Evaluation of bio-gas potential from water hyacinth
Abstract
Lake Victoria is the second largest fresh water lake in the world making it the source of the River Nile which plays host to many dams. Since it has fresh water, it is vested with lots of water hyacinth (Eichhornia crassipes). Its rapid proliferation on Lake Victoria has been as a result of space, fresh water nutrients, and solar energy. Tons of Water hyacinth are harvested regularly from the Nalubaale dam to prevent it from clogging the water intakes to the turbines. This harvested weed is dumped at a waste site in Buyikwe district. It is costly to transport the harvested waste hyacinth and maintain the waste site where it is dumped. The dumped water hyacinth also pollutes the environment with a foul smell. This project aims at finding an alternative use for the water hyacinth instead of dumping it. This is through using the water hyacinth as biomass for biogas generation and exploring its potential to generate electricity.
The research is to be carried out first by studying water hyacinth characteristics as a suitable waste or feedstock for biogas generation. This involves determining the total solids, volatile solids and PH of water hyacinth. There after biogas generation is carried out on a lab scale under different generation conditions in order to ascertain the most suitable digestion conditions which yield the most gas volume and best gas quality. Gas analysis is then carried out to determine the gas quality. This involves finding out the biogas composition. The research also involves calculating the amount of electricity which can be generated from the gas and also selecting the most suitable energy conversion system. Finally, the research involves designing of a large-scale production unit and carrying out a cost benefit analysis to ascertain the economic acceptability of the project.
The research carried out highlights the positive results of water hyacinth as a useful weed or waste that can be used for biogas generation to produce electricity of 63.3MWh which can service about 810 households with and average energy consumption of 78.1kWh monthly bringing in a revenue of about Shs40m monthly. This value exceeds the Shs15m cost incurred by ESKOM Uganda Limited on water hyacinth management monthly.