# How I solved the water heater problem. This page was partially written with the assistance of AI: | AI Facts | Me | ChatGPT | | ----------------------------- | --: | ------: | | Underlying ideas and insanity | 90% | 10% | | Final story and prose | 10% | 90% | ## How it started ![[gas to electric.png]] ↑ The article that started it all This started with a water heater. Bay Area regulators eventually want gas water heaters replaced with electric ones, and mine is a gas tankless unit that I had installed only a couple of years ago. That seemed annoying. Electricity here is expensive, the heater is efficient, it works perfectly well, and it has shown no particular interest in becoming obsolete. The obvious answer was to keep it. A decent gas tankless water heater can last 15 to 20 years, sometimes longer, especially if you maintain it. Mine is nearly new, so if I descale it periodically and repair things as they fail, it could plausibly still be hanging there sometime in the 2040s. This was clearly the sensible answer. I kept thinking about it anyway. ## The strategic reserve My next thought was: if one gas water heater is good, maybe three would be better. Install several while they are still allowed, use one, and keep the others around for later. There is a certain Cold War logic to this. Someday, when everyone else is replacing failed water heaters with whatever the approved technology is at the time, I could quietly put another gas unit into service. Unfortunately, appliances age even when they are not doing much. Electronics fail. Rubber seals harden. Warranties expire. And installing three gas water heaters means gas capacity, venting, drains, permits, wall space, and a plumber eventually asking why there are three of them. "What exactly are you trying to accomplish?" "Energy sovereignty." Still, this seemed pretty reasonable compared with where things went next. ## The hole The Earth is hot inside. So why not just drill down and get the heat directly? I was thinking something like a 1,000-foot hole. At that depth, though, the rock would probably only be modestly warmer than the surface. Instead of finding a cavern full of flaming rocks, I would spend tens of thousands of dollars reaching something roughly the temperature of a tepid swimming pool. To get naturally hot water, I would need to go a lot deeper. Technically possible. Also starting to feel like an overreaction. ## Space-based solar water heating Then I started wondering whether you could just reflect more sunlight onto the house. This took about thirty seconds to become: put a giant mirror on a satellite. The satellite would track the house and focus sunlight onto a boiler in the backyard. No gas bill. No electric bill. Just free sunlight arriving from space. There were some details. Satellites move very fast. The Sun is not a point source. Clouds exist. Launching large precision mirrors into orbit costs rather more than replacing a water heater. Tracking would also be important, since missing the boiler by a few feet could get interesting. Eventually it became apparent that I had reinvented solar thermal heating while adding a rocket. Putting the mirror on the roof accomplished almost the same thing. This was disappointing. ## The teenager array Then I remembered that people generate heat. A person sitting around gives off roughly 100 watts. Teenagers presumably produce at least that much, and probably more under certain emotional conditions. Twenty teenagers in a room would therefore give me a few kilowatts of thermal output. All I needed was a heat exchanger. The basic setup would be a room full of adolescents, with a heat pump pulling their body heat out of the air and transferring it into the hot-water tank. Output could probably be increased through: - romantic disappointment, - parental injustice, - college admissions, - Wi-Fi outages, - and someone using the wrong tone. This system even had demand response. Unfortunately, once I started thinking about the cost of feeding twenty teenagers, PG&E suddenly looked fairly competitive. ## The office battery Then came the first genuinely good bad idea. Electricity at the office is free. Electricity at home is expensive. Electricity can be moved. So I could bring a giant battery to work every morning, charge it under my desk, wheel it back to the car at night, and use it to power the house. The only real problem was that the battery would weigh several hundred pounds and be difficult to pass off as a laptop accessory. "What's that?" "Phone charger." At that point I was basically moving an industrial battery back and forth every day. Then I realized civilization had already solved this problem. It is called an electric car. Charge the EV at work. Drive it home. Plug the house into it. Run the house overnight. Go back to work and recharge. The disturbing part was that this one actually seemed workable. All I needed was the right EV, bidirectional charging equipment, and enough confidence to explain that I was not stealing electricity, merely commuting with it. Anyway, then I remembered the wind turbines at Altamont. ## The Altamont solution Not a little residential wind turbine. A real one. The big ones. A modern utility-scale turbine can produce several megawatts. My house averages only a few kilowatts. So one turbine would be enough for the house, the water heater, the cars, the air conditioning, the geothermal drilling rig, the satellite control system, and probably a few hundred neighbors. There would be some practical issues. The tower would be hundreds of feet tall, the blades would be longer than the property, the foundation would require an alarming amount of concrete, and getting the pieces here would involve oversized trucks and a very large crane. City planning might have some questions. The neighbors would definitely have questions. On the other hand, the water-heating problem would be solved permanently. In fact, I would be generating so much electricity that I could sell the excess back to the grid. Which meant I had started this whole exercise because I did not want to pay PG&E and had somehow ended up considering becoming one of its competitors. There was still one option left. ## The attic reactor If all of this renewable-energy infrastructure was getting too complicated, perhaps I was solving the wrong problem. Maybe I did not need a battery, a deeper hole, a bigger wind turbine, or a mirror in orbit. Maybe I needed a nuclear power plant in the attic. Nuclear fuel is extremely energy-dense. The reactor could run day and night. Weather would not matter. It could heat all the water I could possibly use and power the rest of the house at the same time. There were, admittedly, implementation details: shielding, cooling, containment, control rods, steam handling, structural reinforcement, emergency systems, a turbine generator, radiation monitoring, and a regulatory framework somewhat more demanding than a water-heater permit. There would also be the matter of explaining to the building inspector why there was a reactor vessel above the guest bedroom. "It's for the shower." The insurer might have some questions too. The neighbors, by this point, had probably stopped asking. Still, in pure engineering terms, the attic reactor had one major advantage over every previous idea: It would definitely make enough hot water. At this point I looked back at the gas tankless water heater, which was still hanging on the wall and working perfectly well. I should probably just descale it. ∎