New Kiwi technology cuts farmers' pond methane emissions almost completely

Kiwi scientists say they've come up with a way to reduce ammonia emissions, odour, nasty bugs and phosphate leaching from farmers' effluent ponds - as well as reduce methane emissions almost entirely.

Methane is a more powerful greenhouse gas than carbon dioxide, and thanks to our large agricultural industry, New Zealand is one of the biggest emitters in the world - most sources ranking us in the top 10 per capita. It accounts for more than 40 percent of our total greenhouse gas emissions, almost all of that via agriculture. 

While the Zero Carbon Act requires the country to reduce net carbon emissions to zero by 2050, methane only has to be cut by at least 24 percent - giving farmers more time to adjust than climate scientists say we really have to avoid catastrophic climate change.

But new technology developed by experts at Lincoln University and farming company Ravensdown and launched onto the market this week will help. 

EcoPond, as they've dubbed it, adds treatment agent iron sulphate to effluent ponds, which "is enormously effective at neutralising the methane-producing process", according to Keith Cameron, emeritus professor at Lincoln's Department of Soil and Physical Sciences. 

"Nearly all dairy farms use effluent ponds, which are the second-largest source of on-farm methane emissions, after cow belching," he said. 

EcoPond cuts methane emissions by 99 percent, and can be retrofitted to existing effluent systems - once it's installed computers control the amounts of iron sulphate added, while the farmer goes about their usual business. 

It came about purely by accident while Prof Cameron and colleague Hong Di were developing a system for recycling water.

"In testing the ClearTech system for unintended consequences we found that the gases we collected off the effluent in experimental set-ups indicated a reduction in methane emissions of greater than 90 percent," said Prof Di.

"This was a stunning result. In science, it’s rare to achieve such a large influence on an experiment."

After trying it on "farm-sized effluent storage tanks", they were shocked to discover it worked even better - 99.9 percent in their tests.

"We’re still working on that last 0.1 percent," said Prof Di. "We’ll get there." 

With the first of the Zero Carbon Act's methane targets looming - a 10 percent reduction below 2017 levels by 2030 - Ravensdown says farmers can do about half their share by installing EcoPond. 

"This new tool in the farmer’s toolbox has the benefit of robust science behind it and will assist farmers who want to start tracking towards that target now," said general manager of innovation and strategy Mike Manning.

Climate Change Minister James Shaw is currently in Scotland at COP26, trying to convince other big emitters to do their bit to reduce emissions - while progress is being made, he told The AM Show on Thursday that so far, it's not enough