Wood gasification systems have the potential to contribute to rural electrification in sub-Saharan Africa. This paper presents an operational and economic analysis of two wood-based gasification systems (250 kW and 10 kW) installed in Uganda in 2007. Both systems proved their potential to compete economically with diesel-generated electricity when operating close to the rated capacity. At an output of 150 kW running for approximately 12 h/day and 8 kW running for approximately 8 h/day, the systems produced electricity at US$0 . 18 and 0 . 34/kWh, respectively. A stable electricity demand close to the rated capacity proved to be a challenge for both systems. Fuelwood costs accounted for approximately US$0 . 03 kWh for both systems. Recovery of even a small fraction of the excess heat (22%) already resulted in substantial profitability gains for the 250 kW system. Results indicate that replicating successful wood gasification systems stipulates the integration of sustainable fuelwood supply and viable business models.
Introduction
Electricity access and human wellbeingElectricity access is crucial to attain the Millennium Development Goals on poverty reduction and environmental sustainability (OECD/IEA, 2010). Of the 77% of Ugandans living in rural areas in 2008(FAO, 2011, fewer than 9% had access to electricity (IEA, 2011). Erratic electricity services force industries to spend approximately 34% of total investment into generator back-up systems (Eberhardt et al., 2005). Surprisingly, absent modern energy services are not necessarily caused by poverty. Many poor already pay more per unit of energy than the better off due to inefficient technology and corruption (DFID, 2002).
Electricity from small-scale gasification in UgandaDespite encouraging biomass productivity conditions, modern bioenergy systems are scarce in Uganda. Established small-scale technology such as gasification can be locally operated providing cost-efficient energy (Buchholz and Volk, 2012;DFID, 2002). Wood-fuelled gasifiers combust biomass in an oxygencontrolled environment, generating producer-gas containing 19 + 3% carbon monoxide, 10 + 3% carbon dioxide, 50% nitrogen, 18 + 2% hydrogen and less than 3% methane (Ankur Scientific India, 2012), which then fuels an internal combustion engine. Wood-based electricity production is characterised by low material and energy input (Heller et al., 2004; Pimentel et al., 2002; Zanchi et al., 2012) and can deliver electricity more cost efficiently than alternatives (Banerjee, 2006;Buchholz and Da Silva, 2010). However, implementation hurdles can be substantial (Ghosh et al., 2006) because of its complexity. Systems from 10 kW to 50 MW are under investigation region wide (Buchholz and Volk, 2012;Buchholz et al., 2007aBuchholz et al., , 2007b Pamoja Cleantech AB, 2012), and frameworks to mitigate potential ecological and social risks of these systems are being developed (Buchholz et al., 2009 This study investigated the operational and financial implications of a 250 and 10 kW gasifier in Uganda. Visited i...
