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Comment by gamegoblin | Hacker News Reader

Many American universities use district heating for the whole campus.

Also, as made famous by the many steam vents in NYC movie shots: https://en.wikipedia.org/wiki/New_York_City_steam_system.

More info: https://en.wikipedia.org/wiki/District_heating#United_States

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From finnish point of view, those seem small.

In finnish, the term is ”kaukolämpö”, literally ”far heat”.

You dont heat a ”district”, you heat the entire city. I mean, electricity wires go everywhere, why not heating pipes.

And so the network for Helsinki looks like this: https://twitter.com/energiahelen/status/1511998227008176129?...

The red lines is the heat pipe network, it covers the entire city.

When Americans talk about ”district heating” they miss the scope of the thing.

You're omitting a very important point: the heat sources themselves. The heat for the entire city doesn't come from a single power plant. It is distributed over many heat generation plants throughout the city, some dedicated solely to district heating. I don't think any spot on that map is more than a few km from a heat source.

To be fair, the vast majority of Helsinki's district heating system is powered by three combined heat and power (CHP) generation plants in Vuosaari, Hanasaari and Salmisaari. You're right that there is also 11 dedicated water heating plants to supplement the CHP supply in very cold weather or times of high demand, but they are supplementary.

More people live in New York than in the whole of Finland.

You can sort of tell from the other responses, but really the core of this argument is not the one you think it is: You think this means it is less appropriate for New York because of this fact. It is the opposite. Your population density is higher, so these types of solutions are easier and more cost-effective. This makes the fact that you don't already have it seem even more incompetent, which is the opposite of what you wanted to achieve.

Consider it's a nation that reinvented a crappy version of a metro with bunch of teslas in a very unsafe tunnel, I don't think you can expect reasonable answers. /sarcasm

I know it's hard to develop actual efficient solutions due to the cost of buying land, creating new infra. So you go for the cost efficient route instead of the practical efficiency.

I believe the parent was responding to “seems small” in regards to NYC’s steam heating system, which is the largest in the world.

Which only makes more sense for the New York to be heated by a network of pipes.

Portions of NYC are heated by pipes. ConEd operates the largest commercial steam system in the world.

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

>Today, Consolidated Edison operates the largest commercial steam system in the world (larger than the next nine combined).

Huh, neat.

A series of tubes, you say?

I never understood why it was so funny. For me it was good first order of approximation of how internet works.

We actually do pipe some stuff around and it flows from one place to another.

Is the series of tubes so hilariously unimaginable for Americans?

It’s not a truck.

As the first dorm on the loop my freshman year, I’d get back from crew practice, go into the bathroom, turn on all three showers, and flush the three toilets about three times each to flush all of the hot water out of the cold water line so that I wouldn’t burn myself when taking a shower.

I never heard if anyone got hurt when I took a day off and slept in.

This is most unfortunate but in proper district heating systems the scalding hot district circulation water never touches your house's heating / warm water. A heat exchanger is employed to insulate the different circulation systems. For example, my house has district heating and the warm water side is capped at +65C to protect against burns.

It's still pretty damn hot of course but I've never had any problems like you described, and I've lived in a dozen different houses in my city - all with district heating. Probably the system in the dormitory was somehow badly designed or incorrectly tuned.

I’m not positive I would have been scalded if I didn’t do that, but I do know that just turning on the cold line would yield at least uncomfortably hot water.

Why was the cold water line hot?

It was next to the hot water line and not insulated (enough) and it had pretty much just been sitting there all night.

Lucky you didn't get legionella. That is not up to spec, cold water lines should always be below 25°c. I have never seen such an installation, even in development countries it was done correctly.

> That is not up to spec, cold water lines should always be below 25

Yikes, that's tough. In my city, the cold water pipes are buried close enough to the surface and the brutal sun that it comes out of the tap about 27-29c during the day.

same, been in two developing countries with similar heating system, never seen such a problem. sounds disturbing

It's possible there's a faulty faucet mixing valve somewhere in the building causing hot water to mix into the cold line.

The hot water from the cold tap reliably went away once the water started running which is what made me think that it was sitting still next to the hot water that caused it

The University of Idaho uses district heat. The pipes run under the sidewalks so the waste heat keeps the sidewalks clear in winter.

By German standards that's still poor insulation. In winter in Leipzig the district heating pipes have snow sitting on them.

Sometimes this is intentional to keep paths clear. Idaho is much colder than Leipzig in winter.

You want to do that with the cooler water that is coming back to the power plant after the heat is delivered to the customer. Thus you use lower value heat to melt the streets. Assuming you do combined heat & power, as a bonus you get a small benefit on the power cycle as you get colder water into the pwrturbine cooling.

The sidewalks are actually the tops of tunnels that carry power and steam in both directions.

The historic averages don't look very different:

https://www.timeanddate.com/weather/germany/leipzig/climate

https://www.timeanddate.com/weather/usa/moscow/climate

though Moscow gets rather more snow

When the sidewalks are melted, it becomes waste heat. The rest of the year, it is waste heat. No matter how cold it is, if you accidentally leak heat it is wasteful - even if the side effect is something you may otherwise want.

Idaho summers are very hot. The district heat only runs part time. It is all waste heat from the power plant. There’s ample hydroelectric and wind power in the region as well. I’m not sure if the plant does demand shifting over the course of seasons but it could only run in winter because it runs on biomass and employs students. Many campus facilities are essentially jobs programs for students. The mission is experiential learning. I got a B.S. in business that included welding.

That sounds pretty cool

It was actually a great experience. It’s a land grant university that does a lot of really good research and has solid mechanical engineering, business, law, and architecture schools. I worked several on-campus jobs like janitor and IT support. They set me up with good internships over summers and decent mentors. I wouldn’t be where I am in life without the University of Idaho.

Great. How much energy do you spend clearing paths?

It's a fun set of optimisations: to get the path-clearing effect do you run the pipes on less optimal routes (greater capital costs), or do you using varying grades of insulation (less effective under paths to get the clearing effect, more effective on the short-cuts between paths), and so on. I hope Idaho uses these scenarios in their maths lessons, in place of the hoary "the phone company needs to put a line across a property that includes a river where it costs three times as much per metre..." that I teethed with.

Well the shortest distance between two points is a straight line. Pipe and sidewalk routing have similar objectives and constraints.

Not all sidewalks are heated. It’s more like they paved the top of the service vaults.

I don’t recall this problem specifically but the university employs a lot of students and alums.

Probably less than you lose in energy from heating the paths all year round.

As I explained they aren’t heated year round.

University of Minnesota still has it and has been upgrading it:

https://cpm.umn.edu/combined-heat-power-plant

St. Paul also: https://www.ever-greenenergy.com/project/district-energy-st-...

Texas tech in Lubbock does it. Blew my mind then and now.

Yet anytime it snows/freezes somehow the school shuts down. There is no drainage for runoff to accumulate so it just sits on the roads. Alum from 2012

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