What the XXXX is a BTU when it’s at home?

Since I last made a contribution to this column I have been looking in to options available to providing an alternative to my current Kerosene fuelled central heating system. To be honest, given the convenience oil or gas fired central heating has over others, it is hard to identify a system that uses a fuel that will give a corresponding convenience. Flick a switch and it’s on, and there ye are feet up drinking yer coco watching Emmerdale. I went to see a chap that sells wood pellet stoves and he spoke in glowing terms (excuse the pun) about the merits of his stove - “110,000 BTU output", he said as he patted the stove in the manner you would reward an obedient collie dog.
“What the XXXX is a BTU when it’s at home”, I asked humorously, gratuitously swearing in an attempt to mask my ignorance. I need not have bothered: Poor man didn’t know either. He tried to equate it to the amount of standard size rads it would heat. Still didn’t give me any idea of what a BTU was or indeed what the relevant input in BTUs was required to attain that output, i.e. how efficient is the wood pellet stove. Well fear bocht couldn’t tell me so off to the trusty Internet.
A BTU (British thermal unit) is the amount of energy required to raise 1Lb of water 1 degree F, the same amount of energy in an ordinary match. Now another problem is apparent from my Internet search, namely that there are too many standards for measuring energy, from peta joules to giga calories they are all measuring the same thing, potential energy and the ability to convert that energy in a fixed time.
Now I have had a quick glance back over what I have written and I still have a long way to go before I make my point. So to keep the beardy fellow happy I will have to come to some hasty conclusions.
Wood pellets can only be economically made from sawdust from joinerys and sawmills - the supply is small. Two years ago a plant was set up in Denmark producing pellets from raw timber, it went belly up. Lesson one: there will have to be a huge rise in the price of wood pellets before raw timber can be used to produce them. So how much of a rise? At current prices, in a domestic central heating system oil will cost you 6.21 to 6.59 cent per hour for every Kilowatt of energy produced (3400 BTU). Wood pellets will cost you 4.17 cent per Kilowatt of Energy produced and pellets only have about 30% of energy content of oil by volume, therefore bulkier and significant transport costs apply if it is to become a traded commodity which is looking increasingly likely. I am not going to guess but the costs per unit of energy produced will be higher. So for this month I am going to leave anyone that followed my reasoning to this point to chew on it and explain it all to me if you meet me.