The economics and greenhouse gas balance of land conversion to Jatropha: the case of Tanzania

Abstract

Due to higher oil prices, abundance of labor and suitable land and its stable political climate, Tanzania attracted many investments in Jatropha. Although several studies on Jatropha's economic potential are available, its true economics are still uncertain. This paper aims to add to the growing body of knowledge on the socio-economic performance of the Jatropha system by (i) studying the economic potential (net present value -NPV) of the current most prevailing Jatropha system for Tanzanian farmers and its regional differences, by (ii) making a greenhouse gas (GHG) balance and its economic value of the Jatropha activities on regional level, and by (iii) calculating break-even thresholds for yield and seed price. Therefore, regional yield modeling, regional life-cycle assessment, and NPV calculations based on Monte Carlo simulations, each with its set of assumptions, are combined. This study shows positive economic potential of Jatropha cultivation in most of the Tanzanian regions. However, the results also show that 13 of 20 Tanzanian regions will not attain a net positive GHG balance within 10 years. This indicates that the environmental impacts might be more restrictive for Jatropha's sustainability potential in Tanzania than the socio-economic potential. These results are based on the combination of three models, which consists of strong interdisciplinary modeling work. However, this modeling also contains simplifications (e.g., no opportunity cost for 'marginal' land) and uncertainties (e.g., using globally modeled potential yield estimations), which have to be considered in the interpretation of the results.

Consensus, uncertainties and challenges for perennial bioenergy crops and land use

“…Variations in LCA methodology or scope are equivalent to asking a different 'LCA question' (Adams et al, 2013) and can result in different GHG performance estimates for a given bioenergy system Thornley et al, 2015). One significant source of methodological variation is in the assumptions around business-as-usual counterfactual scenarios for land use in LCA (Thomas et al, 2009;Achten et al, 2015). For example, significant GHG savings were achieved from bioenergy heat pathways utilizing agricultural residues and perennial bioenergy crops, but savings were extremely sensitive to the counterfactual land-use scenario (Welfle et al, 2017).…”

Impacts of land use change due to biofuel crops on climate regulation services: Five case studies in Malawi, Mozambique and Swaziland

“…To our knowledge, this is the first comparative study of the carbon impacts associated with the two main feedstocks (Jatropha and sugarcane) and dominant modes of production (smallholder and plantations) adopted in southern Africa. While there are some studies about the effects of Jatropha on carbon stocks in Africa [18][19][20][21][22], there is a critical lack of empirical research on sugarcane as identified in a recent meta-analysis [1]. To the authors' best knowledge, the only study that has considered the carbon impacts of land use change due to sugarcane ethanol production in Africa (Malawi) has made substantial assumptions [23].…”