> OK, the race is over, and I’ve announced two winners – public transport, and electric vehicles.
He was also very positive about heat pumps.
https://www.withouthotair.com/c20/page_131.shtml
> You’ve shown that electric cars are more energy-efficient than fossil cars. But are they better if our objective is to reduce CO2 emissions, and the electricity is still generated by fossil power- stations?
> This is quite an easy calculation to do. Assume the electric vehicle’s energy cost is 20 kWh(e) per 100 km. (I think 15 kWh(e) per 100 km is perfectly possible, but let’s play sceptical in this calculation.) If grid electricity has a carbon footprint of 500 g per kWh(e) then the effective emissions of this vehicle are 100 g CO2 per km, which is as good as the best fossil cars (figure 20.9). So I conclude that switching to electric cars is already a good idea, even before we green our electricity supply.
So electrification alone can't bring so large reductions in total energy consumption - it is simply one of the prerequisites for that, and it also needs to be accompanied with large scale build-up of non-fossil electricity, of renewables or nuclear.
Those are two separate things - electrifying some transportation need gets us X benefit, and converting some electric generation from fossil fuels to solar gets Y benefit, but the former doesn't automagically create the latter.
2) You are assuming there is no curtailment or rejection of wind, solar, and nuclear, which is categorically false. This is why there are time-of-day rates that vary so drastically. There are large amounts of renewable/low-carbon energy that would otherwise be wasted in pretty much every geography.
If I turn on (or keep on) my light when usage isn't completely covered by renewables, should that be calculated as using all fossil fuels?
The logical extension is that everyone should calculate the carbon intensity as a binary choice which is obviously wrong.
The only reasonable way to go is to look at the actual carbon intensity average.
Probably storing.
Give it 50 years and we're going to be facing some other unexpected global disaster from unchecked battery proliferation.
Hopefully it's less dire than climate change though.
> If you consider the energetic content of the gas burned in a car, then you need to measure the same thing for the EV
This is largely because
1.) big stationary heat engines are much more efficient than small weight-optimized mobile ones, and
2.) the electricity grid also has some renewable energy mixed in, so a growing fraction of the electricity supply doesn't even need an (energetically imperfect) heat engine.
Additionally, the parent overlooks that while a lower number is estimated, they compare against a hypothetical 2000+ TWh number instead of the tightest 900 TWh estimate.