Thinking about batteries

[phantom power]

One popular energy proposal is to use solar and wind power, combined with some kind of energy storage, to meet our energy needs. As always, I was curious about the actual scale of energy storage needed, so I decided to take a stab at estimating it.

Just to make it easy on myself, I decided to assume a pure-solar solution. That means the storage has to handle "nighttime", at least to a very rough approximation. (I couldn't come up with a rough model for wind-power, since it's variation is more complicated, maybe somebody knows a useful approximation)

I'll also stick purely with our electricity usage, which the DOE says was 32,248 trillion BTUs the year of 2003, or 1.12(10^16)watt-hours per year.
http://www.eia.doe.gov/emeu/aer/txt/ptb0201f.html

Solar storage would (roughly) operate on a daily cycle, so that gives us 3.07(10^13)watt-hours per day. Pulling another number out the air, suppose that night-time electric usage is 1/4 of the total for an average day, which gives 7.68(10^12) watt-hours per day. That represents the estimate of how much storage we would have to deploy: 7.68 tera-watt hours.

What to use for storage? Some people have suggested lithium-ion batteries. I see that both the volumetric and mass energy densities are quite superior for lithium-ion: 300 watt-hours/liter, and 150 watt-hours/kg. So, I'll imagine using those.
http://www.afrlhorizons.com/Briefs/Feb04/PR0306.html

At 300 watt-hours/liter, that implies we'd need 2.55(10^10) liters of battery to handle the nightly storage needs of the U.S. How many individual batteries does that translate into? Imagining a system where each battery module is a single liter (seems like a reasonable size), that is about 25-billion batteries.

So, something on the order of 25 billion (one-liter) lithium-ion batteries. I imagine that deploying wind-power could improve the situation, since wind blows at night, and on cloudy days, etc.

I wonder how much that many batteries would cost to manufacture?

[electropop]

1. Think beyond batteries.

There are many other ways to store energy. I certainly haven't done the math on them, but they may be more practical, or make a useful part of the mix. Examples:

(1) Hydrogen. Yes, it's a storage medium, not a source. You can make it with electrolysis (or better yet, photochemical separation) during the day, and burn it in a fuel cell at night.

(2) Water. Some hydroelectric dams already do this: pump water upstream at night, by using some of the generators as motors.

(3) Flywheels

(4) Compressed air

[phantom power]

2. Yep.

I would be strongly opposed to storing potential energy in reservoirs, mostly because I like living rivers far more than I like reservoirs.

The others seem reasonable to me. I'm very luke-warm about H2, mostly because we could just as easily manufacture synthetic hydrocarbons, which will be far easier and safer to distribute.

Like you, I don't know enough about the engineering of flywheels or compressed air to estimate the scale of those solutions. But for anybody who does, the target energy figure to store is 7.7 terawatt-hours.

[Strelnikov_]

11. Pump Back Hydro And Compressed Air Storage Systems

have storage efficiencies of 70% from what I remember.

Both of these are probably the preferable way to store intermittent power generation from wind.

Pump back is a proven 'technology' with extensive use currently in the US. Compressed air is not as widely used, but the technology is proven.

If you look at a map of central US wind potential, the majority is in the Dakotas and surrounding states. Considering the Missouri is already a chain of lakes, pump back is probably the most viable. There are many coulees/valleys feeding into the Missouri that could be dammed for pump back generation, using the already constructed reservoirs as the base pools.

[amandabeech]

12. I grew up near the Ludington, Michigan, pumped storage project.

It uses Lake Michigan as the lower basin, and it's one of the largest pumped-storage facilities in the U.S. However, it is not without its environmental drawbacks.

Those turbines chop fish into the best buffet a seagull has ever seen. Really, when they turned the turbines on in the '70s, it was blood in the water. Of course, the designers had done nothing to mitigate the obvious, and litigation ensued. The settlement is one of the largest environmental settlements seen in the U.S., and created the Great Lakes Fisheries Trust. Now, of course, mitigation devices have been installed, and there are fewer really fat seagulls around the intake/discharge area. Nonetheless, fish eggs and small fry are still being mangled, and studies of additional methods of mitigation continue. I've read that there's a new turbine design that is supposed to cause less fish stew, but I don't have the time to go look for the URL right now.

As to the Missouri Basin, that area of the country is subject to periodic, severe drought, which may only get worse with global warming. Right now, in fact, things are very dry out there, and there may not be enough water in those reservoirs for all those who rely on it for agriculture and general use. I believe that the Missouri above Kansas City may be closed to barge traffic due to low water.

It may turn out that pumped storage for Great Plains wind energy would be better placed on the main stem of the Mississippi or the western Lakes. The electricity would be moved to those locations via high-voltage DC lines. Still, this would be a major undertaking that would require significant study.

All in all, electrical storage is a real hold up to major incorporation of wind, solar, tidal, etc. renewable energy into the grid.

Ludington Pumped Storage Project:

http://www.consumersenergy.com/apps/pdf/Ludington.pdf


Great Lake Fisheries Trust

torg/index.html


Project Fish (summary of settlement)

http://www.projectfish.org/history.html

[lapfog_1]

3. Uhhh, without getting into your numbers....

I doubt that anyone would propose the use of lead acid batteries
(no matter how many or how big) to store energy sufficient to
power all of the US for any amount of time.

However, there are many different ways to store energy, including
ones used today... such as using excess generated electricity
to pump water uphill (recapturing a portion of the energy used
when the water is allowed to flow downhill again).

Also, as for new technologies, flywheel storage is an active
area of research with much promise (and much lower environmental
cost than chemical storage). Of course, using electricity to
split water into Hydrogen and Oxygen for later use (one needs
only to store the hydrogen) is also interesting.

[phantom power]

4. I assumed lithium-ion, not lead-acid

Regarding alternatives, definitely yes. I'm just trying to get a feel for the scale of the problem, if we actually tried to do it in real life. (also, see reply #2)

[lapfog_1]

5. Lith-Ion?

I doubt that we could manufacture that many... not to mention that
after N number of cycles (a few hundred or thousand) the batteries
would have to be replaced.

I did see the other post... just as I posted my response.
(I think we both covered the same list, but I was not copycat'ing
his ideas, they were just the ones off the top of my head... and
I don't type all that fast)

In any event, using a chemical battery of any kind (now invented)
is not the way to effectively store large amounts of electricity.

Remember that batteries are mostly used for PORTABLE applications
(cameras, watches, cars, etc).

I would add that I, too, would oppose the creation of more dams
for hydro storage / generation. However, using already built
facilities is fine (and currently done)... and I am thinking that
building an artificial reservoir/river for storage would not be
out of the question.

[phantom power]

6. I suppose artificial reservoirs are possible.

The only way to tell if it's reasonable is to compute the size of the reservoirs needed. In the case of reservoirs, the two parameters are volume and elevation. An artificial reservoir requires land usage, which could be preferable to damming a river, depending on what land it is, and what we'd have to destroy to build the reservoirs.

This is why I like to try and run numbers, even if they are estimates. It's one thing to say "we might use batteries," or "we might use reservoirs," or any other system. It's hard to argue one option over another until specific numbers become available. Size, scale, cost, etc.

My estimates might suck, but I decided I should at least make the effort in good conscience, if I'm going to take alternative energy seriously.

The data I found estimated the cycle lifetime for lith-ion at ">2000" cycles. It's not very helpful without an upper bound, but just to use the 2000 figure, that would give a calendar lifetime of 2000 days, assuming a basically once-a-day discharge, every night. About 5 and a half years between replacements.

[phantom power]

7. A cost estimate

I see a lith-ion battery with a 1.85 watt-hour capacity, on sale for $50. A simple-minded scaling up to a 300 watt-hour battery would give a cost of about $8100.

Certainly, economies of scale would be applicable. Let's suppose that we can reduce the cost by a factor of 10. That would be $810 per 300 watt-hours of storage. To store 7.7 terawatt-hours would cost of about 20 trillion dollars. I guess that would be every time we replaced the batteries. Hopefully, they last more than 5 years.

Maybe we could do even better than a factor of 10. Let's suppose we achieved a very optimistic factor of 100. Then, we get 2 trillion dollars, per replacement cycle.

[Massacure]

8. Your being optimisitc with 5 years.

Most lithium ion batteries last about 300-500 charges. That would take them out within a year to year and a half. Even at two trillion dollars your are nearly doubling the amount of money the government spends (assuming it is government run).

[phantom power]

9. So far, all of the proposals I've seen will cost trillions of dollars.

They all involve building a whole lot of one thing or another, and none of it is cheap.

Tackling a multi-trillion dollar project should be feasible for a country with our enormous resources, but we may be hobbled by our gigantic deficits.

There was some article a couple weeks ago that floated the possibility of our being forced to get funding from countries like China, to finance these projects when they eventually become unavoidable. In exchange for god knows what humiliating conditions. Maybe they'll force us to change our national language to Swedish.

[One_Life_To_Give]

10. Artificial Reservoir System

For total cost the best bet is an artificial reservoir system. I had posted some numbers a while back on a back of the envelope calculation for running CA's 10GW Base Load for 18hrs/day. It's big and a non-trivial installation.

[Coastie for Truth]

20. Little bit off on a scaling factor.

Don't have numbers, but much of "cost" is in cases, seals, relief valves, and physical handing during electrode fabrication and cell assembly. Those things are generally fairly constant over a wide amph-hour range (e.g., from AAA to D).

Compare, say a D and an AAA of the same technology, you'll see what I mean.

[cprise]

13. Unless you are rural

...this pure-solar infrastructure is entirely hypothetical (a straw man). It has no relevance to the way renewable energy is best incorporated into society.

PVs produce current during peak load hours, so installing them at home and connecting them to the grid makes sense even if you're not home during the day... Power company production credits that you recieve are essentially just a way to re-direct that PV energy from your home to your workplace.

The bottom line is that PV energy will offset the use of fossil fuel to the extent that it is installed on the grid, for the forseeable future. The question isn't how much storage we can manage, it's "How much sun does your roof have?"

If you want batteries to work for the environment, put them in cars.

[hunter]

14. I agree with you.

I was thinking about that the other day. A wealthy person who buys a solar rooftop and an off-grid battery storage simply drops out of the equation. Economically it might be better for the community if they skipped the batteries and connected to the grid.

[phantom power]

15. Some people take "pure solar" very seriously.

I'm not one of them, but I was interested in getting a feel for the kind of energy-storage we'd need if we ever tried to do it.

[cprise]

19. Yes, it makes them feel good.

And it would really matter if they were very rural or lived in a 3rd world country.

Here, we have a grid that we may consider to be "starved" for solar energy during the daytime. This may not be the case in 2030, but until then grid-dwellers should have no compunction about effectively renting their roofs to the utility. If I use 3kw in a day, and my roof offsets 3kw worth of emissions from the grid during the daytime, what's the difference?

I don't get to feel all independant and self-satisfied, that's what.

Solar + batteries are an important combination when it comes to the promise of BEVs, or just plain running our already battery-laden gadgets. But that is just a segment of our energy use.

[Name removed]

17. Deleted message

Message removed by moderator. Click here to review the message board rules.

[cprise]

18. What "solar only advocates"?

The Sierra Club? NRDC? The Heritege Foundation?

Oh wait... Greenpeace! :D I recall someone talking about them.

From the Greenpeace website:

Wind power is already a significant source of energy in many parts of the world. It can supply 10 percent of the world's electricity within two decades.

Solar power has been growing in a global capacity by 33 percent annually. Greenpeace and industry research shows that with some government support, the solar industry could supply electricity to over 2 billion people globally in the next 20 years.

By 2040 solar photovoltaics could supply nearly 25 percent of global electricity demand.

Your argument that they are either solar-only or they support coal because they won't propose a 100% supply program for the present consumer culture, is pretty contrived.

We are still in straw-man land, aproaching city center.

[NNadir]

21. No, we are not in straw man land. What's running the grid?

Like I said, solar only advocates change the subject when you ask what's producing beyond the 25% they claim (as they've been claiming for decades) that will be available in 30 years.

The mystical "grid" is coal or a 75% cut in load and a complete shut down when the wind isn't blowing and the sun is down.

As usual, the solar only crowd refuses to do arithmetic. They say dubiously " Greenpeace and industry research shows that with some government support, the solar industry could supply electricity to over 2 billion people globally in the next 20 years."

There are more than six billion people on the planet. Either Greenpeace intends to eliminate 4 billion via genocide or through an environmental collapse of the atmosphere.

Again, arithmetic: 6 - 2 = 4.

I note too that nowhere near as much solar power as would be required to support two billion people is planned, financed, sited, under construction, built.

Greenpeace is full of shit. It is not thinking. It is religion.

I always have to explain logical fallacies to the solar only crowd. Let me help you with what a straw man argument is:

"Person A has position X.
Person B presents position Y (which is a distorted version of X).
Person B attacks position Y.
Therefore X is false/incorrect/flawed."

However if position Y follows logically from position X, no straw man exists. It follows that if only solar energy is acceptable, and solar - allegedly - can provide 25% of the energy in daylight, when the sun is shining, when it isn't cloudy, when there is no snow cover, then 75% of the energy must be accounted for.

Why can't the solar only crowd think?

http://www.nizkor.org/features/fallacies/straw-man.html

Now the solar only crowd, with their irrepresible hand waving seem to want to say that because they are discussing 2 in the equation above, and someone mentions 6 and the fact 6-4=2, the 6 and the 2 are strawmen. This is damn weak reasoning. Any reasonable person who expects to be able to run his furnace on a clear cold still night has a right to know the answer to this question. How many people after all, would buy a furnace for their home that only ran when the weather was right. That would seem to negate having a furnace at all.

Either Greenpeace supports continued and expanding use of fossil fuels or they support nuclear power. If they have some third option, (and I know they don't) they should identify it.

Here is a new question that the solar only crowd should be asked and which they will not answer because they cannot answer: "What's running the grid on clear, cold, still nights?" Come on, tell us.

It will be interesting to see how the subject gets changed again.

[phantom power]

22. I agree it was a bit contrived.

I assumed pure-solar, so that the estimating was easier. (I think I mentioned that)

However, just observing that we'll also use a lot of wind doesn't really change the scale of the problem.

How many wind-less nights do we have to engineer for, to make sure the power doesn't go off? I don't know, but I guarantee you it will be more than a few, if we want a grid with 99.99% performance, like we have now.

Any solar/wind solution will have to be able to bank a hell of a lot of energy, to *guarantee* the kind of reliable grid our country depends on. If not, our country will look like Iraq, where the power just goes off at unpredictable times.

It doesn't need to be batteries. But any storage system capable of storing terawatt-hours of energy is going to be huge, and expensive. If anybody can describe such a storage-system that won't cost some number of trillions of dollars to deploy, I'd be very interested to hear about it. And that's just the storage system. It doesn't cover the cost of the actual solar or wind power itself.

I'm not asking because I think it's impossible, but any scenario with a good-faith estimate of size and cost attached to it would make it easier to compare against other solutions.

[midnight armadillo]

16. There's always conservation

You know, that old story... Really, I'll wager we could reduce nighttime electricity use by a significant margin. How many businesses do you see lit up like Xmas trees all night long? Same with biz signs by the road. Few people shop at the mall at 4AM, but you wouldn't know it from the appearance...motion sensors could turn on lights for security.

Same with street lights in many areas. Put on IR & motion sensors, have 'em turn on for an hour or so when triggered by a vehicle or large mammal. It doesn't have to be perfect, just good enough. Homes could also use less light at night - perhaps those McMansions don't really need exterior flood lighting all night.
Houses could also (gasp) be designed to cool off at night better, reducing the use of AC. Maybe Southern state residents could sweat once in a while, further reducing AC use. California dropped its electricity by 10-15% or something when asked during the Enron blackout crisis...and what was just by altering human behavior.