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Hairyloon

Joined: 20 Nov 2008
Posts: 15425
Location: Today I are mostly being in Yorkshire.

Posted: Tue Oct 27, 09 10:03 pm Post subject:

stumbling goat wrote:

i would work out what your costs would be with your current boiler set up as is?

No disrespect, but it is actually irrelevant what the current cost is.
The fact is, it offends my sensibilities to burn fossil fuel just for heat when it is relatively easy to get waste heat for heat.

RichardW

Joined: 24 Aug 2006
Posts: 8443
Location: Llyn Peninsular North Wales

Posted: Tue Oct 27, 09 11:05 pm Post subject:

Hairyloon wrote:

The fact is, it offends my sensibilities to burn fossil fuel just for heat when it is relatively easy to get waste heat for heat.

You will be doing just the same.

The elec is the by product not the heat. The amount of elec you make compared to the amount of heat is quite small.

An engine roughly produces

1/3rd motive power
1/3rd wet heat
1/3 exhaust heat
With an efficiency of less than 70%

The alt will only be about 50% efficient at best & prob more like 30% so you will put fossil fuel in & get 11% of that energy out as elec & 23% as wet heat & 23% as exhaust heat (if you recover it).

The elec production is a by-product of the heating not the other way round.

stumbling goat

Joined: 20 Jan 2009
Posts: 1990

Posted: Tue Oct 27, 09 11:39 pm Post subject:

Hairyloon wrote:

stumbling goat wrote:

i would work out what your costs would be with your current boiler set up as is?

REALLY? okay.

sg

Last edited by stumbling goat on Wed Oct 28, 09 10:15 am; edited 1 time in total

Mr O

Joined: 13 Feb 2005
Posts: 5512
Location: Nova Scotia, Canada

Posted: Tue Oct 27, 09 11:41 pm Post subject:

Hairyloon wrote:

Mr O wrote:

do you have acesss to a supply of wood?

People are reasonably prone to paying me to take it away... they usually want it taken out of the top of their trees first though.

I would be looking at how to use the wood that you can get hold of rather than using fossil fuels

Treacodactyl
Downsizer Moderator

Joined: 28 Oct 2004
Posts: 25795
Location: Jumping on the bandwagon of opportunism

Posted: Wed Oct 28, 09 8:03 am Post subject:

Mr O wrote:

I would be looking at how to use the wood that you can get hold of rather than using fossil fuels

That's what I would suggest. A couple years back I did have a dig to see if there's any development of a wood-fired CHP boiler. IIRC a company was developing one but I couldn't get much info at the time.

vegplot

Joined: 19 Apr 2007
Posts: 21301
Location: Bethesda, Gwynedd

Posted: Wed Oct 28, 09 9:37 am Post subject:
As an experiment it might be worth a try just to satisfy your curiosity. However, I doubt you will be satisfied with the results.

RichardW

Joined: 24 Aug 2006
Posts: 8443
Location: Llyn Peninsular North Wales

Posted: Wed Oct 28, 09 9:58 am Post subject:

Even with dedicated designed for the job equipment its still marginal. Thats why there still is no viable affordable system on the market yet.

Some people that run old listers do recover the heat but the primary use was the power & the heat was being lost. In an effort to reduce the cost of running the genny just for power they capture heat as well. They are still using fossil fuels and are using more fuel than taking that heat and elec from the grid. The issue is normally no grid so the large extra cost does nor factor in. Our genny produced elec costs about 50p per kwh & as its a dry engine we cant recover worth while heat from it (plus is not on often enough to make heat recovery worth while).

Can it be done? Yes
Is it cost effective? no
Is it fuel effective? no

vegplot

Joined: 19 Apr 2007
Posts: 21301
Location: Bethesda, Gwynedd

Posted: Wed Oct 28, 09 10:20 am Post subject:

RichardW wrote:

Some people that run old listers do recover the heat but the primary use was the power & the heat was being lost.

The only times I've seen this work well is when they are running on waste oil (veg or mineral motor oil) and where they needed power over extended periods (10 hrs per day lighting chicken sheds is one example).

Hairyloon

Joined: 20 Nov 2008
Posts: 15425
Location: Today I are mostly being in Yorkshire.

Posted: Wed Oct 28, 09 1:35 pm Post subject:

RichardW wrote:

Even with dedicated designed for the job equipment its still marginal. Thats why there still is no viable affordable system on the market yet.

The thing about dedicated designed for the job equipment is that it is expensive to make, and it still wears out.
That would make it very difficult to make a marketable system.

Quote:

Our genny produced elec costs about 50p per kwh

What are you running it on?

Lorrainelovesplants

Joined: 13 Oct 2006
Posts: 6521
Location: Dordogne

Posted: Wed Oct 28, 09 3:07 pm Post subject:

I think you have to look at why you are burning so much gas, what your house insulation is like, your state of dress as you walk round the house, and what alternatives you have.

Our LPG bill was �2500 per year, and that was for hot water and CH (we have no access to mains gas).

We have reduced this now to �600 per year (same house). We still have the LPG (its for baths, really cold snaps and early morning heat only)

We installed a new woodburner with back boiler and this does our Living room heat, radiators in the 3 beds and bathroom down the hall, and gives me hot water in the evening to do the dishes (3rd tap on sink).

Our wood is nearly free.......we use 5 tons a year, this keps us toastie warm. We had cavity wall insulation in the whole house for les than �100 (grant aided), and have heavy curtains on the one draughty door, and wear jumpers and socks (as well as usual cothes)round the house.

We'll recoup the cost of the new woodburner in less than 2 years.
I'd rather spend the money on other things.

vegplot

Joined: 19 Apr 2007
Posts: 21301
Location: Bethesda, Gwynedd

Posted: Wed Oct 28, 09 3:10 pm Post subject:
As Richard W as said you're going to get a lot more heat energy than electrical output. Balancing one against the other and still maintaining some sort of economy is very difficult and is one of the reason household CHP devices have failed in the market place.

Behemoth

Joined: 01 Dec 2004
Posts: 19023
Location: Leeds

Posted: Wed Oct 28, 09 3:12 pm Post subject:
British Gas are just about to introduce a domestic CHP boiler. What that means I don't know but they think there is a market there, for the boilers at least. Last edited by Behemoth on Wed Oct 28, 09 3:35 pm; edited 1 time in total

Hairyloon

Joined: 20 Nov 2008
Posts: 15425
Location: Today I are mostly being in Yorkshire.

Posted: Wed Oct 28, 09 3:34 pm Post subject:

Lorrainelovesplants wrote:

I think you have to look at why you are burning so much gas...

A valid thought, but no.
Once I saw the speed the meter was spinning at I turned it off.

RichardW

Joined: 24 Aug 2006
Posts: 8443
Location: Llyn Peninsular North Wales

Posted: Wed Oct 28, 09 6:33 pm Post subject:

Hairyloon wrote:

What are you running it on?

Red. Read all 57 pages of THIS THREAD & you will understand why (plus you will learn lots about CHP)

If fully loaded to its max out put its cheaper but most of the time you dont have the genny maxed out & the 50p per kwh is the average of all our consumption via the genny.

Behemoth wrote:

British Gas are just about to introduce a domestic CHP boiler. What that means I don't know but they think there is a market there, for the boilers at least.

If I remember right thats the same one the 3 other large elec suppliers have been dabbling with for a few years with promises of it hitting the market some time soon. If so the quoted cost was (please sit down) over �20k. From what the off grid community is saying its just a way that the big suppliers can say they are trying to be greener by supporting this company but the pubic wont buy it.

Hairyloon

Joined: 20 Nov 2008
Posts: 15425
Location: Today I are mostly being in Yorkshire.

Posted: Wed Oct 28, 09 10:21 pm Post subject:

RichardW wrote:

Hairyloon wrote:

What are you running it on?

Red. Read all 57 pages of THIS THREAD & you will understand why (plus you will learn lots about CHP)

I'll have to come back to that later.

Quote:

If fully loaded to its max out put its cheaper but most of the time you dont have the genny maxed out & the 50p per kwh is the average of all our consumption via the genny.

How much is red these days?
From what I can find, diesel has an energy content of 38-40MJ/l.
A kWh is 3.6MJ, so the equivalent gas energy to a litre of diesel would be about 40p.
A bit cheaper I think, but not that much.
What's your peak efficiency with the genny at max?

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