This is no longer correct. We have heat pumps that can be more than 100% efficient, even air-sourced heat pumps in -30° weather. There are still many places where this will still be more expensive than a gas furnace.
Oh, probably because it's cheaper and more efficient.
If you wanted to use the gas in a gas power plant to produce electricity to run an electric heater, there's a bunch of steps where energy gets lost. The turbine and generator isn't 100% efficient and the transformers and transmission wires lose energy along the way to your house. Whereas burning something directly for heat is nearly 100% efficient, the only waste is whatever heat gets carried away by the exhaust. Which isn't much with a modern high-efficiency furnace. I've got one of those and every once in a while I knock icicles off of the exhaust vent outside when I pass it. They use countercurrent exchange to keep all the heat inside the house.
GreyEyedGhost@piefed.ca 17 hours ago
FaceDeer@fedia.io 17 hours ago
I don't know how you're measuring efficiency, but a heat pump with greater than 100% efficiency lets you build a perpetual motion machine. That's not possible.
GreyEyedGhost@piefed.ca 17 hours ago
You just change the definition of your isolated system. It takes less energy to move heat from one place to another than it does to excite matter to release energy. For resistive or combustion heating, the isolated system is your house, plus the gas if using gas heat. For heat pumps, you include the rest of the world.
As an aside, heat pumps are generally considered good when they reach 300% efficiency, i.e., when every watt of energy expended adds 3 watts of heat to your home.
assembly@lemmy.world 1 day ago
Ahhhh. That makes sense. I guess I had always assumed that it would be more efficient to have one centralized “burning of the gas” event to create and distribute electricity than numerous individual burning events to create heat but it makes sense that due to the efficiency of just converting gas to heat directly it would be more efficient.
FaceDeer@fedia.io 1 day ago
There are some cities that do things a third way; they have a centralized facility that burns the gas (or other fuels) to generate electricity, and then also pipe the heat out to the city in the form of heated water or steam running through insulated underground pipes. Buildings tap into those pipes and run it through radiators. That has the potential to be even more efficient because you're using what would otherwise be "waste" heat, but it depends on a relatively compact city to avoid losing too much heat while sending it through the pipes. I understand this is not uncommon in Eastern European and Russian cities. I'm not familiar with the details, though, so if you want to know more about this I'd recommend Googling around a bit.
Fondots@lemmy.world 20 hours ago
New York has one of, if not the largest steam systems like that. A pretty significant chunk of Manhattan is hooked up to it.
Although it should be pointed out that those systems aren’t without their own risks, there have been a handful of pretty bad explosions and such caused by that steam system. Not saying to knock it, any system where you’re trying to distribute a large amount of energy has the potential for some catastrophic accidents to happen, it’s all about weighing the relative pros and cons.
They’re also pretty common on a smaller scale for college campuses, industrial complexes, etc. places with a lot of different outbuildings and such, it can be easier/cheaper/more efficient to have one central boiler room/house and pipe steam around than it is to have heaters in ever building.
Also, bit of a tangent, but many moons ago my dad was a pipefitter/steamfitter, and worked with a lot of steam systems, and from what he’s told me about those days it sounded like absolute hell having to go into cramped service tunnels around searing hot steam pipes, all kinds of dust and asbestos everywhere, rats, high humidity, etc. that was probably almost 50 years ago, but I suspect things probably haven’t improved all that much since then, so kudos to the people who are willing to put up with all of that.