The energy potential of agricultural residues in Tanzania has so far not been evaluated and quantified sufficiently. Moreover, the scientific basis for estimations of the sustainable potential of wastes and residues is still very limited. This paper presents an attempt to evaluate the theoretical and technical potential of residues from the sisal sector in Tanzania with regards to energy recovery through anaerobic digestion. The characteristics and availability of sisal residues are defined and a set of sustainability indicators with particular focus on environmental and socio-economic criteria is applied. Our analysis shows that electricity generation with sisal residues can be sustainable and have positive effects on the sustainability of sisal production itself. All sisal residues combined have an annual maximum electricity potential of 102 GW h in 2009, corresponding to up to 18.6 MW of potential electric capacity installations. This estimated maximum potential is equivalent to about 3 % of the country's current power production. Utilizing these residues could contribute to meeting the growing electricity demand and offers an opportunity for decentralized electricity production in Tanzania.
The CO2 utilisation is discussed as one of the future low-carbon technologies in order to accomplish a full decarbonisation in the energy intensive industry. CO2 is separated from the flue gas stream of power plants or industrial plants and is prepared for further processing as raw material. CO2 containing gas streams from industrial processes exhibit a higher concentration of CO2 than flue gases from power plants; consequentially, industrial CO2 sources are used as raw material for the chemical industry and for the synthesis of fuel on the output side. Additionally, fossil resources can be replaced by substitutes of reused CO2 on the input side. If set up in a right way, this step into a CO2-based circular flow economy could make a contribution to the decarbonisation of the industrial sector and according to the adjusted potential, even rudimentarily to the energy sector.
In this study, the authors analyse potential CO2 sources, the potential demand and the range of applications of CO2. In the last chapter of the final report, they give recommendations for research, development, politics and economics for an appropriate future designing of CO2 utilisation options based upon their previous analysis.