Whoa there Smiley, I never think I know my stuff! I know that I don't know much on these subjects but I'm trying to find out more.
As far as AD goes, I got loads of bumf at the Expo in Oct, but I haven't even glanced at it since which tells it's own story. But I have some names for you in NO particular order!
Weltec Biopower, UTS Biogas, Envitec Biogas, MT-Energie, Xergie, Biogas Nord, FLI Energy, Hockreiter (poss not correct spelling!).
A quick search on Google should give you plenty of info too. What info I've gleaned from the Expo; you need best part of a £million to put up a plant that's capable of generating a whorthwhile amount of electricity in terms of paying back on your investment. You need to be able to get your hands on a good regular reliable supply of feedstock (something which was out of the question on a farm of our size 450 acres). Someone needs to feed and look after the plant constantly, albeit not a huge amount of time. The potential to cock up the mixture, and thus not get any income for up to 3 months while you sort it, is a problem. The FIT rate is lower than for wind power. If you're talking about putting up a decent sized plant (say £2million plus) and will use stuff like food waste and thus be able to charge gate fees, then the return becomes very attractive indeed. There were quite a lot of suits at the Expo which tells its own story! They were obv looking at big plants, and were not farmers as such! If you're putting up a big plant where are you going to spread all the digestate?
We began looking at this because a neighbour was keen on putting up a plant to be serviced by 5 biggish farmers in our area, and he would take all the heat for his chicken sheds. There was a good mix of farm operators in terms of feed stock, but a couple of them were obsessed with how much a tonne they were going to get for any silage they put into the plant, rather than focussing on the income they would get from the electricity. Needless to say it died a death.That would've been a viable operation though.
However, the level of investment, work in running it and income generated by either AD or wind is an absolute no-brainer. It isn't even worth pondering. Good luck in your research though. He-himself sounds a much better informed person than me though as he has turbines up and running!!!