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1) How much heat do these things really generate?
2) How far are they from a suitable densely populated area?
3) How easy is it to retrofit district heating into homes currently heated with a traditional gas boiler?

I get that this would be a great idea if someone was about to build a new housing estate right next to a grid-transformer, but I just can't see it being practical for the vast majority of situations. Unfortunately I see this as yet another "greenwash" story/project designed to take eyes away from the CCGT and biomass.

The heat output from even relatively small transformers is vast. We had to run aircon to control heat from single 2 ft cube units running at 4.5KVa in 20 ft containers. I think this is a good idea. Some of the vast spaces on ships in electrical areas had to be felt to be believed. Better throwing it into water than air for sure.

There is no single silver bullet.

How will they collect the heat? NG is rightly very conservative. They leave huge open areas around their sub-stations.

water jacket is most obvious i suppose? Monstrously pricey though. Wrapped copper coil surely too simple? Heat pumps with massive shaped intakes?

Joeboy wrote: ↑Tue Aug 24, 2021 9:42 am water jacket is most obvious i suppose? Monstrously pricey though. Wrapped copper coil surely too simple? Heat pumps with massive shaped intakes?

High voltage applications are often oil-filled for electrical insulation so I guess they'd circulate the oil through a heat exchanger, then pump the water to houses. But that is the least of your problems! Sending the water through highly-insulated pipes to the nearest village, then piping it the the central heating system of each individual house is a hugely expensive and disruptive project.

The same money could be better spent on a wind turbine, solar panels, or battery storage.

I think that I would want to blow the hot air well away from the live gear before attempting heat exchange.

It's a trial programme to see if it is technically feasible, safe and economically viable. All the DNOs have a wide range of energy innovation projects to experiment with a whole host of ideas to try and increase network and grid efficiency, flexibility, reduce the Carbon intensity of power generation, and lower cost.

I don't see this as greenwashing at all. As mentioned, there's a huge amount of rejected heat simply lost to the environment - surely it's worth seeing if it can be used for something else?

Stinsy wrote: ↑Tue Aug 24, 2021 9:03 am I get that this would be a great idea if someone was about to build a new housing estate right next to a grid-transformer, but I just can't see it being practical for the vast majority of situations. Unfortunately I see this as yet another "greenwash" story/project designed to take eyes away from the CCGT and biomass.

If it can be delivered to high rise blocks it's a winner. Can't see it working on a house by house basis from a purely cost basis.

ASHP's with intake ducting although air to air isn't very efficient yet would work.

I wonder how far the heat to electricity envelope can be pushed? Seebeck effect.

Maybe SSE & NG will branch out into greenhouse & growing products?

There are several other large sources of low grade heat which are sizeable enough to potentially power district heat systems.

One such source is mine water generation from disused coal mines. When the mines were abandoned dewatering ceased and the ground water level in the mines rose, often eventually discharging into springs or water courses. These sources can be several degrees warmer than other sources and could be amplified with a heat pump.

My daughter studied one such outlet from an abandoned coal for her dissertation for her Hydrogeology MSC. She had to use data from the coal board as covid prevented field work. The coal board had hourly flow rates, temperatures etc going back at least a decade. As the mine filled up, warmer water rose to the surface discharge point, raising its temperature. It certainly had enough energy potential to power district heating.

Needless to say, there would be a lot of work to turn potential into a real project.