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> It’s easy for a typical US family of four to net produce electricity with about 800-1000 sq ft of solar panels, assuming all electric appliances and vehicles

> It’s easy for a typical US family of four to net produce electricity with about 800-1000 sq ft of solar panels, assuming all electric appliances and vehicles (with reasonable commutes). The EV’s are basically rolling powerwalls, so this solves the storage problem. Not really. Our solar array is almost 900 square feet (4 x 20 meters). However, most people, even those with solar, have a misconception about the realities of solar power. This, because most people don't have technical backgrounds and never really look at their systems analytically. And, BTW, most arrays are significantly smaller than this one. For example, this is what the array can look like on a good day: https://i.imgur.com/aNnbmDp.png https://i.imgur.com/aNnbmDp.png This is what it can look like during a cloudy day: https://i.imgur.com/breTHQd.png https://i.imgur.com/breTHQd.png Yes! Those are white puffy clouds in sunny southern California! I have posted the math here on HN in detail in the past. The idea of using your EV as a battery simply will not work on multiple fronts. One of the most basic problems is that you'd age your battery prematurely by adding charge/discharge cycles. Need to travel somewhere? Too bad, your battery is down to 25% because it was powering your home. The reality of the situation is that you need many times the storage that an EV is able to provide in order to deal with the unreliability of solar production. If I remember correctly, when I did the math for our system, the conclusion was that we would have to triple the size of the array and have over 400 kWh of storage in place. The effects of unpredictable weather events and just plain clouds during otherwise beautiful sunny days makes this problematic. We had a particularly rough set of days in January of 2023 (and other times, I just have screen grabs for that period): https://i.imgur.com/bo0s7b0.png https://i.imgur.com/bo0s7b0.png It is quite sobering to do the math for what it would take to mitigate this. Adding EV's to charge at home to this equation makes it even worse. > Some of the direct air capture systems rely solely on industrial processes that we know how to scale. When you add-up the realities of manufacturing (which in some cases might include mining), transportation, construction, deployment, operations and maintenance, not one system has yet surfaced that can conclusively operate beyond the lab or, at best, a small test area (like a small farm patch). It is quite a different matter to operate at a the scale of a city, province/state, country and globally. I'd love for it to work, but, so far, everything is in the category of a fantasy. We should focus on cleaning-up our act. Nature will take care of the planet over time. I think I can say that hurricanes and large storms are probably the largest carbon capture mechanism. This is how the planet handles the problem. So, yeah, places like Florida might need to adapt to more intense weather for the next few hundred years. That's just an unavoidable fact as far as I am concerned and until proven otherwise. There are realities that are inconvenient and nobody wants to discuss. Current example: The effect of the fires in Australia. https://apnews.com/article/wild-fires-australia-victoria-d3ffa3454c942eb5d29b618e702c4373 https://apnews.com/article/wild-fires-australia-victoria-d3f... So far, 55K hectares burned and no stop in sight. At 130 tons of CO2 per hectare, that's over seven million tons. Passenger cars in the entire US produce approximately 370 million tons PER YEAR. In other words, in just a few days, a single fire in Australia generated approximately 2% of the CO2 produced by vehicles in the US during an entire year. There are thousands of massive fires around the world, including mine fires that have been burning for hundreds of years. Which means that this idea of achieving net zero or capturing enough CO2 from the atmosphere through technical means is, well, simply not reasonable. As I like to put it, even if all of humanity left this planet it would still take 50K to 100K years for a 100 ppm drop in CO2...because this isn't a lab experiment, it's a planet-scale problem.

kragen 2y ago
> When you add-up the realities of manufacturing (which in some cases might include mining), transportation, construction, deployment, operations and maintenance, not one system has yet surfaced that can conclusively operate beyond the lab or, at best, a small test area (like a small farm patch). In https://news.ycombinator.com/item?id=42425985 https://news.ycombinator.com/item?id=42425985 I corrected you the last time you made this false claim, providing verifiable calculations on lime burning, the simplest system that can conclusively operate beyond the lab, though possibly not the cheapest. So I'm surprised to see you repeating the same false claim again in a different thread. > I have posted the math here on HN in detail in the past. Links to the math you've posted previously to HN (rather than bare assertions that it exists) would be appreciated. If it's correct, it will inform others; if it's incorrect, the correction will inform you. > The idea of using your EV as a battery simply will not work on multiple fronts. One of the most basic problems is that you'd age your battery prematurely by adding charge/discharge cycles. Battery aging has cost, but grid-scale energy storage has value. It isn't sufficient to establish that the cost exists; you must establish that it exceeds the value provided. As we'll see below, the value is typically about five times the cost. > The reality of the situation is that you need many times the storage that an EV is able to provide in order to deal with the unreliability of solar production. Again, I'd like to see your calculations. The Tesla Model Y's LFP battery capacity is supposedly 60 kilowatt hours, and a house averages about a kilowatt, only a small fraction of which needs to be active at night, perhaps 250 watts. So I think an EV provides about 240 hours' worth of nighttime backup power, but only needs to provide about 18 hours' worth. So, rather than needing many times the storage that an EV is able to provide, an EV is able to provide many times the storage you need. LFP batteries are particularly good on the wear-and-tear front, lasting around 5000 cycles. The car costs US$50k, so if we junk the car when the battery wears out, each cycle costs about US$10, about 17 cents per kilowatt hour. This is enormously more expensive than solar energy but still cheaper than grid power in many places. In California it's about half the cost of grid power. However, evidently replacing just the battery costs only US$10-15k: https://old.reddit.com/r/TeslaModelY/comments/1cf1fkr/how_much_is_it_to_replace_a_battery_on_a_2023/ https://old.reddit.com/r/TeslaModelY/comments/1cf1fkr/how_mu... which means each cycle only costs about US$2.50, 4 cents per kilowatt hour. So if otherwise you'd be paying 24 cents per kilowatt hour from the grid, the net value from draining your Tesla battery is about 20 cents per kilowatt hour. Other companies such as BYD, which outsells Ford, Honda, and Tesla, have even cheaper batteries. > we would have to triple the size of the array and have over 400 kWh of storage in place. Where are you getting that? It sounds like you want weeks' worth of energy, not nights' worth. Batteries aren't a practical way to store weeks' worth of power. That doesn't make them useless. > 55K hectares burned and no stop in sight. At 130 tons of CO2 per hectare, that's over seven million tons Burning forests is, counterintuitively, carbon-neutral. The carbon in the forest had been removed from the atmosphere previously, and when the forest grows back, it will be removed from the atmosphere again. Only long-term changes in land use affect the greenhouse effect over more than a few years.

kragen 2y ago

> When you add-up the realities of manufacturing (which in some cases might include mining), transportation, construction, deployment, operations and maintenance, not one system has yet surfaced that can conclusively operate beyond the lab or, at best, a small test area (like a small farm patch). In https://news.ycombinator.com/item?id=42425985 https://news.ycombinator.com/item?id=42425985 I corrected you the last time you made this false claim, providing verifiable calculations on lime burning, the simplest system that can conclusively operate beyond the lab, though possibly not the cheapest. So I'm surprised to see you repeating the same false claim again in a different thread. > I have posted the math here on HN in detail in the past. Links to the math you've posted previously to HN (rather than bare assertions that it exists) would be appreciated. If it's correct, it will inform others; if it's incorrect, the correction will inform you. > The idea of using your EV as a battery simply will not work on multiple fronts. One of the most basic problems is that you'd age your battery prematurely by adding charge/discharge cycles. Battery aging has cost, but grid-scale energy storage has value. It isn't sufficient to establish that the cost exists; you must establish that it exceeds the value provided. As we'll see below, the value is typically about five times the cost. > The reality of the situation is that you need many times the storage that an EV is able to provide in order to deal with the unreliability of solar production. Again, I'd like to see your calculations. The Tesla Model Y's LFP battery capacity is supposedly 60 kilowatt hours, and a house averages about a kilowatt, only a small fraction of which needs to be active at night, perhaps 250 watts. So I think an EV provides about 240 hours' worth of nighttime backup power, but only needs to provide about 18 hours' worth. So, rather than needing many times the storage that an EV is able to provide, an EV is able to provide many times the storage you need. LFP batteries are particularly good on the wear-and-tear front, lasting around 5000 cycles. The car costs US$50k, so if we junk the car when the battery wears out, each cycle costs about US$10, about 17 cents per kilowatt hour. This is enormously more expensive than solar energy but still cheaper than grid power in many places. In California it's about half the cost of grid power. However, evidently replacing just the battery costs only US$10-15k: https://old.reddit.com/r/TeslaModelY/comments/1cf1fkr/how_much_is_it_to_replace_a_battery_on_a_2023/ https://old.reddit.com/r/TeslaModelY/comments/1cf1fkr/how_mu... which means each cycle only costs about US$2.50, 4 cents per kilowatt hour. So if otherwise you'd be paying 24 cents per kilowatt hour from the grid, the net value from draining your Tesla battery is about 20 cents per kilowatt hour. Other companies such as BYD, which outsells Ford, Honda, and Tesla, have even cheaper batteries. > we would have to triple the size of the array and have over 400 kWh of storage in place. Where are you getting that? It sounds like you want weeks' worth of energy, not nights' worth. Batteries aren't a practical way to store weeks' worth of power. That doesn't make them useless. > 55K hectares burned and no stop in sight. At 130 tons of CO2 per hectare, that's over seven million tons Burning forests is, counterintuitively, carbon-neutral. The carbon in the forest had been removed from the atmosphere previously, and when the forest grows back, it will be removed from the atmosphere again. Only long-term changes in land use affect the greenhouse effect over more than a few years.