Prospects of distributed electricity generation and services based on small scale biomass systems in ghana
- Autores: Pol Arranz i Piera
- Directores de la Tesis: Enrique Velo García (dir. tes.)
- Lectura: En la Universitat Politècnica de Catalunya (UPC) ( España ) en 2018
- Idioma: español
- Tribunal Calificador de la Tesis: Emmanuel A Essah (presid.), José María Gil Roig (secret.), Magda Moner Gerona (voc.)
- Programa de doctorado: Programa de Doctorado en Sostenibilidad por la Universidad Politécnica de Catalunya
- Materias:
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- Resumen
Access to energy is crucial to human welfare; no residential, commercial or industrial activity can be conceived without energy supply. At the same time, current dependence on fossil fuels and their negative effects on global climate claim for urgent alternatives. The situation in Sub-Saharan Africa is poignant: over half of the population, mainly in rural areas, live without access to electricity services. Crop residues from farming communities in those areas are unused; while technology for electricity production from agricultural biomass is progressing, managing decentralised rural electricity projects is still a challenge, especially in developing countries like Ghana, given the variety and complexity of the factors conditioning biomass to energy supply chains. Such complexity has been previously formulated in academic exercises, but with limited practical applicability for energy planners, practitioners and investors.
This research has deployed a holistic approach to biomass-to-energy planning, yet flexible to adapt to different regulatory scenarios and energy supply configurations. A qualitative framework has been developed, taking into consideration four critical components: social development, organisational/institutional, technical, and financial, with their respective metrics. Then, the framework has been applied to three real case study configurations in Ghana, involving primary data collection, sustainability modelling and discussion of the techno-economic feasibility results with policy makers and practitioners.
The first configuration consists in decentralised power generation using crop residues from clustered smallholder farms in 14 districts in Ghana; the number of clustered farms, reference residue yields, and residue densities are determined to assess the distances within which it would be feasible to supply feedstock to biomass power plants. The findings show that a minimum of 22 to 54 larger (10 ha) farms would need to be clustered to enable an economically viable biomass supply to a 1000 kWe plant. Financial analyses indicate that such investment would not be viable under the current renewable feed-in-tariff rates in Ghana; increased tariff by 25% or subsidies from a minimum 30% of investment cost are needed to ensure viability using internal rate of return as an indicator. Carbon finance options are also discussed.
The second configuration focuses on co- and tri-generation from clustered crop residues. Techno-economic results show that 600 kW and 1 MW biomass fuelled plants to generate power, heating (for cassava or maize drying) and cooling (to refrigerate tomatoes) are feasible, considering a minimum 20% yearly profit for investors’ equity. Additional income between 29 and 64 US $/tonne of crop residue would be possible for farmers if a minimum of 60% of the heat produced can be traded. The consideration of carbon financing under the most common traded prices has little impact on the project results; if more favourable schemes (like the Swedish carbon tax) are considered, the viability of co- and tri-generation plants run on agro residue can be possible even with a low level of residual heat sales.
The third configuration analyses minigrid electricity generation and services based on biomass gasification in five Ghanaian communities. Results show that the projected electricity demand compares favourably with the potential supply from available crop residues. Project financing via 100% private funding would not be viable under current national uniform tariffs; however, by applying an end-user tariff equal to the current expenditure on electricity-equivalent uses in the communities, a subsidy of about 35% on initial investment would enable a private entrepreneur an internal rate of return of 15%, whereas a 60% subsidy could enable internal rate of return of 25%.
The outcomes of this research have triggered the interest of Ghanaian and international policy makers, developers and private investors.
