Stationary applications: An ever-lasting water battery?

[swbluto]

IN CONCEPT, What if you had a pump that pumped up water a mile high and then you had a reservoir of water that could be dumped through something like a hydro-turbine to generate electricity. Would this, in principle, be a way of building a "battery" that'd last forever, and you could cheaply have whatever energy capacity you wanted(Within reasonable limits), and the pump is analogous to a battery charger (Instead of charging with electric potential energy, it's charging by building up gravitational potential energy)?

Oh, yes, I know of another way to think of this as. A water tower with a hydro-turbine attached.

 

[bigmoose]

Yep, someone did it already. It's called pumped hydro:
http://www.nytimes.com/gwire/2010/10/15/15greenwire-doe-promotes-pumped-hydro-as-option-for-renewa-51805.html

http://gigaom.com/cleantech/pumped-hydro-energy-storage-it-takes-a-heck-of-a-long-time/

I also had tangential contact in a huge regenerative fuel cell concept about 9 years ago. The idea was to disassociate our friendly di-hydrogen oxide molecule into H2 and O2 and store it in treated underground caverns during the night, then change direction to provide power peaking during hi demand times and generate water again. I don't think the project got enough backing on the hill to go forward.

... so someone already thought of that one also!

... Good new ideas are getting scarcer and scarcer!

 

[Floont]

Many power companies already do this by pumping water during their non-peak hours up to an artificial mountain reservoir. Then, during peak hours, they reverse the process by draining the reservoir through water turbine-generators at a lower elevation. In effect, they are using the reservoir to store power. Detroit-Edison does this. I have visited the facility, although I wouldn't say that their reservoir was on a "mountain".

FA

 

[fizzit]

I had a similar idea a while ago! We attach a rope to the moon, and then fly the other end of the rope to the earth, and attach it to a pulley system. When the moon orbits away, it pulls a big weight upwards and then at the top we detach the weight from the rope. There would be wind turbines attached to the weight so when it fell it would generate electricity. Then when the moon came back around we would just reattach it and start again!

 

[bigmoose]

... now that's the kind of idea(s) I've been looking for! Searching Alibaba for 406700 km of kevlar rope!

 

[spinningmagnets]

Those new to this site, be aware that pumped hydro is inefficient. The only reason it is used in those places where its found is that, the very expensive coal-fired generating plants are already installed, and they cannot be allowed to cool down during low demand hours (late at night) so that they can work during peak demand hours (air-conditioning demand during the hot part of the day).

We currently cannot just get rid of the coal-plants. Sometimes there is a low-rain/snow year, and the reservoirs get very low. The water reservoirs are NEEDED for high peak demand during the daytime in summer, because no new coal plants are allowed to be built...but the population just keeps getting bigger.

Since the coal-fired plant has to run at night anyways (to stay hot)...might as well use the electricity to pump some water from down-stream back into the reservoir so it can pass through the hydro plant during peak hours.

Its like spending $10 in coal to regain $5 in hydro electricity during the night...but as long as you have to spend the $10 in coal whether you use it or not, might as well get back $5...better than nothing.

If the water reservoir is high in a certain year, we use more hydro and less coal (during the winter only). If the reservoirs are low, we don't use ANY hydro in the winter, so there is at least SOME reserve for the following summer demand (no shortage of coal, though...the USA is the Saudi Arabia of coal).

Because of heat losses, you will always get less watts from the water flowing down, than the watts used to pump it back up to the top.

 

[Gordo]

It is much simpler to combine wind power (and solar) with dams and run-of-the-river projects into one company, than pump water up hill. Interruptible power (wind, solar, run-of-the-river) is sold for far lower rates than guaranteed power, but by combining them, one can take advantage of a much higher revenue because of higher average output. When the sun don't shine, the wind don't blow and the river is low, you can open all the pen-stocks at the dam and produce your maximum MW's. When any of the first 3 are producing, you can close down some of your pen-stocks and conserve the power in the water behind your dam. This is how 400 MW Innergex does it very successfully.
http://www.innergex.com/en They even own their own transmission lines.
A very, very good investment.

 

[fizzit]

Damn, maybe you could make money by pumping water uphill when power rates are lowest then selling the power back to the utilities when it's expensive!

 

[liveforphysics]

Pumping water, and then extracting the stored potential energy from the water you pumped is highly lossy on both sides of the deal. Certainly does work though!

 

[dogman dan]

Reminds me of regen. Crappy efficiency, but if you are flat out losing it, at least you get some back. Not such a bad idea really, compared to losses caused by a coal or other type of plant that gets ruined every time it ever gets cold. Applying it to already pricy green power would be some really high price power and not a great idea as yet.

My stupid pipe dream is to put wind power to work pumping water uphill from the missisippi river to a point where it could siphon over to the Rio Grande, or Pecos river. Then extract the tiny bit of extra hydro power back out. Meanwhile, thanks for the water dude. Every time I see that flooding, I can't help thinking they don't know how good they have it, compared to the annual trickle of piss we get down the rio grande. Of course, it would be an ecological disaster to introduce a lot of weird mussels or whatever to our river. But what the hey, vacationers bass boats seem to have done it already anyway.

 

[Floont]

...compared to the annual trickle of piss we get down the rio grande...

Having never see the Rio Grande, I always thought it was a "real" river because isn't the name Spanish for "Grand River"? I've never seen it. Apparently it isn't that grand. :wink:

FA

 

[dak664]

Pumped storage can be 85% efficient round trip, not bad at all. If the upper reservoir is filled only through pumping evaporation losses will reduce that by another 15%, but if it is also filled by a river it replaces water that would have evaporated anyway.

The potential energy in 1 cubic meter of water 100 meters high is about 250 watt hours, making lithium batteries more cost effective for the typical homeowner

Actually coal-fired plants can do load following fairly well. As demand changes the turbine output voltage automatically follows to maintain the same power output. Over a few minutes the firing can gradually be changed to restore the voltage. But the output in Nuke plants is trickier to stabilize so they generally are run at a constant power level.

The main benefit of pumped storage is to allow daytime peaking without having to build another baseline plant or incur the fuel expense of a peaking generator.

 

[dogman dan]

For the desert, the rio grande is a huge river. Back in 1580 or so, the travelers went " Wow, we have water again! "and thanked god profusely. We suck it dry as a bone now, by the time it passes El Paso. Seriously, till a tributary from mexico joins, it really is a dry stream for miles part of the year. It used to flood huge before the dams went in 60 miles north of me in 1917. But at no time in history has the water ever been a good flow year round. The river only flows now when the water is ordered by the farms. Much of the year it's just a trickle, and would be less if the gates on the dams sealed better.

This year, instead of the normal 36" of water the farms can order, there is only 4" in the lake. So a trickle year round this year. The drought is pretty bad, but at least the smoke from fires in AZ is free.

Re pumped storage, the key of course, is cheap enough energy in. Coal's pretty cheap. Maybe someday wind and solar will become cheap relative to fossil.

 

[Floont]

...The main benefit of pumped storage is to allow daytime peaking without having to build another baseline plant or incur the fuel expense of a peaking generator.

Bingo.

 

[spinningmagnets]

Apparently it isn't that grand

The Rio Grande used to be pretty big, but one by one, some very big dams have been added to create reservoirs for recreation, irrigation, and hydro-electric. There is a growing battle in the south-west US over water rights, because more water shares must be secured before cities can grow. The question is this: If show falls in Colorado and Utah, how much of the snow-melt belongs to the cities downstream in Arizona, southern Nevada (Las Vegas) and Southern California?

A few years ago, a neighbor in Southern Utah bought a large abandoned farm as an investment, and the water rights went up more than the land value (which also went up)

A Golf course in South-West Utah was recently built as a low-water-use course. There is only a small patch of grass to tee off of, and a normal grass area around the cup. The rest of the course looks like the deserts of Arizona, with natural scrub brush.

In my mind, water is truly needed for farming, and there is no need for a grass lawn that needs to be mowed (most lawn mowers are polluting two-strokes). Ive seen some beautiful Xeriscape (low water) home yards. A swimming pool actually uses a LOT less water through evaporation, than the same area of grass uses from watering to keep it green.

 

[flathill]

The potential energy in 1 cubic meter of water 100 meters high is about 250 watt hours, making lithium batteries more cost effective for the typical homeowner

Why limit yourself to water. Try a magnetohydrodynamic pump with liquid metal for a more compact system and "one" moving part 8) It will also serve as a bank with the full faith and credit of physical metal, but then again the water would be just a good in many ways...the fight in Libya is really about the largest water bank on Earth : http://en.wikipedia.org/wiki/Nubian_Sandstone_Aquifer_System

More fresh water than all you see above ground on the entire planet! The USA plays chess. Remember that.

 

[dogman dan]

Likely that the real future is huge lithium battery storage. Chances are, we'll be getting more and more solar around here that might need storage for the occasional cloudy days.

I'm just stuck on the water/drought issue at the moment. Last time I was able to measure rain at my house was october. In the official guage the drought got broke a week ago, when 2/10 was measured. Woo hooo! For the first time in my life, even the creosote out there looks dead. We're breathing the smoke from the AZ fires, where a full third of the few trees in that state just burned. The rio grande farmers water allotment is the smallest since the dam was built in 1917. Pretty much, La Nina really sucks for the upper rio grande basin.

I do have a grass backyard, but it covers only a tiny portion of my 1/3 acre lot. The front is native rangegrass and wildflowers that I irrigate only in the spring, simulating the spring rains we seem to no longer have.