AD is a posh way of describing a biological way to get rid of S**T. Simple as that. The Govt has committed to big investment in this, which might see fewer rotten old rubbish incinerators being built, but more combined sewage treatment and power plants. Basically, you use bacteria to digest the sewage, and any other organic rubbish, then burn off the methane for heat and power. Some goes to keeping the process going, the rest goes to the National Grid. What's left over should be a sterile but valuable fertiliser. It's quite big in Europe, and does have some significant advantages over other power generation, and reduces air and water pollution (No smoke, you see). Now, wiser men than me will already be looking to the angles here, but I would see big investment in refitting existing Water treatment works, and I can see that a lot of farmers might do quite well out of this. Cows do produce a LOT of crap. At present its a nuisance. Now it could be an asset. See http://en.wikipedia.org/wiki/Anaerobic_digestion for a rough overview.