Paul, the reason why cremation in it's current form is not particularly green is mainly because of the retrictions (specifically in the UK) placed on how you can be cremated.

Because of population density the number of cremations that can take place at any one time in any given area is restricted. This means we would literally not have enough time to burn all the bodies if we used only wood.

Not only that, you average wood fired funeral pyre dosen't actually burn that hot, so you aren't reducing corpses to anything less than bone anyway. There is apparently a way of building a funeral pyre using wood that will break down even bone, but it uses an awful lot of wood.

So you're back to using large amounts of fuel. Gas and coal are both carbon based fuels, same as wood, none are any less polluting than the other when used in large amounts.

I've never understood why people want their bodies embalmed, it merely delays the process of decay and means you take up space for no good reason. But even a body that hasn't been embalmed will take 20 - 30 years to be reduced enough to take to the old practice of removing the bones from the grave and placing them in a crypt.

Exposing bodies to the elements & scavengers speeds up the process by quite a bit, but given the high density of population (and therefore dead people), desease becomes an acute problem if bodies are just left lying about.

( You can tell I've been thinking about this ! )

About 8 years ago, I happened to see a piece on tv about a Norwegian scientist who had discovered that if you freeze tissue using liquid nitrogen and then pulverise the frozen tissue, not only does that tissue take up less space, but as the structure of the tissue has already been broken down, even at a cellular level, the process of decay is reduced to 2 - 5 years. This would include bone. Hence why I'm on the lookout for someone willing to perform this service....