Characterization and Optimization of Coal-Biomass Blends for Syngas Production as Alternative Transport Fuel Sources for Two-Stroke Internal Combustion Engines in Tricycles-Tuk Tuks in Kenya

Abstract

Conventional fuel sources, such as fossil fuels, have become unafordable for the low end of the economy and thus the need for sustainable alternatives. Gasifcation of coal and biomass is considered as an alternative source for small-sized engines, such as tricycles in Kenya. Mui basin coal is a low-quality coal, available in Kenya, and blending with selected biomass (rice husks, Prosopis julifora, and Hyphaene compressa) presents a new source of alternative transport fuel through cogasifcation and upgrading. Te selected biomass samples were collected, air-dried, and crushed to 60μm and subjected to calorifc determination, proximate, and ultimate analysis. Blending was done at various ratios weight by weight, while thermochemical determinations were conducted using the American Society for Testing and Materials (ASTM). Te fxed carbon content was reported as 29.3±5.51% for Mui basin coal, 21.1±1.55% for rice husk, and 31.0±1.00% for H. compressa. Blending was found to improve the hydrogen:carbon ratio with an averagerate of 0.12 and decreasedthesulphurandnitrogencontent, leadingtolowemissions.Testudyrevealedthat calorifc values of the fuel sources were as follows: Mui basin coal, 20.41±0.15MJ/kg; P. julifora, 18.68±0.17MJ/kg; and H. compressa, 18.69±0.00MJ/kg, while rice husks had 12.95±0.1MJ/kg. Blending was also found to improve calorifc values by average values of 0.4MJ/kg for P. julifora, 1.3MJ/kg for H. compressa, and 2.28MJ/kg for rice husk. Te moisture content was reduced by 1–2% for all fuel sources; ash content was reduced by 33%, while the volatile matter was increased by 11% for P. julifora, 7% for H compressa, and 0.2% for rice husks. Te optimal blend of ratio 1:1 when cogasifed produced syngas, which was upgraded through cleaning and cooling. Te upgraded syngas had a moderate ratio of hydrogen to carbon monoxide with the right modifcation and retroftting; it can be applied in internal combustion engines of tricycles-“tuk tuks.” Te study reveals that the optimal blending ratio of 1:1 for coal:biomass reduces the pollution ash content, increases calorifc values, and enhances syngas fuel properties to moderate ratio.