As the biofuel industry matures, there is a greater exploration of potential methods to make it more sustainable, less carbon-intensive and have less of an impact on existing agriculture.
These advances affect every aspect of the manufacturing process, from harvesting biomass to production, refinement and storage in pressurised tanks with safety relief valves.
As there is a concerted effort to move away from fossil fuels and toward renewable alternatives, there will be a need for biofuels and biomass to meet the shortfalls that could potentially come from low wind or solar yields.
However, rather than using potentially viable crops and agricultural land for this purpose, one study claims that invasive species of weeds could be better for the environment.
What Is Wrong With Current Biofuels?
The vast majority of commercially sold biofuels come from food crops such as sugarcane and corn, which have long been used as biocrops to produce ethanol to power cars.
The problem with using food crops is twofold; potential sources of food are harvested to produce fuel instead, and the use of fertile land at the aggressive rates at which biocrops need to be grown for viability has led to concerns regarding the long-term health of the soil and the vast amounts of water required.
A potential solution to this is to use sources of biomass that can grow in otherwise unviable land using water that cannot otherwise be used for food production.
This includes algae, fungi and weeds, all of which are usually considered to be undesirable in agriculture but could prove vital for the sustainable future of the biofuel sector.
Why Weeds Specifically?
The specific study into the viability of invasive weeds as biomass is based on a change in policy in Australia governing the use of renewable fuels.
Historically, all biomass has been considered to be renewable, which has led to the resurgence of wood pellets as a source of fuel for biomass heaters, reviving a source of fuel that had been used since humanity discovered fire until the widespread adoption of fossil fuels.
It also revived a long-running debate about whether wood biomass is truly renewable or is taking advantage of a technicality, whilst reckless deforestation, energy-intensive processing and transportation are offsetting any potential reduction in greenhouse gases.
Following a decision by the Australian government that ruled that wood pellets were no longer considered to be a renewable biofuel, the University of Queensland engaged in a study to see if alternative plants and byproducts of agricultural processes could be used instead to produce wood pellets.
By definition, weeds are plants growing in undesirable locations and when they are cut down or pulled up, they are typically either composted or thrown away.
What Were The Findings?
The study was somewhat preliminary, exploring the potential viability of converting 15 invasive species commonly found close to the Queensland capital of Brisbane into pellets, and which processes can efficiently produce market-grade biofuels.
The results were somewhat mixed but did show some early potential in Climbing Asparagus (an invasive species in Australia but not in the UK) and Brazilian Nightshade, part of the deadly nightshade family that produces poisonous berries.
Interestingly, given that the weeds would be intended to replace wood pellets, the most promising of the 15 species were non-woody species, as they produced relatively little polluting ash, pellets durable enough to be sellable, had a high amount of the binding compound lignin and a remarkable energy density.
Not every species was the same, but it did show some promise in the potential of using weeds for biomass, at least on a small scale.
One issue with using weeds compared to biomass crops is that whilst they are relatively abundant, the volume of weeds is relatively inconsistent, and that could lead to potential supply issues if weeds are used at scale to produce biomass.
However, it also only serves as a starting point; there are countless species that are considered to be weeds that can still be explored, but the process can be expanded to take advantage of agricultural residue and otherwise low-value biomass to produce competitive products.
Straw, wood chips, manure, the stems and stalks of agricultural crops and anything else that would typically be considered to be garden or agricultural waste could potentially be harvested and converted into pellets.
If there is an efficient, low-cost process to execute this at scale, there is a lot of potential to significantly lower the carbon footprint and sustainability of biofuels, although it remains to be seen when these benefits will be realised.
