Cellulosic biofuels more productive, says study

27 February 2018

27 Feb 2018

Using an ecomodelling system, researchers from Colorado State University have found that biofuels made from switchgrass, a non-edible grass that is durable in many weather conditions, may be more productive than those that are crop-based.

An aerial image of the research study area in southwestern Kansas. Image: Colorado State University

The modelling system used – developed at Colorado State in the 1990s – is able to track the carbon cycle, plant growth, and a plants response to varying weather and climate conditions, amongst other factors at a local scale.

It is also able to predict how likely the production of a certain crop is to increase or reduce climate change by modelling different growing scenarios. With this, the group were able to determine that the climate footprint for switchgrass in the production of biofuel was significantly reduced.

Its footprint ranged from -11 to 10g of CO2 per MJ – the standard measurement of carbon emissions – compared with 94g of CO2 per MJ for gasoline.

John Field, research scientist at Colorado State’s Natural Resource Ecology Lab, said: ‘What we saw with switchgrass is that you’re actually storing carbon in the soil. You’re building up organic matter and sequestering carbon.’

Non-edible grasses, such as switchgrass, tend to have high concentrations of cellulose, a structural component in the cell walls of plants, which can be converted into cellulosic ethanol – then biofuel – at high-yields.

The team was based in Kansas for the research, where one of only three US cellulosic biofuel production plants is located.

There are many benefits to using switchgrass – a plant native to North America that contribute to its reduced climate footprint – said Field. ‘They don’t require a lot of fertiliser or irrigation [and] farmers don’t have to plough up the field every year to plant new crops, and they’re good for a decade or longer.’

Traditionally, biofuel research has been centred around corn as a source of energy due to the ease in which it can be converted to ethanol – the replacement for gasoline in biofuel.

However, corn is resource-intensive to grow with high costs and inputs associated with the high yield required, and the food industry also relies heavily on its production, particularly in developing nations.

‘Biofuels have some capabilities that other renewable energy sources like wind and solar power just don’t have,’ said Field. ‘If and when the price of oil gets higher, we’ll see continued interest and research in biofuels, including the construction of new facilities.’

DOI: 10.1038/s41560-018-0088-1

By Georgina Hines

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