There is another source of renewable diesel that I believe has greater commercialization potential than algae. Jatropha curcas is a non-edible shrub native to tropical America, but now found throughout tropical and subtropical regions of Africa and Asia. Jatropha is well-suited for growing in arid conditions, can grow in low moisture conditions, and may be used to reclaim marginal, desert, or degraded land. An estimated 2 billion hectares worldwide is considered to be degraded and perhaps suitable for jatropha cultivation.
Africa has well over a billion hectares that could be suitable for jatropha production. This could provide a valuable cash crop for African farmers while providing renewable fuel for local use and for exports. India is also frequently mentioned as a country with great potential for jatropha cultivation, and farmers there have begun to plant it in specific regions.
The oil content of jatropha seeds ranges from 30% to 50%, and the unmodified oil has been shown to perform adequately as a 50/50 blend with petroleum diesel. However, as is the case with other bio-oils, the viscosity of the unmodified oil is much higher than for petroleum diesel. The heating value and cetane number for jatropha oil are also lower than for petroleum diesel. This means it is preferable to process the raw oil into biodiesel or green diesel.
Jatropha appears to have several advantages as a renewable diesel feedstock. Because it is both non-edible and can be grown on marginal lands, it is potentially a sustainable biofuel that will not compete with food crops. This is not the case with biofuels derived from soybeans, rapeseed, or palm.
Jatropha seed yields can vary over a very large range – from 0.5 tons per hectare under arid conditions to 12 tons per hectare under optimum conditions. This is one of the biggest issues presently with jatropha. Jatropha is essentially a wild plant, and could benefit from some selective breeding in order to improve oil yields and reduce the variability of the crop.
Jatropha has one significant downside. Jatropha seeds and leaves are toxic to humans and livestock. This led the Australian government to ban the plant in 2006. It was declared an invasive species, and ‘too risky for Western Australian agriculture and the environment here’.
While jatropha has intriguing potential, a number of research challenges remain. Because of the toxicity issues, the potential for detoxification should be studied. Furthermore, a systematic study of the factors influencing oil yields should be undertaken, because higher yields are probably needed before jatropha can contribute significantly to world distillate supplies. Finally, it may be worthwhile to study the potential for jatropha varieties that thrive in more temperate climates, as jatropha is presently limited to tropical climates. However, relative to algae, jatropha has far fewer obstacles to overcome before it can make a contribution to renewable energy supplies.
Robert Rapier currently employed as the Engineering Director for London-based Accsys Technologies. Robert maintains an energy blog at http://i-r-squared.blogspot.com/.
[...] Continued here: An introduction to jatropha curcas (part 3) | Green Leader [...]
Companies like Labland, have brought out Tissue culture Jatropha which will
give predicted yield.
Such well researched products should lead Jatropha Plantations