For reasons I don’t understand, American cities seem allergic to installing new municipal steam or hot water utilities, even though things like cogeneration were an obvious use case for it, and now things like solar heat storage.
Steam and hot water pipes are extremely expensive to install, far worse than electricity, fibre, water or sewage.
You need to be more leak-proof than cold water pipes, because loss of pressure with steam and hot water is much more of a problem than with cold water and cannot easily be solved by just adding more cheap water. Pipe materials have to be more resistant to corrosion because higher temperatures and pressures make them corrode so much faster than with cold water. Closed hot water/steam circuits also mean that there won't be a protective limescale coating on the inside. You need insulation that you can bury and which will last for at least 40 years, which is even more expensive than the pipes. And the insulation will double the pipe diameter. And the insulated pipes have a larger keepout area that needs to be kept free of rocks, other pipes and mechanical strain because the insulation is soft and sensitive to those things. Since usually the pipes aren't operated in summer, and since generally thermal variance is far higher than with cold water, thermal expansion needs to be taken into account, so you need expansion corners, sliding sections, different valve constructions that are tight in all temperatures, etc.
And even with perfect insulation, you will loose approximately 30 to 40% of heat in your piping. So all of this is only viable if you don't care about the cost of the heat, your consumers can (be forced to or persuaded to) accept at least 30% higher prices per kWh compared to their local boiler, not to mention the capital cost.
There are only some areas in Europe even, where those kinds of installations take place: Densely packed inner cities with largely rented-out flats in appartment buildings. There, the landlords/owners avoid the cost and risk of a local boiler and don't care about the running cost of heat, because they don't pay for it. In smaller towns, like in the example, mostly public buildings like schools use those kinds of district heating systems, because the municipality doesn't care as much about cost of the heat, and more about cost of maintenance of a hundred local boilers vs. one centralized system. And in the end, it's taxpayers' money, so they don't actually care that much, headlines and opening ceremonies are more important than that.
Individual home owners usually do have their local systems, which can be run cheaper than what district heating will charge you. And since city density is lower and home ownership is more widespread in the US, district heating is even less competitive there.
> And even with perfect insulation, you will loose approximately 30 to 40% of heat in your piping.
At least here in Finland the norm is losses in the range of 5-20%, with the upper end of the scale for smaller scale networks with smaller diameter piping and low flow rate. In the larger cities losses are closer to the low end of that scale.
In the summer when the consumption is very low (essentially only hot tap water production) losses can rise up to 50%.
lots of industrial processes produce waste heat that can't easily be turned into energy, so the comparison isn't to a boiler, but to not having the heat.
It is true that the heat can be used if it is there anyways. But usually not in a big city-wide network. Instead a more localized, larger consumer is far better, because running the hot water network is far too expensive. For example, large producers of heat like data centers, dairy processing or chemical plants around here deliver their heat to public swimming pools, schools or greenhouses that are intentionally built nearby.
Even the grandparent's article says so if you read carefully: "A large portion of the town’s own buildings, including the municipal school, town hall, and library, are connected to the district heating network.". They didn't even attach all of the public buildings. Not to mention about the rest of the town.
That's exactly what I was thinking of. Cogeneration plant goes up right next to datacentre, and then various municipal services are built near that - including other factories, high density commercial and high density residential that can take advantage of cogeneration and use district heat. In particular commercial and industrial uses actually do need heat in the summer.
In some areas, natural-gas fired cogeneration only is really necessary in the winter during dark months/cold weather - which is an ideal situation to be producing district heat.
There are district heating and cooling in cities where it makes sense, both Minneapolis and St Paul, plus the University of Minnesota all have district heating and district cooling systems. The Minneapolis and U of M systems are operated by Cordia Energy and the St Paul system is operated by Evergreen Energy.
This is the coldest large metro area in the lower 48 states, so it’s economical to do district heating and cooling here.
These heating districts don't cover a very large area. It's impressive in its own right, but if you're using them as an example, it just shows that it only works at very specific scales.
Agreed, you need a fairly dense concentration of buildings with heating and cooling requirements in the tens of millions of BTUs per hour for it to make economic sense.
hot water also have pretty high losses, because you need to keep it cycling constantly to keep the heat up (you don't want a case where opening a tap in the morning means letting up the hot water from the 30m length of pipe from the street to your house).
So paradoxically, if your heat is not "free" (cogenerated with electricity) it might be far more efficient to have a boiler in each house (and definitely a heat pump), than to push the heat that far away.