3 ms·

> renewables will provide more high quality energy (that is, looking at work rather than thermal energy produced, since renewables produce the former directly)

by xyzzyz 5y ago

> renewables will provide more high quality energy (that is, looking at work rather than thermal energy produced, since renewables produce the former directly) I have no idea how this makes electricity from renewables “higher quality”.

pfdietz 5y ago
In the sense that 1 joule of electrical energy is inherently more valuable than 1 joule of thermal energy. A current commercial nuclear reactor requires 3 units of the latter to produce 1 unit of the former. This issue comes up all the time in energy analysis where you need to carefully distinguish between "primary" (i.e., before conversion in a heat engine) energy to zero-entropy energy (electrical energy, work).
- xyzzyz 5y ago
  > In the sense that 1 joule of electrical energy is inherently more valuable than 1 joule of thermal energy. A current commercial nuclear reactor requires 3 units of the latter to produce 1 unit of the former. When people are talking about 1 GW nuclear reactor, they mean that reactor is generating 1 GW of electricity, so that the reactor is in fact >3 GW thermal. Nobody is comparing electricity from renewables to thermal energy from nuclear. In fact, this actually makes nuclear superior: you can use the waste 2 GW of heat to run district heating in nearby located cities. Pretty popular in Europe, though with coal/gas plants. There is no similar useful byproduct to solar/wind.
  - ncmncm 5y ago
    1 GW of electrical power driving a heat pumps gives you the other two GW of heat for free. So, no advantage to nukes there. Anyway nukes are generally too far away from pop centers to provide useful secondary heat. But nukes can drive heat pumps too, so no advantage either way. Of course the sun does provide direct heat without need to process it through panels. Solar PV and nuke customers both rely on that.
  - pfdietz 5y ago
    Quality also applies to different temperatures of thermal energy. Low temperature heat, such as the waste heat from a nuclear power plant, has very low quality. It is worth very little, which is why in most cases it is just dissipated to the environment.

by xyzzyz 5y ago

pfdietz 5y ago

In the sense that 1 joule of electrical energy is inherently more valuable than 1 joule of thermal energy. A current commercial nuclear reactor requires 3 units of the latter to produce 1 unit of the former. This issue comes up all the time in energy analysis where you need to carefully distinguish between "primary" (i.e., before conversion in a heat engine) energy to zero-entropy energy (electrical energy, work).

xyzzyz 5y ago
> In the sense that 1 joule of electrical energy is inherently more valuable than 1 joule of thermal energy. A current commercial nuclear reactor requires 3 units of the latter to produce 1 unit of the former. When people are talking about 1 GW nuclear reactor, they mean that reactor is generating 1 GW of electricity, so that the reactor is in fact >3 GW thermal. Nobody is comparing electricity from renewables to thermal energy from nuclear. In fact, this actually makes nuclear superior: you can use the waste 2 GW of heat to run district heating in nearby located cities. Pretty popular in Europe, though with coal/gas plants. There is no similar useful byproduct to solar/wind.
- ncmncm 5y ago
  1 GW of electrical power driving a heat pumps gives you the other two GW of heat for free. So, no advantage to nukes there. Anyway nukes are generally too far away from pop centers to provide useful secondary heat. But nukes can drive heat pumps too, so no advantage either way. Of course the sun does provide direct heat without need to process it through panels. Solar PV and nuke customers both rely on that.
- pfdietz 5y ago
  Quality also applies to different temperatures of thermal energy. Low temperature heat, such as the waste heat from a nuclear power plant, has very low quality. It is worth very little, which is why in most cases it is just dissipated to the environment.