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This study is dedicated to present a reliable numerical methodology using Aspen Plus process simulator capable of performing a sensibility analysis of the downdraft gasification of Portuguese forest residues. Effects of critical parameters, including gasification temperature and steam-to-biomass ratio (SBR) on composition of the produced gas are discussed. The sensibility analysis is conducted using Aspen Plus simulator incorporating Fortran subroutines. The model is validated by experimental data and found to be in good agreement. The results of the sensibility analysis performed using air as gasification agent indicate that higher temperatures are favourable for a produced gas with higher hydrogen content and heating value. The simulation results also demonstrate that the use of steam as gasification agent allows increasing the hydrogen content and heating value of the produced gas in comparison to the use of air as gasifying agent. The knowledge of this data is decisive to the development of projects concerning the use of Portuguese forest residues as energy source.

Cameroon is blessed with a vast potential of renewable energy resources: solar, biomass, hydropower, wind and geothermal energies. These resources are currently poorly valorized. The country depends mainly on hydropower for its electricity supply and traditional biomass for its energy consumption. This dependency on hydropower causes acute power shortage nationwide, especially in remote communities where grid access is limited. Rural electrification is mainly conducted through costly grid extensions, small hydro and diesel plants with enormous health and environmental effects. This study assesses the feasibilities of hybrid renewable power systems for remote applications in Southern Cameroons using the climate data of Wum. HOMER was used to perform the comparative analysis. Nine hybrid systems were considered in this study based on the following components: PV module, wind turbine, micro-hydro turbine, diesel generator, battery, charge controllers, and inverters. Two energy sources and storage battery characterized each system. The PV/diesel/small hydro/battery was found to be the most viable economic system for Southern Cameroons with a 0.443$/kWh energy cost. The optimum system was proven to be very resilient to variations in streamflow, interest rate, fuel price, and PV cost. This outcome was found to be highly relevant to policy makers and investors in Cameroon.