The Baxi Ecogen micro-CHP boiler

Rhodrons

GrahamE - Financially Illiterate - why so?
If I pay 3.552p/kWh for second tier gas then to generate 1kWh of electricity would cost me 6*3.552 = 21.312p. But in return I would get the FIT for generation of 11p plus 50% of the export FIT 50%*3.5p = 1.75p plus I get a saving on the that I will not be buying of 12.1p at the second tier rate. So spending 21.312p on gas would give me a payback of 11+1.75+12.1 = 24.85p. So by my reckoning, based on 6kW of gas heat generating 1kW of electrical power, you would make 3.5p every hour. Incidentally, this money generating venture should be even more lucrative if you are on an economy 7 meter as the daytime rate is higher...... or am I missing something in my sums and assumptions?!

GrahamE

I suggest that what is missing from your analysis is that it is unlikely that you would actually substitute the whole of your electricity usage. A figure of 50% would be more likely (which is why that rate is used for the export payment). On that basis you would earn 6.05p less than your calculation, i.e your gas cost would be 2.5p more than your generation income and electricity saving.

But I accept that someone with an Economy 7 tariff or indeed any higher rate tariff might be able to make more than the cost of gas assuming that the consumption is just 6kWh. But in that case they may be better off ensuring that they are on the most cost efficient tariff for their usage pattern. For example would Economy 7 really be suitable with gas central heating?

In reality though it is unlikely that the boiler will only run with the low output 6kWh burner for the entire period - certainly that is my experience - so the actual usage is greater than 6kWh.

Rhodrons wrote: »

GrahamE - Financially Illiterate - why so?
If I pay 3.552p/kWh for second tier gas then to generate 1kWh of electricity would cost me 6*3.552 = 21.312p. But in return I would get the FIT for generation of 11p plus 50% of the export FIT 50%*3.5p = 1.75p plus I get a saving on the that I will not be buying of 12.1p at the second tier rate. So spending 21.312p on gas would give me a payback of 11+1.75+12.1 = 24.85p. So by my reckoning, based on 6kW of gas heat generating 1kW of electrical power, you would make 3.5p every hour. Incidentally, this money generating venture should be even more lucrative if you are on an economy 7 meter as the daytime rate is higher...... or am I missing something in my sums and assumptions?!

dominator99

GrahamE wrote: »

Hi there Tom,
The Ecogen doesn't have an inverter - the way it works is that the Sterling Engine is a reciprocating magnetic piston which generates electricity by passing up and down through a wire coil, (you'll remember from your school physics lessons that moving a wire through a magnetic field creates an electric current). The piston goes at the same frequency as mains electricity (50Hz) so the power generated is at mains frequency..................

Hi GrahamE

Although the Ecogen may not have an 'inverter' in the true sense there would be electronics that adjust the output voltage used for export to be higher than your incoming mains voltage to allow the export to take place - UK mains is nominally 230V -6%/+10% ie 216V to 253V.
So, if we assume the Stirling engine side produces a fixed voltage (which I doubt) then there must be a way of increasing that voltage to a level above your incoming grid voltage - in my case, my grid voltage is around 250V & occasionally peaks @ 258V!!.
Also, even though the Stirling engine generates AC at 50Hz that still needs to be synchronised with the grid - imagine a phase shift of 180 degrees!!
Also, a system for 'anti-islanding' must exist to prevent export of AC if a grid power cut was in existence.
The only difference I can see is that there is no 'inverting' of DC to AC as in the case of a PV inverter

dominator99

GrahamE wrote: »

I suggest that what is missing from your analysis is that it is unlikely that you would actually substitute the whole of your electricity usage. A figure of 50% would be more likely (which is why that rate is used for the export payment). On that basis you would earn 6.05p less than your calculation, i.e your gas cost would be 2.5p more than your generation income and electricity saving.

Hi GrahamE

Although I agree with the above you seem to have disregarded the waste heat (around 85% of 6kW ignoring losses) that could be used for heating purposes.
ie up to 1kW/h of electricity production PLUS around 5kW/h towards heating demand with only the Stirling side running.
I would only consider running a mCHP unit primarily for heating, with bonus of producing up to 1kW/h of electricity in the process.
I wouldn't use it for generating electricity only - 15% efficiency!!
It would be cheaper to buy electricity from the grid.

On the export issue of 50% deemed use of generated power.
My 'background' use of electricity is around 450W (0.45kWh) 24/7 so it appears to me that my minimum use, when the mCHP unit is running (heating season) would be approx 45% or higher but I suspect that during the heating period (4-11pm) my average electricity usage would be closer to 700W (0.75kWh) ie my export would be closer to 70%.
This would make the mCHP investment more cost effective.

Now I'll wait for the initial cost of mCHP to reduce.

Mr_Thrifty

So basically it sounds like a gimmick. No real cost savings to be had relative to the substantial up front investment. Probably costs a fortune to service too.

Rhodrons

I think Baxi have probably invested too much in this venture to call the Ecogen a gimmick. Perhaps they are taking the Electric Car pricing route and pricing high initially to get a few enthusiasts to give them feed back prior to gradually lowering the price until volumes start to pick up. This is a bit like the Laffer curve - price an Ecogen at the same price as a standard boiler and everyone will want one but Baxi will make no money, price it ridiculously high and nobody will buy one. Somehwere in the middle is the best price to maximise profit. It is far smarter to price high to start with and then reduce it than to pitch the price too low and never be able to raise it!
BTW British Gas offer free Homecare 200 for the first 2 years which I paid £200/year for with my old boiler so I would say that servicing costs will be comparable. It would be difficult for them to say that this boiler costs more to service - that would certainly kill the market.

green8

I live in a 181 dwelling development in Lisburn, N. Ireland which is abandoning a 2009 biomass DH system due to complex design/legal/financial factors including the developer going into administration mid way through the scheme... long sad story aired on this site last Christmas.

https://forums.moneysavingexpert.com/discussion/3671567

Now, needing a solution, I am just beginning to look at gas microCHP as another option as 181 of us need to leave the wood chip fuelled district heating system by the end of the year and install individual boilers en masse in place of the heat exchangers we have. Our district heating contract with Vital Energi terminates mid December. Any thoughts? Looks too expensive.

[Deleted User]

Looked into this two odd years ago, made no economic sense then and still does not today.

Our quote was £6k installed to existing rads/pipes which were past it. The total cost would really be north of £9k with nice new rads/pipes/tank etc

Bear in mind this was the LPG version.

Ended up going down the ASHP route for not much more cash plus RHI and vastly reduced running costs...

Rhodrons

Green8,
I would contact British Gas and see if they will do you a deal. What a PR scoop that could be for them and Baxi Ecogen!

scubadogct

Hi

In response to those earlier comments about the kWh typo....

I think you may be mistken. As far as I see it up to 1 kWh is the orrect thing to say.

This means that the unit can on avergae deliver 1 kW ever hour. This does not mean it will be a constant 1kW form the entire hour but maybe delivered for example 2kW every 30 mins. Either way this equates to 1kWh