5 ms·
"Only about one in four or five of those gallons of gasoline you pump and pay for provide energy you actually use, and perhaps 60-70% of what statisticians call
by ArtDev 7y ago
"Only about one in four or five of those gallons of gasoline you pump and pay for provide energy you actually use, and perhaps 60-70% of what statisticians call the world’s primary energy use is really just waste"
Interesting.
- acidburnNSA 7y agoTotally interesting! It's not waste for no reason. Energy transfers have thermodynamic efficiencies and at practical temperatures the transformation of chemical energy into shaft horsepower is like 30% efficient in a small engine. Making electricity from fossil or nuclear fuel in large plants is between that and 60% efficient.
- Gys 7y agoI was wondering how much then is lost in transport. Turns out to be only 2-4%. The same article also confirms that efficiency in large plants is about 60%: http://insideenergy.org/2015/11/06/lost-in-transmission-how-much-electricity-disappears-between-a-power-plant-and-your-plug/ http://insideenergy.org/2015/11/06/lost-in-transmission-how-...
- Sami_Lehtinen 7y agoNo all plants are combined cycle plants, even if improves efficiency a lot. https://en.wikipedia.org/wiki/Combined_cycle_power_plant https://en.wikipedia.org/wiki/Combined_cycle_power_plant Or even something better Cogeneration plants. https://en.wikipedia.org/wiki/Cogeneration https://en.wikipedia.org/wiki/Cogeneration
- userbinator 7y agohttps://en.wikipedia.org/wiki/Brake-specific_fuel_consumption https://en.wikipedia.org/wiki/Brake-specific_fuel_consumptio... Yes, it's in the 30s for typical petrol engines, and over 50% for large 2-stroke diesels.
- jacquesm 7y ago> at practical temperatures the transformation of chemical energy into shaft horsepower is like 30% efficient in a small engine Does that also hold for hybrid electric vehicles?
- snovv_crash 7y agoYes. That is the percentage of fuel energy that gets to your wheels. The rest is made into heat, and is why fuel engines need such big radiators - for every HP going to your wheels, a minimum of 2 go to the radiator. Hybrids just recapture the heat from the brakes, another major loss point, but unrelated to the engine. If you want to actually get better energy efficiency you need plug-in hybrid or fully electric.
- Gibbon1 7y agoMostly. The efficiency of a gasoline engine varies widely depending on rpm and power output. Hybrids keep the engine in it's most efficient operating range. It's also why hybrids produce about a fifth the pollution as straight gasoline engines. I think hybrids can also make some trade offs losing power density and torque for higher efficiency.
- SigmundA 7y agoMany gas hybrid run the atkinson cycle vs the otto cycle, this improves efficiency some at the expense of torque, which the electric motors make up for. Hybrids are much better in the city due to the stop and go nature allowing lots of braking regeneration and idle savings. On the highway much of their advantage is lost especially if comparing to say a diesel.