Researchers discover use of ‘world’s worst weed’ for biofuel production

By Nneka Nwogwugwu

A startup in western Kenya has developed a process of making bioethanol from water hyacinths, addressing both the need for a clean fuel alternative to charcoal and fuelwood, and the spread of the invasive hyacinths, Mongabay reports.

Proponents say a key advantage of this “second-generation” bioethanol over traditional feedstocks such as sugarcane and corn is that it avoids competition for limited agricultural land.

But although this new bioethanol relies on a plentiful feedstock and is cheaper to produce than charcoal, it’s still more expensive for end users because of limited distribution and the need to buy a compatible stove.
Proponents say they’re determined to scale up production and distribution, pointing out that they’re “turning something harmful into something beneficial.”
Water hyacinth (Eichhornia crassipes) is native to South America and arrived in Lake Victoria in the 1980s.

While there is no conclusive research on its spread, it was likely introduced as an ornament for garden ponds by Belgian colonists in Rwanda and Burundi.

Last year, this fast-reproducing invasive plant, dubbed the “world’s worst aquatic weed,” covered 1,703.7 hectares (4,210 acres) of the lake, causing hydroelectric generation outages and severely disrupting fishing and navigation on the lake.

Over the past century, it has spread to more than 80 countries, thanks to its ability to double its mass in just a week or two. While harder to process, the prolific nature — and nuisance value — of water hyacinth makes it an ideal raw material.

Otieno is part of a team pioneering a new solution to turn this plague into a boon. As the operations manager at the Centre for Innovations for Sustainable Technologies (CIST), he works to turn water hyacinth into bioethanol.

Lifting the interconnected shoots above water, Otieno tears away the glossy, ovate leaves, and cracks the swollen stem open. “This is the part we are interested in,” he says, holding out the gutted, bulbous stalk.

CIST pays local workers to harvest the water hyacinth with a panga, a type of machete, and transport it to CIST’s processing facility some 15 kilometers (9 miles) away in Kisumu, the principal city in western Kenya.

There, the stems are ground into pieces and placed in a pretreatment tank along with a secret blend of enzymes for 24 hours. The mixture is then transferred through three fermentation tanks, spending eight hours in each one, before being condensed and distilled to produce a liquid cooking fuel.

The project is the brainchild of high-school chemistry teacher Richard Arwa, founder of CIST, and a group of his students.

“We started this project as part of an annual activity where students come up with various ideas,” Arwa tells Mongabay.