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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

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_publisher/HMYVGw6PDFKh/content/twenty-electric-buses-meeting-the-highest-euro-6-emission-standards-are-running-in-sofia https://sofia.bg/web/sofia-municipality/start/-/asset_publis...

yincrash 8y ago
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_electric_buses_cleaner https://www.ucsusa.org/news/press_release/study_finds_electr...
sjwright 8y ago
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.
- ychen306 8y ago
  > Large coal plants are more efficient than internal combustion Wish more people know about this.
flogic 8y ago
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.
- sgc 8y ago
  Third, it moves the pollution out of the city center.
  - qznc 8y ago
    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.
    - vorg 8y ago
      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.
      - JshWright 8y ago
        Isn't that exactly what they should do?
    - shiftpgdn 8y ago
      An internal combustion motor is radically less efficient than power lines when comparing input to input.
    - blake1 8y ago
      Transmission loses 1-2%, batteries lose maybe 5%. Compare that to 30% losses for an ICE, above generator losses.
      - jondumbau 8y ago
        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.
phil248 8y ago
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.
- taneq 8y ago
  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.
- seanmcdirmid 8y ago
  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.
majia 8y ago
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.

yincrash 8y ago

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_electric_buses_cleaner https://www.ucsusa.org/news/press_release/study_finds_electr...

sjwright 8y ago

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.

ychen306 8y ago
> Large coal plants are more efficient than internal combustion Wish more people know about this.

flogic 8y ago

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.

sgc 8y ago
Third, it moves the pollution out of the city center.
- qznc 8y ago
  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.
  - vorg 8y ago
    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.
    - JshWright 8y ago
      Isn't that exactly what they should do?
  - shiftpgdn 8y ago
    An internal combustion motor is radically less efficient than power lines when comparing input to input.
  - blake1 8y ago
    Transmission loses 1-2%, batteries lose maybe 5%. Compare that to 30% losses for an ICE, above generator losses.
    - jondumbau 8y ago
      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.

phil248 8y ago

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.

taneq 8y ago
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.
seanmcdirmid 8y ago
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.

majia 8y ago

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.