4 ms·

I mostly agree. Certainly transportation is an obvious one. But of course there are still some losses; when you include all the losses in the system and cold we

I mostly agree. Certainly transportation is an obvious one. But of course there are still some losses; when you include all the losses in the system and cold weather you can easily get ~80% for EVs vs. ~30% for ICE cars. Heat pumps can be very efficient, but 5x more efficient than combustion/resistive heating (which is near 100%...) is not common in practice. 3x, sure, plenty of installations that get that or better in mild climates. That said, those are two pretty large items. If we reached 90% electrification on both it would be a pretty big win: Road transport represents ~26% of global energy use and all heating/cooling (industry, building, agriculture) represents ~50%.

youngtaff 9mo ago
> Road transport represents ~26% of global energy use Does that 26% include the energy that's involved to ship the fuel in tankers? Something like 50% of marine fuel usage is shipping fossil fuels around the world
- SECProto 9mo ago
  > Something like 50% of marine fuel usage is shipping fossil fuels around the world Note that marine shipping is extraordinarily fuel efficient (from a gCO2/(t*km) basis), so I doubt that it adds a lot on a per ton of fuel basis. We just ship a lot of fossil fuels. This [1] graph looks to be in the right ballpark from what i remember in school 15 years ago, i didn't verify it in depth but +- an order of magnitude better than the next best method is roughly right https://image2.slideserve.com/4166134/gco-2-t-km-of-freight-transport-modes-l.jpg https://image2.slideserve.com/4166134/gco-2-t-km-of-freight-...
  - lambdaone 9mo ago
    Even though petroleum product shipping accounts for almost 40% of shipping, the surprising efficiency of ocean transport still means that it's not that big an energy cost; a single-digit percentage of the energy content of the shipped oil/gasoline. But even that is still worth saving - it's a few percent more benefit for electrification.
- jijijijij 9mo ago
  Marine transport is stupidly efficient and probably won’t influence those numbers much. For the same reasons it’s absolutely okay to eat avocados from overseas. I believe the processing of oil to gas is quite energy intense tho.
- adrianN 9mo ago
  You also need to extract and refine the oil before you can put it into a car.
tialaramex 9mo ago
Resistive heating is indeed almost 100% efficient, but combustion is only about 90% efficient and that's using modern technology to scrape almost everything we can, which has a cost in terms of the product upfront cost and maintenance. The reason it's not much higher is that we must vent the exhaust gases. If you were OK with the burned gas vapours in your home you could get close to 100%, but they're poisonous and so they must be vented to the atmosphere where they only cause global warming. Venting those gases means losing heat, so that's inefficient. For the EVs in particular, because motion <=> electrical energy is almost the same either direction (a dynamo and an electric motor are almost identical) we get regenerative braking in most applications. This isn't anywhere close to 100% effective, and of course we net losses from resistance which gets much worse as speed increases - but it's not nothing. The big win is that global warming problem. Electrifying consumption means fungibility. In my lifetime the UK went from mostly coal electricity, to no coal at all. But few cared because to the end users it's the same electricity regardless of how it was made, and most people probably didn't even notice. So if you move consumption to electricity then the generation problem is de-coupled and can be addressed separately.
- jacquesm 9mo ago
  Anywhere you use resistive heating you're better off with a heatpump which is far more efficient than that.
  - zdragnar 9mo ago
    Unless you live somewhere that (air, e.g. in an EV) heat pumps can't function at high efficiency. Tonight and tomorrow night will be -20F/-28C. Always good to have a backup plan, no matter what your primary heat source is.
    - jacquesm 9mo ago
      That's true.
    - pfdietz 9mo ago
      Almost no one lives in a location where heat pumps are never (or even usually) inappropriate. Yes, it might get to -20 F, but how often does that happen over a winter, never mind over a year?
CraigJPerry 9mo ago
in cold weather an ice is not close to 30%, that's an achievable warm weather figure when everything's working efficiently. Many ice journeys are so short in cold weather that efficiency never peaks above 10%
- eigenspace 9mo ago
  Well, EVs also lose a lot of efficiency in cold weather as well. You'll also note that the 70% figure I gave for power plants is more or less a best case scenario for modern, well designed plants. A lot of currently existing power plants do much worse than 70%
  - tialaramex 9mo ago
    True, system thermal efficiency for the UK's CCGT generation is about 50%. Obviously that's with a varying throttle (the UK goes from say 5GW of CCGT to 25GW of CCGT in an hour if the wind drops just as everybody wakes up) and you'd do better than 50% if you were baseload running 24/7 at peak performance - but that's not a realistic place for CCGT to be when nuclear fuel is basically free and the two new big sources (solar and wind) aren't even running on actual fuel anyway.
ncruces 9mo ago
Without disagreeing, I think it's worth acknowledging that vehicle weight will be a confounding issue for long range EVs.

youngtaff 9mo ago

> Road transport represents ~26% of global energy use Does that 26% include the energy that's involved to ship the fuel in tankers? Something like 50% of marine fuel usage is shipping fossil fuels around the world

SECProto 9mo ago
> Something like 50% of marine fuel usage is shipping fossil fuels around the world Note that marine shipping is extraordinarily fuel efficient (from a gCO2/(t*km) basis), so I doubt that it adds a lot on a per ton of fuel basis. We just ship a lot of fossil fuels. This [1] graph looks to be in the right ballpark from what i remember in school 15 years ago, i didn't verify it in depth but +- an order of magnitude better than the next best method is roughly right https://image2.slideserve.com/4166134/gco-2-t-km-of-freight-transport-modes-l.jpg https://image2.slideserve.com/4166134/gco-2-t-km-of-freight-...
- lambdaone 9mo ago
  Even though petroleum product shipping accounts for almost 40% of shipping, the surprising efficiency of ocean transport still means that it's not that big an energy cost; a single-digit percentage of the energy content of the shipped oil/gasoline. But even that is still worth saving - it's a few percent more benefit for electrification.
jijijijij 9mo ago
Marine transport is stupidly efficient and probably won’t influence those numbers much. For the same reasons it’s absolutely okay to eat avocados from overseas. I believe the processing of oil to gas is quite energy intense tho.
adrianN 9mo ago
You also need to extract and refine the oil before you can put it into a car.

tialaramex 9mo ago

Resistive heating is indeed almost 100% efficient, but combustion is only about 90% efficient and that's using modern technology to scrape almost everything we can, which has a cost in terms of the product upfront cost and maintenance. The reason it's not much higher is that we must vent the exhaust gases. If you were OK with the burned gas vapours in your home you could get close to 100%, but they're poisonous and so they must be vented to the atmosphere where they only cause global warming. Venting those gases means losing heat, so that's inefficient. For the EVs in particular, because motion <=> electrical energy is almost the same either direction (a dynamo and an electric motor are almost identical) we get regenerative braking in most applications. This isn't anywhere close to 100% effective, and of course we net losses from resistance which gets much worse as speed increases - but it's not nothing. The big win is that global warming problem. Electrifying consumption means fungibility. In my lifetime the UK went from mostly coal electricity, to no coal at all. But few cared because to the end users it's the same electricity regardless of how it was made, and most people probably didn't even notice. So if you move consumption to electricity then the generation problem is de-coupled and can be addressed separately.

jacquesm 9mo ago
Anywhere you use resistive heating you're better off with a heatpump which is far more efficient than that.
- zdragnar 9mo ago
  Unless you live somewhere that (air, e.g. in an EV) heat pumps can't function at high efficiency. Tonight and tomorrow night will be -20F/-28C. Always good to have a backup plan, no matter what your primary heat source is.
  - jacquesm 9mo ago
    That's true.
  - pfdietz 9mo ago
    Almost no one lives in a location where heat pumps are never (or even usually) inappropriate. Yes, it might get to -20 F, but how often does that happen over a winter, never mind over a year?

CraigJPerry 9mo ago

in cold weather an ice is not close to 30%, that's an achievable warm weather figure when everything's working efficiently. Many ice journeys are so short in cold weather that efficiency never peaks above 10%

eigenspace 9mo ago
Well, EVs also lose a lot of efficiency in cold weather as well. You'll also note that the 70% figure I gave for power plants is more or less a best case scenario for modern, well designed plants. A lot of currently existing power plants do much worse than 70%
- tialaramex 9mo ago
  True, system thermal efficiency for the UK's CCGT generation is about 50%. Obviously that's with a varying throttle (the UK goes from say 5GW of CCGT to 25GW of CCGT in an hour if the wind drops just as everybody wakes up) and you'd do better than 50% if you were baseload running 24/7 at peak performance - but that's not a realistic place for CCGT to be when nuclear fuel is basically free and the two new big sources (solar and wind) aren't even running on actual fuel anyway.

ncruces 9mo ago

Without disagreeing, I think it's worth acknowledging that vehicle weight will be a confounding issue for long range EVs.