3 ms·

Those electrical systems are about 85% efficient once the chemical energy in the coal has been converted to kinetic energy in the turbine. Losses in the generat

Those electrical systems are about 85% efficient once the chemical energy in the coal has been converted to kinetic energy in the turbine. Losses in the generators themselves and in voltage loss through transformers and wires add up to about 15%. But they're only about 33% (old tech) to 45% (best-case new tech) efficient when it comes to thermal potential. Burning coal or natural gas produces lots of heat, and while some of that heat turns the turbine, there's still a lot left that gets lost to the condenser or to the exhaust flue and atmosphere. However, that's where steam distribution is awesome: It enables cogeneration, where some of the waste heat from electricity production can be efficiently used by heating industries. The electrical plant requires supercritical steam at 1000F and 1000 PSI, but the steam network only needs steam at ~150 PSI and 350F, which still has a lot of energy in it from the burners but is of comparatively little use to the turbine.

riggsdk 2y ago
Random thought: could you insulate high voltage wires in pipes and blow cold air through those? Any loss would become “free” heating for homes nearby.
- z2 2y ago
  I feel like this could be a nice high school physics test question. Realistically, I don't think HV lines have much energy loss, owing to the use of high voltage in the first place as a means of minimizing loss. Then there are considerations for air resistance in the tubes, an almost 100% effective insulator, and all those real world issues of gnarly general maintenance. Almost all electricity run through computers are basically resistance losses at the end of the day, so data centers and crypto miners on the other hand...
  - lucb1e 2y ago
    Could not find the answer, kept getting general pages about how much current a wire can pass (without the result even containing the keyword I looked for, like temperature or heat or warm). To still have some indication of whether this is an interesting thing to keep looking into, ChatGPT says: > Typically, high-voltage transmission lines are designed to operate at temperatures of around 75 to 100°C (167 to 212°F). However, under heavy loads, they can sometimes reach up to 150°C (302°F), but this is usually the upper limit for safe operation. If that's a core temperature then the insulation might not make it significant, but if the outside leaks this much... I might not mind paying myself for a plastic tube and a fan to use around the line if I lived near one. Okay okay, it'll be more complicated than that, but still: free energy? And you're doing the power company a favor by decreasing the resistance in the case of most metals (https://www.engineeringtoolbox.com/resistivity-conductivity-d_418.html https://www.engineeringtoolbox.com/resistivity-conductivity-...) including copper which https://en.wikipedia.org/wiki/High-voltage_cable https://en.wikipedia.org/wiki/High-voltage_cable says they're made of
    - Panzer04 2y ago
      It's entirely possible the wires would get hot enough to get useful heat, but I think the much more practical challenge is moving the air and insulating it from the outside. Beyond that, you're likely also decreasing the maximal electrical current the wires can carry, as they won't be able to dissipate the heat as effectively with the additionally insulation.
- immibis 2y ago
  The wire needs to be at least as hot as the desired temperature in the home.
- qwery 2y ago
  I suppose, but (off the top of my head): - insulating high voltage lines isn't trivial - the conductor will be hot inside the insulation... - service cost of either system will be increased (by rather a lot, I'd guess)
vkazanov 2y ago
There's also a hybrid approach: generate electricity and also reuse heat for centralised heating. This can reach 60% efficiency as far as I remember but might require building plants closer to heat consumers.
- vkazanov 2y ago
  Just noticed that this is what you suggested :-)
- 8ig8 2y ago
  Cogeneration https://en.wikipedia.org/wiki/Cogeneration https://en.wikipedia.org/wiki/Cogeneration
- m4rtink 2y ago
  Isn't it actually like (100% - tranfer loses) efficiency ? In modern co-generation you can for example burn gas in a gas turbine & produce electricity. Then heat water to steam with the gas turbine exhaust & power a steam turbine to get more electricity. And then the steam is condensed by the district heating water loop. So in theory you will get more electricity & almost all the "waste" heat is used to heat houses.
- andai 2y ago
  This is common in parts of Europe, an electric power station supplies hot water to apartment buildings via underground tubes. In fact, there's one near me where the pipes cross a bridge! The water isn't quite as hot as it needs to be when it arrives, so it's heated additionally in the building itself. The article mentions a similar approach, with steam instead of water: > They also purchase additional steam from a 322 megawatt plant in Brooklyn
flippyhead 2y ago
I just came here to say that it's for this kind of super interesting and informative comment that I keep returning to HN, for over a decade now.

riggsdk 2y ago

Random thought: could you insulate high voltage wires in pipes and blow cold air through those? Any loss would become “free” heating for homes nearby.

z2 2y ago
I feel like this could be a nice high school physics test question. Realistically, I don't think HV lines have much energy loss, owing to the use of high voltage in the first place as a means of minimizing loss. Then there are considerations for air resistance in the tubes, an almost 100% effective insulator, and all those real world issues of gnarly general maintenance. Almost all electricity run through computers are basically resistance losses at the end of the day, so data centers and crypto miners on the other hand...
- lucb1e 2y ago
  Could not find the answer, kept getting general pages about how much current a wire can pass (without the result even containing the keyword I looked for, like temperature or heat or warm). To still have some indication of whether this is an interesting thing to keep looking into, ChatGPT says: > Typically, high-voltage transmission lines are designed to operate at temperatures of around 75 to 100°C (167 to 212°F). However, under heavy loads, they can sometimes reach up to 150°C (302°F), but this is usually the upper limit for safe operation. If that's a core temperature then the insulation might not make it significant, but if the outside leaks this much... I might not mind paying myself for a plastic tube and a fan to use around the line if I lived near one. Okay okay, it'll be more complicated than that, but still: free energy? And you're doing the power company a favor by decreasing the resistance in the case of most metals (https://www.engineeringtoolbox.com/resistivity-conductivity-d_418.html https://www.engineeringtoolbox.com/resistivity-conductivity-...) including copper which https://en.wikipedia.org/wiki/High-voltage_cable https://en.wikipedia.org/wiki/High-voltage_cable says they're made of
  - Panzer04 2y ago
    It's entirely possible the wires would get hot enough to get useful heat, but I think the much more practical challenge is moving the air and insulating it from the outside. Beyond that, you're likely also decreasing the maximal electrical current the wires can carry, as they won't be able to dissipate the heat as effectively with the additionally insulation.
immibis 2y ago
The wire needs to be at least as hot as the desired temperature in the home.
qwery 2y ago
I suppose, but (off the top of my head): - insulating high voltage lines isn't trivial - the conductor will be hot inside the insulation... - service cost of either system will be increased (by rather a lot, I'd guess)

vkazanov 2y ago

There's also a hybrid approach: generate electricity and also reuse heat for centralised heating. This can reach 60% efficiency as far as I remember but might require building plants closer to heat consumers.

vkazanov 2y ago
Just noticed that this is what you suggested :-)
8ig8 2y ago
Cogeneration https://en.wikipedia.org/wiki/Cogeneration https://en.wikipedia.org/wiki/Cogeneration
m4rtink 2y ago
Isn't it actually like (100% - tranfer loses) efficiency ? In modern co-generation you can for example burn gas in a gas turbine & produce electricity. Then heat water to steam with the gas turbine exhaust & power a steam turbine to get more electricity. And then the steam is condensed by the district heating water loop. So in theory you will get more electricity & almost all the "waste" heat is used to heat houses.
andai 2y ago
This is common in parts of Europe, an electric power station supplies hot water to apartment buildings via underground tubes. In fact, there's one near me where the pipes cross a bridge! The water isn't quite as hot as it needs to be when it arrives, so it's heated additionally in the building itself. The article mentions a similar approach, with steam instead of water: > They also purchase additional steam from a 322 megawatt plant in Brooklyn

flippyhead 2y ago

I just came here to say that it's for this kind of super interesting and informative comment that I keep returning to HN, for over a decade now.