As of now I don’t know of any opportunities, or at least any that I would trust my money with. I don’t know if there will be any in the future or not because the industry is so young it’s farm-by-farm at that moment.
This is the digester co we are working with: http://www.phase3dev.com/
The only other one I know that works is GHD, who we also work with from time to time, http://www.ghdinc.net
Thanks.