Hiding the bodies.

It's clean, it's green, its the body dissolving machine! http://www.bbc.co.uk/news/science-environment-14114555

OK so this hi-tech version of John George Haigh's acid bath might be a very clever way of turning granny into soup but its still using up energy (you don't get to 180 Celsius and 10,000 hPa for free) so how about we do this the old fashioned way, it's called "burial".

In my world it would work like this. You build a few big frozen storage places around the country and when people croak they get sent there, medical and dental students get to have a bit of practice at taking out the metal fillings and granny's hip replacements and then the bodies are put on ice in a dimly lit freezer. These facilities would pay for themselves as they could be rented out to the BBC every year for yet another episode of Torchwood which always seems to be set in places like this. This would have the added benefit of giving comfort to the relatives of the deceased as they would be able to picture their loved ones lying there whilst John Barrowman runs past them in tight-fitting trousers, an RAF coat and a hammy American accent.

Anyway once you have enough bods you go out to a big plantation, dig a bunch of holes, put a body in each one and then plant a tree on top. The body rots, fertilises the young tree so it gets off to a good start and in 50 years you can cut down the tree and use the wood, dig up any remaining bones and crush them up - the resulting grit is handy for spreading on ice in the winter.

All in all 100% eco-friendly and carbon neutral.

It's what granny would have wanted