4 ms·

Uh...when was the last time you checked on the difference between the efficiency of small and large heat engines? A large Diesel engine is going to be vastly mo

by jhgb 4y ago

Uh...when was the last time you checked on the difference between the efficiency of small and large heat engines? A large Diesel engine is going to be vastly more efficient than a small one, for example: > Passenger car diesel engines have energy efficiency of up to 41% but more typically 30% (https://en.wikipedia.org/wiki/Fuel_efficiency#Statistics https://en.wikipedia.org/wiki/Fuel_efficiency#Statistics) > Low-speed diesel engines (as used in ships and other applications where overall engine weight is relatively unimportant) can reach effective efficiencies of up to 55%. (https://en.wikipedia.org/wiki/Diesel_engine https://en.wikipedia.org/wiki/Diesel_engine) Not to mention that a very large percentage of electricity for charging of vehicles is not going to come from fossil fuels in the first place, especially whenever charging can be planned (which is most of the time in Europe).

hoseja 4y ago
I'm thinking more like https://en.wikipedia.org/wiki/Combined_cycle_power_plant https://en.wikipedia.org/wiki/Combined_cycle_power_plant
bionsystem 4y ago
Let's assume we go from 30% (low end of small engine efficiency according to first link) to 55% (high end for a Diesel engine according to the second article), so a little short of twice as efficient. What do you think is going to be the overhead of the conversion rate to electricity, electricity transportation ? Because if it is another 50% you lost all interest (but you built a plant and a float of cars and batteries in the meantime). > Not to mention that a very large percentage of electricity for charging of vehicles is not going to come from fossil fuels in the first place, especially whenever charging can be planned (which is most of the time in Europe). That's not what my parent and I are talking about. But I second that. Except I live in France and we are starting to have electricity cuts because we can't maintain our nuclear plants properly. So we are in a little bit more trouble than you might think.
- jhgb 4y ago
  > What do you think is going to be the overhead of the conversion rate to electricity, electricity transportation ? Well, for example transformers are ~98% efficient, AC lines lose around 7% per 1000 km. So with three transformers between you and the power plant and a ~300 km distance, you lose around 8% between the power plant and you. > Because if it is another 50% you lost all interest (but you built a plant and a float of cars and batteries in the meantime). No, not really. You're still not powering your cars purely from fossil fuels, so even 50% of losses would still be a win when it comes to minimizing fossil fuel emissions caused by road transportation. You'd only have to burn enough fossil fuels to cover whatever the non-fossil-fuel generators wouldn't be able to provide at any given time. But as I pointed out above, you almost certainly won't get 50% of losses. > Except I live in France and we are starting to have electricity cuts because we can't maintain our nuclear plants properly. So we are in a little bit more trouble than you might think. Nah, not really. France is in a great position to generate fairly substantial amounts of electricity from renewables with complementing the rest from nuclear power. Not to mention that I'd expect the EPR design to finally be sorted out after the initial units built. It's not like you'll need it tomorrow -- the transition to BEVs will take a considerable time. Even if sales of ICE cars actually stop in 2035, ICE vehicles won't disappear overnight. They'll only be gradually replaced for a decade or so.
  - bionsystem 4y ago
    I can't judge on your numbers but just to point out that we were comparing gasoline plants + EV vs gasoline cars and I feel that the discussion is switching into NE plants + EV vs gasoline cars. I also think that a lot of steel+copper+lithium and others are not taken into the equation to replace cars and manufacture more plants. Steel particularly consumes a lot of energy to produce. Uranium shortages are going to become a thing too especially with new demand from China. Also I disagree with your optimism on french nuclear and renewable, having worked there and having friends working in EDF and also following various debates, political decisions, and news flow, we went from quite optimistic a few years back to more and more pessimistic about the whole thing. Nobody seems to want a nuclear plant, or a solar/wind power field next to their home. And the competency for nuclear has retired or seems to be going to China or elsewhere for counseling now.

by jhgb 4y ago

hoseja 4y ago

I'm thinking more like https://en.wikipedia.org/wiki/Combined_cycle_power_plant https://en.wikipedia.org/wiki/Combined_cycle_power_plant

bionsystem 4y ago

Let's assume we go from 30% (low end of small engine efficiency according to first link) to 55% (high end for a Diesel engine according to the second article), so a little short of twice as efficient. What do you think is going to be the overhead of the conversion rate to electricity, electricity transportation ? Because if it is another 50% you lost all interest (but you built a plant and a float of cars and batteries in the meantime). > Not to mention that a very large percentage of electricity for charging of vehicles is not going to come from fossil fuels in the first place, especially whenever charging can be planned (which is most of the time in Europe). That's not what my parent and I are talking about. But I second that. Except I live in France and we are starting to have electricity cuts because we can't maintain our nuclear plants properly. So we are in a little bit more trouble than you might think.

jhgb 4y ago
> What do you think is going to be the overhead of the conversion rate to electricity, electricity transportation ? Well, for example transformers are ~98% efficient, AC lines lose around 7% per 1000 km. So with three transformers between you and the power plant and a ~300 km distance, you lose around 8% between the power plant and you. > Because if it is another 50% you lost all interest (but you built a plant and a float of cars and batteries in the meantime). No, not really. You're still not powering your cars purely from fossil fuels, so even 50% of losses would still be a win when it comes to minimizing fossil fuel emissions caused by road transportation. You'd only have to burn enough fossil fuels to cover whatever the non-fossil-fuel generators wouldn't be able to provide at any given time. But as I pointed out above, you almost certainly won't get 50% of losses. > Except I live in France and we are starting to have electricity cuts because we can't maintain our nuclear plants properly. So we are in a little bit more trouble than you might think. Nah, not really. France is in a great position to generate fairly substantial amounts of electricity from renewables with complementing the rest from nuclear power. Not to mention that I'd expect the EPR design to finally be sorted out after the initial units built. It's not like you'll need it tomorrow -- the transition to BEVs will take a considerable time. Even if sales of ICE cars actually stop in 2035, ICE vehicles won't disappear overnight. They'll only be gradually replaced for a decade or so.
- bionsystem 4y ago
  I can't judge on your numbers but just to point out that we were comparing gasoline plants + EV vs gasoline cars and I feel that the discussion is switching into NE plants + EV vs gasoline cars. I also think that a lot of steel+copper+lithium and others are not taken into the equation to replace cars and manufacture more plants. Steel particularly consumes a lot of energy to produce. Uranium shortages are going to become a thing too especially with new demand from China. Also I disagree with your optimism on french nuclear and renewable, having worked there and having friends working in EDF and also following various debates, political decisions, and news flow, we went from quite optimistic a few years back to more and more pessimistic about the whole thing. Nobody seems to want a nuclear plant, or a solar/wind power field next to their home. And the competency for nuclear has retired or seems to be going to China or elsewhere for counseling now.