Micro CHP
- Thread starter FrankE
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I also looked into the idea in my case for a boat 
Wispergen seems a good system but the price tag is £8220 +Vat and to pay back that sort of money it has to save around £400 per year just to break even with interest on investment. As one leaves external combustion engines and go for internal combustion noise becomes a problem. Because buying petrol tax free is a problem you are limited to diesel which make more noise. To work efficient it needs variable speed and to get variable speed the generator has to be combined with an inverter. This means the price sores. Although you can leave the grid as with remote farms more normal is to retain the electric power coming into the house. There are two systems.
1) When you have excess power it is put back into grid. However the cost of installing the system is very high.
2) An inverter puts as much as it can into your system but does not ever back feed into grid.
The
Grid tie inverter is designed to put power from solar cells and wind chargers into the system however the site I have found seems to only go to about 1.2Kw with grid tie. As a stand alone inverter 10Kw are available but there are issues with modified sine wave I have just got the 3Kw version at £130 which is enough for a narrow boat but would be pushing it a bit for a house and to use it a bank of batteries of nearly 400AH.
This is the point with any system either heat or power will need storing to work efficiently. Firms like Glenhill do Thermal Stores which is a big hot water cylinder that is heated when you have power and then delivers heat when required. Since you are unlikely to want electric power at same time as heat power something like this is required.
But then the installation costs go sky high and as with the Wispergen you realise by time you consider interest lost or paid on investment it can never pay for it's self.
Personal I think it's a pipe dream but lets see what others say?
Wispergen seems a good system but the price tag is £8220 +Vat and to pay back that sort of money it has to save around £400 per year just to break even with interest on investment. As one leaves external combustion engines and go for internal combustion noise becomes a problem. Because buying petrol tax free is a problem you are limited to diesel which make more noise. To work efficient it needs variable speed and to get variable speed the generator has to be combined with an inverter. This means the price sores. Although you can leave the grid as with remote farms more normal is to retain the electric power coming into the house. There are two systems.1) When you have excess power it is put back into grid. However the cost of installing the system is very high.
2) An inverter puts as much as it can into your system but does not ever back feed into grid.
The
Grid tie inverter is designed to put power from solar cells and wind chargers into the system however the site I have found seems to only go to about 1.2Kw with grid tie. As a stand alone inverter 10Kw are available but there are issues with modified sine wave I have just got the 3Kw version at £130 which is enough for a narrow boat but would be pushing it a bit for a house and to use it a bank of batteries of nearly 400AH.This is the point with any system either heat or power will need storing to work efficiently. Firms like Glenhill do Thermal Stores which is a big hot water cylinder that is heated when you have power and then delivers heat when required. Since you are unlikely to want electric power at same time as heat power something like this is required.
But then the installation costs go sky high and as with the Wispergen you realise by time you consider interest lost or paid on investment it can never pay for it's self.
Personal I think it's a pipe dream but lets see what others say?
The Whispergen is a very good system for the intended use on marine or land mobile vehicles. The Stirling cycle engine used is very quite so can be inside the vehicle of house.
Some twenty years ago a friend set up the engine from a wrecked Mini to run on gas and drive a recovered 230 volt generator to power much of his house. Hot water from the engine was used to heat water in the hot water storage tank. The exhaust pipe was run through the green house to add heat there.
I recall one of the "experimental / exhibition" estates in Milton Keynes had CHP plants installed in many of the houses. I don't have any details but a search on Google may find some reports about it. ( possibly Kent Hill for the name of the estate )
Some twenty years ago a friend set up the engine from a wrecked Mini to run on gas and drive a recovered 230 volt generator to power much of his house. Hot water from the engine was used to heat water in the hot water storage tank. The exhaust pipe was run through the green house to add heat there.
I recall one of the "experimental / exhibition" estates in Milton Keynes had CHP plants installed in many of the houses. I don't have any details but a search on Google may find some reports about it. ( possibly Kent Hill for the name of the estate )
No - first of all you should only look at the difference between that and the cost of a good condensing boiler, and secondly because it reduces your expenditure, which comes out of taxed income, whatever it does save can be increased by whatever top rate % you pay.
If I recall correctly, and it was over 20 years ago, the system was called the totem(?). The engine was from a small Fiay, possibly the Panda. I was just looking around at what is available at the moment and this http://www.volvoxengineering.com/Slow Speed CHP.htm looks like the best thing around for price. Haveing had some experience of Lister engines in the past I would definitly look at it if I were building a house which was going to be off grid.
But remember, you do not pay to heat the house whatever you use to provide heat. You pay to heat the birds and squrrels outside. Insulation should be your first objective.
How does that work BAS?
This week I save £1, i.e. my electricity bill is £1 less. I use it to pay off the interest on the capital. So instead of paying £1 towards my electricity bill, I pay £1 to the bank from which I borrowed the £8k. Whichever, I still have to pay another £1 income tax (I'm a rich basket, paying 50%
).
Eric's example was different - he was also looking at the opportunity cost not that of servicing a loan.
Assuming CHP costs you £7.5K more than a regular condensing boiler, and you could invest that £7.5K at 3%, if you're paying tax at 40% the break-even point is about £135pa, not £400.
If you're not paying tax at 40% the sums are different. If you're not paying tax at all the sums are different. If you've not used up all your tax-free savings allowance the sums are different. If you're going to have to borrow the money the sums are different.
But the sums are never just the simple gross interest on the whole capital amount vs electricity savings.
Assuming CHP costs you £7.5K more than a regular condensing boiler, and you could invest that £7.5K at 3%, if you're paying tax at 40% the break-even point is about £135pa, not £400.
If you're not paying tax at 40% the sums are different. If you're not paying tax at all the sums are different. If you've not used up all your tax-free savings allowance the sums are different. If you're going to have to borrow the money the sums are different.
But the sums are never just the simple gross interest on the whole capital amount vs electricity savings.
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