Eli5 if electric vehicles are better for the environment than fossil fuel, why isn’t there any emphasis on heating homes with electricity rather gas or oil?

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Eli5 if electric vehicles are better for the environment than fossil fuel, why isn’t there any emphasis on heating homes with electricity rather gas or oil?

In: Physics

A furnace turning fuel to heat is much more efficient than a car engine turning fuel to go power. Therefore, the gains aren’t as evident from going all electric to heat your homes.

Electric heaters are 100% efficient. However, electricity generation is far less than this.

Burning combustible materials for heat is much more efficient than burning them for electricity.

That said, if your electricity comes from renewable sources, it’s better to use electricity. It’s best to use heat pumps rather than resistive heaters (e.g. space heaters), since those can move more heat than the energy they consume (for every watt of electrical power consumed, they can move 2.5-4 watts of heat power from outside to inside).

The useful output of a car engine is kinetic energy (to rotate the wheels), and these engines can transfer ~30% of their input energy (from the gas) to motion. The rest is lost as heat.

The useful output of a furnace is heat, this means that what was previously wasted is actually useful.

So there isn’t too much of a difference in efficiency between electricity and gas heating. The biggest impact to overall efficiency for heating a house is making sure it is insulated as well as possible, so that heat isn’t lost to the outside.

There is, but it’s slower and quieter. You can for sure find people talking about how especially switching to heat pumps will be an important part of limiting climate change. Because they’re just moving heat around instead of creating it, heat pumps can (sort of) be more than 100% efficient. Or at least, you can use 1000 watts of electricity to bring 2500-3000 watts of heat inside.

It’s slower and quieter because cars get replaced much more quickly than houses and apartment buildings do, and probably more quickly than residential climate control systems do. Also, retrofitting heat pumps into homes that weren’t designed for forced-air heating/cooling can be expensive.

In 2040, the housing stock in the US is overwhelmingly going to be the same houses and apartments we have right now, and at least a substantial minority of those places are going to be using the same heating/cooling systems they are right now. But in 2040, the stock of cars driving around will be mostly cars built in about 2030. (unneeded word deleted)

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> why isn’t there any emphasis on heating homes with electricity rather gas or oil?

Isn’t there? Maybe it varies by where you live, but I’ve seen plenty of recommendations to use heat pumps for heating (those operate on electricity). More so than recommendations to drive electric car.

It is done. In French alps they use electricity since the 70s at least, but they use nuclear plants to make electricity.

The new trend is to make electricity on your roof with solar panels (you don’t lose power due to transporting it. Electric lines can lose up to 3%) and tre second step is to use heat pumps instead of electric heaters.

Heat pumps are a lot more efficient than heaters, and they also provide air conditioning in summer.

if you are in the USA, oil and far are so cheap that there is less drive into changing system.

In Europe it is a net gain, you save the planet AND save money.

Electric vehicles aren’t just better for the environment, they’re way more fuel efficient.

When your cars using fuel, the primary byproduct is thermal energy. But your car doesn’t want thermal energy, it wants kinetic energy. So with fossil fuels, a lot of your engine is designed around turning that thermal energy into kinetic energy, and a lot of efficiency is lost.

With an electric car, the energy is applied much more directly.

In a furnace, you have the opposite effect. You want the thermal energy, so there’s no conversion. Since electricity itself doesn’t produce my thermal energy, it’s heating a coil to a temperature and then using constant energy to maintain that temperature.

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A simplified rule of thumb: if you convert heat to motion or electricity, you unavoidably waste about 2/3 of it: only 1/3 gets converted into useful energy. Every other common form of energy conversion is nearly 100% efficient. (These numbers aren’t exact, of course.)

A car turns heat into motion, wasting 2/3 of it as hot exhaust: only 1/3 goes to power the car. A fossil fuel power plant turns heat into electricity, wasting 2/3 of it. If the electricity is used to run an electric car (near 100% efficient) you can see the two are roughly equal. (The electric car comes out ahead because cars are a bit worse than 2/3 and power plants a bit better, and electric cars have access to carbon-free energy.)

But if heat is the goal, it’s different. Burning fuel in a home furnace releases almost 100% of its energy to heat the house. But if we turn it into electricity, 2/3 of the energy is lost at the power plant, and only 1/3 can be used in the home. What a waste!!! This is why electric resistance heat is so expensive.

Where it gets really interesting is heat pumps, which use electricity to push heat into the home from outdoors. These flip the script on the “2/3 rule”: while the power plant uses 3 units of heat to make 1 unit of electricity, the heat pump uses 1 unit of electricity to push at least 3 units of heat — often 5 or 6 or more — into the house. So even if you’re not using green energy sources, heat pumps are a big win.

There is. California is requiring new houses to use electrical appliances, not gas (stoves, ovens, clothes dryers, etc)

Also, gas furnaces are now running over 95% efficient. They are extracting almost ALL of the heat from the fuel they consume. The exhaust can be run through a PVC pipe because it’s so cold. Yes, it creates more carbon, but electrical heating is less efficient, especially considering line transmission loss.

I think it depends on country. Here there is increasing pressure and subsidies to use electricity to heat up homes.

70% of the gas you burn in your car is lost as heat energy, it doesn’t actually help your wheels turn. This is very *inefficient*. Gas burners are not this inefficient so there’s not really a big benefit to using electricity to heat homes.

There is a lot of work on electrifying large parts of the economy going on in conjunction with cleaning up the supply of electricity.

One examples is the progress being made to make heat pumps work in colder and colder places.

So yes electrification is being discussed.

> why isn’t there any emphasis on heating homes with electricity rather gas or oil?

2 big reasons:

1 – Cost effectiveness
2 – Efficiency

Cost Effectiveness:

It is cheaper to burn gas than it is to use electricity. There wouldn’t need to be any social pressures if everyone was acting selfishly and doing what’s cheapest. Gas just happens to be significantly cheaper. By about 50%.

Generally if something is cheaper, it means there are fewer resources used to do it, which means a smaller carbon footprint. Generally the price of something relates to all the things that had to be done to get that product to market.

I.E. Electric cars are more expensive because more industrial activity goes into making them. Off the assembly line, they’re worse for the environment than gas vehicles. Electric vehicles then play catch up, because electricity is generated more efficiently at a powerplant than a gas engine in a car can propel itself, and they eventually in their lifetimes pass gas vehicles for efficiency.

Efficiency:

If your goal is to make heat, the most efficient way of doing that is to directly make heat. Heat is the reason why everything else is not efficient, because some is always lost as heat. If you’re only making heat, ta da, you’re done.

So for your home, if you directly burn natural gas to make heat, it goes like this:

1 – Burn gas in furnace, 2 – House is warm.

But if you heat with electricity, it goes like this:

1 – Burn gas in powerplant to generate electricity (60% efficient). 2 – Transmit power to house (98% efficient). 3 – Run electric heaters. 4 – House is warm.

One additional thing that tips the balance towards electric are “Heat Pumps”. Heat pumps are air conditioners that work backwards. They take advantage of compression to create a heat difference from the ambient temperature, and are more than 100% efficient (not in terms of physics, but they get “free” energy by taking it from the “free” ambient temperature). This is effective when moderate amounts of heat difference are needed, (it doesn’t accomplish much in Canadian winters for example, but Kansas winters would see gains), and in worst case is only as bad as only having an electric heater without a heat pump.

Another consideration is that electricity is as clean as it’s generated. If it’s from solar or hydro, then no gas or oil is being burned. It’s still not cost effective though, which means it’s still net-negative for the environment (until solar power is cheaper, some combination of it requiring resources to have those panels is worse than just burning gas). Solar panels have nearly bottomed out in terms of theoretical maximums for scientific improvements, so there is no change on the horizon there, but they haven’t bottomed out for manufacturing efficiency yet, so there’s still room for improvements to be made.

In the DIY EV scene, because batteries are so expensive (and, by extension, bad for the environment), guys who need heat will install a small diesel heater under the hood instead of wasting precious battery reserves to make heat. It’s amazing how little fuel is needed for heat compared to how mammoth an impact electric heat has on your range.

Depend where you are. In Quebec, the vast majority of available electricity is generated through hydro power and is really cheap compare to the rest of US and some other provinces. Therefore, most houses are heated through resistive heaters. It’s also convenient as you have no central « furnace » and you can easily control temperature on an individual room basis. Also, all appliances are typically electrically powered.

It’s kinda funny because here it’s mostly all heated with electricity. We have big dams that provide plenty of it, so anyone here heating with gas or oil is the odd one out.

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I converted my old house to heat pump a couple years ago, and with my new house I’m planning to install solar panels *and* switch to heat pumps. Eventually, I’ll disconnect the gas line completely.

I also built a small cottage in the back. That was all electric from the start.

My neighbor next door switched to all electric and installed solar panels. Now the power company pays *him* $7000/year.

It’s easier to build an all electric house than to convert an existing house.