BOVINE POWER PLANTS
Another possible growth area being considered is biogas generation on some of the country’s larger dairy farms. How large a farm needs to be to make this viable is still up for debate. A report by Waste Solutions suggested ruling out any farm with less than 400 head of cattle, which would leave about half the nation’s 11,600 herds as possible candidates.
But other estimates suggest an even larger herd of about 1000 cattle would be needed to produce an economically viable amount of waste, of which there are about 400 possibles around the country. A lot depends on how efficiently the waste might be collected.
Currently it is estimated that dairy farms only collect something like a fifth of it, with the rest being plopped out in the paddocks. But the amount of waste produced by the larger herds is difficult and costly to deal with. This provides another incentive to use a biogas digester, especially if cows are increasingly fed on feed pads or put on wintering pads there could be more waste available but, most importantly, it is put in one place and not spread around the paddocks.
But, for the time being, Federated Farmers Dairy chairperson, Lachlan McKenzie, is sceptical. He has had his own dairy operation assessed and found the amount of electricity he would produce from a biogas system would be only roughly the same as the amount of energy it would take to run it. In the meantime, he says, the bulk of the manure from New Zealand’s dairy farms is recycled anyway, by the cow dropping it out in the pasture to grow more grass. But he remains open to the prospect if the technology can be improved, and feels other farmers would be, too.
“If a farmer can spend a dollar and get a dollar fifty back they are sold,” he said.
The same goes for the rest of us, which is why it’s a great time to take a fresh look at poo.