A study found that waste heat generated by a city’s worth of air conditioners during a heatwave can raise the outside temperature by more than 2 degrees Celsius.
All power ends up as heat. Blender: electric -> kinetic -> heat. Toaster: electric-> heat. Computer: see toaster. Hydropower storage pump: heat + potential now -> heat + electricity later. Chemical battery: heat + potential now -> heat+ electricity later. Whatever work gets done electrically or otherwise, the result of that work eventually dissipates its excess energy as heat. How much energy is required to drive 2000 miles at 60 mph? Ideally the same as driving 20 miles at 60 mph, the difference is lost to heat in the air, tires, road, engine components.
Not to mention the power grid bleeds heat as well, a lot of it.
Air conditioners are just icing on the cake because they extract heat from tiny boxes and boot it out into the environment, burning excess power in the process. Heat pumps are a miracle of thermodynamics that actually use less power than the heat they add to a tiny box. Heat pumps cool the city, air conditioners heat it up. Both do work that evaporates almost immediately after it is done, so they have to always run.
Basically the hobbits had it right all along, just build a few feet underground and you’re good
So AC is bad but heat pumps are better ? Can waste heat be used for something else ? Heating greenhouses ? Pumped into water to dissipate the excess heat or used to create steam for turbines ?
Yes! There are plenty of uses for excess heat, especially if you like having hot water on tap, but it’s really difficult to capture or store waste heat, mostly because if the heat is available where it is needed, like the heater of a car in a cool day, it’s not waste heat at all. There is a point where the difference in temperature between the waste heat source and the environment is large enough that it could be used to create electricity, but usually it’s not worthwhile and the equipment needed would would be better used with a dedicated heat source or not at all. I dream of a day when we develop ways to harvest energy from heat more efficiently and can use waste heat for power.
All power ends up as heat. Blender: electric -> kinetic -> heat. Toaster: electric-> heat. Computer: see toaster. Hydropower storage pump: heat + potential now -> heat + electricity later. Chemical battery: heat + potential now -> heat+ electricity later. Whatever work gets done electrically or otherwise, the result of that work eventually dissipates its excess energy as heat. How much energy is required to drive 2000 miles at 60 mph? Ideally the same as driving 20 miles at 60 mph, the difference is lost to heat in the air, tires, road, engine components.
Not to mention the power grid bleeds heat as well, a lot of it.
Air conditioners are just icing on the cake because they extract heat from tiny boxes and boot it out into the environment, burning excess power in the process. Heat pumps are a miracle of thermodynamics that actually use less power than the heat they add to a tiny box. Heat pumps cool the city, air conditioners heat it up. Both do work that evaporates almost immediately after it is done, so they have to always run.
Basically the hobbits had it right all along, just build a few feet underground and you’re good
Thanks for this elaborate explanation. It was fun to read. :)
So AC is bad but heat pumps are better ? Can waste heat be used for something else ? Heating greenhouses ? Pumped into water to dissipate the excess heat or used to create steam for turbines ?
Any other good use for excess heat ?
Yes! There are plenty of uses for excess heat, especially if you like having hot water on tap, but it’s really difficult to capture or store waste heat, mostly because if the heat is available where it is needed, like the heater of a car in a cool day, it’s not waste heat at all. There is a point where the difference in temperature between the waste heat source and the environment is large enough that it could be used to create electricity, but usually it’s not worthwhile and the equipment needed would would be better used with a dedicated heat source or not at all. I dream of a day when we develop ways to harvest energy from heat more efficiently and can use waste heat for power.
Well it sounds like it’s either we hear the environment or spend lots on capturing that waste heat
Don’t get me wrong, there is no way to capture waste heat, it’s going out into the environment somehow