Zero-waste advocates say a government-funded report into the merits of biogas lacks balance, is shortsighted, and risks crowding out more effective renewable energy projects.
Last week, a government-backed study found that 4% of the country’s energy-related emissions could be avoided by switching to low-emitting, renewable alternatives.
It said this could be done through anaerobic digestion (AD), whereby organic waste from the kitchens and the farm is broken down into biogas which is then cleaned and upgraded into biomethane.
The gas could be easily transported within the country’s current gas pipeline network.
AD also produced a byproduct, digestate, which is a combination of organic liquids and solids, which the report said could be used as a nutrient-rich fertiliser or a base for bio-products.
However, the Zero Waste Network (ZNW) said major investment would be required for organic waste processing and might lock in current harmful agricultural practices such as the use of nitrogen-rich fertilisers.
"But these practices are degrading our soils, polluting our waterways, contaminating drinking water, and contributing to climate change," Zero Waste Network member Liam Prince said.
He also questioned some of the claims the report made about the "green credentials" of AD and its byproducts, which are said to have circular benefits.
"But the benefits are assessed using fossil fuels, rather than other practices that could potentially provide far greater emissions reductions and environmental benefits."
More of a focus should be placed on both the prevention and reduction food waste in the first place, Mr Prince suggested.
"We want to see organic-based systems that sequester carbon rather than turning it into gas for burning.".
Mr Prince said composting had been shown to be a more effective process for reducing the carbon emissions from organic waste but the report made no substantial comparison with other approaches to curb, divert and process organic waste.
One of Zero Waste Network’s main criticisms of the report was its narrow focus and that it did not consider other options to help decarbonise the energy sector and mitigate food waste.
"I appreciate that the report is focused on biogas in particular but I think that’s really one of our main concerns with this, it’s not looking what are the best solutions for organic waste as a whole.
"It’s just looking at replacing things that are obviously not sustainable, given the climate crisis."
There was a need for a comprehensive look at the best solutions not only for energy use but for how organic waste was used, he said.
Mr Prince said he would like to see the Government put some money into exploring all of the possibilities.
He made the point that AD was not without its benefits and it should be seen as part of New Zealand’s overall strategy to reduce its carbon emissions.
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'm a believer in climate change and more specifically that mankind have contributed to its acceleration by pumping increasingly large amounts of greenhouse gases into the atmosphere since the start of the industrial revolution.
However, I do not accept for one moment the unsubstantiated and fatuous claims of some numpty from the Zero Waste Network (ZWN).
Firstly, there is no explanation of who the ZWN are. They could be just Mr Liam Prince sitting in his mothers basement and sending out made up press releases.
Mr Prince does not tell us his qualifications or the sources of his claims about the impact of the proposed solutions. He just expects us to accept his criticisms and alternatives at face value.
Neither does Mr Prince identify the authors of the Govt funded research agency that has come up with a possible partial solution to reducing the uncontrolled release of greenhouses gases into the atmosphere. Could it be that he simply thinks he should have been funded to do the research and is going through a fit of pique?
Really, this piece of trash posing as news is a waste of energy.