Gravity batteries try to beat chemical ones with winches, weights, mine shafts • Hacker News Board

Re: Gravity batteries try to beat chemical ones with winches, weights, mine shafts

#131

Post by throwaway189262 » Sat, Apr 24, 2021, 1:15 PM UTC

lai-yin wrote: post #120

throwaway189262 wrote: post #106

Earlier quoted context omitted.

Construction material is a meaningless metric. If you compare coal or gas plants you need to consider the materials they consume and infrastructure needed for fuel transport. This is a big number, many times the material used for the plant itself. The only meaningful comparison is material used vs solar. Once these things are built they use near zero resources. For everything else you have to keep mining shitloads of…

Sorry but you don't get to discount wind turbines' ecological damage just because no more mining is involved post-construction.

It does far less damage than any other source of power. Unlike solar, it uses no space. Unlike fossil fuel and nuclear, it uses no continuous inputs.

Coal and gas plants use many times their weight in materials for a lifetime of operation. Nuclear probably does too because the massive waste involve in uranium refining.

What do you suggest as a greener power source than wind?

Re: Gravity batteries try to beat chemical ones with winches, weights, mine shafts

#132

Post by throwaway189262 » Sat, Apr 24, 2021, 1:16 PM UTC

kleiba wrote: post #109

throwaway189262 wrote: post #100

Earlier quoted context omitted.

> as a single wind turbine, which is already one of the worst ratio of power output per quantity of resource and land use. This is just false. Every wind turbine I've ever seen uses 50 square feet on a farm or cattle ranch. Not once have I seen a wind farm where the land underneath isn't still used for it's previous purpose. And at least in US we have enough farmland to power entire US with wind. And that's not count…

In places with cold winters, it is often forbidden to approach wind turbines because of the risk of falling ice.

The turbines are all in fields, useless scrubland, cattle ranches, and the ocean. Humans don't hang out in these places anyways

Re: Gravity batteries try to beat chemical ones with winches, weights, mine shafts

#133

Post by wizzwizz4 » Sat, Apr 24, 2021, 1:21 PM UTC

throwaway189262 wrote: post #131

lai-yin wrote: post #120

Earlier quoted context omitted.

Sorry but you don't get to discount wind turbines' ecological damage just because no more mining is involved post-construction.

It does far less damage than any other source of power. Unlike solar, it uses no space. Unlike fossil fuel and nuclear, it uses no continuous inputs. Coal and gas plants use many times their weight in materials for a lifetime of operation. Nuclear probably does too because the massive waste involve in uranium refining. What do you suggest as a greener power source than wind?

> Unlike wind, it uses no space.

Unlike solar?

Re: Gravity batteries try to beat chemical ones with winches, weights, mine shafts

#134

Post by tekstar » Sat, Apr 24, 2021, 1:22 PM UTC

FooHentai wrote: post #73

rakoo wrote: post #48

As usual everyone is fixated on price when the real hurdle will be scale. If we're going to replace our existing fossil fuel plants we need at least as much capacity. A quick grep in the article tells me these guys have a plan for a 4MW plant that involves a 1km shaft. That's the same order of magnitude as a single wind turbine, which is already one of the worst ratio of power output per quantity of resource and land…

I did a bit of scratch math with the notion this might be more suited for individual, home power storage rather than grid supply - You need something in the order of a 5m tall tower bearing 73 tonnes to store 1 kilowatt hour (even then, ignoring conversion losses). So that's the weight of ~ten class-4 fully laden heavy trucks. Once you can get it up in the air then the higher you can go you're doubling your storage i…

This exists at least in one place, with trains on a hill in Nevada.

https://aresnorthamerica.com

"ADVANCED RAIL ENERGY STORAGE"

Re: Gravity batteries try to beat chemical ones with winches, weights, mine shafts

#135

Post by ben_w » Sat, Apr 24, 2021, 1:24 PM UTC

pedrocr wrote: post #68

rakoo wrote: post #48

As usual everyone is fixated on price when the real hurdle will be scale. If we're going to replace our existing fossil fuel plants we need at least as much capacity. A quick grep in the article tells me these guys have a plan for a 4MW plant that involves a 1km shaft. That's the same order of magnitude as a single wind turbine, which is already one of the worst ratio of power output per quantity of resource and land…

That's the wrong comparison. We don't need to replace generation capacity with the same capacity of batteries. Batteries don't generate any electricity after all. We need batteries to smooth out differences between demand and generation. The total amount we'll need is very much still up in the air. Better interconnects, good use of existing hydro, overbuilding renewables, shaping demand, are all other ways to balance…

I think[0] we should probably be aiming for a few hours of storage, even with every affordable grid interconnect (which would help a lot with short winter days). We use less power at night — and some of what we do use is incentivised by lower nighttime electricity costs from power plants that don’t scale down well — but I expect we will continue to use some at night forever.

For the sake of Fermi estimation, I assume average electricity use in a developed nation is 1kW/person, and that average all-forms power use in the same is 5kW/person.

Transportation is almost certainly going to be batteries or synthesised fuels like hydrogen, and can only be backed by gravity storage if you have the kind of beamed power that would be banned by international treaty on the grounds of being too easily weaponizable[1].

If you’ll permit me to assume grid interconnects and lower nighttime demand than at present due to different pricing incentives, we might be able to need a mere 3kW-hours/person of electricity storage per night.

Using the lifetime cost estimates in the article, 3kWh/person/night is about $0.51/person/night for gravity storage and $1.10/person/night for LiIon. Neither is bank-breaking, but cheaper is better.

However, the volume required is a different question: 3kWh of batteries has a volume of 4.3 to 12 litres, while 3kWh of gravity storage is 1.1 metric ton kilometres[2].

You can make the distance required smaller by using more mass, but if I assume the average home mass is about 200 tons, you’d still have to raise the entire building 5.5 meters every day to store the same energy as a backpack of batteries. I do not expect construction on this scale to be the optimal solution in general, despite it being a very good idea in some specific cases such as hydro dams and preexisting deep shafts.

[0] Armchair opinion — I’m a software engineer not a civil engineer.

[1] Assuming they’ve read or watched any Larry Niven, the Bobbiverse, The Expanse, Babylon 5, or the news at any point in the decade following the second week of September 2001 — 'A reaction drive's efficiency as a weapon is in direct proportion to its efficiency as a drive.'

[2] http://www.wolframalpha.com/input/?i=3kWh%2F%289.8m%2Fs%2Fs%...

Re: Gravity batteries try to beat chemical ones with winches, weights, mine shafts

#136

Post by cogman10 » Sat, Apr 24, 2021, 1:25 PM UTC

martinald wrote: post #127

audunw wrote: post #90

Earlier quoted context omitted.

It's a common misconception that energy storage needs to handle all the power needs of an area for a significant time. The most immediate need for energy storage is frequency regulation, and short hours-long dips in power output. If we can solve that we can scale renewables very far. For days-long dips in power output, it's probably better to keep some gas power plants on stand-by. I think many areas of the world has…

Not true in northern European countries. The problem isn't day to day regulation, it's the massive demand in cold snaps in winter (when there is very little wind generation - cold weather tends to have little wind). You're talking balancing 20-30GW of additional demand with little solar/wind generation for weeks/months - probably at least 1TWh of storage required for the UK alone. Keep in mind this will only get wors…

This seems like a "running before we can walk" statement. Until we can handle day to day problems, it seems weird to worry about edge cases. I imagine as we transition to renewables and storage we will still have fossil fuel peeker plants to handle these sorts of snaps.

It won't be until our power storage is far more beefed up that we'll shut those down, and that will take years.

Re: Gravity batteries try to beat chemical ones with winches, weights, mine shafts

#137

Post by wizzwizz4 » Sat, Apr 24, 2021, 1:26 PM UTC

darawk wrote: post #44

cheschire wrote: post #34

Earlier quoted context omitted.

I wish that cost basis wasn't the only consideration when evaluating energy storage, but we're so accustomed to money being the great equalizer that things without a financial cost associated are often overlooked. What is the $/MWh cost associated with mining for, recycling, and disposing of battery components? What about the third order effects of centralizing control over the fuel source within only a handful of co…

Not to disagree with your underlying point, but I think it might be more constructive to frame the problem as a failure to internalize the costs, rather than a focus on money. Ultimately we do need a fungible way to compare solutions, and money is the simplest way to do that. We just need to figure out how to effectively internalize those externalities to the price.

Cost functions have an implied ethical system behind them. Using money is just waving your hands over it and going “well, money is objective, so we don't need a value system” – but there's still a value system there. It's like “machine learning” in that regard; there's no magic.

Re: Gravity batteries try to beat chemical ones with winches, weights, mine shafts

#138

Post by dopidopHN » Sat, Apr 24, 2021, 1:28 PM UTC

hutzlibu wrote: post #79

rakoo wrote: post #48

As usual everyone is fixated on price when the real hurdle will be scale. If we're going to replace our existing fossil fuel plants we need at least as much capacity. A quick grep in the article tells me these guys have a plan for a 4MW plant that involves a 1km shaft. That's the same order of magnitude as a single wind turbine, which is already one of the worst ratio of power output per quantity of resource and land…

"Also, we already have gravity-based systems, only nature does all the work of raising the payload for us in gaseous form, and we let it fall in liquid forms. But it takes so much dam place" We actually also do have self created gravity-based systems, where we also do the work by ourself, to have a energy storage on demand: https://en.wikipedia.org/wiki/Pumped-storage_hydroelectricit... They work reliable and with bi…

Side note on what is currently existing with gravity.

The suiss folks are gaming the west European energy market this way.

When the French produce too much nuclear energy, the German have leftover and stop buying it 100%w Price go down.

Swiss buy it cheap and pump water in their dam system with it.

Inevitably, the french grid align and produce a bit less. Price goes up slightly.

That when the suiss comes out, release the water into a turbine system and sell the energy for a higher price that what they bought it for to German, French and Italian grid.

I can’t even be mad at them. They have the perfect setup. But you need the Swiss alp and climate to do what they are doing. And being freaking Swiss.

Source/Context from a Swiss news paper : le temps, in French

They describe that « system » and apparently it’s being disturb in recent years with the evolution of the German market.

https://www.letemps.ch/economie/barrages-suisses-vendre-esto...

Re: Gravity batteries try to beat chemical ones with winches, weights, mine shafts

#139

Post by randallsquared » Sat, Apr 24, 2021, 1:29 PM UTC

SagelyGuru wrote: post #99

chris_engel wrote: post #85

Earlier quoted context omitted.

Hm, you also need to consider that 5 trucks can have a much higher combined output than the 1 truck 5 times as high. The storage might scale this way but not the output when demand is high.

You can make that one truck descend five times faster, giving the same output.

"...for a given drop rate" seems implied.

There will be a maximum drop rate that is supported by the machinery being built, and it seems reasonable, though not mandatory, that a 5x weight system will be designed to handle more generation than whatever it's 5x of.

Re: Gravity batteries try to beat chemical ones with winches, weights, mine shafts

#140

Post by guerby » Sat, Apr 24, 2021, 1:31 PM UTC

kragen wrote: post #51

ardit33 wrote: post #31

Earlier quoted context omitted.

It is over 25 years, I don't think your battery will last 25 year. You probably have to replace it 3-4 times over that period of time. A mechanical system can last that much, even more, with minimal maintenance.

You may have accidentally responded to the wrong comment. The comment to which your response has been attached already takes into account the limited cycle life of batteries.

And I didn't take into account that a third of the paid price was shipping, and that battery prices are dropping like a rock:

https://pubs.rsc.org/en/content/articlelanding/2021/EE/D0EE0...

Re-examining rates of lithium-ion battery technology improvement and cost decline