(Updating my previous note with insightful comments on this post) A heat pump conjures up an image of an appliance, but it is a principle of physics. Heat can

(Updating my previous note with insightful comments on this post) A heat pump conjures up an image of an appliance, but it is a principle of physics. Heat can be created by burning fuel or electric resistance. Cold can't be created. Cold is the lack of heat. Cold is 'created' by removing heat. Fridge keeps the inside cool by moving heat from inside and dumps it outside. This movement of heat is called a heat pump (pumping heat in a specific direction). If we can use a heat pump for creating cold, we can also create heat by pumping heat in the opposite direction. We always have heat in the environment until we get to 0 degree Kelvin. Which means we can have a heat pump water heater in the garage. Or a heat pump furnace. Creating heat from fuel/resistance is at most 100% efficient (most likely a LOT less). Heat pumps are 400% - 500% efficient per unit of electricity, because the idea is just to move heat. In one direction, or another. Indoor air quality is just as bad as outdoor air pollution, because we use natural gas for heating and cooking. Anything that burns creates particulate matter. Most homes are closed spaces, the particulate matter never escapes. Cooking can be done by induction, infrared or electric resistance. Heat pumps replace natural gas water heaters and furnaces. We don’t need to build natural gas pipeline infrastructure to every home, which probably costs million(s)/mile. Household energy bills are fragmented: 2 gas cars, natural gas for cooking, water heater and furnace, and electricity for everything else. EVs replace gas cars. Cooking by induction, and heat pumps replace heating appliances. Now, all the uses of energy are electric. Instead of spending ~$1000+ on 3 different types of energy bills, it creates a clear picture of total electricity consumption. This consolidation makes people think about their energy and how to make the bills disappear. Then they can install solar and make the entire energy bill zero. Forever. With heat pumps, we gain ~5X efficiency, solve indoor air pollution, save on natural gas infrastructure capex, make everything electric, and let people save money. While getting close to net zero. Heating and cooling are also very important for demand shifting. Because of thermal mass (and inertia), heating and cooling can be done when energy is cheapest (which is the cleanest source). If heating and cooling is all electric, smart appliances can connect to the grid and figure out when to use energy. The cost savings of going all electric are going to be significant. There is not only an immediate reduction, but with demand destruction, the price of oil is going to fall precipitously. Oil is priced at the margin, based on demand. If demand is high, people are willing to pay whatever price and costlier sources of extraction (shale, fracking, etc) become profitable. With low demand, Saudi Arabia can supply the world at $10/barrel. There is a small problem with heat pumps though. It's the refrigerant used to transfer the heat. These are mostly synthetic chemicals. Historically, these were Chlorofluorocarbons (CFCs). CFCs cause ozone depletion and have a high GWP of 14,400. What is GWP? CO2 is a warming gas that has Global Warming Potential (GWP) of 1 (the standard). Earth radiates heat back into the atmosphere (exactly the same as it gets from the Sun) and CO2 acts as a barrier for the radiated heat from earth, retaining heat in the atmosphere and warming the planet. Why Greenhouse Gases Make the Planet Warmer: https://www.youtube.com/watch?v=AIBk0pGV_BQ https://www.youtube.com/watch?v=AIBk0pGV_BQ But, there are lots of other gases that have higher GWP. Hydrofluorocarbons, perfluorocarbons, sulfur hexafluoride, and nitrogen trifluoride are synthetic gases used for refrigeration (maybe other applications). These new engineered chemicals replaced CFCs, which were causing ozone depletion. But they have high GWP. HFCs: up to 12,400, PFCs: up to 11,100, NF3: 16,100, SF6: 23,500 (https://www.epa.gov/ghgemissions/fluorinated-gas-emissions https://www.epa.gov/ghgemissions/fluorinated-gas-emissions) HFOs break down and produce trifluoroacetic acid (TFA), which is a PFAS. PFAS rains back down, is a forever chemical and bioaccumulates. (vel0city: https://news.ycombinator.com/item?id=49645555 https://news.ycombinator.com/item?id=49645555) There are billions without ACs. They are all going to buy them. It is better if we figure out better refrigerants. And all refrigerants leak. These will cause problems. Many heating/cooling appliances need to be recharged with refrigerants once in a while. There seem to be several workable alternatives: CO2, isobutane, propane, ammonia. Water is used for district heating. In the middle-east, there is district cooling with water and ammonia. CO2 is a terrific refrigerant because it has GWP 1 and leaking of CO2 is perfectly okay. With 40 - 60 billion tons of CO2 from fossil fuels, CO2 leaks from refrigerants are less than a rounding error. Why aren’t we using CO2? (bronson: https://news.ycombinator.com/item?id=49645996 https://news.ycombinator.com/item?id=49645996) It's because CO2 has to be run at more extreme temperatures and pressures, fine for factory-made connections inside a single unit but a showstopper for field joints.