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There's a new, unlikely energy source that can power farms while reducing greenhouse gas emissions - pig poo.
A team of scientists at NIWA in Hamilton has developed a system that stores greenhouse gases from pig manure in a deep pond, from where it can be used as an energy source.
NIWA research engineer Stephan Heubeck said the system reduces greenhouse gases in the atmosphere while providing an alternative source of energy.
"The manure is introduced into a deep pond and it's an oxygen-free environment,'' he explained.
There, anaerobic bacteria breaks down the manure into biogas; methane and carbon dioxide, the two main greenhouse gases.
"That is producing odour problems. The big driver for many of the pig farms is to intercept the gas before it reaches the atmosphere, reducing odour emissions.''
A large cover traps the gases in the ponds. Farmers can then utilise the biogas by connecting it to a gas boiler or electricity generator, all for a low cost.
"We had great deal of support from the New Zealand Pork Industry Board, they were interested in finding a way of reducing odour emissions from the pig farmers and they were very helpful,'' he said.
The NIWA team also worked in collaboration with the Energy Efficiency and Conservation Authority (EECA).
At Steve Lepper's piggery in Taranaki, where the first system was built, a 7000m3 pond had to be dug, a pond-cover built and an electricity generator purchased.
The system now provides the farm with heat and power, and the waste heat from the electricity generator is used for a heating system that keeps piglets warm.
The total cost was $120,000, including an EECA grant of $30,000, but Mr Lepper expected to recoup his investment within three years.
The project, which had been in the works for 10 years, has also attracted interest in Australia, where four systems are under construction.
Mr Heubeck said the industry there was embracing a "spirit of development'', after the Australian government introduced the Carbon Farming Initiative, which rewards farmers that reduce their greenhouse gas emissions.
"The Australian pork industry association there, Australian Pork Limited, has been very, very supportive in getting this message out there to the farmers and helping with the implementation of those systems''.