District heating systems which are common in some other countries can prove cheaper to run than the combined cost of a comparable number of individual systems. However as heat losses of the houses are fixed no energy can possibly be saved. The efficiency of the individual modern boilers prevalent in the UK are now sufficiently high to make centralised systems uncompetitive in pure energy terms though on running cost only grounds they may compete.

There are unfortunately the distribution losses to consider. These will always be high as insulating the pipes can only reduce the heat wasted not eliminate it. Then there are the high infrastructure costs to deal with not to mention the disruptive nature of the work needed to link existing homes together. This last aspect makes it a non starter for me.

To suggest that district heating of uninsulated homes could work out more energy efficient than the use of insulation .. have we have lost our minds!!!

Posted By: tonyHowever as heat losses of the houses are fixed no energy can possibly be saved.

The real opportunity from district heating comes from CHP. Currently we blow most of the heat from electricity generation into the atmosphere. That's an obvious waste.

Traditionally however generation in the UK is done at large centralised locations (ie: close to coal mines or on the coast) rather than near the population centres. So switching to CHP district heating would mean de-centralising the infrastructure somewhat, which is a change in mindset. On the plus side it might reduce transmission losses and simplify the grid.

I used to live on a large estate in London that had a district heating system. Presumably this was installed for convenience, the local authority preferring to manage one set of plant than 700 boilers. The mental part was that the whole estate was a stone's throw away from a large CHP-ready incinerator, but the two have never been connected!

The key to district heating has to be the insulation of the distribution pipes. When we came here for a time we stayed in a flat, floor 4 of 16, one of several blocks, that was district heated. You knew exactly there the distribution pipes were because whilst every where else had 6" of snow on the ground the heating routes were clear with green grass. Running costs eventually caused the pipes to be dug up and re-insulated but even after this the costs were still higher than individual heating.

This Chp scheme was set up by the council to heat some tower blocks, schools and swimming pools. They claim 45% carbon saving, though I don't know compared to what. P art of the thinking is that the public buildings need heat different times of day from the flats, so increased efficiency.

http://www.aberdeenheatandpower.co.uk/

Think this was discussed recently on gbf?

Posted By: Ed Davies
Should be using that luke-warm water on the input side of heat pumps driven by that cheap electricity, then.http:///forum114/extensions/Vanillacons/smilies/standard/confused.gif" alt="" title="" >

That would be interesting if it was economical, especially for a gas-fired plant. Buy gas, turn it into electricity, use electricity to concentrate waste heat from the gas that you sell for more than the cost of the gas. Money for nothing and your cheques for free?

Fuel cell CHP could be on though, since I don't believe the efficiency of the cell is affected by the temperature of the waste heat as badly as a steam turbine is. If they sort out the platinum problem you could see those come in quite quickly, and they'd be more suitable for distributed production than combustion is.

There's still tons of interest, from all sectors. They're actually pretty old technology, they were using them on the Apollo missions in the 60s, and the original idea is Victorian. The problem these days is finding a way to make them that's economical for the kinds of things we'd like to use them for. Bottom line: they need platinum and that stuff costs too much. Solve or dodge that problem and you'd suddenly see them everywhere.

Posted By: SeretUnfortunately power station owners aren't big fans.

To be useful for district heating they'd have to raise the output temperature of their condensers, which lowers generation efficiency. Taken as a big picture the plant is still using its fuel more efficiently, but it would raise the price per kWh if you look strictly at electricity. Power stations would have to be paid well enough for the heat they sold to make it attractive to them. Until then it's just waste, and they're strongly motivated to produce large amounts of luke warm water instead of nice hot stuff.

Obviously it needs to be taken as a whole, but Im still amazed its not talked about more.

Does anyone know of any reports/papers on the topic?

Daniel

There was a law passed in Denmark lately that Gas or Oil boilers can't be installed in new houses any more.