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Biogas project
Biogas project
A ground-breaking project implementing a prototype methane recovery system on a 950 cow farm in Southland has demonstrated for the first time commercial viability of this technology within a cool climate. Performance has exceeded forecasts, providing 30KW electrical power and 60KW hot water per hour, providing for the majority of the farm’s energy needs, including running an electric farm bike, entirely from waste product.
Dairy effluent storage ponds are known to produce methane, a green house gas more than 21 times worse than carbon dioxide in effect. Despite this the dilute nature of dairy shed effluent means it is not suitable for supplying conventional biogas digesters.
Dairy Green Ltd was contracted by the Fortuna Group to implement methane recovery and electricity and hot water generation at the Glenarlea Farms property. Venture Southland assisted by arranging EECA involvement and funding NIWA’s initial involvement completing a feasibility study.
A generator shed was built to house a second hand spark ignition motor and 75 kW generator. A control system was installed to manage the motor and generator and allow grid synchronisation. A plumbing circuit was installed to utilise hot water produced by the motor to heat water for the dairy shed. This heats water to 90°C for plant cleaning purposes.
The motor was able to run for up to 16 hours per day in the spring and produced 30 kW electrical power while doing so. The heat recovered as hot water equated to 60 kW produced per hour.
The dairy shed electricity demand ranges from less than 10 kW between milkings after the milk refrigeration unit has turned off to up to 45 kW during milking.
The generator is run to minimise the amount of power purchased from the grid.
Photos of the biogas pond, generator and an electric farm bike
