4 ms·

> while a power plant could go to 50-sh Only on very new generation plants (for coal national average is cited as 32% - it may be slightly higher now)[1]. A 20

> while a power plant could go to 50-sh Only on very new generation plants (for coal national average is cited as 32% - it may be slightly higher now)[1]. A 2016 Toyota Prius is advertised as being at 40%[2]. I remember reading a 70% ballpark for Tesla's but it might have gotten better (I can't seem to find the article now). [1] https://www.fas.org/sgp/crs/misc/R43343.pdf https://www.fas.org/sgp/crs/misc/R43343.pdf [2] http://gas2.org/2015/05/27/2016-toyota-prius-engine-achieves-40-thermal-efficiency/ http://gas2.org/2015/05/27/2016-toyota-prius-engine-achieves...

ricardobeat 11y ago
That's just the engine efficiency. They estimate that refining a gallon of gasoline uses 4kw/h of energy, that energy by itself can power a Tesla for 12 miles, and you're not even accounting for fuel transport, storage and handling yet.
- mikeash 11y ago
  Refining a gallon of gasoline uses 6kWh of heat. Turning that heat into electricity involves great inefficiency. You can only convert that amount directly to miles if the heat comes from electricity, but my understanding is that no refinery does anything so wasteful, since they have stuff they can burn on site.
  - giaour 11y ago
    That refineries produce the heat by burning raw crude oil doesn't make the process sound any better for the environment. I'm not sure how much oil needs to be burned to produce 6 kWh, but since a GGE is 33.4 kWh, I'd assume it's at least 1/6th of a gallon. Gasoline emissions need to account for the oil burned to produce that heat and all energy consumed in the gasoline's storage and distribution.
    - mikeash 11y ago
      Certainly, it's not great. But it's not the case that you can run an electric car off the energy needed simply to refine gasoline for a normal car. I'm all for a full accounting of all the energy used in the whole process, certainly.

ricardobeat 11y ago

That's just the engine efficiency. They estimate that refining a gallon of gasoline uses 4kw/h of energy, that energy by itself can power a Tesla for 12 miles, and you're not even accounting for fuel transport, storage and handling yet.

mikeash 11y ago
Refining a gallon of gasoline uses 6kWh of heat. Turning that heat into electricity involves great inefficiency. You can only convert that amount directly to miles if the heat comes from electricity, but my understanding is that no refinery does anything so wasteful, since they have stuff they can burn on site.
- giaour 11y ago
  That refineries produce the heat by burning raw crude oil doesn't make the process sound any better for the environment. I'm not sure how much oil needs to be burned to produce 6 kWh, but since a GGE is 33.4 kWh, I'd assume it's at least 1/6th of a gallon. Gasoline emissions need to account for the oil burned to produce that heat and all energy consumed in the gasoline's storage and distribution.
  - mikeash 11y ago
    Certainly, it's not great. But it's not the case that you can run an electric car off the energy needed simply to refine gasoline for a normal car. I'm all for a full accounting of all the energy used in the whole process, certainly.