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Steam Networks

worksinprogress.co

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Re: Steam Networks

#71

Post by LeifCarrotson »

imglorp wrote: post #30

The article cites end-to-end efficiency as 60%. Plus the costs of maintaining steam generators and the pipe network. Electrical transmission systems are roughly 85% efficient to the consumer; together with boring old resistive electric radiators which are 100% efficient. So is there any reason to subscribe to the steam system for new construction?

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.

Re: Steam Networks

#72

Post by jacobaul »

whatevaa wrote: post #66
nebolo wrote: post #50

Earlier quoted context omitted.

The efficiency of modern cold-climate heat pumps plummets to 200-300% at 40F and perhaps 175% at 5F.

So at -20 and below they are basically very, very expensive resistive heaters. Good for medium climates, bad further north. Also either need very expensive oversizing or backup heat sources to compensate reduced heat output, even if you get occasional cold spikes. Unfortunately nothing in life is as simple as it first seems.

Here is a great Technology Connections video which lays out why the sizing issue might not be as bad as you're thinking. The gist is that many people are steered away from heat pumps (or sold very expensive oversized units) by outdated industry thinking which vastly overestimates load calculations.

I won't try to make his case here, but he is pretty convincing that a reasonably sized heat pump system can be sufficient even in very cold climates (by US standards).

https://youtu.be/DTsQjiPlksA

Re: Steam Networks

#73

Post by 2OEH8eoCRo0 »

jasonthorsness wrote: post #5

Even Seattle has one of these! And the University of Washington as well. It’s amazing that the economics holds up even today. https://en.m.wikipedia.org/wiki/Seattle_Steam_Company

A lot of military bases have steam pipes all over the place. I think they recently demolished the Camp Lejeune steam plant

Re: Steam Networks

#74

Post by mikepurvis »

someuser2345 wrote: post #33
imglorp wrote: post #30

The article cites end-to-end efficiency as 60%. Plus the costs of maintaining steam generators and the pipe network. Electrical transmission systems are roughly 85% efficient to the consumer; together with boring old resistive electric radiators which are 100% efficient. So is there any reason to subscribe to the steam system for new construction?

Most electricity is generated by using steam to turn turbines, right? So it definitely seems more efficient to just use the steam directly, instead of converting it to electrical energy and then converting it back to heat.

I believe in the NYC case, the steam is also not right off the reactor— it's waste steam that has already been through a turbine and so is still hot and under some amount of pressure, but is no longer economically valuable in a power plant context. So it's run into the city as an alternative to just venting it into the atmosphere.

Re: Steam Networks

#75

Post by themaninthedark »

coryk135 wrote: post #25

This part really caught my attention: > in 1962, the anthracite seam under Centralia, PA – 25 miles to the west of Lehigh County – caught on fire and is still burning today.) That’s crazy to think that for over 60 years there’s been an underground coal mine on fire. I wonder how long the mines will burn for. The pictures on Google are quite interesting.

There is also Yanar Dagh in Azerbaijan.

Wiki says the fire started in the 1950's but CNN says 4 thousand years.

https://en.wikipedia.org/wiki/Yanar_Dagh https://www.cnn.com/travel/article/yanar-dag-azerbaijan-land...

Re: Steam Networks

#76

Post by nightpool »

whatevaa wrote: post #66
nebolo wrote: post #50

Earlier quoted context omitted.

The efficiency of modern cold-climate heat pumps plummets to 200-300% at 40F and perhaps 175% at 5F.

So at -20 and below they are basically very, very expensive resistive heaters. Good for medium climates, bad further north. Also either need very expensive oversizing or backup heat sources to compensate reduced heat output, even if you get occasional cold spikes. Unfortunately nothing in life is as simple as it first seems.

How often does it get to -20f in New York City?

Re: Steam Networks

#77

Post by lxgr »

mindslight wrote: post #64
lxgr wrote: post #20

Earlier quoted context omitted.

Part of it is definitely dumped directly into the air through an over-pressure valve on each radiator. At least that's been the case in all steam-heated NYC apartments I've ever visited or lived in. But what counteracts this is a loss in humidity caused by the heating of cold air from the radiator itself (cold air warmed up reduces relative humidity), and in my experience, this more than counteracts the little bit of…

nit: The valve is a thermostat that vents the air/steam in the radiator when it's not hot enough, letting new steam come in and replace it. This gets heat to the radiator quicker (over pure diffusion), and provides a mechanism of controlling its individual heat output. Of course, these valves are often broken.

Interesting, that explains why it's going off so consistently and makes a lot more sense than just avoiding overpressurization. Thank you!

Re: Steam Networks

#80

Post by whatevaa »

jacobaul wrote: post #72
whatevaa wrote: post #66

Earlier quoted context omitted.

So at -20 and below they are basically very, very expensive resistive heaters. Good for medium climates, bad further north. Also either need very expensive oversizing or backup heat sources to compensate reduced heat output, even if you get occasional cold spikes. Unfortunately nothing in life is as simple as it first seems.

Here is a great Technology Connections video which lays out why the sizing issue might not be as bad as you're thinking. The gist is that many people are steered away from heat pumps (or sold very expensive oversized units) by outdated industry thinking which vastly overestimates load calculations. I won't try to make his case here, but he is pretty convincing that a reasonably sized heat pump system can be sufficien…

It's all theoretical. In real life, retrofitting heat pumps into exisinting homes is a bit different, as those homes are neither made for air heat sources (at least in my region), nor they are insullated well. You might say, dough, insulate it, but it is easier said than done, as a lot of those old homes relied on their leakage for ventilation, not to mention that is very expensive investment (much more expensive than the heat pump itself).

I would reccommend keeping backup heat source when installing heat pumps into older homes. A simple wood stove, used during cold spikes, could be enough.

My country has subsidies for heat pump installations into older homes and it had requirement to get rid of chimneys to get that. After the whole europe energy crisis thing, this requirement is gone now. Turns out having alternatives is a good thing :)

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