Sustainable biofuels for electricity generation in Sudan

Abstract

Sudan was separated into two countries in July 2011. Before this Sudan was the most significant country in Africa with a total area of around one million square miles. Due to the separation, Sudan lost about 75% of the fossil fuels resources and currently facing a very severe economic crisis. As a result of this, the government had to abolish the fossil fuels subsidies which used to cost about 15% of the total expenditure of the country. Only about 30% peoples connected to grid electricity. Sourcing fossil fuels alternatives are crucial to meet the growing energy demand, political stability, and growth of the country. This study aims to investigate the feasibility of using locally available renewable biofuels for small-scale electricity generation and implementation in Sudan. A combined qualitative and quantitative methodological approach was used to study the potential of seed based small or community-scale energy production in Sudan to resolve the severe fuel shortage after secession. Estimation of various types of available biofuels was carried out. There is around two million ton of Jatropha biofuel that will be available in 2019; around four thousands ton of cottonseed biofuel and two thousands ton of castor biofuels available annually. In this investigation, 23 types of neat biofuels and blends were prepared using ethanol, butanol, and fossil diesel. Physicochemical properties of all neat biofuels and blends were measured and compared with standard fossil diesel. Heating values of Jatropha, Cottonseed, and Castor biofuels were 39.18, 39.74 and 37.71 MJ/Kg respectively. Neat biofuels and blends were tested in an unmodified 2-cylinder diesel engine. Engine performance and emission characteristics were conducted and compared with standard fossil diesel results. Jatropha, Cottonseed, Castor biofuels were blended separately with 20% butanol and 20% fossil diesel. The neat biofuels and blends were tested successfully in a 7.4 kW indirect injection two-cylinder engine. Jatropha biofuel and its blends showed 7% higher brake thermal efficiency than fossil diesel at maximum load. For Cottonseed biofuel and its blends, Castor biofuel and its blends were 6.7%, 8% higher, respectively. Jatropha biofuel blends with 20% fossil diesel and neat Jatropha oil showed 53%, and 18% high CO and CO2, respectively; while both samples showed a smoke reduction of 96%. NOX emission for neat Jatropha and its blends showed a decrease in the range 5 – 13%. Cottonseed oil and its blends showed NOX emission decrease in the range 5 – 7%. Castor oil blends have demonstrated the highest NOX emission reduction among all tested samples with 24%. Smoke production reduction of Cottonseed oil and its blends were in the range 62 – 91%. Castor oil blends with 20% butanol showed 24% NOX emission reduction, while its blends with 20% fossil diesel showed 10% reduction. Both samples of Castor oil blends showed smoke production cuts; blends with 20% butanol showed a decrease in the range 59 – 62%, while blends with 20% fossil diesel showed 61% reduction. The study concludes by this short-term engine testing that this Compression Ignition engine type can be efficiently operated with 20% butanol blend with any of the three non-edible biofuels, Jatropha, Cottonseed and Castor, without any modification. Sudan has the potential of increasing the production of biofuels from these three plant and butanol can be produced locally to minimise the cost of fossil diesel import. The reduction of NOX emission and smoke production could help Sudan reach its Green House Gas reduction target.