3 leading Jatropha researchers share proof that methodological errors & inadequate data was behind controversial Jatropha water footprint findings.
Posted on : 07 Sep, 2009
The controversial report by University of Twente (Gerbens-Leenes et al), which claimed that Jatropha has the highest water footprint among all the BioEnergy crops caused a stir in the jatropha sector, and now, rebuttals from the Jatropha research community is proving that the findings were wrong.
2nd JatrophaWorld Africa Speakers Prof. Bart Muys and Ir. Wouter Achten along with their colleague Wouter Maes from Belgium’s Katholieke Universiteit Leuven published a clear message to the Proceedings of the National Academy of Sciences (PNAS) rebutting the controversial findings.
Here were some of the key flaws they highlighted in the Gerbens-Leenes et al findings:
- The data used by the authors (Gerbens-Leenes et al) were wrong.
Instead of using data of real water used by jatropha, they summed the total rainfall and irrigation: the actual water used will be only a fraction of this sum, particularly in regions with very intense rainfall events; this has caused a considerable overestimation of the water footprint.
- The other parameters necessary to calculate the water footprint of jatropha ( ffat, fdiesel, and HHVdiesel) were unfounded. The article they cited as reference did not match up to the figures they used.
- The authors only used data of very young Jatropha plantations. Jatropha is a woody species, and at the beginning of its life, Jatropha, like other woody species, invests mainly in non-reproductive tissues, such as stem and root biomass. Mature jatropha plants invest considerably less in non-reproductive tissue and more in reproductive tissues, hence the water footprint decreases with age. Therefore, ignoring the particularities of a woody species additionally overestimated the water footprint. For a correct calculation of water footprint, the entire life span should be taken into account.
- The authors used data of ONLY 5 jatropha plantations.
They also failed to check whether the agronomical practices in these plantations were adequate.
- A recent calculation of the water footprint in an Egyptian Jatropha plantation was only 16% of the Gerbens-Leenes estimate. Maes et al. gave a rough estimate, based on data on an Egyptian 1-year old plantation, and find that the water footprint under optimal irrigation was 65 m3/GJ, only 16% of the estimate of Gerbens-Leenes et al. However, it must be noted that the limited data currently available makes it is impossible for accurate caulculations of Jatropha’s WF.
Other world renowned Jatropha researchers have published similar rebuttals, rejecting the Gerbens-Leenes et al findings, including Raymond Jongschaap R.A.R. Blesgraaf, Thom Bogaard, E.N. van Loo and H.H.G. Savenije from University Wageningen and Delft.
>>Attend 2nd JatrophaWorld Africa<< to hear from Prof Bart Muys who will be speaking on the topic ‘First Worldwide Yield Model For Jatropha’ and Ir. Wouter Achten, who will be sharing on Life Cycle Assessment (LCA) of Biodiesel Production!
