Geothermal may beat batteries for energy storage • Hacker News Board

Re: Geothermal may beat batteries for energy storage

#261

Post by cupofpython » Wed, Oct 12, 2022, 3:15 PM UTC

kenhwang wrote: post #213

cupofpython wrote: post #189

Earlier quoted context omitted.

95% stored energy by what measurement? See my other comment. It is not accessible to everyone, nor can it be made accessible to everyone, and the current storage capacity is a marginal fraction of what we actually use. It's a short term load balancing tool that operates within a small energy window.

95%+ by total energy stored/provided. There's little to no water use in the storage or discharge of pumped hydro, water goes from one reservoir into another. The limiting factor is how much water can be pumped/discharged, not how much water is available in storage (which tends to be significantly more than the amount pumped around). So there's little reason why they wouldn't currently be fully utilized. It's true tha…

the 95% is misleading. it is barely storing or providing energy but it is a passthrough akin to plugging your phone into the charger 24/7 and saying your phone battery is providing 95% of the energy just because the wall outlet charges the battery first then the battery powers the phone (not an exact metaphor). If you unplug your phone and the phone dies 10 minutes later, you wouldnt say your phone has a good energy storage solution.

Pumped storage is great at what it does, no denying that. And what it does is allow energy production to remain near average while demand varies, and consequently allows energy production levels to be adjusted a bit slower. You aren't addressing the raw numbers though. It serves best as a compliment to a continuous energy production system. As an actual battery/storage solution, it is weak. So it will not be the solution used to store a massive amount of energy generated over a short period of time in order to be used over a longer period of time.

I agree they should be fully utilized, but I am trying to explain that if you fully utilize pumped storage you are still going to have an incomplete energy storage problem. Of course the water levels dont get near max or min capacity - it is designed to take out exactly what you put in as soon as possible or else there is too much risk. The raw storage capacity is small to medium sized - about 10 hours at max discharge (and max discharge might not be enough to keep up with demand entirely on its own).

Basically, the more energy you need to draw the faster you need to drain it and the more energy you want to store, the more massive your reservoir needs to be.

These things cannot be made 100 to 1000 times bigger, nor is there capacity to make 100 to 1000 times more of them. We are better off having them vs not having them but it isnt enough, and if we find a better solution it may become obsolete

Re: Geothermal may beat batteries for energy storage

#262

Post by Schroedingersat » Wed, Oct 12, 2022, 3:31 PM UTC

kragen wrote: post #260

Schroedingersat wrote: post #259

Earlier quoted context omitted.

I'm not sure if you're being facetious, but in thinking about it I think you've pointed out the remaining advantages. Current from lithium batteries has to go through a bms (and thus you have to build them to a current rating, even if your cells are 5C the cost of BMS may make lead acid cheaper) and they have low temperature issues so I can see them being useful in current limited situations and in situations where n…

I'm not being facetious, I'm just trying to understand the discrepancy. Your explanation isn't it: battery management systems do not account for a major part of the cost, we don't have low temperatures in Buenos Aires, and the auto parts stores are not selling the lead-acid batteries as specialty parts to people who drive in from Patagonia to replace their car batteries, similar to engine block heaters. sbp looked in…

Are those prices up to date? There are several shops in Brisbane AU that will sell drop in 12V batteris retail for 350USD per nominal kWh (about $320 per real kWh at 0.1C) including taxes. The occasional special is in the 250-300 range. Ebike batteries with higher current are in the 300-500 range.

They're highly unsuitable for an engine starter at that price though (1C BMS) and have no built in low-temperature monitoring. There are bigger systems with better safety features for about $400US/kWh available in europe and asia.

Also note that nominal capacity of a lead acid battery is often not usable capacity. I was assuming 50% DoD as usable daily capacity which may be pessimistic.

Re: Geothermal may beat batteries for energy storage

#263

Post by beembeem » Wed, Oct 12, 2022, 3:41 PM UTC

xienze wrote: post #165

spywaregorilla wrote: post #153

Earlier quoted context omitted.

Iceland has the cheapest electricity in the world. They run heat under their roads so they don't need to be plowed. Aluminum is shipped to Iceland to be smelted just because the energy is so much cheaper. Iceland's electricity usage per capita is 4x that of the United States, and more than 2x the next highest country (Norway). They're the largest producer per capita as well. The population is not large, mind you, but…

> Iceland has the cheapest electricity in the world. Come again? If the parent post about about $0.139/kWh for households is correct, I can assure you there are many places in the US cheaper than that.

There were only 2 markets nationwide with retail rates lower than this [1] in Aug 2022.

[1] https://www.bls.gov/regions/midwest/data/AverageEnergyPrices...

Re: Geothermal may beat batteries for energy storage

#264

Post by kragen » Wed, Oct 12, 2022, 3:46 PM UTC

Schroedingersat wrote: post #262

kragen wrote: post #260

Earlier quoted context omitted.

I'm not being facetious, I'm just trying to understand the discrepancy. Your explanation isn't it: battery management systems do not account for a major part of the cost, we don't have low temperatures in Buenos Aires, and the auto parts stores are not selling the lead-acid batteries as specialty parts to people who drive in from Patagonia to replace their car batteries, similar to engine block heaters. sbp looked in…

Are those prices up to date? There are several shops in Brisbane AU that will sell drop in 12V batteris retail for 350USD per nominal kWh (about $320 per real kWh at 0.1C) including taxes. The occasional special is in the 250-300 range. Ebike batteries with higher current are in the 300-500 range. They're highly unsuitable for an engine starter at that price though (1C BMS) and have no built in low-temperature monito…

It's possible they're not! But I'm suspicious of this notion that prices have dropped by a factor of 5 since last year, and have reached Australia but not Just Catamarans in Florida; maybe they're doing the calculation differently than you are. Or maybe there's a fraud going on.

FWIW your US$320/kWh works out to US$89/MJ. (I try to use SI units when I can; it saves a lot of hassle.)

I think it's fair to exclude taxes, but not to include "the occasional special", since the retailer is presumably taking a loss in that case and will be unwilling to sell you an arbitrarily large number of batteries at that price.

A thing I wonder about is how big a Li-ion battery you really need for an engine starter. 200 amps at 12 volts is only 2.4 kilowatts; a 15C battery with 0.6 MJ capacity could do that, which is about a dozen 20700 cells. You do need a 200-amp BMS, but I think the cost of the cells is still the issue.

Re: Geothermal may beat batteries for energy storage

#265

Post by Schroedingersat » Wed, Oct 12, 2022, 3:53 PM UTC

cupofpython wrote: post #186

PaulHoule wrote: post #131

Earlier quoted context omitted.

They are building a lot of them in China https://en.wikipedia.org/wiki/List_of_pumped-storage_hydroel...

Makes sense, it is definitely a useful tool. I just think it is insufficient to act as storage. It can be good at producing variable amounts of Watts on demand but not so good at storing enough Watt-hours to keep things running for very long. I can see a great appeal for it to help with load-balancing for a significant amount of choppiness between supply and demand on the hour timescale. For something like solar, whe…

Sodium ion is expected to sharply take over cost limited applications some time in the next couple of years. There are pilot mass production programs designed to avoid scarce materials that drop into existing processes. Natron have products on the market (at presumably high cost) targetting datacenters for high safety applications.

For longer scale storage it's a tossup between opportunistic pumped hydro, CAES where geology makes it easy, hydrogen in similar areaswith caverns, ammonia, synthetic hydrocarbons, sodium ion, and one of the emerging molten salt or redox flow battery technogies. Lithium isn't really in the running due to resource limits.

Wires also have a lot of value for decreasing the need for storage. Joining wind and solar 1000s of km apart can greatly reduce downtime. Replacing as much coal and oil with those, and maintaining the OCGT and CCGT fleet is the fastest and most economic way to target x grams of CO2e per kWh where x is some number much smaller than the 400 of pure fossil fuels but bigger than around 50. Surplus renewable power (as adding 3 net watts of solar is presently cheaper than the week of storage to get an isolated area through that one week where capacity is 1/3rd the average) will subsidize initial investments into better storage and electrolysis with no further interventions needed.

Re: Geothermal may beat batteries for energy storage

#266

Post by cupofpython » Wed, Oct 12, 2022, 3:56 PM UTC

im3w1l wrote: post #214

cupofpython wrote: post #113

Earlier quoted context omitted.

emphasis on massive scale. Moving 500,000 kg (over 1 million pounds) 7.5 meters (~25 feet aka the height of a house) will give you about 10 kWh of energy. This is equivalent to running a 425W device all day, like a small air conditioner. The relationship is linear. Double the weight or the distance to double the energy. All of the metal at a scrap yard I know of amounts to less than half that weight, for reference. I…

What if you go down instead of up? Drill like a kilometer or two and then build a huge cavern at that depth.

that is something people are doing. Also when you go down into rock, you are able to leverage pressure as energy storage as well - which is similar to what this article is about.

There was 1 design I saw where they have a large cylinder cut out of the ground but left in place (so it is loose). Pump water underneath it to raise the cylinder up, then flip the valve and the cylinder squeezes the water back out for power through gravity. I am not sure how the sealing works on that, probably similar to hydraulics

Re: Geothermal may beat batteries for energy storage

#267

Post by kragen » Wed, Oct 12, 2022, 4:00 PM UTC

dahfizz wrote: post #258

kragen wrote: post #252

Earlier quoted context omitted.

It's a good question! For years I've been hoping for the legendary Lithium-ion Crossover Event after which lead-acid batteries become obsolete for all purposes, but the auto parts stores in my neighborhood are still stubbornly stocking lead-acid starter batteries for some reason; so, too, the burglar alarm folks. Maybe the Crossover has already happened in the developed world, by which I mean China, but the news hasn…

There's really no benefit to lithium batteries in a car. They perform much worse in the cold, and they are more expensive. You don't cycle your car battery 100-0-100 so the fact that the useable capacity of lead batteries is lower doesn't matter.

Yeah, but the question is whether they are more expensive. If they were cheaper (per watt in this case, rather than per joule) people in Brazil and northern Argentina would probably use them to start their motorcycles. I think they're closer to that crossover than to the cost-per-joule crossover.

Re: Geothermal may beat batteries for energy storage

#268

Post by cupofpython » Wed, Oct 12, 2022, 4:23 PM UTC

Schroedingersat wrote: post #265

cupofpython wrote: post #186

Earlier quoted context omitted.

Makes sense, it is definitely a useful tool. I just think it is insufficient to act as storage. It can be good at producing variable amounts of Watts on demand but not so good at storing enough Watt-hours to keep things running for very long. I can see a great appeal for it to help with load-balancing for a significant amount of choppiness between supply and demand on the hour timescale. For something like solar, whe…

Sodium ion is expected to sharply take over cost limited applications some time in the next couple of years. There are pilot mass production programs designed to avoid scarce materials that drop into existing processes. Natron have products on the market (at presumably high cost) targetting datacenters for high safety applications. For longer scale storage it's a tossup between opportunistic pumped hydro, CAES where…

Awesome response. I've come across the molten salt option but havent researched in depth. I saw it referenced as something a lot of scientists are hyping up, but I am not sure what kind of engineering challenges exist for implementation and maintenance.

Second paragraph is a bit too information dense, I had trouble following some of it. Renewable energy deficiencies will be localized, so i understand how wires help here. A larger connected area produces more stability, makes sense. Agreed with the carbon reduction priority to tackle coal and oil first. Surplus renewable power acting as a subsidy checks out, but that is skirting around the energy storage problem imo. Sounds like you are saying "instead of storing renewable energy, get more than you need and sell it back to the grid and then use those funds to buy the energy back later". This would certainly work for local consumers, but doesnt do too much to help the power grid itself manage what to do with the surplus energy. Sell it to neighboring power grids? Ties in to the first point about connecting a larger area - but what are the limits here? Can we physically connect the sunny side of earth to the dark side? (ignoring that it seems logistically/legally prohibitive)

the question really comes down to what should we be spending money on to get "better storage"? What are the best solutions for long-term local storage?

Re: Geothermal may beat batteries for energy storage

#269

Post by cupofpython » Wed, Oct 12, 2022, 4:34 PM UTC

SECProto wrote: post #163

cupofpython wrote: post #113

Earlier quoted context omitted.

emphasis on massive scale. Moving 500,000 kg (over 1 million pounds) 7.5 meters (~25 feet aka the height of a house) will give you about 10 kWh of energy. This is equivalent to running a 425W device all day, like a small air conditioner. The relationship is linear. Double the weight or the distance to double the energy. All of the metal at a scrap yard I know of amounts to less than half that weight, for reference. I…

> All of the metal at a scrap yard I know of amounts to less than half that weight, for reference. That's not a great reference point when you're trying to visualize to pumped storage, as water is 1t/m3 while steel is up around 7 or 8. Also, 500t of steel at a scrapyard seems very small - 70m3? A better reference might be a back yard pool, which might be in the 30-40t range - so like lifting 15 back yard pools the he…

good point, and yes its a small scrap yard. I was trying to emphasis that it's possible for a full-time commercial operation moving heavy metal to involve less weight than what was referenced. The backyard pool paints a better picture though

Re: Geothermal may beat batteries for energy storage

#270

Post by cupofpython » Wed, Oct 12, 2022, 4:40 PM UTC

xyzzyz wrote: post #201

cupofpython wrote: post #113

Earlier quoted context omitted.

emphasis on massive scale. Moving 500,000 kg (over 1 million pounds) 7.5 meters (~25 feet aka the height of a house) will give you about 10 kWh of energy. This is equivalent to running a 425W device all day, like a small air conditioner. The relationship is linear. Double the weight or the distance to double the energy. All of the metal at a scrap yard I know of amounts to less than half that weight, for reference. I…

> Moving 500,000 kg (over 1 million pounds) 7.5 meters (~25 feet aka the height of a house) will give you about 10 kWh of energy. In dollar terms, 10kWh is worth around $1. 1 million pounds is the weight of 2-5 residential homes, depending on size. Think about it: the cost to lift a couple of entire houses three stories up into the air is literally just one dollar. That’s why gravity energy storage only makes sense a…

it's also why "storage" is a very loose term for gravity based energy storage. at a massive scale it is still only best at storing/discharging the difference between demand and supply - while still trying to keep actual energy production as close to demand as possible at all times. It really should never be used to power a city the way we would use a battery to power our phone. As in, spend significantly less time charging it than discharging it