4 ms·

So they claim this is the cleanest way to deliver energy, but that’s very unintuitive to me. It seems like there would be a huge transmission loss in piping hot

So they claim this is the cleanest way to deliver energy, but that’s very unintuitive to me. It seems like there would be a huge transmission loss in piping hot steam through the whole of Manhattan, and I didn’t think steam engines were particularly efficient. So my intuition is failing here. For those in the know, what makes a steam system like this effective as a clean energy distribution system, and how does it compare on a cost basis?

tb_technical 4y ago
https://www.esmagazine.com/articles/83622-heating-with-steam-efficiently https://www.esmagazine.com/articles/83622-heating-with-steam... It looks like it's efficiency has to do with the fact that it's an entirely passive heating system - it doesn't require any infrastructure except laid pipe to operate. (I went on a Google quest after reading your comment and wondered the same thing. Thought I would share...)
marmetio 4y ago
They're just referencing the earlier claim that the new natural gas boiler is cleaner than the old coal boiler. The sentence is worded incorrectly, and doesn't claim to be a cleaner distribution method either. They said they keep it because it's too difficult to sufficiently upgrade the buried electrical distribution system.
retrac 4y ago
Not to get off topic, but steam engines still drive the whole world; whether nuclear or gas or coal fuel, or concentrated solar power, steam turbines are how heat is turned into motion to make electricity. Modern ones operate very close to the theoretical limit of efficiency (around 40% [1]). The great advance James Watt made in the late 18th century, was a technique to recapture heat from the exhaust and raise practical efficiencies to several percent, with the remainder of the theoretical limit eeked out progressively over the following century. One of the ways that limit is approached is to use the largest temperature difference the materials can stand; steam for large turbines is hot. The exhaust is still steam, but no longer hot enough to drive things efficiently. Indeed, the cooling loop of many plants run steam-hot, just not superheated-hot. Another common district heating approach (used in NYC) is a small direct gas-fired turbine driving an electric generator, with steam cooling. Combined generation is the use of that waste heat, for other heating purposes, and can raise total system efficiency. Similarly, Iceland uses a lot of geothermal heating; some directly but much is waste heat from geothermal-electric plants. Since the geothermal taps are not that hot, an enormous volume of fluid is moved and the cold side needs to be quite cool; the output is barely-hot water after going through the cycle. But there's a lot of it. So much so, that they have under-sidewalk heating in Reykjavik and outdoor pools in winter. Most places just throw such heat away without making further use of it. It's traditionally been cheaper (or at least easier/simpler) to distribute and burn fossil fuels than to try and recapture and redistribute low intensity heat. The pipes are indeed heat-leaky, despite usually being heavily insulated. [1] https://en.m.wikipedia.org/wiki/Carnot%27s_theorem_(thermodynamics) https://en.m.wikipedia.org/wiki/Carnot%27s_theorem_(thermody...
- electroly 4y ago
  > gas or coal fuel ... steam turbines are how heat is turned into motion to make electricity While steam turbines can be found at natural gas plants, it's typically only for waste heat recovery in combined cycle plants. Primary generation is more commonly done with combustion turbines, which are more like jet engines. They don't use steam.
whiddershins 4y ago
My understanding, as I mentioned in another comment, is that to some degree this steam is waste heat from generating electricity (where does the steam go after it turns the turbines?) so basically free. Possible I’m misinformed.

tb_technical 4y ago

https://www.esmagazine.com/articles/83622-heating-with-steam-efficiently https://www.esmagazine.com/articles/83622-heating-with-steam... It looks like it's efficiency has to do with the fact that it's an entirely passive heating system - it doesn't require any infrastructure except laid pipe to operate. (I went on a Google quest after reading your comment and wondered the same thing. Thought I would share...)

marmetio 4y ago

They're just referencing the earlier claim that the new natural gas boiler is cleaner than the old coal boiler. The sentence is worded incorrectly, and doesn't claim to be a cleaner distribution method either. They said they keep it because it's too difficult to sufficiently upgrade the buried electrical distribution system.

retrac 4y ago

Not to get off topic, but steam engines still drive the whole world; whether nuclear or gas or coal fuel, or concentrated solar power, steam turbines are how heat is turned into motion to make electricity. Modern ones operate very close to the theoretical limit of efficiency (around 40% [1]). The great advance James Watt made in the late 18th century, was a technique to recapture heat from the exhaust and raise practical efficiencies to several percent, with the remainder of the theoretical limit eeked out progressively over the following century. One of the ways that limit is approached is to use the largest temperature difference the materials can stand; steam for large turbines is hot. The exhaust is still steam, but no longer hot enough to drive things efficiently. Indeed, the cooling loop of many plants run steam-hot, just not superheated-hot. Another common district heating approach (used in NYC) is a small direct gas-fired turbine driving an electric generator, with steam cooling. Combined generation is the use of that waste heat, for other heating purposes, and can raise total system efficiency. Similarly, Iceland uses a lot of geothermal heating; some directly but much is waste heat from geothermal-electric plants. Since the geothermal taps are not that hot, an enormous volume of fluid is moved and the cold side needs to be quite cool; the output is barely-hot water after going through the cycle. But there's a lot of it. So much so, that they have under-sidewalk heating in Reykjavik and outdoor pools in winter. Most places just throw such heat away without making further use of it. It's traditionally been cheaper (or at least easier/simpler) to distribute and burn fossil fuels than to try and recapture and redistribute low intensity heat. The pipes are indeed heat-leaky, despite usually being heavily insulated. [1] https://en.m.wikipedia.org/wiki/Carnot%27s_theorem_(thermodynamics) https://en.m.wikipedia.org/wiki/Carnot%27s_theorem_(thermody...

electroly 4y ago
> gas or coal fuel ... steam turbines are how heat is turned into motion to make electricity While steam turbines can be found at natural gas plants, it's typically only for waste heat recovery in combined cycle plants. Primary generation is more commonly done with combustion turbines, which are more like jet engines. They don't use steam.

whiddershins 4y ago

My understanding, as I mentioned in another comment, is that to some degree this steam is waste heat from generating electricity (where does the steam go after it turns the turbines?) so basically free. Possible I’m misinformed.