Abstract
Emissions of greenhouse gases mostly from fossil fuels are responsible for global warming
and climatic changes. This has led to research in bioenergy to reduce greenhouse emissions
because bioenergy is part of the carbon cycle, and can only emit greenhouse gases that are
part of the carbon cycle. The drawback is its low calorific value when it is in its raw form.
Torrefaction improves its energy content to values that are comparable to coal.
In this study, marula seeds and blue gum wood, two of South Africa most abundant biomass,
were blended with coal both raw and torrefied to see the impact of the torrefaction process on
energy density. Blending was done at different ratios to see the optimum results. Results
showed that highest calorific value was obtained at 100% marula seeds and 0 % coal, and it
was recommended for further studies. Blue gum wood due to its high moisture had slightly
higher heating value than the reference coal but from an economical point of view it was not
attractive for further studies. This showed the significance of the torrefaction process in
increasing heating value of selected biomass in the hope of reducing effects of greenhouse
gas emissions.