It’s hard to escape the talk of energy supplies at the moment, with the geopolitical situation surrounding the Ukrainian invasion putting gas supplies across the continent at risk.Fortunately, we are seeing the buds of early spring in the northern hemisphere, so the worst of winter weather is behind us, but industrial customers can’t take such comfort from this season and will have to weather any price hikes that are coming. An alternative idea is on the table, and with the parallel necessity of decarbonizing the economy, this goes beyond the short-term into the future without much reliance on gas.
The collaboration between the Finnish district heating network and Microsoft caught our attention, as the tech giant’s new data center is sited specifically to supply waste heat to the network, rather than releasing it into the environment.It is not uncommon for European cities to use district heating networks, but they are usually supplied by waste incinerators, boilers or cogeneration stations.The use of waste heat in data centers is a novelty, especially since the location of data centers is determined by the network.
Individual gas-fired boilers are economical and convenient, but while more environmentally friendly than the coal fires they replaced when they were first introduced, their carbon footprint is higher than ideal by today’s standards.Governments around the world are encouraging their replacement with more efficient air source heat pumps, but when we read about Microsoft’s waste heat deployment, we can’t help but wonder if it’s worth considering the frontiers of district heating – the cloud is someone else’s server, after all .
When we think of district heating systems, our attention immediately shifts to enlarged versions of domestic heating boilers.A very large boiler or other heat source heats the water, and this piped hot water is piped underground to our homes, where it flows through our radiators and keeps us warm.It’s easy to understand and has stood the test of time, but anyone walking around a centrally heated school or hospital on a cold morning and seeing the melt on the ground where the pipes are can tell you that even if is the best – insulated pipes will waste some heat into the soil.The lower the temperature in the duct, the less energy is transferred to the soil, but as the duct temperature approaches ambient, it is certainly not enough to heat the home.At this point we go back to those heat pumps mentioned above and come across so called cold district heating systems.
Unless we happen to exist in absolute zero, everything has some heat.An icy lake has some heat because it can get colder by taking some of that heat away, and that’s what a heat pump does.Air sources get heat from cold air, but heat pumps can use any medium as a source.A “cold district heating network” that delivers water to the surroundings at near-ambient temperature as a source of heat pumps for customer premises seems like a pointless exercise until we consider that while some heat pumps can be extracted from the system Absorbs heat, others can put heat into it.Industrial users can transfer waste heat into pipes for consumers to recycle, and the network becomes much like a grid with many smaller source nodes, rather than a simple distribution system with one large node.
It may be too late for many cities to switch to cold district heating momentum, but we’d love to hear from any readers knowledgeable on the subject.Do any of you live in a city where the cold areas are heated?Or maybe you know of another data center district heating project?We’d love to hear it in the comments.
I’m glad to see systems like this discussed more often.It’s annoying to see a huge plume of steam being released into the air in winter from some industrial process in a residential area across the road.
A really efficient air source heat pump is great, but you’re trying to dump heat from your house into the outdoor air at the worst possible time: when it’s the hottest of the day.(Similar situation in winter.) I would like to know where is the break-even point between the heat pump efficiency gain and the cost of efficient thermal storage capacity.I want to try building a small system these days just to see what happens.
One possible way to store energy is to use a heat pump to freeze a basin of water in winter and thaw it in summer.That pot, isolated, can be placed under the house.The energy of (un)chilled water (state switch) is about 320 MJ/m3.It should reduce your heating/cooling bills when you are mainly using solar power to power your heat pump.
I think like all community challenges, positive change rarely happens with top-down policies.There are also practical limits to imposing one’s own compromises on others, rather than showing people’s gas bills being reduced.Also, solar-heated buildings may work in some places, but the campus green building on the north side is known for professors who have electric space heaters in their offices.
Heat exchangers typically have a coefficient of performance in the range of 2 to 5, thus saving the energy needed to run the system.Their prices are dropping, and luckily many models do qualify for government green grants in many areas, and air-to-liquid systems are the most efficient.However, the upfront investment for a whole-home central climate control solution can range from $6,000 to $24,000, maintenance costs are high even with warranties on certain brands, and various financing scams can taint customers’ goodwill.So it’s hard to justify the cost of such a system for someone who doesn’t intend to own a property for over a decade.YMMV
As a side note, did you know that goat wool sweaters are incredibly warm…goat pull carts are the future given the ubiquitous technology of our past.
Often top-down changes are required – or at least some entities with significant capital have to put in an initial investment, such as M$ siting a data center to provide waste heat to a district heating system…without it, individuals typically cannot generate any huge Change – the only thing we can do to our homes is replace boilers with heat pumps, we can’t magically generate investment to use all the waste heat, sewage from the local university computer racks effectively – this has to be a wider area and at least Partly paid for by governments or corporations (presumably at least in part for their own benefit).
With gas prices likely to go up, and for a long time to come, I think even short-term expected ownership calculations tend to skew toward installing greener, less expensive systems to run – that’s the selling point for a gas house, which is very Might end up paying for itself at the sale price…
Also, wool may be warm and often naturally fire resistant, so is heavily used and undervalued today, but since a considerable number of people are allergic to wool, this can’t be the whole future – presumably linen will also make a comeback.
It’s a “novel” idea: to heat people, not buildings.Yep, that winter coat of yours…can be used indoors too.
“You’ll have nothing and you’ll be happy.” Don’t worry, our “elite” will still be warm at 23C.
The person sitting on the sofa/table is usually still.Brought my wife to the couch last night and I was cold when I was completely naked and comfortably warm.I took the duvet from the bed and she was delighted.
My parents have central heating and it’s a little cold for me after being off for a few hours in the morning, but shorts and a t-shirt are acceptable in winter.Give it a few hours of central heating, and while they’re comfortable now, I’m unbearably hot for the rest of the day.So yes, I’m all for personal heating – it’s so much easier than personal cooling!
Moisture and cold can still erode and destroy masonry buildings – moss and mold will help water get into cracks and ice, become landing sites for seeds that will sprout and tear things apart, and these buildings also have a lot of wooden elements, of course it Won’t break the whole structure, but it won’t do any good…
Might work in some places – like the UK, where temperatures don’t drop far below freezing or very often, as that’s still warm enough that a thin pullover is probably comfortable for most indoors (And personally I’m still shorts and a t-shirt person in freezing temperatures (if the wind chill is really severe, or if I’ll be outside for a long time inactive, put on a jacket/pullover) – once it’s there , is always more comfortable in a cool environment than in a warm environment 20c outside I really don’t do well) ..
As Twisty Plastic says, lack of heat in a building is almost certainly a problem with humidity – but you don’t have to heat it to 23C…
The one that goes into my house, fully open, delivers 100 L/min, dropping 500 kPa in the process.It can easily handle 10 L/min flow with much lower pressure loss.
This only provides about 5 kW before the delta-T starts to get bigger.5 kW is barely enough heating or cooling power for my house.An additional 10 kW is required on cold winter nights.
So, what is the pump power associated with providing enough water for each insignificant source or sink?
The city uses 200 tons of water a day, serving a population of 400,000, and needs about 10 megawatts of pumps to supply it.
Providing each resident with enough water to supply or remove 5 kW of heat would increase water demand and pumping power by a factor of 30 to 300 MW.
It’s also probably not a good idea to use your drinking water supply to transfer heat — you don’t want warm water circulating around the ever-growing pesky bugs.
However, if you’re going to use it, the pumping requirements will likely increase dramatically with all the drag caused by the heat exchanging surfaces.
It feels like some enterprising bitcoin miner could create a furnace-sized heater made of GPUs, which could then be given to homeowners for free, and miners and homeowners could split the operating costs or a similar arrangement.
Just buy some cheap Antminers from Ebay and be done.Or if you prefer to mine Curecoin/Foldingcoin, use some used servers.
As mentioned, moving a lot of heat requires a lot of water (and pump power), especially when the delta-T (required by the heat pump) is very small.The local loop is heated with hot water using a reasonable flow rate because the water is indeed “hot” and the delta-T is large.
But even so, it cannot exceed the scale of a single building.The way to transfer a lot of heat is of course with steam, but that doesn’t cool servers very well because they don’t work well at the boiling point of water.
Steam also has its own problems.The local hospital is heated by steam from a not so close gas turbine cogeneration plant.The pipeline is 3km long and *always* someone maintains it somewhere along the line.For the crappy few megawatts they get, they have to spend a trillion dollars a year on maintenance.But that means hospitals don’t need to maintain their own boilers and chimneys.But it also means hospitals are vulnerable to supply disruptions due to that long, thin tube.
Sweden has good fvärrvarme – ‘central’ (like heating somewhere in the city) heating where hot (near boiling?) water with green dye is pumped.Seems to work well, the green dye looks cool when the leak shows up and helps show it’s a heating leak and not a hot water leak (it can also be concentrated if you prefer).On cool, clear nights, they’ll cruise around in helicopters equipped with infrared cameras, mapping out a grid that makes it easy to spot any leaks that haven’t broken through to the surface.
The waste heat in the data center is still too cold for district heating.All of these installations require large, high-temperature heat pumps that are around 50% efficient and are very maintenance-intensive.You have to put in a lot of electricity, which makes the concept too expensive on average European electricity prices.Oh, and you’re still burning tons of coal and natural gas to generate electricity.
Remember, they’re talking about Microsoft being involved, hence the Windows system.When Windows on these Intel CPUs runs multiple things at once, they get pretty hot.Running multiple services means they have to run virtual machines, also mentioning the datacenter, so that’s n times Windows is on Windows.smoked
Today, the cold aisle in a new data center may be 30-35 degrees Celsius, and some data centers want to run at 45 degrees Celsius, which is the “cold” side of the server.On the warm side, things might get warmer by 10-20 degrees Celsius.(I don’t envy the technicians serving these servers)
Now yes, it would be impossible to put that heat into district heating pipes that typically operate in the 70-90 degrees Celsius range without a heat pump.
But it’s more than enough for local heating needs, as the water may only reach 35-50 degrees Celsius, which is warm enough for a lot of heating needs.
For underfloor heating, it is rarely necessary to exceed 30 degrees Celsius, and an air handling unit can perform well below 40 degrees Celsius, although a radiator is a different beast that requires higher temperatures.
We have the same situation in the Netherlands.Microsoft has also made a green commitment.The greenhouse next door will be heated using waste heat from its data center.The end result: because of the low output temperature, it’s too expensive to use, and nothing.
Central city steam heating and later steam/electricity cogeneration have been used in May City.Indianapolis (https://en.wikipedia.org/wiki/Perry_K._Generating_Station) still has the second largest steam plant in the United States.Fortunately, they phased out coal and switched to natural gas in 2020.May I live long enough to see fusion heat up.Originally built in the 1890s, it increased the amount of electricity produced later when light bulbs were the new thing.Perhaps when we have enough renewable energy to generate electricity, steam areas can be phased out through electrical heating of individual buildings.
We did have a steam clock playing “Back Home Again in Indiana” next to the state museum.https://www.youtube.com/watch?v=GuVZ1Pq7NBE Several other cities also have steam clocks.
After mentioning “Back to Indiana,” I’d neglect to mention Jim Nabors (The Andy Griffith Show’s Gormer Pyle) who sang at the Indy 500.https://www.youtube.com/watch?v=7wcgaRkHAWY
I work in the data center where my office is located.This DC is part of a larger facility where I have my own HVAC system for heating and cooling.In winter I don’t need to run the gas stove because it gets hot when only the server farm and switches are running.Even though the air conditioner was running at 65F during the summer (Texas…) the fan still spins up a notch….
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