Biomass sources for a sustainable energy supply in Ghana - A case study for Sunyani

摘要

A stable and affordable energy supply is the indispensable basis for the successful development of countries in West Africa. Ghana currently suffers from an energy crisis. The country is no longer able to meet the rising demand for electricity. At the same time, the energy supply needs to be switched to renewables to protect the climate and increase local added value. Therefore, local biomass utilization is crucial for the future Ghanaian Energy Mix. In this case study for Sunyani, suitable biomass residue sources were identified. The residues are divided into forest biomass, namely logging and sawmill residues from production zones of a forest reserve and residues from Tetrapleura tetraptera and food waste, consisting of residues from Manihot esculenta (cassava), Musa x paradisiaca (plantain) and kitchen waste. Abundance and energetic potentials were calculated and the feedstocks were characterized (elemental analysis, moisture content, ash content, calorific value, ash melt behavior and crude fat content). Sawdust from logging and sawmill residues, remaining from a specific harvested forest area, have an average abundance of 3.18 t/ha and 1.97 t/ha, respectively. This sawdust can be pressed to pellets and converted to 3.4 MWh(el)/ha in a wood gasifier system. The average theoretical biogas yield from food waste and cassava/plantain peel residues is 823 l/kg with an average methane share of 48.6 vol%. A design of an integrated sustainable energy system consisting of a solar thermal dryer, a biogas plant, a wood gasifier and an absorption cooling machine, was proposed for electricity, heat, cold and cooking gas production in Sunyani. The study showed that utilizing biomass in Ghana in a modern and efficient way is applicable to solve energy problems, affect local markets positively and support the implementation of renewable energies in Ghana.