Steam Networks | Hacker News Reader

Steam Networks

worksinprogress.co

361 pointsherbertl155 comments

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?

At least where I live, the Steam is either reused from thermal power plant waste heat which would be evaporated off anyways, or its the heat directly produced from specialised combined electric/thermal gas plants (Blockheizkraftwerk). Also, general industrial waste heat is sometimes used (glass plants e.g).

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.

Except you can ONLY use steam for heating and transporting it over distance is not efficient. If you turn steam into electricity you can use it for ANYTHING and transport it over long distances efficiently.

It also means that at the local scale it might be better to distribute steam. Think about future residential nuclear plants. It might not be worth investing into steam distribution on top of electrical as electrical is more flexible, but there might be steam that's residue otherwise that could be used on heating.

> future residential nuclear plants

What does this mean? Are you imagining a future where individual houses have their own nuclear plants? Or where nuclear plant workers live on-site?

I'm get the argument that we should have more nuclear power, and that some future reactors may be small, but I don't understand the expectation that they would be close enough to residences to pipe steam.

In many places in the world people don't live on ranches or in 1000 m² houses, but in 80-150 m² twin houses or even flats.

In such tighter conditions, you can easily have enough inhabitants per km² that it would justify building small mobile nuclear reactors.

Who would like to live next to a reactor if it can melt down? Well, you have reactors using fuel pellets locked in marbles that due to their diameter can never meltdown.

There has been a couple small scale nuclear power projects for a while now,

- https://newatlas.com/energy/oklo-aurora-nuclear-microreactor... - https://www.popularmechanics.com/science/a33896110/tiny-nucl... - https://www.nuscalepower.com/products/nuscale-power-module

They target from home to residential scale. I hope they are eventually a thing.

Steam in NYC is also used for cooling https://en.wikipedia.org/wiki/New_York_City_steam_system

That reasoning isn't enough on its own, because on the clients' end, electric heat pumps can be more efficient than direct steam heating. Actually their "efficiency" is far above 100%,

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

And their efficiency plummets starting at 40F and below.

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

But 5f is still high.

This is actually terrible and supports their point. Heat pumps are not sized as if they were running at a mere 100% or less, they are sized for the btus they normally produce, and aim to run close to 100% of the time, meaning they will be too small and not be able to do the job when they drop below 200-300% efficiency, unless they are grossly oversized. That leads to short cycles which makes condensation and moisture in the summer and wear and tear all year and less electrical efficiency because starting a pump and blower costs more than running it.

Current inverter types that can run slow do allow them to be oversized but it's still not great. Those are more expensive and have more failure points in electronics too.

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

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 :)

I live in Canada in an older home with terrible insulation.

Out two tonne heat pump works just fine even at -25C this past winter.

We still have a natural gas furnace but our gas usage is down 65% despite this winter being colder than last year’s.

Tell me again how heat pumps don’t work in colder climates?

This is why I opposed historical designations. Most old buildings are obsolete and need to be destroyed. There are only a tiny number of buildings that are really historic, sure save them, but the vast majority are just old and need to be knocked down for something better. If it isn't taught in history class then it isn't historic.

It is easy to see the loss of something old. However the opportunity cost from not building new is something that is very hard to get people to understand.

This is not theoretical: my heat pump purchased in 2021 worked well for four straight days of below 0F. Kept our temp at 68 inside. We live in an old home from 1917 with poor insulation between the brick exterior walls and drywall.

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

Ahh damn, I forgot unit, I meant -20C, so -4F

You have to go quite far north for -20F to become frequent.

If it EVER gets to -20 that is what matters. You need to prepare for the worst case weather, not the common ones.

Fortunately resistive heating is just about the cheapest possible heating in capital costs and trivial to retrofit as a backup.

It will still work, just not as efficently as in normal temperatures. So you're using 50kWh for the 3 days a year it's that cold and 10kWh for the other 362 - better than using 20kW every day.

Only if there is enough power generation

And a good 24,000 BTU rated heat pump will produce just under 20,000 BTU at -13 F, about 18,000 BTU at -22 F (-30 C).

1990s called, they want their efficiency back ;)

Sure, you can still find good weather heat pump that crap their pants near or under freezing. However, the majority sold here in Europe still stay well of 200% down to -15C, some even -25C.

75% of rated capacity at -22 F (-30 C), over here.

“Fifth generation” district heating uses heat pumps to extract heat from a network of lukewarm water.

Yep and IIRC you can even dump waste heat back to the loop at what would normally be just consumers - eq. to cool a hockey stadium or for a big building AC system.

That's not true. Except for nuclear and solar collectors, all renewables, especially hydro, have nothing to do with steam.

What isn't true?

> Most electricity is generated by using steam to turn turbines

That is true. It is also true that renewables usually do not use steam. But they don't answer for "most electricity". That's natural gas, coal and other types of thermal plants, including nuclear.

Renewable power is 30% of the world grid.

Gas combined cycle power plants get part of their power from gas in the turbine directly, and part of it from steam cycles. I can't figure out what % over of power comes from which part, and not all gas power plants are combined cycled.

It seems reasonable to say that most electricity is not generated by steam turbines. However I'm not sure how to find the real data to verify this. (and pedantically the gas in a gas turbine is mostly steam)

Geothermal plants also use steam (not to be confused with geothermal heating/cooling, which is just a heat pump with the heat exchanger underground rather than in the air).

Where I live most electricity is generated from wind. Solar also has a large share of some grids. Your location may be different but it should have a significant renewable share by now.

There's no single efficienty number for "steam". Steam turbines in large power plants for example are >90% efficient when considering just the thermodynamics. There are a hundred other variables involved.

I'll note that powerplant steam turbines are often pretty cutting edge & supported by essentially a special plant to achieve this levels of efficiency and reliability. Stuff like hydrogen cooling the generator bit:

https://en.wikipedia.org/wiki/Hydrogen-cooled_turbo_generato...

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.

The inefficiencies come from infrastructure. Transferring electricity is so goddamn cheap, that city planners and developers hardly consider it a footnote. Water, sewage and drainage on the other hand are much, much more expensive. They require much more space, and oft times need to be pressurized. Imagine that with steam pipes where the steam on top of all that, needs to be heated too. Sure, hooking up to an existing steam main probably doesn't cost too much, but building new mains can't be worth it, even in the long run, as infrastructure constantly needs to be upgraded.

In terms of thermodynamics, a electric resistive heater is 100% efficient, but if the measurement is how many BTU of heating you can put into a room in a day with a certain amount of watt hours, a modern heat pump will always beat it. Also of course 100% electric.

A heat pump is more than 100% efficient on that measure.

I am not sure about "always". Does it not depend on the temperature difference?

The use cases for steam seem to be where you need more than room heating though: the first paragraph mentions sterilising medical equipment, humidity control, and washing.

My understanding is that it varies by temperature difference, but there's specialized series of heat pumps which work "okay" with very cold outside temperatures, even down to -25C, which are becoming popular to replace oil tank heating systems in Atlantic Canada. Apparently even when operating at -20C outside air they're still more efficient than electric baseboard heating.

I don't know of any of the customers of the steam system in downtown Vancouver that use it for sterilization purposes, it connects almost exclusively large office towers. There's no hospital or medical facilities connected to it.

> I am not sure about "always". Does it not depend on the temperature difference?

My understanding: A heat pump is always better than resistive electric heating. Sometimes a outside air using heat pump needs to use extra energy to defrost the outside unit (with resistive electric heating). The defrosting is driven by sensors, but rarely happens more than e.g. once an hour for 5 minutes at a time. Heat pumps really do win over resistive electric heating on everything except initial cost, and that's not even hard -- resistive electric heating is very wasteful.

Most energy is generated from steam that has a terrible efficiency of 40%

> Electrical transmission systems are roughly 85% efficient to the consumer;

Electrical generation itself isn't a 100% efficient. For example a gas powered electricity plant is about 60% efficient for generating electricity. Generating heat from gas is far more efficient.

Then again if you use the electricity not for direct heating but for example to power a heatpump on the other end (i.e. you use the electricity to extract heat from the air) then it could be more efficient.

Yes: very low temperature steam is useless from a thermodynamic perspective, cannot be used to perform (meaningful amounts of) work or generate electricity. When sourced a waste byproduct of an electric power plant, it's essentially free—it has no other economic value.

There's zero opportunity cost of "you could use it for some other purpose instead".

Sadly this article doesn't make it clear whether it's waste steam from electricity generation or steam made explicitly for this purpose. It also doesn't specify what the fuel is now - it used to be coal, is that still the case?

Wikipedia says "Approximately 30% of the ConEd steam system's installed capacity and 50% of the annual steam generated comes from cogeneration" i.e waste steam, which is .. half good, I suppose.

It also gives https://web.archive.org/web/20101207021857/http://coned.com/... which I guess has the rest of the details in.

There is cost though - the pipes needed to get steam someplace are not free. Those pipes can explode when things go wrong so people can die. How you add those costs up is a debatable question, but it isn't free.

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

Not my expertise, but my understanding is that district heating is a very very efficient way to store electricity, such that the inefficiencies in transmission are mitigated in part by the storage efficiency. This allows you to more reliably depend on energy sources that don't have 100% uptime.

That said, I think most of this applies to heated water, not steam.

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.

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...

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-...) including copper which https://en.wikipedia.org/wiki/High-voltage_cable says they're made of

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.

The wire needs to be at least as hot as the desired temperature in the home.

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)

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 :-)

Cogeneration

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

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.

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

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.

In most places with district heating, the heat that goes to the heating system is waste heat which turbines of a nearby power plant cannot use. This applies to fuel-fired and nuclear power plants alike. (Keywords: Carnot cycle efficiency.)

So using electricity for heating would be just throwing free heat away. Heat distribution networks are of course not free though.

Electric heating would be an economical win if the electricity could be harvested by solar and wind generators, and stored. Storing solar heat directly is much trickier.

It's not quite waste heat because the cold side of thermal power plants wants to be colder than district heating temperatures for best efficiency. There is some loss in electrical efficiency compared to non cogeneration plants, but the combined efficiency is a lot higher.

> Usage fees are then added on top, paying anywhere from $11.35 per megapound in the summer to $35.013 during peak season.

Steam with <1112 BTUs per pound vs room temperature will condense, so the heat value of a megapound of steam is at least 325,895 kWh. That's a marginal cost of 1 cent to 3 cents per MMBtu or 3.5 cents to 11 cents per MWh. The hookup cost ($3,555) is much smaller than the cost of the steam ($13k-$44k per the article).

For comparison natural gas costs a couple dollars per MMBtu and wholesale electricity costs $40-$60 per MWh. *The steam is orders of magnitude cheaper.*

If the article's quoted prices are accurate (note: Lincoln Towers seems to pay $2.43 per megapound, significantly less than the $11.35 usage fee the article gives immediately before. Not sure what's up.) then steam is practically free. I'm not really sure how that's possible; maybe there are subsidies or regulations enforcing production. A significant amount of the steam is from cogeneration, where steam is a byproduct of pollution-reducing processes- it makes sense that would reduce the cost, almost all steam would need to be a byproduct to explain the price.

>Electrical transmission systems are roughly 85% efficient to the consumer; together with boring old resistive electric radiators which are 100% efficient.

I'm wary of attempting comparisons of end to end efficiency, just because these aren't apple to apple comparisons. Solar panels are 20% efficient. Nuclear power can be anywhere between 60 and 90% efficient. Coal plants can be between 35 and 50% efficient. Each of these can have an economic rationale despite these differences in efficiency.. A Dyson sphere with 0.001% efficiency could be a winning value proposition. Granted, these are energy sources rather than transmission infrastructure, but the point is the same.

I would want to know about the efficiency loss from whatever primary source of energy was generated before it gets transmitted across the electrical transmission infrastructure, and I would want to know how it compares to a steam source, which could plausibly be such a thing as waste heat. If your steam is cheap or potentially even free it could conceivably win out in the final assessment, even if it has higher relative transmission losses.

Maybe this just makes your point, but solar panels being 20% efficient is about "how efficiently it converts energy from the sun into usable electricity"

All that matters is the actual power generation since there's no marginal utility of "what else we would use that space for" (unless you're consuming farmland etc for the solar panels)

Ah, but a thermal solar panel is more like 60% efficient, and it's built of glass, black spray paint and a garden hose. If the ultimate goal is to heat something with sunlight, you know which approach is the best. Several times as much area coated in special silicon stuff, or.... garden hose spray-painted black.

If the purposes are mixed, of course a photovoltaic panel can generate electricity for many purposes, while sunlight shining on a garden hose can only heat water. So it might be a more useful system, even more cost-effective, despite being much less thermally efficient.

It's the same with burning things to make heat, versus burning them for electricity and then using electric heaters.

Right. And the same with electrical energy transmission for the purpose of delivering heat compared vs steam infrastructure.

Steam is Carrington event resistant not electric system.

Where/how is the electricity sourced in a given case is probably worth consideration. If you have alternative sources for generation of steam vs generation of electricity, the methods/approach may vary. Not to mention the impact of the equipment necessary, the build process, availability and dependency on supply lines should all be considered.

If you had industry nearby like a foundry or glassworks that throws off unimaginable waste heat, you can pump that heat into homes instead of the atmosphere.

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 Burning Mountain in Australia which has been burning for thousands of years.

And a burning crater in Turkmenistan that's been going since the 70s.

6,000 years, according to Wikipeda. That is wild.

Yeah the Centralia story is wild. Who knows when the fire might ever go out? It's caught the imagination of many writers over the years, who have either been inspired by it or used it directly as a setting. Mostly in horror/paranormal content. As the Wikipedia entry notes

"Centralia has been used as a model for many different fictional ghost towns and manifestations of Hell. Prominent examples include Dean Koontz's Strange Highways and David Wellington's Vampire Zero."

I was thinking about that. It sounds like a great setting for a story but I felt like I’d seen it before and I guess this is why.

I've been there. It's where my ancestors are from, and an area of PA where all the jobs and civic like burned up long ago as well. Not a fun region.

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...

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

When you're driving through North Dakota and see the red clinker in the cliffs along the highway...

https://www.dmr.nd.gov/ndgs/ndnotes/ndn13_h.htm and https://www.dmr.nd.gov/ndgs/documents/newsletter/2013Winter/...

> Several early explorers reported coal fires in the northern Great Plains region. Over the years, range fires have ignited lignite beds many times. In two places in western North Dakota, in Theodore Roosevelt National Park and near Amidon, lignite seams were recently burning for many years. A seam of lignite at Buck Hill in the park burned from 1951-1977.

And that's the modern history.

> Years ago, during fieldwork on the major buttes of western North Dakota, John Hoganson and I discovered clinker pebbles in the Arikaree Formation indicating that coals had been burning prior to when these rocks were deposited some 25 million years ago. Probably as far back as 40 million years ago, when grasslands were first established, fires have swept across the plains of North Dakota igniting coal seams.

I see your underground coal fire and raise you https://en.wikipedia.org/wiki/Oklo

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

Vancouver as well:

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

And UBC

Indianapolis, too [0, 1]:

> the second largest district steam system in the United States. The plant provides steam for heat and hot water to more than 200 commercial buildings and industries across downtown. Perry K's steam also helps power chilled water facilities which cool more than 60 large facilities around downtown. [1]

I grew up going to downtown Indianapolis as a kid and was always freaked out by the steam emanating from the manholes and grates on the street. It turned out not to be an unfounded fear--they have occasionally exploded [2].

0: https://en.wikipedia.org/wiki/Perry_K._Generating_Station

1: https://info.citizensenergygroup.com/thermal/history

2: https://www.wfyi.org/news/articles/locking-covers-installed-...

Grand Rapids, MI, too: https://www.vicinityenergy.us/blog/our-history-vicinity-ener...

You can see the steam plant from pike place market and the steam stacks look like there’s some sort of industrial thing going on which now looks very out of place. It was interesting to figure out what the building was for! The biggest customers are the hospitals up on the hill, and the steam is used to sterilize instruments alongside heating.

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

Montpelier, Vermont as well: https://www.montpelier-vt.org/427/Project-Background

A LOT of universities have a central heat plant that pumps hot water to all the other buildings. I think steam has been phases out because it is so much more dangerous and electric pumps make it unnecessary.

Yeah, a lot of institutions are removing steam for heating and replacing it with glycol loops.

Must be a lot lower maintenance.

Much lower maintenance, and VFDs have made pumping glycol a lot more energy efficient than an older across-the-line starter.

One of my three favorite books growing up is relevant to this article. It’s also a great allegory about the passage of time and technology. Maybe worth picking up a copy…I still own mine:

https://en.m.wikipedia.org/wiki/Mike_Mulligan_and_His_Steam_...

Fantastic book, great recommendation.

It was read to me as a child, and I read it to both of my sons. It's one of the few things I have from my childhood.

TIL that steam distribution was invented in the USA around 1880, and is still used in NYC. Never occurred to me that “Steam Plants” literally produce steam for distribution. I thought that was a glib reference to the white smoke they produce!

Valve's "Steam" platform naming makes more sense from this perspective. Literally the pipes transporting games to customers.

I was hoping this article would be about some crazy new networking inovation from Valve!

Fun fact: it's not just small grids that run on steam - Munich's steam heating dates back to 1908 and since 2022 it's being reworked at massive expense to hot water to better accommodate geothermal and other renewable forms of heatpump based generation because these sources cannot get hot enough to produce supercritical steam [1].

[1] https://www.swm.de/dam/doc/geschaeftskunden/fernwaerme/flyer...

New Yorkers love putting things in pipes, don't they? Not content with putting normal things like water, sewage, and gas in pipes, they apparently put steam in pipes, on Roosevelt Island they put a mix of rubbish and vacuum in pipes [1], they used to put the post in pipes [2], apparently they pipe rats to people's houses or something, occasionally once of them puts gunpowder in a pipe [3], and they even put themselves in pipes [4]. It's all very Freudian, they should talk to their therapist about it.

[1] https://www.untappedcities.com/inside-roosevelt-islands-futu...

[2] https://www.untappedcities.com/pneumatic-tube-mail-new-york-...

[3] https://en.wikipedia.org/wiki/George_Metesky

[4] https://en.wikipedia.org/wiki/Second_Avenue_Subway

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.

How common are district heating systems? Montpelier in Vermont uses wood stoves to deliver steam to a large part of their small downtown: https://www.montpelier-vt.org/427/Project-Background

I live in Minnesota and both Minneapolis and St Paul have district heating and cooling systems in their downtown core areas. Cordia Energy operates the Mpls network and Evergreen Energy operates the St Paul network. I’m unsure what the fuel source is for the Mpls network but the St Paul network uses wood chips/wood waste and natural gas.

Minneapolis: https://cordiaenergy.com/our-networks/minneapolis/

St Paul: https://www.districtenergy.com/

Charlottetown, a city of 38,000, has a waste-to-steam plant that heats the hospital, downtown and the university.

The 30-year-old steam network springs leaks every so often, so you see gurgling hot springs from the ground.

I’d love to know how much cheaper it would be to use this form of heating for my home compared to oil heat.

(1) https://www.enwave.com/locations/pei.htm

Incredibly common in continental Europe. Wikipedia has an overview: https://en.m.wikipedia.org/wiki/District_heating

Yep, we have a big distric heating system here in Brno, Czech Republic - in operation since 1930, with 110 000 housholds & most big public and commercial buildings connected. It started as coal fired, but the modern system combines natural gas cogeneration (gas turbine -> steam turbine -> district heat) and waste incineration (that also includes a steam turbine to make some electricity). In the summer the waste incinerator provides all the necessary heat for the system alone. :)

Eventually the city would like to make the system stop using natural gas, so there is a wood waste burning plant comming online at the end of this year & hot water pipeline is being built from the nearby Dukovany power plant. This two together should make the system natural gas indepedent in the future. :)

While it started as steam based system & powered most of then very important textile industry, steam also has issues. Old pipes loose quite a bit of heat on the way (there used to be evergreen meadows even in winter in places above the old steam pipes), the pipes flex quite a bit when heating up/cooling, so they need to be placed on rollers in underground channels with U shaped sections to account for the pipe stretching/contracting. The steam also condenses & you need to get rid of that condensate on the way. And while unlikely, it is possible for a steam pipe to burst/explode, which is very dangerous for any bystanders.

For these reasons & because the textile industry being much less important, the Brno district heating system is being converted to hot water distribution, which is quite a bit more effcient apparently. Reportedly, with modern insulated pipes, the heat loss on the way is negligeable, the pipes can be placed directly in the ground & they form a closed loop - no more mucking with rollers, condensante or explosions.

So in a few years, the often seen steam ventilation pipes (from the various steam related texhnical spaces) around the city will be a thing of the past. :)

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....

Similarly propane powered refridgerators.

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

Ah, I was always wondering why they weren't more commonly used, but that's a pretty horrible coefficient of performance. I guess it's really only worth it if you want no moving parts for quiet or maintenance-free operation?

I suppose if they can use waste heat they make sense.

I always thought watching films that steam in the dark streets was some cool 80s aesthetics. As in 'You are in this dark corner of the city where nobody can hear you' scary or edgy.

It would be a shitty steam network that allowed steam to just leak.

Steam rising out of manholes is definitely commonplace in NYC: [1]

There's a stretch of sidewalk in the Financial District that gets so hot that you can feel it walking past on some days. And apparently, sometimes these things explode... [2]

As far as I've heard it's not (all) actual leaks, though, but rather water dripping on the exterior of the hot pipes carrying the steam itself being evaporated.

[1] https://en.wikipedia.org/wiki/New_York_City_steam_system

[2] https://en.wikipedia.org/wiki/2007_New_York_City_steam_explo...

It's often not the steam pipes leaking. The sewers are very humid and warmer than the air above. As the air convects up it hits the cold air and the humidity condenses. The same thing happens in lots of other cities when the weather is right.

Maybe the steam pipes keeps the sewers warmer in places with steam but they should be well insulated in the end.

you can see it pretty often in NYC, coming up from vents/pipes in the road

i don't think it's steam leaking. it's drainage/sewer water being heated by the steam system (and other heat sources down there) enough that it evaporates and rises up to the street, and then condenses into vapor/fog because the street level is cooler

That's what I figured.

Then every city with a steam network is shitty! They bleed them with steamstacks all over the place.

Apparently it's to regulate pressure.

I grew up in a city without steam and the sewers would still smoke like that when it got cool out, like early morning; its still fairly warm down there

I thought that too (but more New York Christmas Eve movie impressions) until I saw steam coming from manholes in Denver. Blew my mind that it was a real thing haha.

In addition to the heating/cooling uses, the mint in Denver uses it to clean coins!

Related: "The Lost Art of Steam Heating" by Dan Holohan (2017)

https://news.ycombinator.com/item?id=18430512 (2018)

Holohan argues that we've mostly lost competence at maintaining steam heating systems, and it's not that hard. The lack of understanding has led to many expensive and ineffective refurbishments.

"A recent study found that a fireplace pumps out 58 milligrams of particles under 2.5 microns in diameter (PM2.5s) per kilogram of firewood burnt. This means that every hour you spend in a room with a fireplace burning wood reduces your lifespan by about 18 minutes, equivalent to smoking 1.5 cigarettes"

These kinds of stats really irritate me. Sure, smoking isn't great. Breathing in small particulates also isn't great. However, the 18 minutes is such a weird thing. There are so many people that have lived longer lives by smoking than people that work out all the time. There's just no real evidence this stat is true. You can't clone a person and sit one clone in the room with a fireplace, and then the other not in the room. Then watch which one dies first.

The only test I've seen with evidence of one doing something the other doesn't was the twin brother astronauts where one went to space and the other did not.

That's why they don't look at 1 person but at aggregates. If the world was made of twins and triplets and they lived identical lives (nutrition, stress levels, air quality, ...) besides the 1 factor you're interested in (fireplace yes/no), that would be great for learning from, but of course that's not the case, not even for that astronaut

I'd encourage you to open up one of these studies. The language in scientific papers is made to sound smart but it's still English (most of the time) and you'll see these sorts of things are established by looking at many people in many situations and then use maths to tease out how much each of the factors (living near a major road, for instance) contributes to the thing being investigated (such as longevity). Many of the factors, also depending on the number of people involved, will not turn out to be statistically significant, meaning that the error margins are too large to be sure. For smoking and woodfire particulates though, we're certain that it's unhealthy to within extremely low error margins. Whether that's precisely 18 minutes: probably not, but presumably that's our best guess, even if it has uncertainty associated with it. The paper is linked literally within the quote you gave, if you want to check how uncertain the value is: https://www.sciencedirect.com/science/article/pii/S235271022...

Skimming this one, they didn't establish the relation between particulate matter and lifespan themselves but they cite other studies that did this:

> correlating average PM2.5 levels during a shorter time interval and the average life expectancy during that same time period. In Taiwan, this method used data from 17 counties for the 2010 to 2017 period and resulted in a DLE factor of 0.798 years per 10 μg/m3-increase in exposure to PM2.5 [50]. Using data from 545 counties in the United States for between 2000 and 2007 [51] and data from 214 cities in China for between 2013 and 2017 [52], resulted in lower DLE factors: 0.14 and 0.18 years, respectively, per additional 10 μg/m3 of exposure to PM2.5.

If you doubt those methods, you should click through to sources 50, 51, and 52. This study just measured the amount of PM2.5 in three situations and then multiplied it with that value from the other studies (I didn't read far enough to see which one they ended up picking, that should be mentioned somewhere if you want to know/check it precisely), and that's how they get to this value

> There's just no real evidence this stat is true.

They don't just pull stats from thin air. If you think they made a mistake somewhere and arrived at the wrong number, I'm curious to hear where they went wrong, and the authors would probably be happy to be get an even better stat as well

Growing up in Southern California and New Mexico, the first exposure I had to systems like this was in Cities Skylines. It boggled my mind that this type of thing was still used enough to feature in a modern simulator game until I started researching them and found them to be a great solution. Very interesting article.

Cities Skylines was created by a Finnish company, where this is normal heating system.

An incredibly interesting piece. I live in NY, but didn't know the history.

This did make me chuckle

> reduces your lifespan by about 18 minutes

As George Carlin said, "yeah, but it's the last 18 minutes".

Today's ConEd seems to lag environmentally on the generation side: still runs on fossil fuels, and only half of the steam is by cogeneration of heat and power. (Going by https://en.wikipedia.org/wiki/New_York_City_steam_system)

Indianapolis also has a large steam network, with a prominent steam plant located in the southwest corner of downtown proper -- just down the street from Lucas Oil Stadium.

https://en.wikipedia.org/wiki/Perry_K._Generating_Station

> Traditional fireplaces are immensely inefficient, drawing in 300 cubic feet of air per minute for combustion and expelling up to 85 percent – along with the heat – up the chimney.

So the other 45 cubic feet exhaust per minute go where? Into the rooms to suffocate the people there?

Also, isn't that heat only convection? This doesn't seem to take into account the fact that brick or stone fireplaces absorb heat and then radiate it back into the room. It's not all about moving hot air. The fireplace itself gets hot and that feeds back into the room through radiative heat.

This is one of the coolest articles I’ve come across on HN ever. Also - it’s true steam punk (sorry).

There's an interesting lecture about the New York city steam heating system by Dan Holohan at https://m.youtube.com/watch?v=nkgM0qCy5o4

How is mildew and mold avoided in the pipeline and interior spaces being heated by steam?

Pretty sure the steam is ran through radiators and not just dumped directly into the air.

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 steam hissing out of the radiator valve.

As a side note, I've always wondered if the steam being vented that way is actually coming from the steam plant, or whether there's a heat exchanger somewhere in between that isolates a building's steam network from the distribution one (which is the case for liquid water heating, as far as I understand).

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!

Super heated water is a pretty effective disinfectant within the pipes. For interior spaces ventilation is a legitimate problem in non-forced-air systems.

Historically, you open a window.

if steam leaks out and gets trapped somewhere, presumably that's a breeding ground for mildew and mold

inside the pipe, can much life survive? is there anything to eat in there? has anything evolved specifically to live in NYC steam pipes?

Mold doesn't grow well outside of around 60-80F (15-26C), and it needs food. Steam and hot water systems also use treated water to help reduce corrosion in pipes. That said, radiators themselves still do corrode and create nasty looking water even if it's generally sterile.

You should be more worried about Legionella, but proper steam and hot water systems will stay above 140F (60C) as that temperature not only prevents the bacteria from multiplying but will kill 90% of them within 2 minutes.

The temperature of this is such that industrial heat pumps are available to produce the steam. I don't imagine these are used in NY City, but they could be.

Marsh Island, Maine as well:

https://umaine.edu/umec

Pratt university in Brooklyn used to have a gentleman working there named Conrad Milster. He is a steam head and machinist who maintaining Pratts secret "working museum", a turn of the century steam generating plant for the campus. The plant also features two boilers, the original boiler which originally provided both heat and power and an additional boiler was added in the 30's to add capacity as the campus expanded. Milster also lived on campus in the old row houses. His was special, a full set of gauges and meters in his living room was plumbed to the plant so he could keep an eye on the boilers from he comfort of his home. He also said that steam from the plant not only heated the campus but a few buildings off campus that surrounded it. I never got to ask which buildings though. So there very well might be a little steam network in Brooklyn around Pratt.

This is located in the basement of one of the buildings on campus. The power plant consists of three Ames Iron works single piston steam generators producing 120V DC fed to a marble switch board. Another piece is an early non-functioning steam turbine DC generator, WW2 era diesel generator from a battle ship. A 30HP motor-generator set used to provide 120V DC to the two service elevators in the building. And in the boiler room are numerous antique yet still functioning feed water pumps (the original steam driven feed water pumps actually do most of the work with newer electric pumps kept for standby) On the wall of the boiler room is a functional steam driven Ingersoll Rand air compressor. Amazing place. When I first visited in the 90's the MG set was still running providing power to the service elevators though they were replaced in the 00's leaving the MG set idle. There is also an old giant wood and brass Master clock in the office that was wired to every other clock on campus so whatever time you set on the master, the other clocks would then run super fact until they come around to the set time. It was running up to the 80's I think but Milster said a renovation crew hacked up all the wiring and no one ever bothered to fix it.

Milster was fired a few years ago supposedly after he refused to remove the resident stray cats who lived in the plant (they even had their own little decorated doorway.) The reason being a union employee was allergic to the cats and kept complaining until they fired him. Shame because anyone who works with antique steam equipment knows Milster and hes full of ancient knowledge no one will ever regain.

Edit: If you are into steam then look up Conrad Milster. I had the pleasure of talking to him a few times and he's such a nice and knowledgeable individual. He even started one of the 120V generators just for me after I said "Wish I could see it run" and he was like "sure" then opens a valve and slowly opens another to get it up to speed. Scary as the inertial lever arm bangs around loudly in the flywheel but then its goes near silent and hums away. Steam engines are very quiet.

Saas - Steam as a service

Pocket steam

(carries a nuclear pellet around) just add water

> 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, and one woman died of a heart attack while fleeing

The photo of this explosion makes it look huge. I wonder how much the pent up infrastructure work to avoid these issues would cost. Are water or gas pipes also vulnerable to this sort of thing?

> I wonder how much the pent up infrastructure work to avoid these issues would cost.

The cost is essentially incalculable. Back in the 1800s people kept poor records of what they were stuffing under the streets, and the records that were kept were lost, and the ones that weren't lost are sitting in a box who knows where. NYC has effectively no idea what they're going to find under a street every time they tear one up, and the deeper you dig, the more you find.

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.

I happened to be walking a few blocks north and one east of this when it happened. I saw dozens of people running up the street in a panic. Office ladies running barefoot with their heels in hand. I asked what had happened and they said there was a giant explosion that could only have been terrorism.

The wikipedia article has a few more photos: https://en.wikipedia.org/wiki/2007_New_York_City_steam_explo...

The aftermath photo gives you a good sense of it: https://www.nbcnews.com/id/wbna20184563

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