Hacker News Board Hacker News, browsed like a classic message board
Live data from Hacker News

Steam Networks

worksinprogress.co

Post reply on HN
Print view View original

101–110 of 161 posts

Re: Steam Networks

#101

Post by z2 »

riggsdk wrote: post #90
LeifCarrotson wrote: post #71

Earlier quoted context omitted.

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…

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.

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...

Re: Steam Networks

#102

Post by UltraSane »

lxgr wrote: post #29

My favorite fact about steam distribution systems is that they can be used for cooling, using either a steam-powered compressor or using adsorption refrigeration. At least the former seems to actually have been employed or at least studied as an option by ConEd in NYC: https://web.archive.org/web/20071008014254/http://www.coned....

adsorption refrigeration has a really bad coefficient of performance, typically 0.3 to 0.7, while vapor compression systems get 3-5

Re: Steam Networks

#103

Post by bluGill »

blackeyeblitzar wrote: post #51

> The last total system failure was in 2007, when an 82-year-old pipe at 41st and Lexington exploded, showering Midtown in debris. Heavy rainfall had cooled the pipes, producing large amounts of condensate quickly, and a clogged steam trap meant that the system was unable to expel the water. When this build-up hit a critical level, the internal pressure shot up, causing the explosion. Almost fifty people were injured…

Compressed gasses are worse than fluids. I'm not sure if a water pipe even can explode - as soon as the pipe shatters there is no more energy as the water isn't going to expand. Gases will expand in the explosion and drive the pipe parts to more energy.

That isn't to say water/fluids are not dangerous. They can kill. However for the same pressure gases are much worse.

Re: Steam Networks

#104

Post by UltraSane »

The Shoreham Nuclear Power Plant was built between 1973 and 1984 by the Long Island Lighting Company (LILCO) at a cost of approximately $6 billion. It was never put into use and was fully torn down in 1994. It stands as one of the most expensive industrial projects ever completed but never used for its intended purpose.

Re: Steam Networks

#105

Post by vkazanov »

LeifCarrotson wrote: post #71
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…

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.

Re: Steam Networks

#106

Post by vkazanov »

vkazanov wrote: post #105
LeifCarrotson wrote: post #71

Earlier quoted context omitted.

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…

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.

Just noticed that this is what you suggested :-)

Re: Steam Networks

#108

Post by 8ig8 »

vkazanov wrote: post #105
LeifCarrotson wrote: post #71

Earlier quoted context omitted.

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…

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.

Cogeneration

https://en.wikipedia.org/wiki/Cogeneration

Re: Steam Networks

#109

Post by jabl »

bluGill wrote: post #103
blackeyeblitzar wrote: post #51

> The last total system failure was in 2007, when an 82-year-old pipe at 41st and Lexington exploded, showering Midtown in debris. Heavy rainfall had cooled the pipes, producing large amounts of condensate quickly, and a clogged steam trap meant that the system was unable to expel the water. When this build-up hit a critical level, the internal pressure shot up, causing the explosion. Almost fifty people were injured…

Compressed gasses are worse than fluids. I'm not sure if a water pipe even can explode - as soon as the pipe shatters there is no more energy as the water isn't going to expand. Gases will expand in the explosion and drive the pipe parts to more energy. That isn't to say water/fluids are not dangerous. They can kill. However for the same pressure gases are much worse.

The city where I live has a district heating system using water, the temp in the mains is up to 130C or thereabouts. Occasionally there are failures, but they tend to be fairly undramatic. Due to the temperature the water flashes to steam when released. It's not recommended to go too close to the leak due to the risk of scalding from the hot water and steam. But no explosions like can happen with a hydraulic block in a steam system.

Re: Steam Networks

#110

Post by toenail »

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's also one in Germany that's been burning since the 17th century, Goethe even visited and wrote about it, https://en.wikipedia.org/wiki/Brennender_Berg
Post reply on HN