The fuel that keeps on growing and growing
Researchers at Lincoln University trying to boost the biofuel industry have found ways to lift yields of crops that can be turned into fuels, while reducing inputs.
Their work has focused mostly on canola, which is turned into biodiesel, but the researchers are also looking to do work on a type of giant grass that can be turned into a product called renewable diesel.
During a six-year project, with funding from the Government and Chevron, the research team evaluated 15 different plant types, before concentrating largely on canola. Following on from that project it is also looking at a giant grass called miscanthus.
Professor of ecology Steve Wratten said canola was already a biofuel crop in many parts of the world, particularly Europe. The oil was squeezed from canola seeds under pressure and then processed to produce biodiesel, and "any diesel engine can then burn it".
Part of the research involved mixing the fungus trichoderma with canola seeds. The fungus reduced the amount of fertiliser needed and helped produce a higher yield.
"It protects them from fungal diseases in the soil and makes the plants healthier in some ways," he said. Though trichoderma was already mixed with some other crops, he thought it was the first time it had been tried with canola.
Results in laboratory, greenhouse and small-field plot trials had been "quite dramatic", Wratten said. Through mixing in the fungus and using such things as dried waste from sewage, a 30 per cent increase in yield was achievable in field trials.
Trials had also been carried out in a large field and the results from that were expected this year, the final year of the project, he said. The research had also aimed to improve pollination and the biological control of pests. Flowering plants such as buckwheat had been grown around the canola to reduce the high exposure to aphids, which were a common canola pest.
"[Canola] is softer on the environment than you would imagine, and it needs fewer inputs," Wratten said. Strengthening the case for canola over other plants, the crushed seed material made a high-value cake for animal feed.
Canola also provided a useful crop rotation option, with cereals performing well after it had been grown.
The Lincoln researchers were now looking to work with two US companies on producing renewable diesel from the giant grass miscanthus.
While some chemistry still had to be done to the oil from canola seeds before it became biodiesel, under the system being considered for making renewable diesel, feedstock could go in the front of the machine and the liquid that came out the other could go straight into a vehicle fuel tank.
Miscanthus New Zealand managing director Peter Brown said miscanthus had been grown in this country for about seven years, and maybe up to 50 hectares was growing now. He expected that amount to double in the next growing season, and then to keep increasing after that. An advantage of miscanthus as a biofuel feedstock was that it was largely dried out by the time it was ready to be harvested in the winter, so its moisture content was considerably lower than most alternatives.
The giant grass also produced more biomass than probably any other plant grown in temperate climates and it was a perennial so did not have to keep being replanted. It also had a range of uses.
Research was already under way into using miscanthus to provide shelter from northwesterly winds on Canterbury dairy farms. Because miscanthus was a grass rather than a tree, irrigators could operate through it successfully.
Brown said he had been approached by people from the US who had access to technology for making renewable diesel from organic matter. The technology had been around for maybe 25 years, but only in the past four or five years had a few kinks been ironed out to enable it to work commercially.
The technology's main attraction was that, unlike other processes for making biofuels, it did not need enormous industrial plants and huge quantities of feedstocks. A processing plant could need just 12 tonnes of dry matter a day, producing 150 litres an hour of renewable diesel.
Charging $1.10 a litre for the renewable diesel would cover all costs and allow for a return on investment, Brown said. "The real attractive thing is the smaller scale, so it could be affordable for a small group of farmers."
Despite his enthusiasm for miscanthus, he expected any plant set up to make renewable diesel in this country would start using sawdust as the feedstock. Brown said he would be surprised if a couple of plants were not operating in this country within a year.
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