Technical applications of Jatropha oil—environmental effectiveness of renewable resources

Abstract

To address the non-renewable resource scarcity problem, vegetable oils have been used in many technical applications such as fuel and lubricants. In this context, cultivation of the oil-bearing plant Jatropha curcas is currently seen as one option. As renewable resources are limited as well due to their occupation of land, it is important to investigate which application of Jatropha oil provides the highest environmental saving potential compared to the current use of a non-renewable resource. This research investigated the potential environmental benefit of four technical applications of Jatropha oil by comparing them in a Life Cycle Assessment with the equivalent conventional products. Besides energy use (biodiesel), three examples of material use have been investigated: cold form oil (CFO), multifunctional oil (MFO), and a coolant emulsion. The service delivered by 1 kg of Jatropha oil was chosen as the functional unit resulting in specific reference flows for the different types of application. The centre of environmental science (CML) method was used to calculate the environmental impact results in six different impact categories (GWP, ADP, EP, AP, ODP, POCP). Furthermore, the influence of Jatropha cultivation on overall results was analyzed in a sensitivity analysis. First, absolute results for the Jatropha products are given indicating the contribution of Jatropha oil supply chain, supply of other ingredients and biodiesel and lubricant production, respectively, use, and EoL phase. Second, relative results in comparison to conventional products are shown. Finally, the environmental benefit is calculated in, e.g., kilograms of CO2-equivalent per kilogram of Jatropha oil. Results reflect that the environmental benefits gained from using Jatropha oil for lubricants are higher than using it for biodiesel. The study showed that twice the amount of greenhouse gas (GHG) emissions can be saved per kilogram of Jatropha oil when Jatropha oil is used in lubricants like CFO instead of using it as biodiesel feedstock. In addition to a sensitivity analysis addressing agricultural practice in the Jatropha supply chain, the critical GWP for Jatropha oil production was calculated that would negate any environmental benefit over the conventional lubricant. The choice of an application may strongly influence the environmental effectiveness of a renewable material. To identify the environmentally preferable application for a given renewable material, calculating the environmental benefit per kilogram of applied material can be a helpful indicator. Future work is suggested on matching applications and renewables in a way to efficiently combine reduction of fossil resource depletion with further environmental goals like reduction of GHG emissions.