4 ms·

> "By comparison, the US uses 12,500 TWh of electricity daily" I was suspicious of your numbers so I did a bunch of math and then realized you're using the Eur

by elihu 5y ago

> "By comparison, the US uses 12,500 TWh of electricity daily" I was suspicious of your numbers so I did a bunch of math and then realized you're using the European comma rather than a decimal. So 12,500 means 12.5, not 12500. (EIA.gov says the U.S. used about 3.8 trillion kilowatt hours in 2020 [1]. 3.8 trillion kilowatt hours equals 3.8 billion megawatt hours, equals 3.8 million gigawatt hours, equals 3.8 thousand terawatt hours per year or 10.4 twh per day. If we figure the U.S. has about a hundred million households and divide 3,800 twh by that, we get 38 megawatt hours per household per year. This is a very rough estimate, as it doesn't include industrial/commercial/government users. If we divide by 365*24 to cancel out the time units, we get an average consumption of .004338 MW or 4.338 kilowatts per household. That sounds about right.) Current battery production is only just barely getting started. China dominates production of LFP cells (which are ideal for grid storage) because of patents which are expiring, so hopefully we'll see more production outside of china in the near future. LFP cells aren't bottlenecked by nickel or cobalt, and so the main resource constraints I believe are lithium, aluminum, and copper which are all quite a bit cheaper and available in bigger quantities. I think prices are expected to eventually settle somewhere around $80 per kwh of capacity for the cells, and I don't think we're that far off that now. (LFP may eventually be displaced by something else, like lithium sulfur or solid state batteries or something, but I think LFP is probably good enough.) Maybe lithium or copper will become bottlenecks and prices will rise. Let's say prices do hold at about $80 per kwh. Maybe we'll round up to $120 per kwh to account for pack construction, a building to store the batteries, inverters, chargers, and so on. If the average U.S. adult-aged person uses about 2kw on average, then they need 48kwh of storage for 24 hours. That would be about $5760. If we amortize that over ten years, it's about $48 a month. That's kind of expensive, but it's within the realm of what can be done without assuming any major technological breakthroughs. We probably don't need 24 hours of storage, though, if we have enough renewable energy over-production and backup fossil fuel plants to use in extreme situations. [1] https://www.eia.gov/energyexplained/electricity/use-of-electricity.php https://www.eia.gov/energyexplained/electricity/use-of-elect...

newyankee 5y ago
LFP is also actually the perfect battery for urban transportation in tropical countries. Their low cost and economics would ensure a big transformation in coming years because few people understand the tremendous impact they have on lifecycle cost (due to high no of cycles). I personally feel that in 10 years in India it will be cheaper to rent an electric car running on LFP for trips < 300 km along with a driver (cheaper here) than buy your own car.
thow-58d4e8b 5y ago
Just because CATL can manufacture LFP cells at $80/kWh doesn't mean the end-to-end system is available at that price. Home battery storage is nowhere near $80 or even $100 per kWh. It's at $500-$1000/kWh. Tesla Powerwall 2 has the best price per kWh available on the market, at $560/kWh. Inverters able to handle the currents necessary for turning on an electric oven are in the thousands. Installation costs are in the thousands. And then, these batteries do not last forever - they're rated at 3000-5000 cycles If we imagine a near-future scenario - a battery powered house heated with heat pumps, driving an electric car, during central European foggy winter, which tends to last for about a week at a time. Let's say they use 60kWh/day. We're looking at $100k just for the batteries and installation, even assuming electricity comes free. In ~15-20 years, the batteries reach their recommended cycle life, requiring a choice of another $100k or accepting that what used to be a 3-day storage becomes 2-day This is not some "extreme situation". It's a completely predictable scenario that recurs with near 100% probability every single year. Then there are places like Ganges river, Bangladesh or Indonesia, home to hundreds of millions of people, where neither solar, nor wind is viable (and land is scarce)
- elihu 5y ago
  Those prices for home storage units are the price we pay for not having significant domestic LFP production. Maybe making a cheap battery unit is harder that I think but to me it sure looks like there isn't a lot of serious competition in that space, otherwise the units would correspond better to battery costs. (And why would you try to build a company around a product that some Chinese company can make the product at a cheaper cost because they have access to the necessary patents on more favorable terms? Maybe everyone knows that and is staying away, at least until LFP cells become a thing anyone in the world can buy at roughly-equal prices.) I think it's useful to think in terms of cars. I'm actually doing an EV conversion right now, and I have a motor controller that puts out about 100 kilowatts of 3-phase AC. It came with the motor so I don't have an exact price, but fair market value is probably around $1500. (That's retail cost in quantities of one. Wholesale cost is presumably somewhat less.) It weighs maybe ten pounds or so. That's adequate to power probably about a dozen houses. I don't know if it puts out a sine wave or a square wave. Even if it's the latter, you could imagine a hundred of these things putting out square waves with, say, randomly-varying pulse width and having it average out to a sine wave. There's probably better ways to do that, but anyways the point is that we do have the capacity to switch enormous amounts of power in a very small package for pretty low cost. It's actually kind of amazing. Maybe if the batteries feed into an HVDC line or they're co-located with a solar plant, then you don't even need to deploy more inverters. A battery management system for my conversion is a little over a thousand dollars for a setup with about 48 cells. In a big installation you could amortize BMS costs by using bigger cells, or placing them in parallel groups -- the downside being that it might take longer to notice if a cell is going bad. My BMS is made by a company that caters to EV conversions; they're doing low-volume sales. A major utility ordering the equivalent for hundreds of thousands of cells probably can get a nice volume discount. As far as foggy winters go: renewable energy needs to be traded over a wide geographical area. Purely local generation doesn't really make sense, unless you have some useful purpose for unpredictable amounts of surplus energy. Wind power would need to be a part of it. Even fossil fuels are a reasonable option as long as they're not used very often. Running natural gas plants for a week or two in the dead of winter or in case of grid disruptions seems like a reasonable use of fossil fuels. Indonesia has a lot of land outside of Java. Even Java is pretty sparsely populated outside of cities. Most of it is jungle which we'd like them to keep and farms, but solar doesn't need to take up a huge percentage of available land. Even solar panels on roofs can go a long way.

by elihu 5y ago

newyankee 5y ago

LFP is also actually the perfect battery for urban transportation in tropical countries. Their low cost and economics would ensure a big transformation in coming years because few people understand the tremendous impact they have on lifecycle cost (due to high no of cycles). I personally feel that in 10 years in India it will be cheaper to rent an electric car running on LFP for trips < 300 km along with a driver (cheaper here) than buy your own car.

thow-58d4e8b 5y ago

Just because CATL can manufacture LFP cells at $80/kWh doesn't mean the end-to-end system is available at that price. Home battery storage is nowhere near $80 or even $100 per kWh. It's at $500-$1000/kWh. Tesla Powerwall 2 has the best price per kWh available on the market, at $560/kWh. Inverters able to handle the currents necessary for turning on an electric oven are in the thousands. Installation costs are in the thousands. And then, these batteries do not last forever - they're rated at 3000-5000 cycles If we imagine a near-future scenario - a battery powered house heated with heat pumps, driving an electric car, during central European foggy winter, which tends to last for about a week at a time. Let's say they use 60kWh/day. We're looking at $100k just for the batteries and installation, even assuming electricity comes free. In ~15-20 years, the batteries reach their recommended cycle life, requiring a choice of another $100k or accepting that what used to be a 3-day storage becomes 2-day This is not some "extreme situation". It's a completely predictable scenario that recurs with near 100% probability every single year. Then there are places like Ganges river, Bangladesh or Indonesia, home to hundreds of millions of people, where neither solar, nor wind is viable (and land is scarce)

elihu 5y ago
Those prices for home storage units are the price we pay for not having significant domestic LFP production. Maybe making a cheap battery unit is harder that I think but to me it sure looks like there isn't a lot of serious competition in that space, otherwise the units would correspond better to battery costs. (And why would you try to build a company around a product that some Chinese company can make the product at a cheaper cost because they have access to the necessary patents on more favorable terms? Maybe everyone knows that and is staying away, at least until LFP cells become a thing anyone in the world can buy at roughly-equal prices.) I think it's useful to think in terms of cars. I'm actually doing an EV conversion right now, and I have a motor controller that puts out about 100 kilowatts of 3-phase AC. It came with the motor so I don't have an exact price, but fair market value is probably around $1500. (That's retail cost in quantities of one. Wholesale cost is presumably somewhat less.) It weighs maybe ten pounds or so. That's adequate to power probably about a dozen houses. I don't know if it puts out a sine wave or a square wave. Even if it's the latter, you could imagine a hundred of these things putting out square waves with, say, randomly-varying pulse width and having it average out to a sine wave. There's probably better ways to do that, but anyways the point is that we do have the capacity to switch enormous amounts of power in a very small package for pretty low cost. It's actually kind of amazing. Maybe if the batteries feed into an HVDC line or they're co-located with a solar plant, then you don't even need to deploy more inverters. A battery management system for my conversion is a little over a thousand dollars for a setup with about 48 cells. In a big installation you could amortize BMS costs by using bigger cells, or placing them in parallel groups -- the downside being that it might take longer to notice if a cell is going bad. My BMS is made by a company that caters to EV conversions; they're doing low-volume sales. A major utility ordering the equivalent for hundreds of thousands of cells probably can get a nice volume discount. As far as foggy winters go: renewable energy needs to be traded over a wide geographical area. Purely local generation doesn't really make sense, unless you have some useful purpose for unpredictable amounts of surplus energy. Wind power would need to be a part of it. Even fossil fuels are a reasonable option as long as they're not used very often. Running natural gas plants for a week or two in the dead of winter or in case of grid disruptions seems like a reasonable use of fossil fuels. Indonesia has a lot of land outside of Java. Even Java is pretty sparsely populated outside of cities. Most of it is jungle which we'd like them to keep and farms, but solar doesn't need to take up a huge percentage of available land. Even solar panels on roofs can go a long way.