The Blackpool-based green energy producer said its £3m anaerobic digestion plant at Carr Farm in Warton, near Preston, is set to start producing electricity at the end of May.
An official opening ceremony is being carried out by Mark Menzies, parliamentary private secretary to energy and climate change Minister Charles Hendry, on Saturday 21 May.
Farmgen, which has embarked on a £30m investment drive nationwide, said the power plant will generate 800kW of electricity; the equivalent of powering more than 1,000 homes.
Ed Cattigan, Farmgen's chief operating officer, said: "We firmly believe Carr Farm will point the way forward for future farm-based AD plants across the UK.
"Carr Farm has already generated major interest from farmers who can see the benefits and the opportunity to create a sustainable and stronger future for themselves by switching to energy farming and once it is operational we believe that interest will increase even further.
"Renewables and other sources of green energy will play a critical role in providing the country's power supplies over the next decade and we believe farm-based AD plants will have an important role to play in that transformation.
"We are getting interest from across the whole of the UK and we expect to be making some further major announcements in the very near future."
Carr Farm will be Farmgen's first operational power plant, with building continuing on a second plant near Silloth in Cumbria and a further two operations planned in the area at Cumwhinton and Ivegill.
Cattigan added Marks & Spencer has signed a five year contract to buy the energy generated from the Warton plant at an undisclosed price as part of its Plan A commitment to procure more renewable energy from small-scale energy sources.
Farmgen was set up in 2009 and its board includes Simon Rigby, the founder and former chief executive of utilities group Spice.
Rigby netted a £22m last year when Spice was sold to private equity investors Cinven for £251m and is backing Farmgen's ambitious plan to set up AD plants on farms across the UK.