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Comment by simplyinfinity | Hacker News Reader

The city i live in Sofia, just got 20 electric busses [0], and are planning to bring 142 new LPG (propane) busses. This is a big deal! However, given that about half of the country's electricity is still from coal, not sure how "clean" those busses really are. (30-35% is from Nuclear power)

[0] https://sofia.bg/web/sofia-municipality/start/-/asset_publis...

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There are still 2 basic sources of benefit. First, power stations generally use turbines which are much more efficient than internal combustion engines. Even after accounting for inefficiencies electric often comes out better. The other benefit is that it decouples the vehicle from the energy source.

Third, it moves the pollution out of the city center.

But minus points because transfering the energy and storing it in a battery loses some.

Still, China is probably completely content with getting the pollution out of the city.

That should be "China content with getting the pollution out of the tier 1 city". Those old diesel buses were probably moved to some tier 2 or 3 city to replace an even older fleet.

Isn't that exactly what they should do?

An internal combustion motor is radically less efficient than power lines when comparing input to input.

Transmission loses 1-2%, batteries lose maybe 5%. Compare that to 30% losses for an ICE, above generator losses.

30% is the efficiency of the energy in fuel being turned into work.

You need to consider the efficiency of the power generation, power lines, battery and then the electric motor. Any other comparison is misleading.

And gasoline has efficiency of exploring, pumping, refining and transferring it (tankers, pipelines, trucks to the gas station)

Correct that his is thermal efficiency, and I apologize for not breaking into out earlier.

An ICE is ~20% efficient.

A combined cycle gas turbine is ~60% efficient, transmission systems ~98%, LiIon ~99%, motors around 85-90%. The first is thermal, the rest are electrical. Well-to-wheel this is about 50%.

My point was just that you really do get a large efficiency improvement (50 - 20 = 30) by electrifying cars. Climate argument aside, energy is simply being wasted.

I don't see how hiding your pollution is helpful, in fact it may do the opposite as it allows people to delude themselves into thinking they are living a 'green' life. I already see this sentiment a lot, of people believing living in a city makes them 'greener' because they can't see the pollution their daily life creates everywhere else to supply them.

You can clean the emissions, using carbon capture etc, much easier in a power plant, even a coal one.

moving pollution far away means people don't have to breath dirty air which leads to all the obvious health problems which cost society

> The other benefit is that it decouples the vehicle from the energy source

until, you run out of the juice (electricity)

Large coal plants are more efficient than internal combustion; electric drivetrains are more efficient than gasoline or diesel.

Slow, frequently stopped vehicles like buses derive the maximum benefit from electrification.

And their emissions improve automatically as the grid improves. You could easily schedule bus recharging to occur during maximum solar electricity generation times, as it falls between morning and evening peak times. Each bus in the fleet just needs one hour downtime in the middle of the day to recharge; that’s only a 25% downtime ratio across a 4 to 5 hour window of opportunity.

> Large coal plants are more efficient than internal combustion

Wish more people know about this.

In _all_ parts of the US, electric buses would cut emissions compared to diesel buses[1]. I suspect in Sofia, it would absolutely be a reduction in emissions.

[1] https://www.ucsusa.org/news/press_release/study_finds_electr...

Another benefit: it is much easier for power plants to remove sulphur and nitrogen based pollutants and organic particles due to imcomplete combustion from emission. Those pollutants are much more harmful than CO2.

The potential for a gas powered bus to become "clean" is nonexistent. They will always run on 0% clean energy.

The potential for those electric buses is completely maximized. They likely run on greater than 0% clean energy now, and can potentially run on 100% clean energy in the future.

The difference could not be more stark or significant.

It's a lot easier to get natural gas to burn down to CO2 and water than it is to get diesel to do so. You might be conflating 'clean' ( = minimal harmful emissions) with 'renewable'?

Agree that electric is the way to go for both goals, though - EVs are as clean and as renewable as their power generation method.

Natural gas powered buses are already pretty clean, it’s the ones running diesel that are a problem. Though I guess NG has issues with green house emissions if not what in what we would call air pollution.

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