Author Topic: Bill Gross Keynote at DLD Munich 2019 on cheap gravity energy storage  (Read 4850 times)

cherzeca

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Re: Bill Gross Keynote at DLD Munich 2019 on cheap gravity energy storage
« Reply #10 on: February 26, 2019, 01:57:23 PM »
if amortization and maintenance are included, then this is just a guess, right, since tower's useful life and maintenance costs are currently just a guess.  don't know if people will want to spend $7MM if so.  I am thinking this would be a great IP company where the IP is licensed to small scale utilities etc, but at some point early in the process the operational chasm needs to be leapt to establish value of the IP


Pelagic

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Re: Bill Gross Keynote at DLD Munich 2019 on cheap gravity energy storage
« Reply #11 on: February 26, 2019, 03:12:54 PM »
cost is said to be $.03/kWh. 

what does this mean? costs $7MM to build tower.  is some amortization figured into this cost? what is the delta between energy put in to raise blocks and energy coming out when blocks come down. is this delta the $.03/kWh?

From looking at other similar energy storage solutions like pumped hydro the efficiency usually runs in the 70-80% range. So in essence they're taking surplus power generated by solar/wind when it is "free" from the grid and are able to return somewhere in the range of 75% of that back to the grid. I'd expect this to have a similar efficiency, maybe somewhat higher say 85%.

The $.03/kWh figure I believe is their all in break even price for the crane/blocks. Assuming their costs are accounted for accurately, it's what they expect to be able to sell electricity back to the grid at and not lose money. So to the .03/kWh they add $.02/kWh which is what they're claiming the all in price of solar is and the total system, solar panels and the crane/block contraption, can reliably sell power to the grid at $.05/kWh at any time.

Cardboard

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Re: Bill Gross Keynote at DLD Munich 2019 on cheap gravity energy storage
« Reply #12 on: February 27, 2019, 06:04:33 AM »
"From looking at other similar energy storage solutions like pumped hydro the efficiency usually runs in the 70-80% range. So in essence they're taking surplus power generated by solar/wind when it is "free" from the grid and are able to return somewhere in the range of 75% of that back to the grid. I'd expect this to have a similar efficiency, maybe somewhat higher say 85%."

On pumped hydro, 70-80% efficiency is impossible IMO.

You have energy that you want to store, you pump water up the hill with a pump and electric motor. Right there you lose around 25% (motor loss of around 5% and pump loss of around 20%).

Then you take that water back down in a pipe to generate electricity with a generator. So you have energy lost as it flows down the pipe or friction loss along with efficiency loss of the generator. This is probably another 30%.

So 0.75 x 0.70 = 52.5% efficiency.

On the other hand, this block lifting idea is much more efficient since you lose energy when you lift the block (motor loss + friction in pulleys/cables) and lose some again as you drop it back down (generator loss + friction in pulleys/cable).

This is probably 80% efficient unless I am missing something.

Cardboard

 

Liberty

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Re: Bill Gross Keynote at DLD Munich 2019 on cheap gravity energy storage
« Reply #13 on: February 27, 2019, 06:13:33 AM »
If you watch the video and check the slide I posted, they claim 91% round-trip efficiency on this gravity system.

For pumped-hydro:

"The round-trip energy efficiency of [pumped-hydro storage] varies between 70%80%, with some sources claiming up to 87%".

This exists and can be measured, so no need for fuzzy napkin math based on the average efficiency of very different motors and pumps.

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

https://web.archive.org/web/20180716054047/https://www.colorado.edu/engineering/energystorage/files/MSThesis_JGLevine_final.pdf

https://books.google.co.uk/books?hl=en&lr=&id=TPReBwAAQBAJ&oi=fnd&pg=PA25&dq=info:1fSw0yVikpMJ:scholar.google.com&ots=nOV5mvjb3R&sig=-mVET6C_qQosE11doraPLlwi0e0&redir_esc=y#v=onepage&q&f=false

https://www.economist.com/technology-quarterly/2012/03/03/packing-some-power?frsc=dg%7Ca

« Last Edit: February 27, 2019, 06:15:23 AM by Liberty »

Cardboard

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Re: Bill Gross Keynote at DLD Munich 2019 on cheap gravity energy storage
« Reply #14 on: February 27, 2019, 08:32:44 AM »
Fuzzy napkin math heh?

"The roundtrip efficiency (electricity generated divided by the electricity used to pump water) of facilities with older designs may be lower than 60%, while a state-of-the-art PHES system may achieve over 80% efficiency."

"Many existing PHES stations may increase capacity by (15-20)% and efficiency by (5-10)%.

Must be some fuzzy new fluid mechanics theory and electric motor efficiency that may deliver unheard of efficiencies.  ::)

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Liberty

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Re: Bill Gross Keynote at DLD Munich 2019 on cheap gravity energy storage
« Reply #15 on: February 27, 2019, 08:45:37 AM »
Fuzzy napkin math heh?

"The roundtrip efficiency (electricity generated divided by the electricity used to pump water) of facilities with older designs may be lower than 60%, while a state-of-the-art PHES system may achieve over 80% efficiency."

"Many existing PHES stations may increase capacity by (15-20)% and efficiency by (5-10)%.

Must be some fuzzy new fluid mechanics theory and electric motor efficiency that may deliver unheard of efficiencies.  ::)

Cardboard

Yeah, and really old cars could get 5-10 MPG too, but it doesn't make it "impossible" for modern cars to get 30 MPG. We're talking about new technology and building more to clean up the grid for the future. You said: "70-80% efficiency is impossible IMO", so looks like you were wrong.
« Last Edit: February 27, 2019, 09:05:33 AM by Liberty »

Cardboard

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Re: Bill Gross Keynote at DLD Munich 2019 on cheap gravity energy storage
« Reply #16 on: February 27, 2019, 10:48:05 AM »
60% or less + maybe 5 to 10% from your own article what does that give you? A solid 70-80%?

I will say it again, it is impossible. Maybe in a lab but, not in real life.

Then we have not even got into AC vs DC, need to transform power up or down, power line losses, breakdown/maintenance.

It is like these numbers being published by this Bill Gross guy, are they correct? Do they include all costs and a reasonable safety factor?

If you are a promotter or CEO or salesman will you publish best case or base case? What about rounding?

I am not saying this is all crap. I mentioned that the crane idea is much more efficient. It is actually very clever.

However, I am saying that they are likely embellished numbers by people selling their ideas or not different at all from all corporate presentations. Greed is good you know?


Pelagic

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Re: Bill Gross Keynote at DLD Munich 2019 on cheap gravity energy storage
« Reply #17 on: February 27, 2019, 12:59:44 PM »
I don't disagree with the point that older systems are likely to be less efficient and that there tends to be a lot of promotional cherry picking by founders/early adopters of these technologies. However, I think the debate on the specific efficiency in terms of power in vs. power returned to the grid somewhat misses the point. These systems, by design, work when the grid is producing excess electricity. Any electricity they're able to capture, store, and return to the grid in a manner that makes economic sense for the investors in the project is a positive. Whether they're 50% efficient, 95% efficient, or 20% efficient is less important than if they can reliably work and return capital to those who invested in them since the energy they're capturing is excess. For utility scale solar in particular, the recurring maintenance costs are negligible so any storage designed to capture excess energy it produces is a positive.

This is the company (perhaps there are others) working on developing rail based systems where a heavy concrete/aggregate load is carried uphill and stored there then brought downhill when electricity is needed. They claim around 80% efficiency.

https://www.aresnorthamerica.com/grid-scale-energy-storage

Liberty

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Re: Bill Gross Keynote at DLD Munich 2019 on cheap gravity energy storage
« Reply #18 on: February 27, 2019, 01:32:15 PM »
Indeed, in the end all that matters is the price. The efficiency is one of the factors that goes into the costs, but a 10% efficient system that could capture energy at 2c/kwh round-trip is better than a 90% efficient system that captures it at 3c/kwh round-trip.

bizaro86

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Re: Bill Gross Keynote at DLD Munich 2019 on cheap gravity energy storage
« Reply #19 on: February 27, 2019, 02:06:31 PM »
In/Out capacity is important here as well. The faster you can pull the power out of storage the better price you'll get for it, as you can sell it all at the peak price.