Hemanatha Jayasuriya and Ahmed al Busaidy
The Sultanate of Oman is estimated to produce more or less 400,000 metric tonnes of dates annually and certainly producing a huge amount of date plant residues.
There are other crops that produce plant residues seasonally and in most cases these residues are burnt at farm sites. In addition, there are unwanted weed plants destroyed at farm level either by using chemicals or by other means.
Mesquite weed plant is found to be rapidly spreading in the Sultanate of Oman affecting farmland and other areas such as wadis and canals affecting drainage systems. Mesquite eradication and control is one of the challenges in Oman.
This article highlights the benefits of using weeds and agricultural residues to harness bioenergy that can be used in cooking, barbeque and other heating applications.
Mesquite has several species native to America and later introduced to many other continents such as South America, Africa, Australia, Asia and the Mideast.
Some countries introduced the plant to use as a stock food, shelter, and erosion control considering its fast growing characteristic even under arid conditions. Several negative effects of the Mesquite weed plant has readily recognised as follows:
• The plant has large thorns that can injure animals and humans,
• People have shown allergic behaviour to pollen from the plant,
• The toxic behaviour of its fruit to foraging livestock, causing their teeth to fall off.
• This plant quickly grows and covers large parts of a wadi, and tends to alter wadi flows and thereby have a negative impact on groundwater levels.
It is well-understood fact that the need for eradication of this plant and its’ rapid spread over wadis, arable or abandoned landscapes in Oman.
An SQU funded research project, which is in-progress proposed two methods eradicating the weed plants and using farm residues; developing a bioenergy harnessing method and making charcoal as a soil amendment, hence realising financial benefits while accomplishing the weed eradication and profitable use of farm residues.
Under bioenergy harness system, shredding the dried plant components and making biomass briquette can be done. These briquettes can be used for heating, cooking and barbeque making.
Under the project, bioenergy harness system, biomass briquette making system was developed and the energy potential was evaluated.
The calorific values of the biomass made from different components of the plant were estimated using a bomb calorimeter, and compared with date palm residues as shown in the Table 1.
When compared with the other heating sources (Calorific values of Gasoline, Diesel, Biogas, Wood are 47, 44, 30 and 15 MJ/kg respectively) harnessing this unutilised energy is not a waste.
However, when using the briquettes as bioenergy source for cooking or other purposes, it is important to make sure the properties and components in the gasses emitted are not harmful.
The properties of exhaust gasses evaluation was also a part of the project to make sure there is no beyond-limit toxicity development creating asphyxiation of bystanders or contamination in food. Exhaust gas analyses were done and currently under experimental stage.
Initial tests burning the biomass and briquette samples revealed that existence of H2S, CO, CO2, NO, etc. in the exhaust gas. In applications, arrangements should be made for a complete combustion of the materials to minimise some of the gasses emission.
This bioenergy harness method can be extended to residues created by date palm or any other agricultural crop residues, and as this can be executed with a little investment, would be a good option as a village level cottage industry or Small and Medium Enterprise (SME).
[This research is funded by SQU deanship research project ((RF/AGR/SWAE/21/01)), involved by; Faculty and staff: Hemanatha Jayasuriya (PI), Ahmed al Busaidy (Co-PI), Seif al Adawi.(Co-I), Mohamed al Balushi, Undergraduate students: Noof al Qamshuii, Basma al Kiyumi, Marwan al Majarfi, and Badar al Nasseri]
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