A NEW innovation on a Southland dairy farm is saving money and keeping harmful methane gas out of the atmosphere.
Glenarlea Farm, at Isla Bank, is now converting methane captured from its dairy effluent pond into electricity for the dairy shed, as well as heating water used for washing down on the farm to 91degC.
The farm’s effluent pond, containing wash-out from the milking shed, has been capped with a black lining which traps the gas so it can be fed through a generator to produce electricity.
“It’s a simple formula. The more volatile solids [animal manure] you have, the more energy you can produce,” Dairy Green Ltd agricultural engineering consultant Quinton Scandrett said.
Mr Scandrett estimated a 400-cow herd would be able to create enough energy to produce hot water only, but 800-850 cows would be the “trigger point” for a full electricity generating set-up. Mr Scandrett also estimated greenhouse gas emissions would be reduced by about 30% using the system.
Mr Scandrett said the challenge for Southland farmers would be keeping effluent ponds well insulated, since cooler temperatures slowed the natural bacteria which produced the methane. The pond at Glenarlea Farm had been specially designed and built for this purpose.
Mr Scandrett’s father, John, who is also an agricultural engineering consultant for Dairy Green, said existing effluent ponds could be retro-fitted with the technology. The technology had already been successfully implemented on European farms, which typically had smaller herds, he said.
It was also being trialled on dairy farms in the Waikato and Canterbury
Energy Efficiency and Conservation Authority (EECA) project director Bill Brander said “successful demonstration of the technology in a cooler climate like Southland will provide confidence it can work anywhere in New Zealand”.
The project is the result of a collective effort by the EECA, the National Institute of Water and Atmospheric Research (NIWA), agricultural engineers Dairy Green, Venture Southland, and the Fortuna Group, which runs the farm.
EECA and Venture Southland will monitor the Southland project to prove the economic payback of the investment.
business and strategic projects general manager Steve Canny expects the technology to be available to roll out on Southland farms next year.
“Depending on what effluent pond systems are already in place, costs will vary, but with the savings in electricity from farmers being able to generate it themselves, the recovery system will eventually pay for itself,” Mr Canny said.