Real kWH costs of solid fuel

Qyburn

From memory stoves used to be rated according to their average output at a standard refuelling interval, which in the British Standard days was four hours. Hence our Rayburn was rated 35,000 BTU/hour, while its maximum output was given as 55,000.

If that's still the methodology then from fully fueled up your stove should average 8kW for four hours, then over maybe another eight hours gradually reduce down to eventually zero. All the stoves we've had would still be hot to a greater or less degree after being left overnight (using solid fuel). Is yours stone cold in the morning?

I expect Hunter would confirm the methodology behind their rating.

Qyburn

chrisw2k said:

Yeah, Im thinking 50kWH would be the equivelent to me having about 8 of those 2kwh electic radiatiors running full power for 3 hours. 1 is enough to keep the downstairs warn in the mornings when I havnt lit the fire, and thats not constantly on..

You can't directly compare electric heating, which you can switch off instantly, with a stove that takes time to get going and even longer to shut down. Think of it more like 2kW for 24 hours, or 20 hours to allow for stove efficiency. Also allow for water heating, how much of that 8kW goes to water, Hunter should have that information as well.

FreeBear

chrisw2k said:

FreeBear said:

This study might be of interest - http://assets.publishing.service.gov.uk/government/uploads/system/uploads/attachment_data/file/933099/burning-wood-consult-bsria-report1.pdf

It primarily looks at the effects of moisture content and how that affects heat output. But it also provides some data for coal, so may give the OP some real world numbers to compare. Should point out the cost per KW the report gives is based on 2020 prices, so doubling the numbers should put you in the ballpark for costs today.

Thanks FreeBear, this is exactly the sort of study I was looking for.  I'll take a good look tomorrow but if im reading this correctly, efficiency of smokless fuel is around 5-6kWh which is a bit less than what Nottingham Energy suggest, and probably around the figure i think im getting (working out to  15p/ kWh based on this years prices).

The fuel loads are only 2Kg for each test, and they don't give any indication on how long the fuel lasted, just that the full load was burnt. In that respect, the report missed a trick.

chrisw2k

FreeBear said:

chrisw2k said:

FreeBear said:

This study might be of interest - http://assets.publishing.service.gov.uk/government/uploads/system/uploads/attachment_data/file/933099/burning-wood-consult-bsria-report1.pdf

It primarily looks at the effects of moisture content and how that affects heat output. But it also provides some data for coal, so may give the OP some real world numbers to compare. Should point out the cost per KW the report gives is based on 2020 prices, so doubling the numbers should put you in the ballpark for costs today.

Thanks FreeBear, this is exactly the sort of study I was looking for.  I'll take a good look tomorrow but if im reading this correctly, efficiency of smokless fuel is around 5-6kWh which is a bit less than what Nottingham Energy suggest, and probably around the figure i think im getting (working out to  15p/ kWh based on this years prices).

The fuel loads are only 2Kg for each test, and they don't give any indication on how long the fuel lasted, just that the full load was burnt. In that respect, the report missed a trick.

I dont think the duration of the burn matters, they took a measurement every 30 seconds until the fuels were fully burnt out so the kWh should be calculated correctly (and therefore I should be able to use this figure to compare to electricity costs).  I guess a good comparision would be if I full up my car - it doesnt matter if i use up the full tank in a week, or over the whole month, the mpg will be roughly the same.

Thanks again for finding the link - with Google now being an ad platform rather than a search engine, it appears to be getting harder to find useful info!!