Essential oil production in rural Africa
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The goal of this study is to identify opportunities to reduce the fossil energy use for the steam distillation process of essential oils (EO) in rural Africa. Therefore, renewable energy technologies (RETs) and energy efficiency measures (EEMS) were identified, evaluated and assessed on applicability. As a results, eight technologies were found suitable to achieve this goal, these are: CSP-, biomass- and efficient boiler, an economizer, solar water heating (SWH) system, feedwater condenser, insulation and cascading heat (using a heat pump). These technologies were evaluated on fitness for rural Africa, energy reduction potential and costs. A model was constructed to assess the fitness for rural Africa for each technology. This model was based on relevant technological criteria found in a case- and literature study. In addition, a model was constructed to calculate the energy requirements for EO distillation. Moreover, this model was used to calculate the potential energy reduction and levelised costs of energy for the identified technologies. At the evaluation step, it was found that insulation, an economizer, CSP boiler and SWH system are most fit to be implemented in rural Africa. RETs (CSP- and biomass boiler), cascading of heat and an efficient boiler, respectively have the highest energy reduction potential. The most cost effective energy reduction technologies identified are insulation, feedwater condenser and an economizer, respectively. However, not all identified technologies can be implemented simultaneously, since some compete with each other or are subject to case specific factors. Therefore, the technologies were assessed on their applicability. This was done by using a reference case, an EO distillery in the Baviaanskloof, South Africa. A decision tree was constructed to identify the applicable technologies for a specific case. For the reference case it was found that an efficient boiler, insulation, SWH system and a feedwater condenser could be applied. Here a feedwater condenser is preferred over the competing SWH system technology, since it has higher energy reduction potential and lower associated costs. As a final result of this research, an extensive overview and evaluation of fossil energy reducing technologies is given, that fit the EO production process in rural Africa.