[Stoves] benefits from reduced indoor air pollution.

[Crispin Pemberton-Pigott]

Dear Andrew

This is an interesting way to look at the combustion:

>One can make a fair stab at this from the other angle; burn a kg of oven dry wood, using the formula C5H7O3 as the approximation for wood that Tom Reed suggested all those years ago, to give its Higher Heating value, 20.5MJ. Burn an amount of carbon with the same mass as the carbon content of the wood, 0.52kg @33MJ/kg =>17.16MJ. You will see the "spare" hydrogen atom in the wood only contributes a little more than the energy changing the H and O in the wood solid to a vapour.

Similarly, it is reasonable to look at the energy released when burning the H and leaving the C behind (because that happens a lot).

If a biomass was 6% H, then a kg contains 60g of it. At 120 (LHV) MJ/kg that is 7.2 MJ but to 'get it out' requires energy to be put in. Because wood gas yields perhaps 9-12 MJ/kg of fuel, it means there must be some carbon combustion taking place. 

Thanks
Crispin