As an American it completely breaks my expectations that district heating not only works can be more efficient that decentralized heating. The amount of heat lost just moving water from the water heater on one side of the house to the shower on the other is ridiculously high in houses here. The idea that you can insulate well enough to efficiently move heat across a city is amazing to me.
As a German living in a city with mandatory district heating... the end result is to be that people seem pay more for heating than they would with a decentralised system.
I think that's mostly due to the high upkeep costs of the system, though, the transmission loss is quite manageable, I think.
Of course there are arguments to be made that when accounting for the cost of installing a heating system, and the space it takes, the premium paid for district heating is not that high.
But still... if district heating is so smart, why ain't it cheaper?
What's nice about it, and maybe hard to quantify, is how this limits air pollution in the city. However, people are still allowed wood burning ovens... which they are now all turning to since the district heat is getting really, really expensive..
Most household water pipes really aren't insulated, or aren't insulated well enough. Plus, moving water under the frostline means that the ground it's moving through might be upwards of 55 degrees F.
My house came with an outdoor wood boiler (it's more a rural cabin than a house, really). It moves 180*F water from the boiler 50 feet underground into the house, where it runs through an air exchanger in the central air system and pipes it back out to be reheated.
Newer models of these things can get upwards of 98-99% burn efficiency, and ~85% heat transfer efficiency- as good as or better than you can get with standard efficiency furnaces.
My hometown has a power plant in city center. During winter it uses the entire downtown area as a heat sink. It's great. Power plant gets cooling for its hot water, city residents get cheap heating for their homes.
Best part is you don't even care about heat loss because you're trying to get rid of all that heat anyway.
Traditionally when using combustion plants the great advantage in nordic countries comes from CHP (combined heat and power), you can extract much more energy from the fuel this way vs having separate electricity and heat plants. But yep great insulation in the network is a requirement.
For USA, district heating made sense in the coal power era. Today, why burn natural gas at a central plant and then have to manage a complex steam distribution network with associated losses when you can simply distribute natural gas instead and get 98% AFUE at the point of use? Even better is a heat pump with gas backup at point of use. Triumph of technology.
Also, You dont really insulate the steam distribution pipes, you just count the loss bug as a feature “heated roads and sidewalks to melt snow!”
Lastly, district heat doest work in American low density
The idea that anything can be insulated at all is fucking novel.
New construction has minimum standards these days, but that does nothing for the majority of older house which have single glazed window, iron roofs, and no insulation whatsoever and, if you're renting, lucky to have a heat pump.
And yeah, no insulation on the hot water piping means massive loses from water heater to tap.
I have a hot water recirculator installed and love it. It's even faster than on demand.
Faster hot water incentivizes hand washing. Just think about how many more people would wash their hands at the airport if they didn't have to wait 2 minutes (or forever) to get hot water.
It is cost effective, efficient and saves on emissions. Nowadays, all major cities and towns in Sweden have district heating systems. Stockholm also has a distric cooling system, although not as developed.
I once visited a geothermal plant about 20km outside Reykjavik that supplies hot water for heating the city. Even in the depths of Icelandic winter, the temperature only drops 1 deg C between the plant and the city. A lot of Rockwool around the pipe IIRC.
Well, if you want to hear from the darkside... Romania.
Badly maintained infrastructure (as an American you're probably familiar with the idea). Keeps breaking down. Not enough money invested to bring it to modern standards. Pipes are not well insulated, they break down constantly, huge leakages and losses.
Cost of heating is so high that about 20% or more of the entire Bucharest city budget (I've just checked, budget: ~$1.8 billion, subsidies: ~$450 million; Bucharest has about 2.2 million people) is spent on subsidizing heat for poor families. Heating/hot water sometimes go down for hours or even days in random districts.
In many districts district heating is mandatory because everyone who can pull out does so and that makes the system even more inefficient, which would cause the collapse of the entire system, hurting poor families even more.
Well there is district steam in New York. Another thing may be density: you will lose less heat due to distance travelled for central parts of New York than for a less dense(?) European city which is itself much much denser than a typical American suburb-city
This is actually a really good business for natural gas utilities to switch to if they want to survive in the future.
They have tons of experience with pipes, they can swap gas furnaces for heat pumps and exchangers.
And it turns out that the areas that district heating works well with are really comparable to where it makes sense to pump natural gas. Yoi don't necessarily need heated pipes, just using the ambient temp in the ground is usually good, with very small bits of storage/heating.
Even just adding a little inuslation to a pipe will drop the heat loss down to a few watts/ft when dealing with a pretty large delta T. If you’re using 20k+ watts to heat a home the losses on the pipe are minimal. And I’m guessing these homes are all pretty close together. Not a mile apart.
I wonder how far out one can scale a cooling, rather than heating, system. Probably not worth it making it city-wide, but then - who knows? If it works for heating...
> It has a particularly strong use case in Finland which sees long and very cold winters, and was recently cut off from Russian gas supplies over a payments dispute.
Well I guess that's one way to characterize war-related sanctions and their side effects.
I've proposed several times on HN a "box of rocks" at the house level to store heat/cold when electricity is cheap, and release heat/cold when electricity is expensive. It was ridiculed every time.
HVAC engineer here. At the residential level this is already achievable with hot water storage from either solar thermal and/or heat pumps. Plus you get to use the hot water (assuming you've sized the tank correctly!)
Storing heat in rocks or sand doesn't make sense from a thermal efficiency standpoint unless the temperature is high and that isn't economically viable unless you have large volume storage - typically district or precinct level.
Interesting idea. Something I do on cold nights when camping in the back country is to put some rocks in my fire and bury the firepit when the coals are hot and sleep on top of that. Usually keeps me warm enough to at least get 4 or 5 hours of comfortable sleep during cold nights.
The ‘sand battery’ explained: Insulate a lot of sand and heat it with an electrical element (300-500°C). When you need the energy back, pump air into it and you get hot air to power generators and heat buildings.
It's important to remember with most of these thermal batteries is that they are limited in efficiency by the laws of thermodynamics, both when putting the energy in and then again pulling it back out.
The net round trip total power loss is usually well above 50%.
What's the round trip efficiency of something like this, and what's the rate of loss to the environment? There's been a couple of these posted in the last few days and I have no feel for these numbers.
From this article it seems like they are using the sand to store heat that would otherwise go to waste due to temps too low to otherwise turn it into other forms of energy.
At least that’s what it seems like. They aren’t very specific, but it explains why they aren’t using something more akin to pumped water energy storage.
How about putting a thermoelectric device in orbit- you know one of those things that generate electricity from a temperature differential- the sun facing side is hundreds of degrees above zero,the shadow side is hundreds of degrees below zero. Beam the energy to earth with a maser
There are times in Europe during the summer when power is free, due to excess wind and sun power. Meanwhile winters are dark and cold. If you could keep the heat for 6 months that is very useful.
We are running out of angular sand, not desert sand. Angular sand can be used for building materials like concrete but desert sand is smooth so doesn't work well for it. For this battery, I would expect either sand would work (but I didn't see any details in the article)
[+] [-] pavon|3 years ago|reply
[+] [-] gamegoblin|3 years ago|reply
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
[+] [-] konschubert|3 years ago|reply
I think that's mostly due to the high upkeep costs of the system, though, the transmission loss is quite manageable, I think. Of course there are arguments to be made that when accounting for the cost of installing a heating system, and the space it takes, the premium paid for district heating is not that high.
But still... if district heating is so smart, why ain't it cheaper?
What's nice about it, and maybe hard to quantify, is how this limits air pollution in the city. However, people are still allowed wood burning ovens... which they are now all turning to since the district heat is getting really, really expensive..
[+] [-] zdragnar|3 years ago|reply
Most household water pipes really aren't insulated, or aren't insulated well enough. Plus, moving water under the frostline means that the ground it's moving through might be upwards of 55 degrees F.
My house came with an outdoor wood boiler (it's more a rural cabin than a house, really). It moves 180*F water from the boiler 50 feet underground into the house, where it runs through an air exchanger in the central air system and pipes it back out to be reheated.
Newer models of these things can get upwards of 98-99% burn efficiency, and ~85% heat transfer efficiency- as good as or better than you can get with standard efficiency furnaces.
[+] [-] Swizec|3 years ago|reply
Best part is you don't even care about heat loss because you're trying to get rid of all that heat anyway.
This scheme has been inplace since the 60's. https://en.wikipedia.org/wiki/Ljubljana_Power_Station
District Heating is quite popular in much of the world. USA built the first such system back in 1853. https://en.wikipedia.org/wiki/District_heating
[+] [-] fulafel|3 years ago|reply
[+] [-] ethagknight|3 years ago|reply
Also, You dont really insulate the steam distribution pipes, you just count the loss bug as a feature “heated roads and sidewalks to melt snow!”
Lastly, district heat doest work in American low density
[+] [-] TheSpiceIsLife|3 years ago|reply
The idea that anything can be insulated at all is fucking novel.
New construction has minimum standards these days, but that does nothing for the majority of older house which have single glazed window, iron roofs, and no insulation whatsoever and, if you're renting, lucky to have a heat pump.
And yeah, no insulation on the hot water piping means massive loses from water heater to tap.
[+] [-] dubswithus|3 years ago|reply
Faster hot water incentivizes hand washing. Just think about how many more people would wash their hands at the airport if they didn't have to wait 2 minutes (or forever) to get hot water.
[+] [-] bjelkeman-again|3 years ago|reply
More info “District heating and cooling in Sweden” https://www.sciencedirect.com/science/article/pii/S036054421...
[+] [-] kitd|3 years ago|reply
[+] [-] samatman|3 years ago|reply
1/16th probably sounds high, but the extra halving is because flow rate increases as radius^4, not cubed as one might guess.
[+] [-] oblio|3 years ago|reply
Badly maintained infrastructure (as an American you're probably familiar with the idea). Keeps breaking down. Not enough money invested to bring it to modern standards. Pipes are not well insulated, they break down constantly, huge leakages and losses.
Cost of heating is so high that about 20% or more of the entire Bucharest city budget (I've just checked, budget: ~$1.8 billion, subsidies: ~$450 million; Bucharest has about 2.2 million people) is spent on subsidizing heat for poor families. Heating/hot water sometimes go down for hours or even days in random districts.
In many districts district heating is mandatory because everyone who can pull out does so and that makes the system even more inefficient, which would cause the collapse of the entire system, hurting poor families even more.
[+] [-] dan-robertson|3 years ago|reply
[+] [-] epistasis|3 years ago|reply
They have tons of experience with pipes, they can swap gas furnaces for heat pumps and exchangers.
And it turns out that the areas that district heating works well with are really comparable to where it makes sense to pump natural gas. Yoi don't necessarily need heated pipes, just using the ambient temp in the ground is usually good, with very small bits of storage/heating.
[+] [-] vkou|3 years ago|reply
It only works well when heating is 'free' - such as when you're using waste heat from a nuclear power plant, or from overproducing solar/wind plants.
[+] [-] schmichael|3 years ago|reply
[+] [-] conk|3 years ago|reply
[+] [-] einpoklum|3 years ago|reply
[+] [-] unknown|3 years ago|reply
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[+] [-] excitom|3 years ago|reply
Well I guess that's one way to characterize war-related sanctions and their side effects.
[+] [-] jpollock|3 years ago|reply
https://en.wikipedia.org/wiki/Drake_Landing_Solar_Community
[+] [-] WalterBright|3 years ago|reply
I should have patented it :-)
[+] [-] tjmc|3 years ago|reply
Storing heat in rocks or sand doesn't make sense from a thermal efficiency standpoint unless the temperature is high and that isn't economically viable unless you have large volume storage - typically district or precinct level.
[+] [-] hunter-gatherer|3 years ago|reply
[+] [-] raverbashing|3 years ago|reply
Doesn't mean the idea can't be implemented better, of course.
In fact I do think there's a lot of low-hanging fruit that remains to be explored in energy production.
[+] [-] treerock|3 years ago|reply
https://en.m.wikipedia.org/wiki/Storage_heater
[+] [-] zardo|3 years ago|reply
[+] [-] plutonorm|3 years ago|reply
[+] [-] punnerud|3 years ago|reply
[+] [-] koheripbal|3 years ago|reply
The net round trip total power loss is usually well above 50%.
[+] [-] DavidKarlas|3 years ago|reply
[+] [-] FastMonkey|3 years ago|reply
[+] [-] jsnell|3 years ago|reply
[+] [-] aaaaaaaaaaab|3 years ago|reply
- water has 5x the specific heat capacity of sand
- water can be pumped around easily
- water can be used directly for district heating
[+] [-] Animats|3 years ago|reply
[+] [-] kumarvvr|3 years ago|reply
Would bring down a lot of AC usage in tropical countries.
[+] [-] dghlsakjg|3 years ago|reply
At least that’s what it seems like. They aren’t very specific, but it explains why they aren’t using something more akin to pumped water energy storage.
[+] [-] bawana|3 years ago|reply
[+] [-] matthewsinclair|3 years ago|reply
https://news.ycombinator.com/item?id=31999241
I am really intrigued as to how some posts for the same (or similar) story get to the front page and others don't rate a mention.
[+] [-] unknown|3 years ago|reply
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[+] [-] htk|3 years ago|reply
Can anyone here expand on this?
[+] [-] rr808|3 years ago|reply
[+] [-] zaxpr|3 years ago|reply
https://www.bbc.com/future/article/20191108-why-the-world-is...
[+] [-] yellow_lead|3 years ago|reply
[+] [-] julienreszka|3 years ago|reply
[+] [-] unknown|3 years ago|reply
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[+] [-] pyrolistical|3 years ago|reply
[+] [-] Jistern|3 years ago|reply
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[+] [-] aaron695|3 years ago|reply
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