Dr Jan Wright warns the lignite-fed synthetic fuel plant Solid Energy is considering for Mataura, and whatever plant used the lignite L and M Energy had identified at Hawkdun, near St Bathans, would increase greenhouse gases.
In her report on the state of New Zealand's biofuel industry, she urges the Government not to support large-scale synthetic fuel production facilities without first considering whether they could run on wood.
She suggests the Government could use its influence on state-owned Solid Energy to ensure lignite was not the only resource ripe for conversion to diesel.
"Solid Energy is a state-owned enterprise and when it invests in infrastructure it pays a lower dividend, thus reducing Government revenue," Dr Wright says in "Some Biofuels Are Better Than Others: Thinking Strategically About Biofuels".
"The responsible ministers should take a strong interest in any major long-term investment by Solid Energy, especially one with the potential to increase national greenhouse gas emissions."Solid Energy has 1.5 billion tonnes of lignite reserves in Southland.
Plans to convert some of it in a liquid-fuel plant near Mataura are at the pre-feasibility investigation stage.
Solid Energy chief executive Don Elder said the state-owned miner was committed to addressing the plant's environmental effects.
It would have full carbon compliance, and the company was investigating carbon capture and storage, and bio-sequestration.
The real question was "how do we provide New Zealanders with transport fuel security and affordability while addressing environmental sustainability", Mr Elder said.
In her report, Dr Wright says there was no doubt the plants would increase domestic fuel production, but that they would also increase greenhouse gases unless many trees were planted nearby or underground carbon storage became feasible.
Dr Wright acknowledges there is not enough wood near Mataura to feed a conversion plant, and that it would be difficult for such plants to be economic using wood.
However, that may change.
She also says even commercial-scale production of the likes of whey ethanol, tallow, and canola biodiesels would provide only a fraction of the more than eight billion litres of fuel used in New Zealand each year.
Only New Zealand's plantation forests are big enough to produce biomass on the scale needed.
Growing hardy grasses would take up cropland and have adverse effects on food production, and canola and maize would stretch water resources.
