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2023-11: Warosu is now out of extended maintenance.

/sci/ - Science & Math

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2836225 No.2836225 [Reply] [Original]

As I've understood it, one of the major problems with wind energy is smoothing the peaks and valleys in power production that come with variations in weather conditions. On a windy day, you may produce multiple times more power than is being drawn and on a still day you'll have no power generation but the same amount of power draw from the grid.

I know that people have proposed batteries and mixed grids as solutions but they're overly expensive, to fix this what about using gravity? The concept is used in every town in the US, it's called a water tower.

- They maintain water pressure during periods of high demand by using gravity as a free pump.

- They lower power costs of pumping by using the force of gravity to maintain pressure during hours of high energy costs (prices for large users fluctuate based on time of day) then running the pumps during low cost hours to refill the towers. The same amount of energy is used but the time difference lowers overall cost.

Why can't the same idea be used for wind power? You have an unlimited source of water where off-shore windmills operate and on land you could use weights like a grandfather clock or possibly the underground water table if it's available like the midwest.

On a day of good production day water is pumped into towers or the weights wound up using the excess power. On an off-day gravity is used as falling water spins turbines or the weights gear down to generators. It might not cover all the production gap but it could definitely smooth out the supply. This would even work for solar.

Would the scale of the gravity storage be too large to be unfeasible? Is this idea already in use somewhere?

>> No.2836236

20,000kg lifted 50m only has ~2800w of energy. The scale of mass you'd need would be too large.

>> No.2836239

>>2836236

OP WHY DON'T YOU EAT THIS GUY'S PHYSICS AND SHUT THE HELL UP

>> No.2836248

Very interesting idea indeed.

This concept is already in practice on a large scale in a town. The difference being instead of wind power, they pump water into a huge reservoir during the night when electricity prices are cheaper and let the water out during the day generating electricity when the prices are higher.

I think this same thing could be accomplished with wind energy by diverting the excess power to pump water into a reservoir therefore storing energy and letting it out when the wind energy is not sufficient therefore generating electricity.

Very good idea sir.

>> No.2836250

wind power is fail, unless you're a sailboat. then it's win

>> No.2836252

>>2836225
http://en.wikipedia.org/wiki/Pumped-storage_hydroelectricity

>> No.2836266

Dams damage the environment more so than any other source of power, and they have the history of being the most lethal in the cost of human lives.

>> No.2836276

>>2836266

Pumped storage hydroelectricity is not a dam. Think of it as a big swimming pool at a high elevation. It does not harvest energy from rivers, it stores water then releases it down to lower elevations through turbines to generate electricity.

>> No.2836282

>>2836225
The largest water tower in Canada is 27,276,540 liters. Water weighs ~1kg per liter. So you've got 27.2m kg at your command. That same water tower is 38.1m tall.

That's 10184514505.2 joules of potential energy. That's about 2 megawatts of power that's available for an hour. .117mw if spread over a whole day. Not super practical on a large scale to build that kind of infrastructure.

>> No.2836292

>>2836236
>>2836239
That's only 20,000 liters or 5200 gallons. That's a small above ground pool in size.

>> No.2836302

>>2836276
Any container that could only store a couple of days worth of power generation would be impractical when scaled up to meet the demands of a city, and possibly dangerous to nearby citizens. Unless you're only trying to fill and empty YOUR pool, for YOUR house.

>> No.2836303

>>2836252
There's my answer, I wonder if there are enough sites with suitable geography for this.

>> No.2836313

>>2836292
>>2836282

Idiots. this is in practice on scales of small lakes. Move away from the water towers. I know that's what op said but I think it was just because it was a lack of a better word.

http://en.wikipedia.org/wiki/Pumped-storage_hydroelectricity

>In 2007 the EU had 38.3 GW net capacity of pumped storage out of a total of 140 GW of hydropower and representing 5% of total net electrical capacity in the EU

>> No.2836318

>>2836302
You don't need a couple of days, the deviation from average wind speed isn't that huge. The purpose of such a system is to smooth out a few hours of outlier conditions.

>> No.2836349

>>2836318
You've never had a 3 day long low pressure system hang over your city?

Well, then your pool idea is good enough for you, I guess.

>> No.2836352

Is this really the best way to do this? I guess batteries aren't that capable.

>> No.2836361

>>2836313

>>2836292 here, my point was to back the OP. 22k kg is very tiny in volume, far smaller than even a water tower as OP envisioned. The way volume increases in cubic fashion means you get huge payoffs when you scale things up. Going to the size of a small lake and you're getting into the billions of watts of stored energy. The lake near me is artificial and is dyked up about 40m in some places. Put a pump at the bottom of those and it can produce 25,000mw, 10x what the nuclear plant near me can put out.

>> No.2836379

>>2836349
You wouldn't have just a single storage container and it wouldn't be nearly as tiny. As expressed elsewhere, a large water tower can provide 2 megawatts, which is roughly equivalent to what the best windmills can produce at 100% capacity. You could probably get away with 2-3 windmills per tower as wind farms are sized to work at 1/3rd capacity. It's not that far fetched really.

>> No.2836400

>>2836379
Oh, so now we have to scale your design up to meet the unanticipated demands of the environment.

You must be an engineer.

>> No.2836412

>>2836400
Nowhere in the OP did it express a defined scale and the entire basis of this idea is that it exists to counter the effects of the environment. I don't get what you're arguing when it's shown that the exact concept being discussed is already in use.

>> No.2836417

>>2836412
It might be in use, but it is not universally adaptable.

>> No.2836430

>>2836361
> billions of watts of stored energy

You use that word but i don't think you know what i means.

>> No.2836510

Why don't we provide all men with a Fleshlight fitted with an induction loop.

>> No.2836529
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2836529

>>2836510

>> No.2836538

How about this? I bet a lot of anons are obese. Let's siphon their fat and burn it for fuel. We'll hit two birds with one stone. All the fat anons will become skinny and our energy needs will be solved.

>> No.2836549

i think the biggest setback is the economic feasibility.

there would be a heck of a lot of energy loss through the system.

>> No.2836592
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2836592

>itt: people implying that a watt is a unit of energy

mfw

>> No.2836606

>>2836592
wat?

its power, energy(Joules) per second. wtf are you derping about?

>> No.2836919

>>2836549
> there would be a heck of a lot of energy loss through the system.

Pumped storage is 75% to 80% efficient. OTOH, if you just don't bother with wind power you get 0% efficiency, so 75% is a big improvement.

Also, nuclear power is a bigger driver of pumped storage than renewables. Nuclear power is geared toward producing constant power 24/7, while demand follows a daily cycle. In practice, this means that 100% nuclear isn't viable; once you get to the point where nuclear can meet 100% of night-time demand (which is already pretty much the case for western Europe), further expansion suffers from diminishing returns.

>> No.2836981

Not feasable for large scale operation in Europe. We simply do not have the place or the water reservoirs to store enough energy with pumped storage systems. If we could pump the mediterranian up and down, then we'd be talking business. However, I might predict, that this will not happen for several reasons. haha.

Another interesting technique that goes into the same direction is compressed air storage.

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

Suffers from the same problem: namely not enough energy storage capacity on a large scale.

>> No.2837046

>>2836981

the latest thing is liquifying the air instead of compressing it. it's less efficient but you can store more and it's much safer since you can store it at atmospheric pressure.

>> No.2837234

>>2836606
Technically a Watt is a unit of power, like you said. In other words, it's units are how much ability to do work/second are being produced, used, etc. It is not a unit of energy (that would be the Joule) as you also pointed out. It's a matter of definition.

>> No.2837241

>>2837234
what this dude said. kilowatt hours would be a unit of energy, kilowatts is power