Kia-Ora Piggery
A DECADE ago, powering an intensive farm and its enterprises economically using pig pee and poo might have seemed out of this world.
But pig farmer Tom Smith and turbine distributor Brendan Mason claim they have created a system that does just this at a piggery at Yarrawalla in northern Victoria.
Tom says the system can produce all its own electricity, including enough heat for its vast intensive farrowing and weaning sheds. With 24,000 pigs on the farm at any one time and an annual $350,000 power bill, that’s quite an achievement.
What’s really special is that this custom-made system, which took four years to create, incorporates gob-smackingly simple adaptations. The idea began with the farm generating lots of methane.
The entire operating system is automated to respond to heat and electricity demand.
“If demand is high, the motors rev up,” Tom says. “We have a sensor that detects if more power is needed. The computer then tells the carburetor to put more fuel into the motor so it can rev more. When there’s little demand, when just the exhaust fans are operating in the sheds, the motors will just tick over.”
The car motors have been adapted to produce direct current, which is fed into inverters where it’s converted into alternating current – usable energy.
Another plus is that the entire system is monitored off-site and is 30 to 35 per cent efficient. That is, for every 10 units of the scrubbed methane gas fed in, it generates between three and four units of power. Tom estimates he’ll recover the cost in five years.
“That’s a 20 per cent return,” he says. “For farming, that’s good.”
After trialing one set of motors and inverters for 12 months, Tom’s satisfied the others are right to go. Once they pass grid feed-in compliance inspections early this year, the entire system will kick in and start feeding excess power back to the electricity grid.
As well as powering the farm, the pig waste will become an earner, bringing in money for power sold at wholesale rates.
Because the effluent ponds (held in three dams ranging in size from 14 to 20 megalitres) hold plenty of methane or source fuel, there’s no need for battery back-up.
“We’ve got two days of biogas (methane) sitting under cover in those ponds, so we already have storage and it’s a lot cheaper than batteries,” Tom says.
