Using waste heat from underground power cables

Capt'n Midnight · 18-09-2019 8:27pm #1

Not huge amounts of power, but it would only be wasted otherwise

https://spectrum.ieee.org/energywise/energy/environment/londons-hidden-cable-tunnels-could-warm-thousands-of-homes

Underneath London’s bustling streets lie several kilometers of 2.5-meter-wide concrete tunnels lined with power distribution cables that can reach blistering temperatures. To cool the tunnels, vertical shafts spaced out every kilometer or two supply fresh air and eject hot air out into the open. ... A heat exchanger installed at the supply shaft reduced cable and tunnel air temperatures by 8 degrees Celsius, but the amount of heat recovered varied from about 100 kilowatts in colder months to 460 kW in high heat. Installed at the exhaust shaft, the system produced around 400 kW during all six months.

Markcheese · 18-09-2019 10:46pm

Always a bit surprised that Riverside offices and appartments, don't have heat exchangers going into the river, heat in winter, aircon in summer..

AngryHippie · 19-09-2019 12:26am

Salinity would be an issue I'm guessing.

Nukem · 19-09-2019 7:58pm

Capt'n Midnight wrote: »

Not huge amounts of power, but it would only be wasted otherwise

I like the idea - I know they use oil to cool or transfer heat to heat sinks too

Only need to look at electrical transformers also around the country, where large rads or oil filled heat dumps are used to dissipate heat from the units.

Water from rivers to cool is a great idea and never understood why not indirect cooling loops for offices or whatever, or even put data centers closer to rivers and use ambient cooling where possible, complimented by river cooling

theguzman · 19-09-2019 8:07pm

The Peat fired station in Offaly was closed due to using river water for cooling, the reason given was hot water returning to the river.

ted1 · 19-09-2019 8:22pm

Markcheese wrote: »

Always a bit surprised that Riverside offices and appartments, don't have heat exchangers going into the river, heat in winter, aircon in summer..

Waterways Ireland may have an issue with regards changing temperatures in rivers

Mezzotint · 14-11-2019 2:08am

Markcheese wrote: »

Always a bit surprised that Riverside offices and appartments, don't have heat exchangers going into the river, heat in winter, aircon in summer..

They do in Paris. There's a whole district heating and cool water supply to various clusters of big buildings using the Seine.

Impact on the river temperatures are probably relatively small and it's into a highly artificial channel that has far more impact on the river temperatures anyway.

They're not comparable to the kind of heat being dumped by a power station but obviously you'd have to monitor it. Small scale projects have negligible impacts but if entire cities were to start doing it... You get into another issue.

Nukem · 23-11-2019 9:49pm

theguzman wrote: »

The Peat fired station in Offaly was closed due to using river water for cooling, the reason given was hot water returning to the river.

Funny how this is a sudden issue, even though the plant has been operating in the same manner for years. Its as if...…...someone...……... suddenly started measuring the outflow temperature :rolleyes:

Markcheese · 23-11-2019 11:14pm

Nukem wrote: »

Funny how this is a sudden issue, even though the plant has been operating in the same manner for years. Its as if...…...someone...……... suddenly started measuring the outflow temperature :rolleyes:

I think they changed how the measuring was done... Something like it was taken at single point x distance downstream of the outflow but that got changed to multiple points across a broader section of the river..
Anyway upshot was they were taking the river temp too high
How much waste heat does a (small) power plant dissapate, seems bonkers that at least some of it can't be used....

Mezzotint · 24-11-2019 6:27pm

If there's little development near by its very hard to use it.

I always thought though in Cork the old Marina power station and in Dublin the Pigeon House should have been supplying district heating. In both cases they were burning fuels (mostly gas in modern times) and dumping waste heat into waterways.

It would have been possible to heat areas near the docklands in both cities. The Marina plant could even have supplied heat to the city centre in Cork and definitely to industries and office space in the docks. Same with the power plants in Dublin. It would have definitely been done in Scandinavia or many continental European places.

L1011 · 25-11-2019 10:26am

There is still a gas plant in Ringsend and the incinerator and there is a half built district heating system coming under the river to the north docks. I think the funding to finish it has been approved.

The heat off the under construction Amazon data centre in Tallaght will heat apartments across the road also

Mezzotint · 25-11-2019 4:31pm

We could make a lot more use of district heating. It just needs to be seen as a utility like gas. You could feasibly heat a few streets or a housing estate with deep geothermal for example.

Del2005 · 25-11-2019 4:43pm

Nukem wrote: »

put data centers closer to rivers and use ambient cooling where possible, complimented by river cooling

Isn't the reason for building data centres here because they don't need cooling they just dissipate the heat to air, which can still be used, the energy usage is the processing of data.

Mezzotint · 25-11-2019 5:02pm

In part yeah, but if you can sell the waste heat, why just dump it into the air?

Del2005 · 25-11-2019 6:46pm

Mezzotint wrote: »

In part yeah, but if you can sell the waste heat, why just dump it into the air?

Because we don't have any infrastructure to utilise it. The incinerator is designed to supply district heating and is open several years, how many premises nearby are using the excess heat from this?

Using waste heat from underground power cables

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