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Comment by GaelFG | Hacker News Reader

"So using electricity instead of natural gas in your home is wasteful." I (genuinely) wonder if what's true. I remember thinking the same things about electric car "how can burning fuel in a factory, storing it, send it thought line for kilometers and then store them in a car batteries and then feed the motor be more efficient than burning fuel directly in the motor" and was proven false. Assuming we aldready have the electric lines of course. (I also dont know the ergy waste of packaging the gaz in usable bottle, move them and retrive them, I assume it's significant, maybe i'm wrong).

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If you're burning fuel for power that's one thing, but you don't get any conversion losses at all if you're burning it for heat underneath/inside the thing you want to be hot.

You're not losing any if you're burning it inside the thing you want to heat (your home). You definitely lose a lot if you're burning it underneath the thing you want to heat (a pan on the stove); a lot of the heat goes around the pan. Just feel the air above the pan. All of that is wasted heat.

I could see gas being less efficient at heating a pan since it's using convection in an uncontained space.

What I was getting at was the fact that with electric, you're burning the gas inside a heat engine to generate power first, so right off the bat your best outcome is the Carnot limit.

The modern power plants with combined cycle have an efficiency of up to 65%.

The power plants with heat cogeneration have an efficiency of up to 80%.

I doubt very much that even half of the energy consumed by burning gas ends inside the cooking pot in most cases.

Regardless of the energy efficiency or pollution risk of gas stoves, there are people who prefer other cooking methods just because they like their results better.

Even if I have a gas stove and I continue to pay for gas as if I would use it, because I live in a condo and there is no individual metering, I have stopped using the gas stove several years ago.

An electric motor is more efficient mostly because of regenerative braking. Not having an engine with variable RPM helps.

They should make a car that's basically a generator charging a medium sized battery, and everything else is electric. (Don't directly power the wheels from the engine, that makes things too complicated.)

Kind of like a diesel-electric train, but with a battery to capture energy from regenerative braking, and for surge power.

No, the regenerative breaking isn't the reason why electric vehicles are more efficient. Traditional ICE are very inefficient, only converting 20% of chemical energy to kinetic energy (with the rest being turned to heat). Diesels are a better at 40%. (modern ccs gas power plants get to 65% from gas to electricity)

Electric motors in cars are approx. 90% efficient. Combined with charging losses and others, that comes out to approx. 70%-80%.

Regenarative breaking only adds an additional ~20%.

Isn’t that just a series hybrid?

Yes, that's exactly what that is, and apparently there are none for sale.

There must be a reason why not, but I don't know what it is.

Chevy had one called the Volt, but ended production in 2019.

From Wikipedia:

“In 2018, General Motors decided to end production in March 2019. The primary reason given was that the Volt is a sedan, and sales of traditional sedans were in decline. Car salesmen were proving resistant to selling the car because it was more complicated (and thus took more of their time) to explain how the vehicle operated. Marketing trends showed that sales of hybrids were dropping as more customers were turning to all-electric vehicles like the Chevrolet Bolt. The range-anxiety associated with all-electric vehicles had been in decline due to better battery technology, and most hybrid drivers were turning on their gas-powered engines less frequently. The battery technology developed for the Volt had already been incorporated into the Bolt.”

It's not very efficient, certainly not enough to be "better" than a conventional IC-engined car.

You're carrying around a lot of batteries, motor, and generator that are basically just dead weight. A petrol engine and gearbox is light.

In trains it works quite well because you need an immense amount of torque to pull away, proportionately far far more than you need from even a large truck, and then you need a relatively small amount of power to keep it moving. Having a big generator driving bogey-mounted traction motors with simple reduction boxes means you don't need a huge gearbox and very complicated driveshaft system, and you don't care so much about weight.

I've seen this series-hybrid system also used in buses in my town. I'm not a mechanical or electrical engineer, but as far as I understand, the advantage in this scenario is that the motor can run nearly continuously at lower RPM where it is apparently more efficient. The spike in power usage that's needed during acceleration is then handled by the battery acting as a buffer.

It isn't efficient exactly but it can make financial sense depending on the cost of electricity. Efficiency is not the only metric and needs to be balanced with other issues. An ice engine may be less efficient than a turbine but that does not mean you put a turbine in a pickup truck.

> but it can make financial sense depending on the cost of electricity.

Don't forget to price in carbon emissions and the cost of pollution.

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