtime

[NNadir]

13. Simply shutting off hydroelectric plants.

Failing that, pumped storage is the largest storage system used in the electric grid world today. It is generally fairly expensive, but it works.

[skids]

15. A couple avenues...

Aside from large hydroelectric pumpback systems and CAES in underground rock formations, there are some solutions
that would not rely on geology and would be portable -- flywheels, ultracapacitors, and flow batteries. Flywheels are a few years ahead in development having already been approved for use. Ultracapacitors are showing astounding gains in tech, but costwise it is hard to project where they are headed -- there are more profitable markets than grid storage for them to target first.

http://www.beaconpower.com/

http://vrbpower.com/

Also worth note is that tidal power is extremely predictable and wave power is relatively constant compared to wind.

[razzleberry]

16. you can't store two months worth of electrity

except as hydro, and the good hydro sites are already taken

I just donn't see wind/solar going much beyond...
saving the expenditure of some natural gas.

you just, must have the 'normal'
generating capacity anyway

edit, adding...
I don't understand why people push solar/wind. in the US.
a better place would be, where they burn fuel oil for base load.
(which is lots of places, but not the US)

the benefit, immediate economic payout.

[phildo]

18. It is a money thing . . .

ror folks on the dollar and sense end of this . . . In some -- or even many -- US locations and applications Solar and Wind can be MUCH cheaper than what has now become conventional (Coal, Gas, Nukes). If local utilities are really gouging the locals -- e.g. Texas, Florida, California, Hawaii, and the conditions are favorable to Solar and/or Wind -- which is the case with all those locations, then Solar and Wind make good sense.

For other folks it is a daydreamy poser sort of thing. Think of any recent Save the Earth concert thingy. :) :)

[razzleberry]

19. how much cheaper? .n/t

[phildo]

22. Cheaper is a relative thing, but getting specific . . . .

If you are in a remote location (e.g., an off-shore island, middle of nowhere / a desert, etc.) then almost any RE (renewable energy) source beats a conventional source. Even the most expensive -- solar PV, beats the cost of running power lines and/or supplying fuel to a generator. So anything -- wind, mini-water wheels, solar PV or solar thermal are all good in those applications.

Next layer out -- moneywise -- If you are in one the gouge 'em States for electric bills -- for example Texas, California, Hawaii -- all have typical billing rates of over 10 cents per kWh -- where they also have good RE options, using some careful selections in the methods can produce good results.

On the domestic (non-industrial) side of things most power goes to heating water and space heating and cooling -- all these can be done by simple solar thermal collection (again, NOT PV). There was a time -- before my time -- when most water was heated in Florida by rooftop solar heat. Those things cook in Florida, and they have only gotten better over time. But now you see mostly gas or electric water heaters there. Sort of silly.

In West Texas, the wind blows so hard and so steady the power poles are bent. Great place for wind.

On the other hand, some places are rough for RE (again speaking moneywise), and in some cases it is because of already existing RE. In the Pacific Northwest, the dams create power and it sells in the 5 cents per kWh. That is hard to beat.

Overall you really have to do the hard banker's math on any particular project or method as it being applied in each case, and not get into the airhead marketing stuff from any side that any particular method, whether Coal, Gas, Nukes, Wind, Solar, Hydro, Geothermal (on and on) is best.

[skids]

20. Two months?

Why would we need to store two months worth of electricity?

[razzleberry]

21. store wind energy in Spring, to use in Summer

the wind usually blows, whan you don't need it the most

something similiar could be said for solar.
it can overcast, for days on end.


keep in mind that, if storage could be done now,
it would be done for daily load leveling.

[skids]

25. Well, I'd question that...

Solar productivity is usually highest in the daytime during the summer. Right when you need it for AC.

Lighting demand is higher during the winter, when the wind is blowing. Were the AC handled by solar...

Wind may not be as reliable as we'd like it to be, but the wind rarely ever "stops blowing"

Solar you can easily guess the shape of the graph.

Wind:


http://www.worldenergy.org/wec-geis/publications/reports/pgp/renewable/performance.asp

Demand (sorry graph won't post here):

http://www.fsec.ucf.edu/en/publications/html/FSEC-cr-381-91/index.htm

And this is handy for the individual case of the UK:


http://www.parliament.the-stationery-office.co.uk/pa/ld200304/ldselect/ldsctech/999/4021102.htm


I believe most of this data is for the residential sector.

This page has some very interesting charts, BTW:
http://www.fsec.ucf.edu/en/publications/html/FSEC-PF-369-02/index.htm

[jpak]

26. You can do it with hydrogen - all you need is the tanks

n/t

[garybeck]

23. Lead acid batteries are just fine. It's a myth that they aren't good.

They are over 80% efficient and recyclable.

[skids]

27. And can be improved on...

http://blog.tmcnet.com/beyond-voip/green-technology/firefly-breathes-new-life-into-lead-acid-battery-design-and-scores-10-.asp

[Javaman]

24. The super candle!!! nt