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The country’s biggest gas distributor has announced plans to help transform kerbside waste into energy for homes and businesses.
First Gas Group have teamed up with Ecogas to develop the country’s first large-scale biogas project, which will take organic waste, such as food scraps, to produce biomethane through a process called anaerobic digestion.
The plant is expected to be completed by the middle of next year and First Gas said it would be able to supply the equivalent of 9000 homes and businesses.
“It is expected to eliminate more than 11,000 tonnes of carbon dioxide per year; action that helps move New Zealand towards its target of net zero carbon emissions by 2050,” it said.
First gas chief executive Paul Goodeve said biomethane is chemically identical to natural gas, so there is no need to modify the country’s existing gas pipeline or gas appliances.
“It has the potential to replace all of new Zealand’s residential and three quarters of commercial gas use, which is equivalent to taking 415,000 cars of our roads.”
This figure based on the findings for a part-government funded report into the potential of biogas in New Zealand.
Goodeve said Ecogas would spend about $30 million on building the first stage of its digestor facility at its Reporoa site in the central North Island.
How the biogas process works.
It would be able to take 75,000 tonnes of organic waste from both businesses and kerbside food scrap collections and put it through an anaerobic digester to produce biogas.
First Gas would spend about $6m on the infrastructure needed to clean and upgrade the biogas, turning it into biomethane, which is then injected into the pipeline, Goodeve said.
Anaerobic digestion also produces a by-product, digestate, which is a combination of organic liquids and solids that can be used as a nutrient rich fertiliser or a base for bio-plastics.
Goodeve said that the biomethane would be more expensive than natural gas, but he expected the price point would come down over time.
Ecogas general manager Alzbeta Bouskova said the project was an great example of a low carbon circular economy in action.
“Anaerobic digestion is the most environmentally responsible way to recycle organic waste and works in tandem with cities facing waste challenges and companies trying to reduce their emissions,” he said.
However, zero waste advocates have been critical of the merits of biogas.
The Zero Waste Network had said in the past that organic waste processing might lock in current harmful agricultural practices, such as the use of nitrogen-rich fertilisers on farms.
The organisation also challenged the green credentials of anaerobic digestion because its benefits were often assessed against fossil fuels, rather than other practices that could potentially provide far greater emission reductions and environmental benefits, such as composting.
It had said more focus should be placed on both preventing and reducing food waste in the first place.