A study uncovers vetiver's potential for biorefining
Vetiver grass is well-suited to the climates of India and Africa. © iStock
Replacing the wheat straw used in biorefining with vetiver could cut greenhouse gas emissions by 180%. What’s more, the grass is easy to grow, is not a food source and can reinforce damaged soil.
Using vetiver as a feedstock in India’s biorefineries could slash the country’s greenhouse gas emissions, according to an EPFL study published in Bioresource Technology.
In the study, carried out by EPFL’s Bioenergy and Energy Planning Research Group, scientists calculated greenhouse gas emissions over the entire life cycle of a biorefinery that processes vetiver, a type of grass found in India, and compared the results with the emissions of a biorefinery that processes wheat straw – a second-generation biofuel which, along with rice straw, corn stalks and bagasse (sugar cane residue), is becoming increasingly widespread.
The scientists found that using vetiver can cut a biorefinery’s CO2 emissions by up to 180%, largely because vetiver’s roots can store much more CO2 underground than wheat straw’s. This could result in biorefinery coproducts that are highly competitive in the market.
Several advantages
Unlike first-generation biofuels such as corn and cane sugar, vetiver does not divert crops away from food production and needs fewer inputs. It can be cultivated on land that is currently lying fallow in arid and semi-arid regions. And because the grass’ roots can stretch up to one meter into the ground, they can help reinforce damaged soil.
Growing vetiver can also be a way to revitalize India’s rural areas, since the crops don’t require much work and can withstand severe weather conditions. The EPFL scientists believe vetiver could be cultivated in Africa as well for biorefineries there. Despite this rosy outlook, the scientists are careful to point out that technical and economic feasibility studies still need to be done to evaluate the cost of large-scale vetiver farming in India’s drier regions.
A sophisticated computer model
Edgard Gnansounou, an EPFL professor and head of the Bioenergy and Energy Planning Research Group, recently developed a computer model to calculate the breakdown of greenhouse gas emissions among a biorefinery’s various coproducts. That lets engineers compare those emissions with their fossil-fuel equivalents and eventually make coproducts that are more cost-competitive (see the EPFL article dated 29 January 2018).
In this new study, Gnansounou – along with co-author and post-doc Jegannathan Kenthorai Raman – went even further and applied the model specifically to India. The goal was to provide the Indian government with reliable figures for setting sustainable development goals.
Reachable targets
As a signatory of the Paris Climate Agreement, India has committed to cutting its greenhouse gas emissions by 30–50% from 2005 levels by 2030. It also seeks to increase its production of non-fossil-fuel energy by 40% and creating large carbon sinks in the same timeframe.
But achieving those targets will be a challenge. In 2003, the country set a goal of 20% blending of biofuel and biodiesel in traditional fuels by 2017, but came up short. The EPFL scientists hope their research on biorefineries’ carbon footprints will help the country reach its targets this time around.
Seeking a low-oil species
Gnansounou’s research group has already spent several years studying the beneficial properties of vetiver leaves and roots. For instance, they looked at potential applications in Haiti. For now vetiver leaves aren’t used much in industry, but the oil in the grass’ roots is a popular ingredient in cosmetics. The scientists are now looking for a vetiver species whose roots don’t contain much oil so that the plant can be cultivated on a large scale without the risk of it being pulled out of the ground.