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"The combination of these problems [storage and transmission aren't 100% efficient] means that household energy conservation is mainly a way for wealthy Western

by jbert 18y ago

"The combination of these problems [storage and transmission aren't 100% efficient] means that household energy conservation is mainly a way for wealthy Westerners to feel virtuous rather than an actual attack on energy costs. Household conservation slightly decreases the maximum capacity needed locally where the conservation is being practiced, but has little impact further away, where demand has to be supplied by different plants." Errm...doesn't the fact that transmission is less than 100% efficient just multiply up the gain? If I lose 50% of power sending it to a house, if that house saves Y kwH, I need to generate 2Y less kwH? i.e. the worse the transmission %, the more effect I get from efficiency at the point of use? Or did I miss his point?

streety 18y ago
I haven't read the whole post yet but what I think he means is that if energy efficiency goes up locally there will be a bunch of power stations sat idling because it isn't efficient to send the energy long distances to areas where demand hasn't fallen. For example cutting demand in the US by 100MW won't stop a 100MW power station from being built in India. It makes sense but only if you confuse efficiency and demand. Increased efficiency should decrease demand assuming all other things are equal. Surprisingly all other things aren't equal.
- jbert 18y ago
  Ah, thanks. Well, the demand generally increases over time, so efficiency just means you can delay building that next 100MW plant in the US a while longer - which is useful. I agree with his basic point that "a dense form of energy is useful for transport". But he doesn't seem to have much beyond that. He also neglects the point that turning power -> useful work done is more efficient for electricity from a battery, which is pretty relevant. And for fuels, is more efficient in bigger engines/power plants. Wikipedia tells me diesel engines get in the region of 45% efficient, petrol 30%, electric 90%. That's a lot of room for transmission loss.
  - streety 18y ago
    Absolutely. Demand is, to my knowledge, rising and showing no signs of stopping any time soon. The aim of efficiency drives are to slow this rise, not lead to the decommissioning of power stations.
  - stcredzero 18y ago
    High energy density is indeed key for mobile applications. This is why Diesels are so popular. 45% efficiency is 1/2 that of 90%, but the fuel is very energy dense and the fuel tank is compact. In addition, the storage and transfer technologies are simple, low-tech, and cheap. The key is that not everyone needs that kind of power. Most of the people here in Texas running around in work trucks would be just fine with one of those little euro coupe utility vehicles that's as small as a compact car. It's only in a minority of cases where you need the heavy hauling capability of even an F-150.

by jbert 18y ago

streety 18y ago

I haven't read the whole post yet but what I think he means is that if energy efficiency goes up locally there will be a bunch of power stations sat idling because it isn't efficient to send the energy long distances to areas where demand hasn't fallen. For example cutting demand in the US by 100MW won't stop a 100MW power station from being built in India. It makes sense but only if you confuse efficiency and demand. Increased efficiency should decrease demand assuming all other things are equal. Surprisingly all other things aren't equal.

jbert 18y ago
Ah, thanks. Well, the demand generally increases over time, so efficiency just means you can delay building that next 100MW plant in the US a while longer - which is useful. I agree with his basic point that "a dense form of energy is useful for transport". But he doesn't seem to have much beyond that. He also neglects the point that turning power -> useful work done is more efficient for electricity from a battery, which is pretty relevant. And for fuels, is more efficient in bigger engines/power plants. Wikipedia tells me diesel engines get in the region of 45% efficient, petrol 30%, electric 90%. That's a lot of room for transmission loss.
- streety 18y ago
  Absolutely. Demand is, to my knowledge, rising and showing no signs of stopping any time soon. The aim of efficiency drives are to slow this rise, not lead to the decommissioning of power stations.
- stcredzero 18y ago
  High energy density is indeed key for mobile applications. This is why Diesels are so popular. 45% efficiency is 1/2 that of 90%, but the fuel is very energy dense and the fuel tank is compact. In addition, the storage and transfer technologies are simple, low-tech, and cheap. The key is that not everyone needs that kind of power. Most of the people here in Texas running around in work trucks would be just fine with one of those little euro coupe utility vehicles that's as small as a compact car. It's only in a minority of cases where you need the heavy hauling capability of even an F-150.