The aim of the article is to present of economic determinants the functioning of a prosumer biogas plant and prospects of development of this activity. It was found that at current energy prices and a functioning system to support production from renewable energy sources (RES), the investment in the micro biogas plants have little economic justification. The expected payback period exceeding 15 years and the IRR is at 9.81%, even with the optimistic assumption of obtaining a grant to start operations in the amount of 500 000 PLN. The development of micro agricultural biogas plants therefore requires changes in the system to support this type of RES.