Researchers at the University of Queensland have discovered that two invasive weed species—Brazilian nightshade and climbing asparagus—can be converted into biomass pellets for use as a renewable fuel. The study, published in June and highlighted this week by the Queensland Alliance for Agriculture and Food Innovation, assessed more than 20 weed species for their potential as biofuel.
The process involves compressing plant material into small pellets that can be burned in residential or industrial heating systems or used for electricity generation. Lead researcher Dr Bruno Rafael de Almeida Moreira explained that different plant materials must be mixed carefully to ensure the pellets burn well and safely, avoiding issues such as excess moisture or ash-producing minerals that can damage equipment or release toxic emissions.
Pelletising also reduces production costs and emissions, as pellets are easier to transport and store more energy per volume than raw material. The global solid biofuels market is growing rapidly, particularly in Canada, the US and Europe, where wood from forests is traditionally used. In Australia, however, wood pellets from native forests are not classified as renewable, prompting a search for alternative sources.
Study co-author Associate Professor Sudhir Yadav said the research could help reduce agriculture's carbon footprint while boosting the bioenergy sector. The Australian Renewable Energy Agency has predicted that bioenergy could supply 20% of national energy demand by 2050, up from just 0.3% currently. Dr Moreira described this target as ambitious but achievable with sustained research and innovation.
However, challenges remain. Supply of invasive weeds is limited, and harvesting them without damaging ecosystems is logistically difficult. Dr Ian Paulsen, a microbiologist at Macquarie University not involved in the study, noted that large-scale biofuel production is not economically viable without significant government subsidies or a sharp rise in petrochemical prices. Despite these hurdles, the researchers are continuing to test more weed species and explore other biomass sources such as green waste and crops like sorghum.
