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Recycling Excess Heat From the Data Center

kdawson posted more than 4 years ago | from the talkin'-'bout-my-generation dept.

Earth 121

itwbennett writes "A new data center being built in Helsinki, scheduled to go live at the end of January, will generate energy and deliver hot water for the city. The data center is located in an old bomb shelter and is connected to the Helsinki public energy company's district heating system, which works by pumping boiling water through a system of pipes to households in Helsinki. The recycled heat from the data center could add about 1 percent to the total energy generated by the energy company's system in the summer." The article doesn't say what the overall efficiency of the heat recovery is. Researchers at MIT are working on a new energy-conversion technology based on quantum dots that they say has already demonstrated 40% of the Carnot efficiency limit — 4 times what is achieved by current commercial thermoelectric devices. The researchers believe they can reach 90% of the Carnot limit.

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121 comments

WTF, why is a Carnot reference here? (3, Insightful)

ElSupreme (1217088) | more than 4 years ago | (#30287174)

How is the Carnot cycle apply here? This is direct heat conversion, and the efficiency should be near 100%, you would have line losses.

Migration and Carnot (-1, Flamebait)

Anonymous Coward | more than 4 years ago | (#30287426)

What is the best way to migrate my cock to your mouth?

Re:Migration and Carnot (-1, Troll)

Anonymous Coward | more than 4 years ago | (#30287750)

A nigger

Re:WTF, why is a Carnot reference here? (0)

Anonymous Coward | more than 4 years ago | (#30287462)

Because you need a cycle to extract the waste heat. Lookup Organic Rankine Cycle.

Re:WTF, why is a Carnot reference here? (3, Informative)

vlm (69642) | more than 4 years ago | (#30287692)

How is the Carnot cycle apply here? This is direct heat conversion, and the efficiency should be near 100%, you would have line losses.

Reading thru a filter of journalist ignorance, I think the journalist is trying to say they're using a heat pump to reject the heat from the cooling system into the heating system's boiling water. There is a Carnot cycle limit to heat pumps.

Re:WTF, why is a Carnot reference here? (1)

The Archon V2.0 (782634) | more than 4 years ago | (#30287762)

Why is a Carnot reference here? Probably because there's not that many publications with user forums where you can mention a thermodynamic cycle in the first paragraph and get back responses more coherent than "I saw Lance Armstrong riding one of those!"

Re:WTF, why is a Carnot reference here? (4, Informative)

jank1887 (815982) | more than 4 years ago | (#30288036)

because the summary is talking about two entirely separate topics. (1) Helsinki data center will deliver waste heat in useful form to the city. (2)Researchers at MIT are working on a solid state heat-to-electric conversion element called a thermoelectric device. current devices are at best ~10% of Carnot (practical devices approach 10% total efficiency on a good day), and they say they'll hit 40-90% of carnot with their new quantum dot TEG's. We'll see.

You are correct, though. Carnot efficiency discussion only really applies to (2) not (1). Mister itwbennett just decided to lump these two things into one submission.

Re:WTF, why is a Carnot reference here? (2, Informative)

Snufu (1049644) | more than 4 years ago | (#30289044)

The summary writer may also have wanted to suggest that thermoelectric devices may be used to convert the waste heat at the data center into useful energy. However, thermoelectric devices are not really feasible for this application. To achieve the efficiencies cited for thermoelectric technologies, you need temperature gradients in the 100's degrees C, as in, for example, a car engine. Typical temperature gradients at data centers are on the order of tens of degrees C. This is considered "low-grade" heat in the renewable energy vernacular.

Re:WTF, why is a Carnot reference here? (1)

MillionthMonkey (240664) | more than 4 years ago | (#30288196)

You're taking conservation of energy into account, but you're forgetting entropy. Think about it... do you really suppose, even in theory, that you could pump electricity into a datacenter, put pretty pictures on people's screens all over the world, and then pick up 100% of that electricity back for use in heating your hot water? As if the electricity were merely waving "Hi" to the datacenter on its way to this water being boiled?

You can shorten the line to as much as you want. Assume no energy is lost to heat in the transmission lines. You'd still have a heat loss problem near the datacenter and whatever heat reclamation gizmo it's using. The max efficiency that can be extracted from a heat engine is 1-(Tc/Th) where Tc and Th are the absolute temperatures of the inside and outside in Kelvin. And 1-(273 / 300) = 0.1 or 10%. Meaning that (assuming it's freezing outside and 27 degrees C in the datacenter), 10% of the electrical power going to the datacenter could be reclaimed, in theory, if they were to extract all the energy that went into heating it from freezing (so the datacenter is freezing again). They're proud of themselves for getting 40% of that or 4%.

The rest of that energy goes toward warming the great outdoors which is at Tc. The Swedes have an advantage being so far North, but if they were to move their datacenter inside the Large Hadron Collider- or if they were to move the population of Sweden into the datacenter- your post would have more merit.

Re:WTF, why is a Carnot reference here? (1)

ElSupreme (1217088) | more than 4 years ago | (#30288430)

You are looking at all of this to complexly. Carnot cycles are for calculating heat engines. This is not a heat engine. There is NO WORK being done.

I put electricity into a chip. The chip uses X amount of energy and ~100% of the (electrical) energy is converted to heat energy.

If I run water over the chips (lets assume fully submerged for simplicity) and maintain their temperature at 20 degC. ~100% of the heat is removed by the water.

I realize there are line losses in the electrical wires. There are heat losses from the pipes piping away the heat. There are also radiation losses in the form of light and other waves that transmit through the water.

But anyway a heat exchanger (properly and sufficiently sized) should be near 100% (~97%-98%) efficient.

Now when you use a heat pump cycle you start loosing efficiency, but it is again almost 100% loss of heat, which goes to the hot water loop.

I would imagine that such a system is ~90%+ efficient from electrical energy (going to all items being recovered) and the heat pump cycle.

You need to ask yourself how and where does the energy go if it doesn't end up in the hot water loop?

Re:WTF, why is a Carnot reference here? (1)

Smidge204 (605297) | more than 4 years ago | (#30289126)

And this is exactly why heat pumps are not rated by efficiency but by coefficient of performance (COP).

Of course nobody seems to have noticed that the 40% claim is completely unrelated to the headline story and seems to have been needlessly tacked on by the editor.
=Smidge=

Re:WTF, why is a Carnot reference here? (2, Interesting)

MillionthMonkey (240664) | more than 4 years ago | (#30289684)

We've both made errors. I made a reference to "Swedes" and not Finns because I read too fast. However, you said:

Carnot cycles are for calculating heat engines. This is not a heat engine. There is NO WORK being done.

First of all theoretical efficiency limits apply to both types of reversible heat engines- steam engines which extract work and heat pumps (e.g. air conditioners) which require it. (In the heat pump case I guess Th would still be a temperature in the datacenter somewhere, but Tc would now be their hot water heaters' temperatures, not the temperature outside- another mistake I made. These Finns are confusing.) But RTFA- this looks like a heat engine:

Helsinki public energy company Helsingin Energia will recycle heat from a new data center to help generate energy and deliver hot water for the Finnish capital city, it said on Monday.
The recycled heat from the data center, being built by IT and telecom services company Academica, could add about 1 percent to the total energy generated by Helsingin Energia's system in the summer, according to Juha Sipilä, project manager at Helsingin Energia.

You DO have more to stand on here if the water were flowing (say) into some hot water heater before being heated to a desired temperature, so the heater would has less work to do- but what's this then in your post about "transmission lines"? It's clear that work is being done here if they're generating electricity in the summer.

I put electricity into a chip. The chip uses X amount of energy and ~100% of the (electrical) energy is converted to heat energy.

Yes that's conservation of energy. But notice that the energy has been converted into a less useful form, even if the flow goes directly off that chip into someone's bathwater. There isn't enough water being heated by that chip, or if there is, it's too cold for anyone to notice. Finns want water to come out of their hot water faucets at temperatures greater than if it were just pumped through datacenters.

If I run water over the chips (lets assume fully submerged for simplicity) and maintain their temperature at 20 degC. ~100% of the heat is removed by the water.

Whoa whoa slow down there, Tex. You're still thinking in terms of conservation of energy. But there are entropy losses- how will you maintain the temperature at 20 deg C unless you're pumping loads of water across the chip- so much that the heat is dissipated across a volume of water too large to make any difference? Or if you're not- say you pump a low flow across the chip so it maintains a temperature at 30 deg C. A heat engine running on that potential difference (back to generating electricity for transmitting over these transmission lines) you won't be able to extract all the electrical energy that you needed to run the chip. Most of it will heat the great outdoors. But that's not what's going on- either in the article, or an imagined situation involving generation of electricity to go across power lines.

I realize there are line losses in the electrical wires. There are heat losses from the pipes piping away the heat. There are also radiation losses in the form of light and other waves that transmit through the water.

Yes yes I realize that too, but we're both waving that stuff away.

Re:WTF, why is a Carnot reference here? (1)

ElSupreme (1217088) | more than 4 years ago | (#30290514)

Ok so as a mechanical engineer that does this stuff for a living here is how you would design such a system.

You design a cooling loop of water that cools the data center. You pump water fast enough to remove the amount of heat generated by the data center, and maintain a certain liquid temperature, which will translate to a certain chip temperature.
This water say enters the data center at 20C and leaves at 50C, you can change the temperatures of these by adjusting the flow rate of water (assuming a constant chip loading, in reality this flow rate will change based on temperature probes).
You dump the 50C water into a tank (heat storage vessel, think of it as a battery for heat). You then take this 50C water into a heat pump, this is reversible and such follows carnot cycle laws. This chills water back to 20C (and ready to cool processors), by heating a refridgerant, the refridgerant then heats your hot water city loop, with all the carnot losses ending up as heat in the refridgerant (losses get conserved and used). All your losses end up being used, as they are in the form of heat, and you are collecting WASTE heat.

The reason why your AC unit has to be outside is because of this, the losses incured would end up heating your house instead of cooling it.

Now on to your claims. There is NO reference to a heat engine, or anything that would require knowledge of a Carnot cycle. Thinking about how I would attain higher temperatures you would employ a heatpump (but this pump would contribute ~95%+ of its losses to heat the final fluid).
Ok so keeping chips at 20C isn't realistic, it should be more like 50C. Doing this would rais the efficency of the heat pump required to get higher temperatures. BUT ALL the HEAT would STILL be RECOVERED!
And I am sorry but you will recover (assuming chip surrounded by your heat recovery fluid) near 100% of the energy used. This is because near 100% of the energy used by processors is converted to heat. There is no way for the heat to get 'outdoors' if it is surrounded by a fluid. All the heat must pass to the fluid before it goes anywhere else.
And it is also worth noting that 'losses' in a carnot engine are almost purely heat. When you are trying to heat something you get to keep all your heat, it is not lost. Say you have 10kW of waste heat, and your heat pump is 1kW. You will put out 11kW of heat. If your heat pump is 10kW you will put out 20kW (10 + 10) of heat. Both ways you still recover the entire 10kW, and if you need more heat anyway then the effiecency is a moot point (in reality it is relevent because it is cheaper to heat water with natural gas, than electricity).

Re:WTF, why is a Carnot reference here? (1)

MillionthMonkey (240664) | more than 4 years ago | (#30290896)

Wow I'm too tired to read all that. Actually RTFA more closely I think you win, if by "transmission lines" you meant water pipes and not wires and their intention is to reclaim the energy in a disordered form of heat instead of electricity. The article mostly talks about how they're going to "generate energy" which doesn't make it clear.
(But psst... there is no "d" in "refrigerant".)

Re:WTF, why is a Carnot reference here? (2, Funny)

daremonai (859175) | more than 4 years ago | (#30290698)

There is NO WORK being done.

You know way too much about computers.

Re:WTF, why is a Carnot reference here? (1)

pookie13 (832250) | more than 4 years ago | (#30289418)

The Swedes have an advantage being so far North, but if they were to move their datacenter inside the Large Hadron Collider- or if they were to move the population of Sweden into the datacenter- your post would have more merit.

Sweden? Last time I checked, Helsinki was still in Finland. And no. We Finns wouldn't like the idea of 9.3 million more Swedes in Helsinki.

Re:WTF, why is a Carnot reference here? (2, Interesting)

MillionthMonkey (240664) | more than 4 years ago | (#30290032)

Yeah I read too fast. Although when I was a kid I used to have a Finnish pen pal in Turku. She stopped writing.

Re:WTF, why is a Carnot reference here? (2, Insightful)

pookie13 (832250) | more than 4 years ago | (#30294682)

Yeah I read too fast. Although when I was a kid I used to have a Finnish pen pal in Turku. She stopped writing.

No wonder she stopped writing if you thought that Helsinki is in Sweden. We do have a hate / love relationship with the Swedes.

Re:WTF, why is a Carnot reference here? (1)

Intron (870560) | more than 4 years ago | (#30290250)

The system I liked was the guy who cut the big hole in his kitchen wall. In winter he puts the insulated board in front. In the summer he pushes the back of his refrigerator through to the outside so its exhaust heat doesn't end up in his kitchen. Cuts his A/C bill enough to be noticeable and takes less than one roll of duct tape per year.

Re:WTF, why is a Carnot reference here? (1)

mosb1000 (710161) | more than 4 years ago | (#30290592)

"do you really suppose, even in theory, that you could pump electricity into a datacenter, put pretty pictures on people's screens all over the world, and then pick up 100% of that electricity back for use in heating your hot water?"

Yes. Where do you think the energy goes? The first law of thermodynamics requires that you get it all back.

Re:WTF, why is a Carnot reference here? (1)

MillionthMonkey (240664) | more than 4 years ago | (#30290966)

Yeah but what I meant when I said "pick up 100% of that electricity back" was getting all the power back in the form of electricity before the end users convert it to heat again. I didn't RTFA carefully enough and pictured the wrong scene when he said "transmission lines".

Re:WTF, why is a Carnot reference here? (0)

Anonymous Coward | more than 4 years ago | (#30292808)

Because the temperature at which the "heat" comes out of a data centre is simply not high enough to use it for most practical purposes so the temperature has to be increased. From the Helsinki article "The pump is also very efficient -- you get five times the amount of energy you put in, he said" so the data centre is using a technology similar to ground source heat pumps with the district heating system as the sink. The problem with the efficiency claims here is that they are spending more electrical power to recover the heat from the data centre which doesn't need any air conditioning to start with due to it's location in Helsinki. Electrical power tends to be an inefficient way to heat things because the heat - electricity conversion is normally less than 40% efficient whereas if you delivered that heat directly to the heating system....
So if we take the waste heat from the data centre they are recovering 4 units of heat for each unit of energy it consumes, we have, say 3 units of heat being converted to 1 unit of electricity for the data centre to use, we recover that 1 unit and add 0.25 units of electrical power (that is derived from 0.75 units of heat) to run the pump and we extract 1.25 units of heat for the district heating system out of 3.75 units of heat consumed by the system. No laws of entropy broken and no magic taking place.
There is a theoretical "saving" here of 0.5 units of heat out of every 3.75 assuming they achieve peak efficiency and have no losses elsewhere. There is no "data centres use 50% of their power in cooling, we are more efficient" argument because they need to be compared with what would be built now and not some out of date design.
I would rather see them spend the time and effort writing slightly more efficient software that didn't need quite so many servers.

I think it's great, but... (3, Insightful)

natehoy (1608657) | more than 4 years ago | (#30287184)

Is pumping boiling water through pipes the most efficient way to heat houses? Isn't there a pretty massive heat loss in the pipes?

Having said that, if they are already using this system for heat, the introduction of waste heat from a datacenter seems to make a lot of sense. Acts as a heat sink for the data center, reduces the amount of energy needed to heat the water.

It works well in cities. (1)

FatSean (18753) | more than 4 years ago | (#30287260)

Sure, you do get some loss but the simplicity and reliability of these system is quite impressive. I suppose they could always get extra-big pipe wrap :)

Re:It works well in cities. (1)

zippthorne (748122) | more than 4 years ago | (#30287726)

Well, they have to be, because you're basically threading a steam bomb [google.com] throughout your entire house. I'll stick with forced air thank you.

Re:It works well in cities. (1)

FatSean (18753) | more than 4 years ago | (#30287828)

Ew, forced air? What a pain that is. I'm all about radiant hot water heat these days. You don't have to worry about mold and pathogens in your ductwork.

Re:It works well in cities. (1)

vlm (69642) | more than 4 years ago | (#30287922)

I'm all about radiant hot water heat these days. You don't have to worry about mold

Until it starts leaking. Then you have cold, and mold.

Re:It works well in cities. (1)

FatSean (18753) | more than 4 years ago | (#30287964)

Well the baseboard heaters in my 60-year-old home haven't leaked yet...so I'm not so concerned about that issue. Maybe the modern under-floor systems are prone to leakage, but the tech I have seems bullet-proof. If you need AC then forced air is your only hope...but we are cool with a well-shaded lot and a window unit or two.

Forced air is too dry (3, Informative)

mi (197448) | more than 4 years ago | (#30287930)

Well, they have to be, because you're basically threading a steam bomb throughout your entire house. I'll stick with forced air thank you.

Forced air will dry you into a raisin. It is December — do you notice, how dry your lips are in the morning?

You need humidifiers to fight that effect... No, hot water — pumped through fixtures made of cast iron, or something, that's even slower to warm up and cool down — is the best heating solution... It could be expensive, but it is the most comfortable of what's commonly available today.

The oft-used copper and/or aluminum fixtures are bad, because the temperature will be fluctuating widely between the times, the heat is turned on by your thermostat and the times, when it is off. Our bodies are more sensitive to changes in temperatures, than to the temperatures themselves. Also, a quickly-heating material ends up losing heat mostly through convection (heating up air, that rises to the ceiling), than through radiation, which warms you directly (via infra-red).

Stainless steel is better in that regard than copper/aluminum, but not as good as cast iron, heavy and "unattractive" as those things might be...

Re:Forced air is too dry (1)

fedos (150319) | more than 4 years ago | (#30288248)

Stainless steel is better in that regard than copper/aluminum, but not as good as cast iron, heavy and "unattractive" as those things might be...

I happen to love the look of cast iron. I recently had trouble buying a cast iron dutch oven because most of those available in retail are coated in enamel. Although this is popular, I prefer the rustic look of the cast iron.

Re:Forced air is too dry (1)

lewiscr (3314) | more than 4 years ago | (#30289084)

Buy from a camping/outdoor store. They usually have the non-enameled versions, for a lot less. Or search Amazon, and take advantage of super-saver shipping on a 15 pound item. :-)

Re:Forced air is too dry (1)

scottv67 (731709) | more than 4 years ago | (#30293362)

>Forced air will dry you into a raisin. It is December — do you notice, how dry your lips are in the morning?

I'm sorry but I'm going to have to call bullshit on your comment. You implied that running hot water through cast iron radiators will result in a comfortable house but using a forced air system (let's say it uses natural gas) dries out your lips. Please provide some details, math and/or science to back up your claim. If you use hot water to heat the house to 70 degrees, how can the relative humidity in the house be any different than when you heat the house to 70 using a forced air furnace (assume the furnace is a high efficiency model that has its own air intake and exhaust pipes).

I don't see how using those two different heating methods can result in different relative humidity levels at the same indoor temperature.

Re:It works well in cities. (0)

Anonymous Coward | more than 4 years ago | (#30289876)

Most residential buildings in Finland are heated by piping hot water through radiators (often located under windows, which helps air circulate in the room). The water isn't boiling hot (you can grab the radiators with bare hands even if its thermostat is wide open), nor it is under high pressure (about same pressure and temperature as what you get from a faucet). Buildings in cities and towns get the hot water from the municipal water mains (heated by cogeneration power plants). Buildings in the boonies have a furnace or a heat pump in the basement that heats the water.

Steam bombs my ass - I swear there's FUD against everything imaginable.

Re:I think it's great, but... (0)

Anonymous Coward | more than 4 years ago | (#30287280)

Is pumping boiling water through pipes the most efficient way to heat houses? Isn't there a pretty massive heat loss in the pipes?

Presumably these pipes are insulated, and/or buried. And it is quite common for large buildings or campuses to use hot water with a central boiler for heat distribution.

In fact, many cities do that for heating & cooling:

http://en.wikipedia.org/wiki/District_heating [wikipedia.org]

Re:I think it's great, but... (4, Informative)

onionman (975962) | more than 4 years ago | (#30287284)

Is pumping boiling water through pipes the most efficient way to heat houses? Isn't there a pretty massive heat loss in the pipes?

Having said that, if they are already using this system for heat, the introduction of waste heat from a datacenter seems to make a lot of sense. Acts as a heat sink for the data center, reduces the amount of energy needed to heat the water.

Actually, it's a reasonable system for heating large building complexes where a central facility can heat the water. Many Universities and large corporate complexes already use similar methods for heating their campuses. Insulation on the pipes keeps the water warm in transit. These complexes can also cool their buildings in the summer by pumping chilled water through the system.

Re:I think it's great, but... (1)

DerekLyons (302214) | more than 4 years ago | (#30288896)

Actually, it's a reasonable system for heating large building complexes where a central facility can heat the water. Many Universities and large corporate complexes already use similar methods for heating their campuses.

'Already' is a bit misleading however - central heating installations like these, using steam or hot water, go back over a century - New York's dates from 1880.
 
 

These complexes can also cool their buildings in the summer by pumping chilled water through the system.

Or they can use hot water to drive absorption chillers, or steam to drive turbine centrifugal chillers.

Re:I think it's great, but... (0)

Anonymous Coward | more than 4 years ago | (#30287424)

On its own it isn't the most efficient system, but these systems are typically build to make use of waste heat produced by electricity plants or heavy industries, thus increasing overall energy efficiency.

Re:I think it's great, but... (4, Insightful)

sfcat (872532) | more than 4 years ago | (#30287542)

Yes and no, water actually is a very good "thermal" battery. That is why coastal regions have a more temperate climate than inland region. Its cheap and we know a lot about how to move it around and have existing infrastructure for doing exactly that. Its not the most efficient way, but often it is the most practical and economical.

Re:I think it's great, but... (2, Insightful)

vertinox (846076) | more than 4 years ago | (#30288206)

Its not the most efficient way, but often it is the most practical and economical.

Also, if the pipe breaks, then its not really that bad of a cleanup.

Re:I think it's great, but... (1)

amorsen (7485) | more than 4 years ago | (#30287594)

It's fairly common in Northern Europe (excepting England, for some reason). Losses aren't very high because the pipes are insulated. In modern systems the water isn't boiling, but it will take a long time before everything has been converted to lower temperature systems.

You can get extremely efficient by using low-temperature (30C or lower) remote heating plus a heat pump, but that means a large investment per house or apartment block.

Re:I think it's great, but... (1)

pla (258480) | more than 4 years ago | (#30288990)

In modern systems the water isn't boiling, but it will take a long time before everything has been converted to lower temperature systems.

Not to say that lower-temp systems don't exist (I can see the appeal in single-building residential systems in particular), but I'd point out that virtually all non-residential heating loops don't actually carry water they carry steam (at least on the efferent lines). They do so for the simple reason that steam-at-100C carries 3-5x the energy of water-at-100C (depending on the return temperature, of course) and also has a lower thermal conductivity (so lower unintentional losses on the way).

Additionally, using a steam to water conversion has the bonus that you don't actually need any explicit pumps - Valves in the line ensure that the steam pushes itself out via high-pressure, and the phase change causes low pressure on the return side. You really couldn't ask for a more convenient arrangement.

So I would certainly say that it will take a long time to get people to switch over, since doing so makes the system drastically less efficient, more complicated, and less reliable as a whole.

Re:I think it's great, but... (1)

amorsen (7485) | more than 4 years ago | (#30294844)

but I'd point out that virtually all non-residential heating loops don't actually carry water they carry steam

Not around here (Denmark) they don't. Steam used to be popular, but it's a waste of energy which could be used to make electricity.

But as I said, not everything has been converted yet.

Re:I think it's great, but... (1)

jo_ham (604554) | more than 4 years ago | (#30289484)

What do you mean "excepting England" - almost all houses here have central heating based on water-filled radiators. I'm having to think very hard about the last house I visited here that *didn't* have a piped water heating system.

The water isn't usually boiling though, since the systems are almost always open circuit (so not pressurised). The one in my house uses water at about 60C, and also provides hot water for the tank for showers/dishes etc. I don't have a combi, so if you want hot water, you have to switch it on ahead of time, unless you set timers and so on, which I don't bother with.

Re:I think it's great, but... (1)

discomike (1291084) | more than 4 years ago | (#30290560)

He's not talking about distribution inside your house from a central heating point, but for distribution to your house from a central heating point in the city. Like here in Gothenburg(pop ~0,75 million). Total heating capacity for the central system here is a bit over 2000MW, our (clean*)garbage power plant provides 28% of the city's heating & hot water, and 5% of electricity needs. Among other providers is a biogas furnace from the sewage treatment plant, waste heat from industries like refineries, and Volvo, also about 150MW is recovered with heat exchange from the sewage. About 80% of the heat provided used to be waste in some form. *meets future EU-demands on cleaning. First electro filter, then wet cleaning which removes particles and condenses acid gases, then a textile filter which removes almost all dioxin and most of the sulfur.

Re:I think it's great, but... (1)

smoker2 (750216) | more than 4 years ago | (#30290614)

He meant, they aren't connected to a large facility that sends hot water their way, which they aren't. It's really not difficult if you just read the whole summary.

Re:I think it's great, but... (1)

jo_ham (604554) | more than 4 years ago | (#30290846)

I well understood the summary (and the FA), but "sending hot water around liquid filled radiators" is a very popular method of heating your home in England, centralised distribution or not.

There are examples of centralised distribution here - mostly pilot projects, since the infrastructure for houses is already here and well understood - ie, liquid pipes and metal radiators, so conversion to centralised systems is simplified.

It's really much easier if you don't misinterpret what I say and apply your own meaning.

It IS great (3, Informative)

dgr73 (1055610) | more than 4 years ago | (#30287614)

Not to mention that when you have hot water coming out of the pipes, you don't need a water boiler, which is something all houses without kaukolämpö (remote heat) need. All in all, the infrastructure is in place in many places in Finland, with insulated pipes dug deep enough into the ground to keep the heat, so why not take advantage of it.

Re:I think it's great, but... (1)

Cyberax (705495) | more than 4 years ago | (#30287624)

Usually, district heating uses waste heat from power plants. It'll be wasted anyway, so why not use it to heat houses?

Re:I think it's great, but... (0)

Anonymous Coward | more than 4 years ago | (#30287752)

It is very efficient if central planning is politically feasible option in the region, population density is high enough (town or city consists of relatively uniform area with apartment blocks) and there's actual need for heating. In Helsinki area virtually all apartment buildings use the system - practically only problems that can occur are overloading of the power plants on extremely cold weather... and much more commonly, skimpy apartment block landlords not turning the house valves quick enough to keep in pace with cooling weather when winter approaches. As insulation tends to be much more reasonable than many other Europeans seem to use, cold temperatures (15 degrees C) are almost unheard of even on worst situations...

Re:I think it's great, but... (1)

Idiomatick (976696) | more than 4 years ago | (#30287870)

It is actually decently efficient.

However, the cost of installing these systems is often costly. Since pipes obviously cost much more than water. For a good example we can look on a smaller scale. Many houses and buildings built 50+ years ago had cast iron radiators. We don't use them anymore because they are expensive as fuck to install and maintenance is more expensive. But overall efficiency is similar and in some cases better than present day systems.

So I would guess it is a system already in place from older times. That or it is in a situation where it is still worth it over newer tech.

Re:I think it's great, but... (2, Interesting)

sjames (1099) | more than 4 years ago | (#30289152)

It depends on the priorities and the source of the heat. Steam turbines have a considerable load of waste heat that has to be dumped somewhere. No sense heating a lake if it can heat homes instead. Since it is waste heat, the efficiency hardly matters, any usefulness beats the alternative.

In other cases the choice is between many small boilers or one big one with exhaust scrubbers and more complete combustion. With good pipe insulation that can be a win.

Re:I think it's great, but... (0)

Anonymous Coward | more than 4 years ago | (#30289920)

1) The pipes have some 4" of polyurethane insulation and they are buried 4-6 feet underground
2) the heat used in the district heating systems is excess heat from coal/natural gas/wood burning powerplants that primarily generate electricity
So all in all, the district heating system is not too bad. It does have the downside that there is only one provider per area (your local power utility), so once you have joined the system you have to take any pricing changes they decide to make.

It's much much much more efficient (1)

Colin Smith (2679) | more than 4 years ago | (#30290096)

Is pumping boiling water through pipes the most efficient way to heat houses?

Yes. Easily. The pipes in district heating systems are heavily insulated, and large.

http://www.exakm.gr/images/Transmission%20pipe%20installation.jpg [exakm.gr]

1. It's WAY better than burning fuel to create electricity to transmit to the houses to create heat.
2. It's substantially better than pumping gas out to millions of tiny water boilers which do nothing but heat water.
3. it's "waste". The bit most power companies throw away after generating electricity. Anything you get from it is essentially "free".

You can turn a 35% efficient power station into an 88% efficient one by making use of waste heat in this manner.

http://www.helen.fi/energy/yhteistuotanto.html [helen.fi]
 

Re:I think it's great, but... (1)

DavMz (1652411) | more than 4 years ago | (#30290172)

I know for sure it is used in France in houses especially when heating is through the floor. I have also seen the hot water underfloor heating Efficiency of underfloor heating isn't bad: if you have good insulation below the pipes, you don't loose too much heat through the ground; as the floor is warm, convection occurs naturally and the room temperature gets more uniform; you don't have the "cold feet" effect which makes you heat more (remember, no shoes inside the house).

Quoting Wikipedia [wikipedia.org]: "Warm water UFH is 30% more efficient than low temperature radiators with a ground source heat pump, 20% more efficienct with an air source heat pump, and 5-15% more efficient than low temp radiators with a condensing boiler, according to a major study produced by EU-RAY, the European Radiant Heating & Cooling Association."

In France, you can also find hot water heating in habitation buildings, where you have one heater for all the appartments, and I think that similar system is used in the Russia (or at least it used to be).

The problem with approaching Carnot efficiency... (1)

gyepi (891047) | more than 4 years ago | (#30287228)

... is that the process will take longer and longer time. Carnot efficiency is defined by the efficiency of a reversible heat engine operating between the given temperatures; but truly reversible processes would take infinite amount of time. Efficiency is certainly an important aim, but certainly not the solely desirable aim.

Re:The problem with approaching Carnot efficiency. (1)

wealthychef (584778) | more than 4 years ago | (#30287564)

the process will take longer and longer time

Well, but in a flow reactor, that won't matter. It might take an ounce of water a long time to go through whatever this system is, but once it's flowing, it does not matter how much time it takes. Flow in == flow out, presumably. It will seem instantaneous after the startup time.

Re:The problem with approaching Carnot efficiency. (1)

pla (258480) | more than 4 years ago | (#30289042)

Carnot efficiency is defined by the efficiency of a reversible heat engine operating between the given temperatures;

"Heat engine" != direct thermoelectric conversion (whether via quantum dots or just plain ol' Peltier junctions).

The Carnot limit simply doesn't apply to direct conversion, and AFAIK, no theoretical limit to near-100% efficiency (minus entropy) exists for the latter.

Re:The problem with approaching Carnot efficiency. (1)

Rising Ape (1620461) | more than 4 years ago | (#30290504)

The Carnot limit applies to any heat engine, no matter how it works. Heat -> work means no efficiency higher than Carnot, sorry. Your "minus entropy" part gives that away really, as that's what's responsible for the Carnot limit in any case. Entropy change of X = heat transferred into X / temperature of X. So taking heat out of something causes an entropy decrease, hence the need for a cold sink to create an entropy increase so the overall entropy change is positive.

Valium and Xanax for Engineers and Physicists (5, Funny)

NoYob (1630681) | more than 4 years ago | (#30287312)

The pump is also very efficient -- you get five times the amount of energy you put in, he said.

So, engineers and physicists, when you see statements like that, how do you cope:

  1. Stiff drink(s)
  2. Xanax(s)
  3. Dust off plans for your perpetual motion machine company to go public
  4. Cry yourselves to sleep.
  5. Other

Re:Valium and Xanax for Engineers and Physicists (1)

maxume (22995) | more than 4 years ago | (#30287500)

It doesn't bother me much, lots of problems from school involved modeling the environment as a magic line.

Re:Valium and Xanax for Engineers and Physicists (0)

Anonymous Coward | more than 4 years ago | (#30287654)

Didn't bother me much either, given that it was clear that we were talking about a heat pump, which one would hope moves more heat energy than energy it uses to perform its work, and which the thermodynamic laws only care about making sure you can't get more energy from running it in reverse than you did in moving the heat in the first place.

Re:Valium and Xanax for Engineers and Physicists (5, Informative)

JessGras (953965) | more than 4 years ago | (#30287600)

Heat pumps can be this efficient when you consider the claim is they can move five times as much (heat) energy as they consume (in electicity or other organized source). They are not claiming to generate more than they consume: only pump more than they consume - though vague and sensationalist phrasing in the journalism makes this unclear in the OP.

Re:Valium and Xanax for Engineers and Physicists (1)

wealthychef (584778) | more than 4 years ago | (#30287606)

when you see statements like that, how do you cope

Well, you could just try to understand from context, that they mean, five times the energy put into the system besides the energy recovered from the waste heat, which is "free" in this context.

Re:Valium and Xanax for Engineers and Physicists (1)

fred fleenblat (463628) | more than 4 years ago | (#30287634)

you could assume he might be talking about coefficient of performance but he doesn't remember the exact right phrase.

more troubling, even if he used the correct phrase, his intended audience probably wouldn't understand him.

Re:Valium and Xanax for Engineers and Physicists (1)

kryptKnight (698857) | more than 4 years ago | (#30287898)

You might want to go read about heat pumps [nrcan.gc.ca]. What the article describes is perfectly possible, using heat pumps for heating and cooling is very common in temperate climates.

Re:Valium and Xanax for Engineers and Physicists (1)

david.given (6740) | more than 4 years ago | (#30287990)

So, engineers and physicists, when you see statements like that, how do you cope:

Easily, because I know that a heat pump [wikipedia.org] is a machine that allows me to move 5X amount of heat from one location to another while only using X amount of energy to do it.

(BTW, if you heat your house using electrical resistive heating, and you have a garden... go look up 'ground source heat pumps' from that article and save yourself lots of money.)

Re:Valium and Xanax for Engineers and Physicists (1)

danlip (737336) | more than 4 years ago | (#30288668)

Heat is not energy*, at least not useful energy. Specifically heat alone is not useful for doing work. You need a heat gradient to do work. Heat pumps increase the heat gradient, and that gradient could be used to do work, but the amount of energy you would get out of that is always less than you put in.

Heat pumps are a rather efficient way to heat your house, within a certain temperature range it can be much more efficient than burning chemical fuels.

*(yeah, heat really is energy, but heat pumps just move it around, they don't create it)

Data center cooling in the winter (0)

Anonymous Coward | more than 4 years ago | (#30287348)

I know, this is off topic but...
I never understood why datacenters never had direct outside ventilation. In the winter, this could cut down on cooling costs and could benefit the building as well for heat. Depending on the incoming and exhaust temperatures, you could either redirect the exhaust outside or into the building. Lack of humidity control would be concern but is that the only reason this is not used more often?

Re:Data center cooling in the winter (2, Informative)

afidel (530433) | more than 4 years ago | (#30287548)

That's correct, in many climates you would spend more energy trying to maintain humidity then you would save by not running the AC system. For larger systems many have a "freecool" option which runs the waste stream through the heat exchanger without running the compressors thus saving ~80% of the energy.

Obligatory (2, Funny)

interiot (50685) | more than 4 years ago | (#30287642)

"The Internet is not a big truck. It's a series of tubes. And if you don't understand, those tubes can be filled and if they are filled, when you put your message in, it generates more heat and it's going to be delayed by anyone that puts into that tube enormous amounts of boiling water, enormous amounts of boiling water."

It's a fucking heat pump, people. (1)

R2.0 (532027) | more than 4 years ago | (#30287670)

It uses cold water from a central plant and then it gets cooled back down by a chiller/heat pump. The condenser water off the heat pump is then used to heat homes. Basically, the plant is rejecting it's heat into the local housing system.

The part about thermoelectric devices is a total non-sequiter.

Central Heating to the extreme (1)

OzPeter (195038) | more than 4 years ago | (#30287746)

I experienced this to some extent when working in Magnetogorsk, Siberia in '94. The hot water for a lot/all of the town was supplied centrally and piped all over the place in 1m diameter pipes (above ground).

Aside from the efficiency issues due to heat loss from the pipes, the main fun factor in this system was that the distribution was not terribly fine grained. As a result the authorities shut down the hot water for entire sections of the city when they wanted to do extended maintenance - and by that I mean up to a month at a time.

Its amazing how short a time it takes to get enough hot water for a bath when you are heating it up one saucepan at a time on a stove!

Hopefully the people who will be reliant on the excess data centre heat won't have the same dependency problems. Its much easier to hook up a spare electrical system than it is to re-pipe hot water

Re:Central Heating to the extreme (0)

Anonymous Coward | more than 4 years ago | (#30287916)

Magnetogorsk design sounds like good old Stalin-age design; industrialisation and solution of some kind was OK even with huge inefficiencies when the empire had practically free energy to burn to cover defects of over-the-top large scale design. And well, inhabitants probably rather hard some heating outages than froze to death in middle of Siberia... Helsinki doesn't do it quite that way. :)

Re:Central Heating to the extreme (1)

badran (973386) | more than 4 years ago | (#30288314)

You should have bought a pair of buckets... This is what the locals do ;)...

Re:Central Heating to the extreme (0)

Anonymous Coward | more than 4 years ago | (#30288490)

Helsinki is in Finland, not in Soviet Russia 15 years ago. Almost whole city is heated by district heating system.

http://en.wikipedia.org/wiki/District_heating#Finland

Re:Central Heating to the extreme (0)

Anonymous Coward | more than 4 years ago | (#30291182)

The system in Helsinki is considerably more fine grained thankfully. Quickly looking at wikipedia, it says the availability is a whopping 99.98%, I would assume for the duration of the remaining 0.02%, the water in the system will retain enough heat not to affect much. The Helsinki network is also huge, so there is plenty of redundancy. Basically the entire metropolitan area is hooked up, fed by the excess energy of four coal plants, as well as perhaps 15 heat only plants that are fired up in the winter.

Space Heater (1)

jgtg32a (1173373) | more than 4 years ago | (#30287936)

See my sig; My computer also functions as a nice little space heater, if I leave the door to the study closed it will become the warmest room in the house.

What about the exec office? (2, Funny)

filesiteguy (695431) | more than 4 years ago | (#30288016)

Now that we have the issue with the heat coming from the server room solved, let's tackle the hot air coming from the executive offices next.

Any ideas?

Re:What about the exec office? (1)

sjames (1099) | more than 4 years ago | (#30289538)

It's been tried many times, but no matter what you do to it, you just can't get the bullshit smell filtered out.

Quantum Dot (1)

physburn (1095481) | more than 4 years ago | (#30289238)

Looking forward the Quantum Dot heat engine, it nothing to do with the Helskini project and deserves a thread of its own. The authors claim up to 90% Carnot efficency is possible. Even at 40% this is better than almost every heat to electricity generator mankind has made so far. It would replace turbines and generators everywhere (if they can run that hot), and doubling the efficiency of gas/coal/oil and nuclear power stations. That's fantastic, and probably decades aways.

---

Heat Recovery [feeddistiller.com] Feed @ Feed Distiller [feeddistiller.com]

Heat Recovery Ventilation (2, Interesting)

Doc Ruby (173196) | more than 4 years ago | (#30290274)

Common commercial devices for homes already use heat exchangers to recover 66% or more of heat from vented air, heating the incoming fresh air with it. During heating seasons, machinery's inefficiency generating heat can replace heat that would have consumed more energy. Bathroom fan vents cost under $300.

What we need is good heat storage devices. If a lot of heat can be stored during the cooling season, and released during the heating season, these electrical devices become close to 100% efficient. Places like Helsinki have much longer heating than cooling seasons, so they're good places for datacenters that can recover heat for use.

The problem is that water is about the densest heat storage material we have, but it doesn't store very much. And even the most cutting edge insulators, aerogels, are only about 2x as insulating as the current common top performers, closed cell foams, and only about 4x as insulating as the earlier common stuff like fiberglass and cellulose. If we could store in similar volume the energy that fuels like oil store in chemical covalent bonds instead in physical materials like high specific heat fluids that don't get that hot, we'd have a lot more options in engineering efficiency. If we could regenerate chemical fuel from heat at very high cycle efficiency, we'd have something of a miracle cure for many of the worst of our industrial ills.

Telehouse West, London (1)

Anonymice (1400397) | more than 4 years ago | (#30291362)

...the new £80m extension to Telehouse Europe in the Docklands, is also being built with a similar idea in mind [telehouse.net] & is scheduled to begin operations during the first quarter of 2010 [telehouse.net].

The partnership will see Telehouse West save up to 1,110 tonnes of CO2 emissions per annum and provide up to nine megawatts of power for the local neighbourhood. The energy savings will equate to boiling 3,000 kettles continuously. The disposal of waste heat from cooling systems is one of the most significant sustainability issues associated with data storage. This will be the first time a heat export strategy has been introduced in the UK for this type of data centre facility.

In fact, I seem to recall a discussion about this on here a couple of months ago about yet another project doing the same thing. The consensus was that whilst there was a lot of air pumped out, it wasn't exactly hot & it wasn't useful for much more than good PR for the host - far better efficiencies could have been made, spending the money elsewhere. (This statement brought to you by Slashdot whispers of an oriental nature.)

Industrial Water Treatment (0)

Anonymous Coward | more than 4 years ago | (#30293858)

I tend to think that some of the problem they will see with trying this is scale build up on the pipes as well as corrosion of the pipes unless they are doing something for the water treatment end of itself. I am by no means an expert but green technology has been around for over 100 years when dealing with cooling and heating and water ( http://www.g-c.com/ )

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