EU Imported firewood into the UK

[PremiumWood]

I couldn't agree with what you said A, according to forestry commission linkthe numbers are slightly different:

25%MC~ 14MJ/KG

16%MC~ 15MJ/KG

theory:

Let's say that one log (25% moisture content)weighs 1kg. It will produce 14MJ of heat energy.

If you dry this log until it reaches 16%- it wouldn't weigh 1kg anymore, 90grams of water will be gone (91% of weight left).

15MJ * 91% = 13.65 MJ

So no!- you don't get 50% more heat per same log, in fact- you lose some of the energy.

cheers, Dan

[Woodworks]

"Process your uk logs, wack them in a barn for 12-18 months and you should have 16% or less"

 

This depends were you live. I am also a furniture maker but I have not heated my workshop for some time I tested some wood in there that's been there for years and it was only 18% so no chance of getting our logs down to 16%. Sadly Dartmoor is a very soggy place.

[MattyF]

Considering the threats of disease threatening species of uk trees all imports should be banned immediately and is a complete p take it has not already

[kev7937]

Does the kiln not sort out any p+d?

 

 

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[WFWales]

I couldn't agree with what you said A, according to forestry commission linkthe numbers are slightly different:

25%MC~ 14MJ/KG

16%MC~ 15MJ/KG

theory:

Let's say that one log (25% moisture content)weighs 1kg. It will produce 14MJ of heat energy.

If you dry this log until it reaches 16%- it wouldn't weigh 1kg anymore, 90grams of water will be gone (91% of weight left).

15MJ * 91% = 13.65 MJ

So no!- you don't get 50% more heat per same log, in fact- you lose some of the energy.

cheers, Dan

 

Your point regarding the weight of the same log reducing as its moisture content drops is valid Dan BUT...

 

..These figures quoted by the FC are theoretical figures based on the chemical composition of wood and not the actual heat that will be produced by burning them using stoves or whatever....

 

FACT IS you will get a LOT LESS heat out of a log with a higher moisture content - We know this to be true from our own personal experiences. Burning a wet log does not allow the firebox temperature to get high enough to fully burn the gases so we lose energy up the chimney in smoke...

 

Only burn wood at less than 20% m/c...!!

[hot logs]

I couldn't agree with what you said A, according to forestry commission linkthe numbers are slightly different:

25%MC~ 14MJ/KG

16%MC~ 15MJ/KG

theory:

Let's say that one log (25% moisture content)weighs 1kg. It will produce 14MJ of heat energy.

If you dry this log until it reaches 16%- it wouldn't weigh 1kg anymore, 90grams of water will be gone (91% of weight left).

15MJ * 91% = 13.65 MJ

So no!- you don't get 50% more heat per same log, in fact- you lose some of the energy.

cheers, Dan

 

 

Your calculations are based on water making up the whole weight of the log,when in reality 25% moisture content means that water only makes up 25% of the weight i.e. 250g

 

16% moisture content means water makes up 16% of the weight i.e. 160g

 

This 90g is the weight that is lost through drying.

 

The amount of wood remains the same but is now in a higher proportion to water. Which is why the log releases more energy per unit weight.

 

 

To suggest that drier wood releases less energy when burned is nonsense.

Edited October 23, 2012 by hot logs
spelin

[Alycidon]

I couldn't agree with what you said A, according to forestry commission linkthe numbers are slightly different:

25%MC~ 14MJ/KG

16%MC~ 15MJ/KG

theory:

Let's say that one log (25% moisture content)weighs 1kg. It will produce 14MJ of heat energy.

If you dry this log until it reaches 16%- it wouldn't weigh 1kg anymore, 90grams of water will be gone (91% of weight left).

15MJ * 91% = 13.65 MJ

So no!- you don't get 50% more heat per same log, in fact- you lose some of the energy.

cheers, Dan

 

 

 

I implied that I was unsure, thanks for that link, I have been looking for it for some time. Got a feeling there was something on the Hetas site as well but i cant find it.

 

I dont dispute your figures but with less water to evaporate there must I would have thought be more energy available to turn into heat. Anyone care to comment of shall I start this as a new thread.

 

A

[Alycidon]

Your point regarding the weight of the same log reducing as its moisture content drops is valid Dan BUT...

 

..These figures quoted by the FC are theoretical figures based on the chemical composition of wood and not the actual heat that will be produced by burning them using stoves or whatever....

 

FACT IS you will get a LOT LESS heat out of a log with a higher moisture content - We know this to be true from our own personal experiences. Burning a wet log does not allow the firebox temperature to get high enough to fully burn the gases so we lose energy up the chimney in smoke...

 

Only burn wood at less than 20% m/c...!!

 

So what we need are hard and fast (ish) figures of say Ash and Larch or Spruce. Has anyone produced those?.

 

The other issue is that those gases contain crerosote, if its not ignited due to low fire temps then it will condense in the chimney setting things up for a chimney fire.

 

A

[hot logs]

 

I dont dispute your figures but with less water to evaporate there must I would have thought be more energy available to turn into heat. Anyone care to comment of shall I start this as a new thread.

 

A

 

No need to start a new thread - I explained it in my previous post.

 

 

Another way of looking at it is this...

 

Imagine our "1kg log" dries from 25% to 16% and loses 90g of water.

 

If you replace that 90g of water with 90g of wood (at 16%mc) it now weighs 1kg and you would arrive at the figure of 15MJ per Kg.

[billythegoat]

Isn't the whole point of not importing firewood from abroad to encourage further active management of our woodlands especially privately owned woodland which is often left unmanaged for a long time?

Our native hardwoods are the best out there growing in these dump conditions they are used to, and not just for firewood.

I think people who care educate their customers and keep them informed of where their wood comes from and everybody asks more questions now about quontidy, type of wood , provenance etc.

Funny on a previous reply that someone mentioned that 90x90x90 was a cubic metre of firewood!!!

Good luck to all those caring honest wood people out there and hope we all have a good season.