Environmental legislation and interest in using newly utilized renewable biomass energy sources in a medium-scale, intensified fixed-bed gasifier has stimulated this research work. Biomass waste gasification for the production of green energy in the form of electricity and/or heat is a viable alternative to fossil fuels and a clean technology, which can reduce greenhouse gas emissions and facilitate closure of the carbon cycle. In this research work, mixed biomass and waste including but not limited to refuse derived fuel (rdf) as feedstock was considered for clean synthesis gas production using an intensified updraft fixed-bed gasifier. The study showed rdf mixed with biomass is a suitable fuel for gasification in an updraft gasifier producing an average of 2.25 Nm3 of product syngas per kilogram of biomass waste with a calorific value ranging from 5.50-6.50 MJ/Nm3. More than 80% conversion of biomass waste to product syngas was achieved using the gasification process developed at the pilot scale retrofitted with a 2MWh power generation capacity of ORC Turbine Generator. Fuel to Power ratio was successfully observed between 1.0 to 1.1. However, it was necessary to use intensive gas clean up system including water scrubber and wet electrostatic precipitator (wesp) to mitigate against any potential adverse impacts on the environment.