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''.
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