Kenyan scientists laud plan to harness hyacinth weed

A woman cleans basins in the hyacinth-choked waters of Lake Victoria in Homa Bay County. PHOTO | TONNY OMONDI | NMG
A woman cleans basins in the hyacinth-choked waters of Lake Victoria in Homa Bay County. PHOTO | TONNY OMONDI | NMG  

Scientists have welcomed the use of water hyacinth to generate energy amid the near financial closure of a $250 million (around Sh26 billion) biogas plant in Homa Bay County that will make use of the problematic weed.

Researchers from the Kenya Marine and Fisheries Research Institute (Kemfri) say the idea is a useful way to tackle the plant whose eradication from the shores of Lake Victoria is still a mirage.

Kemfri assistant director for freshwater systems research, Dr Christopher Aura, said researchers predict that the weed could return to Kisumu in the next four to five months, hence the need to find useful ways of dealing with it.

“The idea by the government to use of hyacinth as a resource is a blue economy idea. Instead of complaining of hyacinth as a menace, we can set up a biogas plant. We can get gas for cooking, electricity and bio-fertiliser out of that single project,” said Dr Aura.

Water hyacinth has impressive survival mechanisms, including quick multiplication and production of thousands of seeds that can lie dormant in the river bed for 20 years, the scientists say.

“Assuming the entire 60,000 hectares of Winum Gulf is covered by hyacinth, and from research, one hectare of hyacinth weighs about 448 tonnes. If you multiply, you realise the standing crop biomass of the Gulf can weigh 27 million tonnes available for the blue economy and the biogas plant,” added Dr Aura.

Generate energy

A UK-based company, Equinox Energy Capital, has partnered with the government to set up the 35-megawatt hyacinth-to-energy plant in Homa Bay County.

Lord Barker, a representative of the firm, earlier this month said the plant is making progress and is nearing launch.

The move follows constant re-emergence of the weed on east Africa's largest freshwater lake, wreaking havoc on water transport, fishing and tourism businesses in Kisumu, Homa Bay, Siaya, Migori and Busia counties, which share the waters.

The latest cover, which took a record six months on the waters, was deemed the largest - covering over 60,000 hectares of the Winum Gulf as well as other bays.

It disappeared two weeks ago, but Dr Aura said locals should not celebrate yet as their mapping shows that it will soon return.

“We do the prediction using a scientific software called Geographical Information Systems, which can tell the occurrence of microphytes in lake ecosystems. They are processed on a computer and after monitoring for a period of more than five years, it will tell which months these plants occurring mostly in particular bays,” said the researcher.

Stubborn spread

The scientists have printed charts that show the quarterly distribution of the weed's re-occurrence along the lake's shore, which they have shared with fishermen and other stakeholders to guide them on when and how to access the resource.

Hyacinth hotspots in the first quarter (January to March) are in Homa Bay, Nyakach, and Kindu Bay.

Between April and June, it normally covers Homa Bay, Nyakach and traces parts of Osoto Bay.

Through June and September, the menace occurs in Homa Bay, Osoto Bay and traces in Asembo Bay, while in the last quarter of the year, hotspots are Kisumu, Asembo, Nyakach and Kindu Bay.

“With increased nutrient loading which comes from fertile agricultural soil, industrial and sewer waste and additionally the decomposing water hyacinth, there will be increased nutrient loading which speeds the germination of hyacinth plants,” said Dr Aura.