我在哪里為設備充電有關係嗎?


10

我有很多小型設備,可以在汽車上(使用插入汽車電氣系統並由汽車汽油發動機供電的充電器)或我的家中(使用本地電網供電)充電。

給汽車中的電話或其他設備充電會改變汽車使用的汽油量,還是使用原本會浪費的能源來進行充電?如果確實使用汽油,那是使這樣的電力效率比我的提供者所使用的電力效率更高或更低的過程(我住的地方,這是核電廠,化石電廠和水力發電廠的混合物,並輔以一些瘋狂的昂貴風能和太陽)?

給我一個選擇,既可以在開車回家時充電(例如,我的電池電量為20%),也可以一直待到回家後再使用壁掛式充電器充電,這對我來說便宜還是對地球有利?這在多大程度上取決於我的家庭發電方式?

9

Yes, it matters, a little, but it also depends on your location.

In your car, the process of converting fuel to movement is pretty inefficient (about 25% to 30%, according to this). That movement (kinetic energy, if you're a physicist) is then converted to electrical energy with an efficiency of 75% to 80%, giving you an overall efficiency of 18.75% to 24%. You might also consider the inefficiency of getting the fuel to the service station that you bought it from.

Using more electricity in your car means a higher physical resistance experienced by the engine when it tries to turn the core of the alternator. ie it's harder to turn the alternator when more electricity is being drawn from it, and thus more fuel is used to keep the vehicle at the same speed, unless the vehicle is idling, or overrunning the engine downhill.

In your home, electricity is generated with varying efficiencies depending on the generation that supplies it. Transmission losses in the US are apparently about 6.5% (ie 93.5% efficient). It looks like an average for generation efficiency would be around 39%. This last link also says the overall efficiency of getting power to the consumer is about 33%, which seems about right, given the previous two figures. The efficiency is somewhat higher than when you use electricity from your car.

It's better to charge your phone from home.

Of course, it very much depends on how your electricity for your home is generated. If you use an electricity retailer that leans towards renewable energy, it's going to be much better for the planet. It's clear there would be very few cases where the electricity grid generation was so inefficient that your car did a better job.

All that said, cellphones don't use much power. It's probably not worth worrying about too much. For most people, there are much bigger energy efficiency improvements that can be made through actions like improving home insulation and heating/cooling systems, reducing use of hot water, and analysis of home appliance electricity use.