Help- working out calorific values

[StephF]

To work out the energy you need to know the weight of either the bag of wood or the weight of the whole load. Then using the tables in the link above you can work out the energy per load.

 

I did so calcs for 0.75cbm bags for softwood and hardwood and they came out as 760kWh and 1200kWh respectively at and average MC of 20%. The only problem I had was getting the weight of the bags of wood (they were educated guesses from previous threads about the weight of a cbm).

 

And before Mark Bolam says anything, No they weren't a ton :001_tt2:

 

Hope this helps Steph.

 

Hi Sam, I got my calculator out, and just worked out the cost per \kwh of my logs based on your figures is:

H/W 15P Kwh,

M/W 15p Kwh

S/W is 16p per Kwh.

I then looked up current prices on internet ( we are not on any kind of mains here, I have no clue what everyone pays for electriciy or gas etc!) and most electric companies charge between 14.5 & 16.5 pence /Kwh, so heating by wood is definately not cheaper that mains electric.

[luke_mclachlan]

Yer I found weights for seasoned 1cbm bags and then scaled it down to a 0.75cbm bag.

 

He does seem like the awkward customer that will question everything you say.

 

 

Hi Sam, would you mind me asking what weight you found for the 1m3 bag of loose hardwood, seasoned? I've seen figures of 360kgs. cheers.

 

sorry, silly of me, i could calculate it from your kwh calculations. Just to be sure, you were basing this one a m3 weight of 400kgs?

Edited March 21, 2014 by luke_mclachlan
correction

[Lucan]

Think you might have got your sums the other way around Steph. Based on £75 for a 0.75cm3 bag of hardwood (1200 kWh) you should get 6.25p kWh.

[SamWhiting12]

Hi Sam, I got my calculator out, and just worked out the cost per kwh of my logs based on your figures is:

H/W 15P Kwh,

M/W 15p Kwh

S/W is 16p per Kwh.

I then looked up current prices on internet ( we are not on any kind of mains here, I have no clue what everyone pays for electriciy or gas etc!) and most electric companies charge between 14.5 & 16.5 pence /Kwh, so heating by wood is definately not cheaper that mains electric.

 

I think your figures are a bit wrong, I sell HW (0.75 bag) at £80 and I get a number of 6.7p/kWh, unless your sell at over £160.

 

I found the biomass centre a good reference for gas and electric prices, from the link you can see wood is more expensive than everything else.

 

Fuel costs per kWh

 

But I push the fact that your buying a renewable product, and renewable, eco and free range products come at a price.

[SamWhiting12]

Hi Sam, would you mind me asking what weight you found for the 1m3 bag of loose hardwood, seasoned? I've seen figures of 360kgs. cheers.

 

sorry, silly of me, i could calculate it from your kwh calculations. Just to be sure, you were basing this one a m3 weight of 400kgs?

 

Yer that's the weight im using, maybe completely wrong but Ive forgotten to reference my figures so I don't know where I have got them from.

[StephF]

whoops, not much good at maths!

[daltontrees]

I found the biomass centre a good reference for gas and electric prices, from the link you can see wood is more expensive than everything else.

 

Fuel costs per kWh

 

Eh? The link takes me to a web page that shows that wood is CHEAPER than everything else...

[SamWhiting12]

Eh? The link takes me to a web page that shows that wood is CHEAPER than everything else...

 

Yer I know they must be selling some cheap wood I just use it for the electric, gas and oil prices.

[ArthurBottlesworth]

Doesn't the efficiency of woodburner come into this too?

Ditto electric/gas boiler etc

 

Sounds like nerd to me.....

Refer him to websites and let him work it out.....

 

But keep him happy too he may work out best way of marketing logs ..... i don't think either tonnes or cubic metres is optimum

[Woodworks]

Doesn't the efficiency of woodburner come into this too?

Ditto electric/gas boiler etc

 

Sounds like nerd to me.....

Refer him to websites and let him work it out.....

 

But keep him happy too he may work out best way of marketing logs ..... i don't think either tonnes or cubic metres is optimum

 

He does sound like a nerd but nerds tend to earn good money and if you can justify your product you can have some of the nerd's money