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From a nuisance to a benefit, ‘world’s worst weed’ finds new use as biofuel

Boats afloat in a lake of hyacinth at Kisumu. Image by Richard Portsmouth via Flickr (CC BY-ND-2.0)

Boats afloat in a lake of hyacinth at Kisumu. Image by Richard Portsmouth via Flickr (CC BY-ND-2.0)

  • 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.
  • 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.”

KISUMU, Kenya — First light finds Edikite Ochieng’ Otieno waist-deep in weeds on the banks of Lake Victoria in western Kenya. A nearly unbroken mat of water hyacinth covers the surface of Africa’s largest lake here, blocking fishing communities’ access to the shore.

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.

Edikite Ochieng’ Otieno with water hyacinth near Kisumu, Kenya. Image by Kang-Chun Cheng for Mongabay.

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. In 2016, he and his pupils at Mudhiero Secondary School in Kisumu entered their project into a national competition, the Kenya Science and Engineering Fair (KSEF), which they won.

Several grants and a startup incubator later, Arwa says CIST has come up with the optimal recipe to break the cellulose in a water hyacinth’s stalk down into simple sugar so that it can be fermented.

The great majority of ethanol is produced from sugarcane, mainly in Brazil, and from corn in the United States. This production of what is called “first-generation” ethanol has been criticized for the impacts of large-scale cane and corn cultivation on soil and watersheds, for setting food and fuel production in competition with each other. “Second-generation” ethanol is derived from cellulose biomass, including leaves and stems, allowing the use of a much wider range of feedstock; its proponents say this reduces placing additional strain on limited agricultural land.

Production of ethanol from cellulose rather than a sugar- or starch-based feedstock is more challenging because the cellulose must first be broken down into sugars that can then be fermented and distilled as a fuel. Devising a cocktail of enzymes able to do this to water hyacinth was a challenge, Arwa says.

CIST currently produces up to 600 liters of bioethanol a day from water hyacinth. Image by Kang-Chun Cheng for Mongabay.

CIST currently produces up to 600 liters (nearly 160 gallons) of bioethanol a day, consuming a maximum of 7 metric tons of water hyacinth. Alongside contributing to ridding Lake Victoria of an invasive plant, ethanol responds to Kenya’s need for clean cooking solutions. Eighty percent of Kenyan households cook with charcoal or firewood. Smoke from this causes serious health problems, including lung cancer, bronchitis, and cardiovascular disease.

Awuor Dorothy Otieno grew up with firsthand experience of how these fuel sources disproportionately impact women’s lives. “At times, I was not able to eat the food I had cooked for my family because I felt dizzy and nauseous,” Otieno, who is not related to CIST’s Edikite Ochieng’ Otieno, tells Mongabay.

In 2018, she founded Nyalore Impact Limited, a social enterprise that now distributes around 5,000 liters (1,320 gallons) of ethanol per month across largely rural western Kenya. Until July 1, ethanol’s competitiveness with other fuels in Kenya was hobbled by a 25% tax. Otieno is among the business owners who successfully lobbied the government for the removal of the tax.

However, a number of obstacles are still preventing this cleaner solution from gaining a greater foothold in the market. An ethanol stove costs around 2,000 Kenyan shillings ($18.20), an investment that many households are unable or unwilling to make.

According to the CIST, a liter of bioethanol costs around 100 shillings (90 cents) to produce, while an equivalent amount of charcoal costs 160 shillings ($1.45). But packaging and distribution drive the price of bioethanol up by 50-100%, depending on transportation costs.

“Currently, we transport small quantities [of bioethanol], but we are trying to find an investor to support dispensers in targeted areas,” Otieno says.

The company currently distributes single-use 20-liter (5-gallon) bottles door to door to clusters of clients who have acquired the stove. However, it is looking to set up dispensers — either at local supermarkets or independently — to move greater quantities in one go and reduce the per-liter price of transport.

Customers would then bring their own bottles to be refilled, which Otieno says is also a way to cut down on both packaging costs and on plastic pollution.

Scaling up production will also require guaranteeing a supply of raw materials, even when water hyacinth retreats from the Kenyan shores of Lake Victoria.

Chrispin Kowenje, a chemistry professor at Maseno University in Kisumu, is conducting research in collaboration with CIST to identify alternative feedstocks that would present greater advantages than first-generation raw materials.

“So far, we identified five,” he says.

Among them are cassava and tropical sugar beets, which require only a third of the water needed to grow sugarcane.

Kowenje, who studies water quality and aquatic life in Lake Victoria, says the economic and environmental benefits that come with using this invasive plant make it the number one option.

So far, efforts at eradicating water hyacinth have yielded few results. Kenya’s Ministry of Environment bought a mechanical harvester in 2013 for 81 million shillings (nearly $740,000), thanks to funding from the World Bank. According to local media, however, it has not yet been put to use.

As ethanol production ramps up, the hope is that so will the eradication of water hyacinth from Lake Victoria. “We are turning something that is harmful into something that is beneficial,” Kowenje says.

Banner image: Boats afloat in a lake of hyacinth at Kisumu docks in 2011. Image by Richard Portsmouth via Flickr (CC BY-ND-2.0)

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