CHP boilers produce both electricity and hot water!
We get an awful lot of interest in CHP boilers for the home; these are pretty much like conventional boilers, however the difference is that they also produce electricity when they fire up as well as hot water.
On the face of it, that seems fantastic – since they not only meet your heating demand, but a CHP can also be used to power some of your appliances. So why then doesn’t everyone have a CHP boiler in their home?
Well the truth is that they actually produce relatively little electricity. When we went to Ecobuild a month or so ago, we came across one model that produced 2kW per hour when it was on – so just 2kWh per hour.
During the winter months, a household may have their heating on for 5 hours, so in theory you would be producing 10 kWh per day, however – just because the boiler is programmed to come on for 5 hours, if there is any sort of thermostatic control, then the boiler won’t actually be running for every minute of those 5 hours.
Normally a thermostat will instruct a boiler to turn off when the home reaches a set temperature, and then it will instruct the boiler to fire up and down to keep the temperature fairly consistent.
So for arguments sake, lets say this boiler was actually only on for 3 hours and that was just during the winter months (November to March), the total kWh produced would be
3 hrs x 2 kWh x (150 days) = 900 kWh
That obviously doesn’t take into account hot water production (it is just heating), so adding another 300 kWh for this, it takes the total to 1200 kWh.
That means you are saving per year about £120 at 13p / kWh on your electricity bill provided you can use all the electricity in your home.
In addition you get paid to produce the electricity via the Feed-in tariff, which is an additional 13.24p per kWh (at time of writing – March 2015).
This brings your yearly return to about £250 (including the energy savings + the FIT payments) – so not too bad – or at least it would be if the cost of the CHP boiler was competitive!
The price of the Baxi EcoGen 24 in 2011 when the company briefly made a foray into the residential CHP industry, was £3,750 – that is about £3,000 more than one of their typical condensing gas boilers that are available today.
Now a new condensing boiler is deemed to have a lifespan of 12 years (look up planned obsolescence!) – so if you take the £250 saving and multiply it by this 12 year lifespan – you get £3000, which covers the incremental cost of getting one of these boilers installed.
The issue is that this deemed lifespan is for a normal new boiler not a CHP one. A CHP boiler is unlikely to last 12 years – in fact the one we saw at EcoBuild came with just a two year warranty! The stirling engine technology while simple in principle does increase the amount of moving parts in the boiler.
So is the future of CHP boilers doomed?
In our opinion, the future of CHP will be bright, however the conditions for it to flourish aren’t right at the moment.
It is all down to the cost of electricity – at the moment, electricity for homes is normally a set price regardless of when you use it during the day. Even if you are on Economy 7, you only have two prices for electricity.
Within the next decade, we would be hugely surprised if the UK didn’t move to Time of Use tariffs. You can learn more about this tariff here, but essentially electricity is priced differently throughout the day. The Energy companies will charge far more (maybe even 50p / kWh) for electricity at peak times for example 7pm when everyone arrives home from work and far less when demand is very low.
The theory is that by charging more at peak times, it will dampen demand, meaning our installed capacity can be lower. It is very clever, because it is far cheaper to do this rather than installing new power plants over time – however at present it is impossible because the technology is not there. As the Government roles out smart meters though, that all changes – the energy companies will have the capability to do just that.
This is when CHP will make sense, since you will be able to sell the electricity back to the grid at a huge mark up at these peak times (based on the Time of Use tariffs). So it will make sense to run these boilers at these times since you return will be far larger than today. This will be the moment that CHP will suddenly shine.
So while the technology appears only to be for early adopters at the moment, it is certainly not unthinkable for us all to have CHP boilers in the relatively near future – it is just going to be after smart meters are rolled out and the energy companies start implementing time of use tariffs.
In our opinion then, if you need a new boiler now, we would probably stay clear of CHP, just get a good condensing boiler installed instead since it is far cheaper. It will become obvious when the time is coming to seriously consider CHP and that is when the big boys start entering the CHP market!
Installing Micro CHP
Interested in installing a micro CHP boiler? We have scoured the country for the best tradespeople, so that we can make sure we only recommend those we really trust.
If you would like us to find you a local installer to help install micro CHP in your home, just fill in the form below and we will be in touch shortly!
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