A rubbish truck that runs on biogas derived from waste caught the eye of the judges at the Energy Efficiency and Conservation Authority Awards this week.
The project - a collaboration between the National Institute of Water and Atmospheric Research (Niwa), Greenlane Biogas, Dieselgas International and Transpacific Industries - was highly commended.
The awards have been held annually since 2010, and 29 finalists were selected from 90 entries. Awards were handed out on Wednesday.
The truck, used 250 days a year by Redvale Landfill, substitutes 12,000 litres of diesel with biogas derived from energy emitted by the rubbish tip, reducing carbon dioxide emissions by 290 tonnes a year.
Gas is extracted while rubbish is added to the fill, and the truck is powered by a mix of diesel and biomethane.
If the project was developed to a commercial level, Redvale Landfill resources could provide enough alternative transport fuel to replace 54 million litres of diesel a year.
Forty per cent of New Zealand's energy use is in transport and most of it is fossil fuels.
Stephan Heubeck, of Niwa, said the idea came out of a biogas conference in 2008. People there asked why, with all the technology available, nothing more was being done to develop biofuels.
At first, the aim was to work with Fonterra and run a truck out of the Tirau dairy factory. A short dairy season put an end to that.
Redvale Landfill was then settled on because it had the key ingredient: a heavy vehicle that always went back to a refuelling station.
Heubeck said the project had shown him the innovation capacity that was available in New Zealand. Dieselgas International, for instance, supplied 40 per cent of Sweden's biogas requirements.
"But no one knows about them. The aim of the project was partly to raise the profile of small, innovative New Zealand companies."
He said the project had been expensive but once it was available at a wider level, the innovation would save a lot of people money.
"If the whole upgrading and compression of gas is done on a commercial basis, biogas can be made available for a third of the cost of diesel at the pump."
There would also be costs associated with vehicle modification, but Heubeck said it was expected that the savings in fuel would pay that back in about a year.
He said there was no reason why every landfill in the country could not supply biogas and provide 5 per cent of the country's road fuel requirements.
All landfills had energy they needed to get rid of. Many converted it to electricity, but Heubeck said converting it to diesel substitute instead would return about six times the amount to the economy. "We're proving it's not only technically viable but economically preferable," he said.
Air New Zealand took the top award. It is avoiding 142,000 tonnes of CO2 emissions each year, and has saved $500 million since 2005 due to a range of fuel efficiencies.