Following on from the boiler thread ...

[The Other Mike]

For Malmo substitute lots of places in Sweden. Some even keep the pavements clear of ice with waste heat.

[John Williamson]

When the pavement and toad would otherwise be a nice, slippery, ice covered area. you might think differently, especially as it's effectively a use for low grade heat that would otherwise be wasted.

Probably only economically worthwhile if you're using geothermal heat, though.

[Dave Plowman (News)]

I was replying to the idea of some form of central boiler - hence pointing out the need to insulate things. If the heat is waste heat, possibly a different matter. But even then it would be nice to think that energy could be put to a better use than de-icing roads or pavements.

[RJH]

I think if the system was installed (or even existing systems used) with the 'blessing' of householders, it'd stand a decent chance of working. Grass roots and all of that.

Of course.

[Brian Gaff]

Might need to be some kind of novel way to charge for the heat though, and some very good lagging for the underground pipes. Brian

[Alan Braggins]

Works in Iceland, but the central heat source is free geothermal....

[The Other Mike]

In the past both tomatoes and eels were produced with the aid of waste heat at Drax.

[The Other Mike]

It's using very low grade heat, after it has gone through houses and offices.

Given the choice betwen slippery pavements or shoes ruined with salt then it's a good choice for limited urban areas. For instance they heated the pavement and road around a town square but not the centre of the square.

Compared to the slushy mess in the UK and salt encrusted footwear then its a brilliant idea, the pavements are completely dry too.

[The Other Mike]

The temperature of the cooling water is so low its not really suitable for use 'as is' for heating and if you did the levels of flow needed are such that you'd probably not be able to pipe 100% of it around an urban area for district heating. Some other means of losing heat to maintain condenser vacuum has to be maintained, either closed circuit coolling towers, or an industrial process, or horticulture, or a dump to a river, lake or the sea.

District heating is often not a case of utilising waste heat from electricity generation, boilers are deliberately over sized and purposed for heating, electricity can be a secondary product, using the excess then the space heating demand drops off.

You could also use heat pumps on the large quantities of cooling water.

[SteveW]

I saw an article some time ago suggesting using low-level waste heat from power stations to boil lpg, then running the lpg through an expander to drive a generator. The lpg exits the expander at a low pressure and temperature (at least partly re-liquified) and requires very little cooling before re-use.

I've not heard anything since that article though.

SteveW

[harryagain]

All been done in the past.. And still being done with wood pellet boilers. The commies were big into it using waste heat from power stations.

Large commercial buildings./factories/hospitals have it.

This was especially so when coal/steam was the main fuel/distribution source. There are huge energy losses in the distribution pipework. So all this stuff is being ripped out. Decentralisation is the keyword now. ie samll boilers dotted around the place. Also simplified maintentance.

[harryagain]

There are indeed. They are really expensive and unreliable.

[The Other Mike]

That'll be why Sheffield are expanding their centralised district heating scheme then, fuelled by waste.

[harryagain]

What drivel. We need ways of increasing efficiency not wasting energy on such trivia.

[harryagain]

Only viable with free fuel.

[Chris J Dixon]

As are Nottingham.

Chris

[RJH]

Not exactly free, but 'waste', and energy is needed to convert waste to heat:

Cheers, Rob

[The Natural Philosopher]

hear hear!

[The Other Mike]

Dig salt out of big hole underground, transport a few hundred miles using hydrocarbon fuels, buy grit spreader, employ people to drive grit spreader, employ people with shovels to treat pavements. Or dig up the road and pavements once every 50 years, lay pipes, use heat that would otherwise be dumped into nearby river or lake disrupting and altering the local conditions, resulting in algal blooms and the loss of some native species. In addition the number of slips and falls is reduced or eliminated, meaning less risk to health particularly in the elderly from broken bones, and less spent on heathcare

In countries colder than the UK the use of waste heat to keep roads and pavements clear in limited areas is viewed as a very good idea.

No one was saying it was a good idea for the UK you dozy twonk.

[The Other Mike]

Even more viable with fuel that has a negative cost in that the council would otherwise have to pay landfill tax.