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Is domestic CHP dead and buried?

Posted by Simon Fixter on 21 April 2011 at 1:56 pm

The going price of a Stirling based domestic micro-CHP (combined heat and power) unit of between £3000 - £8600¹ takes some swallowing, when you compare it to prices for the most efficient A-rated (Sedbuk) central heating boilers of around £600-£1,000, (some with 5-year service-free periods included)! 

So the cost per kW of heat and power over the lifetime of these devices marketed by British Gas (Baxi Ecogen) and E.on (WhisperGen) appears much higher than at first it seems.  For the Baxi system, no break-even for about 7 to 8 years, by which time, perhaps, the system will need to be replaced.  So at first glance the cost of ownership looks prohibitive, despite micro-CHP electricity being generated much more efficiently.  

Micro CHP could be one thread of a solution to reducing the cost of electricity production if the capital prices can be substantially reduced. They can also reduce our need for coal and nuclear generation methods on centralised electricity suppliers whose efficiency, due to technology,  is poor;   in fact, half as efficient in comparison to CHP, 45% and 90% is the differential quoted!  

I am no economist, but would be interested to see if CHP can stand the light of day, in comparison to say, the costs of building and the ongoing running overheads of 2 nuclear power stations? Just think, if that money was routed instead to the installation of CHP's, what would their cost be then? 

Who is distributing CHP domestic systems to the market  on behalf of the manufacturers Baxi and WhisperGen? E-on and British Gas.  The question has to be asked ... is it in their interest the let the householder generate their own power?  Is it in the interests of Government to lose power tax income? It's early days to see if these distributors deliver the perceived promise of the efficiencies that CHP appears to offer.   

Ecogen doesn't fill me with enthusiasm for a system I would dearly consider buying, if I could be given the information upon which to make a decision!  The Shrewsbury Ecogen Case study was so banal as to be insulting. Detail quoted from 'John' the homeowner, such as 'it's a fair bit of kit' and ' I like the wall plate that the unit is attached to' beggars belief.  

Where are the running cost comparisons between his specific new and old systems? Cost of servicing, noise level measurements, re-piping costs, boiler re-location, response times to heat 'n' litres of hot water etc?  Perhaps I'm acting as devil's advocate, as the the spreadsheet provides some figures. I'd have liked to have seen John's bills, as after all he offered himself as a case study.

I may be doing them a disservice, but the distributors have and are not helping themselves by their poor quality responses to enquiries and sparse information they are releasing.  Baxi has been trialing these units for years.  Why the reticence to release meaningful information on their trial sites? Is it because the results are so good it will bring a seismic change in heating and electricity generation, or so poor the apparent benefits come at a prohibitive cost of ownership?

We can't evaluate anything until we have someone to give a practical analysis of these systems.  Are these prices good or are they being front loaded to discourage uptake?

All interesting questions on which the jury is presently out, but for now with the current information levels I can't make any decision.  Some people know the answers and they aren't letting on.

I note that only a limited number of units are attracting feed-in tariffs.  Why is that? Who is getting these units?   British Gas are failing to respond to me, so I can't delve more deeply into costs at this time.  What do you think?

¹ £3000 - quoted from the British Gas price comparison spreadsheet. - an incremental (?) capital cost
£8600 - approx cost of a basic E.ON system in Germany

More information about CHP from YouGen

CHP information page

About the author: Simon is an electrician and plumber, and has refurbished his own home.

If you have a question about anything in the above blog, please ask it in the comments section below.

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10 comments - read them below or add one


nomisComment left on: 2 May 2015 at 10:14 am

in 2010 we needed a new boiler, and I went Ecogen, not to save money but because it was enviromentally agreeable.  Over 5 years the FiT and "free" electricity has been worth 2k so far BUT the problem is when something goes wrong....which it does.  The sales patter about the stirling engine was all about their reliability....b00l0cks.  Our third one has just packed up, taking out all our gas heating.  Typically British Gas would be called (I dare not change our service contract as they put it in) a day is taken off work and an engineer arrives (despite a reminder its an ecogen) sucks through his teeth and arranges for Baxi to call - another day off.  They then cannot fix it and have to come back - another day off.  This time they insist on doing a test on the water before even considering fixing the thing, and the test is going to take two WEEKS to do.  And then they have warned that they may not agree to fix it!  So if you were thinking BG, Baxi or stirling engine solutions I suggest you don't.


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GeronimoComment left on: 28 March 2013 at 8:34 pm

I,ve been in contact with Genlec ( re Kingston chp boiler) for years even to the point where I was asked if I would be interested in trailing a boiler which I was,then nothing,I,ve tried numerous times to get some sort of response ,but nothing! On the issue of Stirling or rankin system I have always believed that the Rankin system is up and running ( producing electricity) within seconds compared to the long start up time to generation for the Stirling from Baxi.

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Cathy Debenham

Cathy DebenhamComment left on: 31 January 2013 at 2:30 pm

Hi Rick. Each year at Ecobuild I have a conversation with Baxi about why the Ecogen isn't rolling out successfully. Last year, having ended the exclusive deal with British Gas and found a number of distributors they were quite bullish. However, as you say, all seems quiet. I look forward to hearing what they say in March this year - and I will then update it!

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Rick Hankin

Rick HankinComment left on: 30 January 2013 at 11:08 pm

It is interesting to note that it is 21 months since anyone contributed to this blog. So domestic CHP might be dying if not actually dead.

I have engineered some commercial industrial CHP's and the only clients who make savings are the one who need both the by products, ie lots of heating medium and generated electricity.The electricity can be exported under normal conditions or be used as an emergency supply when the transmission/distribution system fails. A surgical hospital is a case in point. 

Even then there are downsides, the maintenance costs are often so high any saving is negated, the prime reason for the CHP is the "always on" generator that can heat the building envolope and charge the batteries of the UPS.

I think for the domestic market we need to do a large re-think 

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chriswComment left on: 16 May 2011 at 5:46 pm

I take it back - got a reply from Genlec today. I gave them a link to here and hopefully someone from Genlec will be posting some info on their product  here...

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chriswComment left on: 13 May 2011 at 7:22 pm

I've tried registering interest in the Genlec CHP as a consumer via their website contact form and also via direct email but so far a total lack of response. Doesn't seem to bode well for this to be available any time soon if they can't be bothered to respond to potential customers.

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Simon Fixter

Simon Fixter from Comment left on: 3 May 2011 at 11:43 am

Hi all, thanks for adding your comments regards MCHP.  I was really keen to see how practical it was as so much was going for the concept.  I have found another little glitch.  Namely 'burn-time'. Enquiries have elicited that to get your generation going requires several things.  1) That the CHP gets up to temperature, which takes time.  So no meaningful quantitiy of electricity until say 30 mins elapsed. So then fir the first hour say 1Kw with the Sterling version, and 500W with the Rankine. 2) Consequential, is this precludes any real payback generation except in winter when the CH is active.

I installed a modern heat-store for underfloor. central & water. Not clever in summer as no hot water in the morning though lots at the day's end. So the heat-store ( 300 litres ) has to be heated for 3 mins water for a morning wash! Very expensive!  A better solution would have been to have a small combi with cold water fed through the heat store.  If the heat-store warmed the water sufficiently, the combi wouldn't need to fire up, else it would top up the heat to your desired temp, at a better flow rate.  Am seriously thinking of having one installed, with my system boiler off during the summer. It'll save a fortune in gas.  Next ... MCHP ?  The Yanks have a new solar panel crystaline structures that convert up to 50% of light to electricity.  Now that's a lot better thatn< 5%.  

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Cathy Debenham

Cathy DebenhamComment left on: 2 May 2011 at 8:39 am

Hi Matt - do let us into the secret ... which one are you talking about. And do you have a commercial interest in it?

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chriswComment left on: 29 April 2011 at 10:42 pm

Matt - are you talking about the Genlec CHP with the Organic Rankine Cycle module? 

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Matt Lucas

Matt LucasComment left on: 27 April 2011 at 7:49 pm

Interesting read and I think you are right in respect of the Stirling Engine.

From what I have seen of the current models on the market, I'm guessing they are pretty heavy so you need a decent weight bearing wall to install it before you start.

I would imagine it might make a noticeable noise as well when running?

I don't believe the Stirling Engine or Fuel Cell model is right for the UK domestic market just yet, however I have seen a new CHP technology that is coming which has a considerably lower price point and doesn't need 2 men to lift.

It's got me excited to the point where I will install one when it comes to market....

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