Dry Fermentation

"Dry Fermenters" designed by Will Brinton circulate liquids through solids.

Research underway at Woods End on biogas production is suggesting that dry fermentation (from Trockenvergaerung in German) can work well, according to Brinton, who has led the efforts following a survey of European innovations. The process, more correctly called “high solids” fermentation, contrasts with liquid fermentation of lagoon slurries and municipal waste water at solids levels of 2-3%. By pushing over 20% TS, one outcome is significant reduction of installation size and potential alteration in a wide range of operations and management parameters, “making this approach very amenable within farming” says Brinton. All three big expense areas – repair, maintenance and wear & tear are expected to be significantly lower with these systems – and, furthermore, groundwater is protected since the mass remains in a solid “stackable” state throughout. “This may not be technology that traditional engineering firms will readily take up”, says Brinton, “but it has a potential role to play in farming”. Pictured at right are Woods End prototype dry fermentation tubes with 30% solids “percolating through the system” producing steady gas output.