Modelling by Crown research institute Scion has provided some insights on how NZ could grow its way to lower carbon emissions using biofuels, which also provides some welcome cropping opportunities for the pastoral sector. Richard Rennie spoke to Scion’s lead researcher for clean technologies Paul Bennett about growing biofuels.
THE prospect of New Zealand growing feedstock crops could bring a double-headed benefit for greenhouse gas reduction.
Not only would it offer a crop alternative over gas-emitting livestock, it would also lower the country’s greenhouse gas emissions from the transport fuel sector.
Scion clean techology lead researcher Paul Bennett said the study aims to generate some robust fact-based debate about the ability to move to large-scale production and use of biofuels in NZ, backed up with robust data to contribute to the country’s aims to reduce its greenhouse gas emissions.
At the heart of the work is the modification Scion researchers made to a computer model developed specifically by the United Kingdom’s Energy Technologies Institute. It models scenarios of what crops and processing facilities could be required to produce varying quantities of a transport fuel sustainably.
“But for NZ considerable time was spent modifying it to reflect the country’s landscape and crop types. It breaks the country broken into 50km by 50km areas.
“It’s a complex model that includes calculations for locating infrastructure to process the crops.”
Researchers covered a arange of fuel substitution from conventional to biofuel from 5% to 50%.
Bennett said the debate about biofuels has progressed in the past decade when food crops like beets and corn were competing for arable land space.
“If you take that growing resistance for using land to grow food for biofuels then you tend to start looking at woody matter for biofuel feedstock, including trees.”
The report set out to be agnostic about crop type and researchers allowed a range of crop types including miscanthus, canola, forestry and forestry waste to be used.
“But as you move to higher biofuel substitution then you have to have a dedicated feed stock source.”
Pine trees are an obvious but not necessarily sole option for bulk fuel source.
The challenge for NZ in using a crop source is timing, with even short rotation forestry needing between seven and 15 years to be mature enough to harvest for fuel.
With the Government pushing for another 50,000ha of trees a year to be planted, starting planning now means those trees would have another use at harvest while sequestrating carbon during their growth phase.
“And biofuels bring emission reductions of over 80% over fossil fuels because taking the lifecycle approach the crop has absorbed carbon.”
But even sourcing 30% of the country’s liquid fuel from home grown plants on non-arable land would slice GHGs by 5m tonnes a year, the equivalent to taking half the country’s car fleet off the road.
Heavy transport, marine and air industries are particularly hard to decarbonise and use two-thirds of NZ’s fuel.
But Bennett sees a good opportunity to progress technology beyond the intermediate bio-sourced fuel known as pyrolysis oil, used for heating in the United States.
“This is where the model results suggests one of our research focuses needs to be from here.”
To put some scale around the plantings required to make a difference, the report estimates a forest of 7000 square kilometres, the size of Taranaki, would sustainably make 2.3 billion litres of liquid fuel a year, more than enough to meet South Island liquid fuel demand.
Bennett believes the mood of the Government and the world has shifted from a decade ago when there was a flurry of work around bio-diesel when the excise tax on it was removed.
“We have some huge tasks ahead to meet our Paris Accord commitments and biofuel has a role to play there.
“We also import about $5 billion a year (2015 figures) in crude oil which is a major demand on our earnings as a country, with exposure to geopolitical shifts.”
At a trade level there is also the spectre of trade partners demanding greater transparency around carbon footprints for products NZ exports thousands of miles from their origin.
“The same applies to the tourism sector. People come here expecting to find a clean, green sustainable country and biofuels will help achieve that.”
He also sees the value hitting closer to home in terms of regional revitalisation.
Areas like Northland, East Cost and the central North Island stand to benefit the most from forest sourced biofuels development, with processing plants usually near to the feedstock crop. They are also the same areas targeted by the Government’s $1 billion regional development scheme.
The biofuels report was backed by some heavy hitters in the fuel and transport industry, including Air New Zealand, Kiwi Rail and Z Energy.
