TITLE:
Biogas Production Using Water Hyacinth (Eicchornia crassipes) for Electricity Generation in Kenya
AUTHORS:
Paul Njogu, Robert Kinyua, Purity Muthoni, Yusuyuki Nemoto
KEYWORDS:
Renewable Energy, Biogas, Water Hyacinth, E. crassipes, Pollution
JOURNAL NAME:
Energy and Power Engineering,
Vol.7 No.5,
May
18,
2015
ABSTRACT: Water hyacinth, E. crassipes, an invasive water weed thrives in fresh water bodies causing serious
environmental problems. In Kenya the weed has invaded Lake Victoria and poses great socioeconomic
and environmental challenges. Currently the weed is harvested from the Lake and left in
the open to rot and decay leading to loss of aesthetics, land and air pollution. There is therefore
need for development of value addition and economic exploitation strategies. The aim of the study
is to assess the potential for utilization of the weed as a renewable energy resource for biogas production.
Samples were collected from Lake Victoria, pulped and blend with cow dung at a ratio of
3:1 as inoculum. The resultant mixture was mixed with water at a ratio of 1:1 and fed into a 6 m3
tubular digester. The digester was recharged with 20 kg after every three days. The temperature,
pH variations, gas compositions, upgrading and gas yields were studied. The temperature ranged
between 22.8°C - 36.6°C and pH 7.4 - 8.5. Biogas was found to contain 49% - 53% methane (CH4 ),
30% - 33% carbon dioxide (CO2 ), 5% - 6% nitrogen (N2 ) and traces of hydrogen sulphide (H2S).
The biogas was upgraded using solid adsorbents and wet scrubbers increasing the methane content
by up to 70% - 76%. The upgraded gas was used to power internal combustion engines coupled
with an electricity generator and direct heat applications. The study concludes that E. crassipes
is a potential feedstock for biogas production especially in areas where it is abundant.