Rapeseed Oil Can't Take the Heat or the Pressure
by Jenna Watson, Barcelona on 06.29.07
Research undertaken at the University of Bath and published in the Journal of Industrial Ecology [2004 (7):3-4)]: considers the life cycle of mineral and rapeseed oil in mobile hydraulic systems, i.e. a forestry harvester and a road sweeper. The general conclusion showed that the systems that used rapeseed oil were not necessarily “better” for the environment. With the exception of greenhouse gas emissions, the rapeseed oil had more negative impacts than mineral oil. The study includes the production of the machinery, the oils and their use during the lives of the machines. They attributed the poorer environmental performance of the rapeseed oil to:
“…its poor performance in the field. This is because it does not respond as well to high pressure and temperature as mineral oil, causing it to need more frequent replacement during use….Also, the rapeseed oil has more corrosive qualities than the mineral oil, and more hydraulic components need replacing during the life of a machine running on rapeseed oil than one running on mineral oil.”
Because hydraulic systems operate with lots of oil – around 100 + liters – the desire for and use of biodegradable oils is increasing in forestry machine users. The possibility of spillage has big implications for the environment. Dr. Marcelle McManus and her co-authors note that local impacts (or impacts on the local environment) can be severe and depend on the surrounding conditions. These impacts are not reflected in LCA for various reasons, but McManus et. al say that,
“…a spill of either type of oil results in ecological and environmental damage. Oil is often released at high temperature and pressure; therefore, plants and animals may be burned or scorched with a significant spill of oil of any type. The use of rapeseed oil within a system is not a license to minimize maintenance procedures and worry less about spillage into the environment. Spillage of rapeseed oil may result in a faster recovery, but it still causes environmental damage.”
We’re not trying to knock rapeseed oil here, but it is important to note where improvements and further research should be conducted for new green technologies. In fact, the LCA notes repeatedly that the impact on greenhouse gases of the mineral oil systems far outweighs any of the other categories considered (ozone-depleting gases, acidification, heavy metals, carcinogens, pesticides, etc.). The results are also influenced by the performance of the rapeseed oil. The more often it needs to be replaced in machinery the more impact it causes. This study helps us realize the importance of considering the full life cycle impacts before choosing an oil type and that further investigation should be conducted to improve rapeseed oil performance. The purpose of this study is not to show that mineral oil is better, but to emphasize that rapeseed oil needs to be improved to make it a more viable and truly greener choice. Read the article. Via: Journal of Industrial Ecology. More on rapeseed oil here, here and here. Image credit: GABI.
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Well. Hydraulic hoses and bushings and seals were designed for mineral oil compatibility and improved for that purpose over many many decades. Dropping mineral oil into a system not designed for compatibility with it and then commenting about incompatitibility is tossing a card in a cocked hat.
Scorching of people and plants is a function of heat, not the fluid. They key attributes for spilling comparisons would be biodegradability and eco=toxicity.
This study was done as PhD research, so I doubt the researchers just "dropped" oil into those two motor types without first making sure that it was designed for compatibility. As well, the impacts of scorching on the environment are still valid and concerning impacts, although not comparable to eco-toxicity or biodegradability (nobody was comparing them to those two impacts). I think they are simply trying to say that just because it is not mineral oil, doesn't mean it has no impact and precautions shouldn't be taken. It's okay that a rapeseed oil spill burns X meters of land, as long as it later biodegrades? I don't think that's a fair argument.