Depending on which vendor (and in which part of the world) you ask, anaerobic digesters could cost anywhere between $2 million - $ 4 million per MW. Now, that’s a huge amount of money, well, it is almost the same as solar PV! (But solar PV costs are coming down all the time, so you can expect that figure to be much lower 3 years down the line).
Why should digesters cost so much? If they are just fertile grounds for methanogenic bacteria to have fun and break down organic matter into methane, what is the technology sophistication that makes it cost so high?
And more important, how can these capital costs be brought down?