The majority of biobased lubricants are created from esters. The ester types vary. There are natural esters which are triglycerides of vegetable oils. There are also oleochemical esters of fatty acids such as diesters, polyol esters and complex esters. The best application for biobased lubricants is in machinery that loses oil directly into the environment during use, and in machinery used in environmentally sensitive areas, such as in or near water, agriculture, forestry, food processing, and public areas. Biobased lubricants produce a cleaner and less toxic work environment, fewer skin problems for workers, and less oil mist and vapor emissions.
Biobased lubricants are defined into two categories:
- Readily - Degrading 80% within 21 Days. Vegetable-based lubricants and some synthetic ester- based products exhibit ready biodegradation.
- Inherently - propensity to biodegrade, with no indication of timing or degree. Many Petroleum products claim inherent biodegradability.
There are also marketing terms that show up but these do not necessarily represent technical classification for certification.
- Environmentally Friendly Lubricants (EFLs)
- Environmentally Adapted Lubricants (EALs)
- Environmentally Considerate Lubricants (ECLs)
Biobased lubricants have several advantages for environmentally sensitive work locations, as well as certain lubrication performance advantages which include:
- Low aquatic toxicity
- Highly biodegradable
- Require less stringent disposal requirements.
- Slower evaporation rate compared to mineral oils
- Better adherence to metal surfaces and thin film strength than petroleum based lubricants, providing good lubricity and wear protection
- Higher flashpoint for a safer work environment
- Higher natural viscosity index (VI)
When considering the use of biobased lubricants there are several disadvantages to take into account:
- Bad odors can occur if contaminants are present or product is overly oxidized.
- Biobased lubricant have a high viscosity at low temperatures.
- Poor oxidative stability at high temperatures, although additives designed specifically for plant-based lubricants improve oxidation.
- Though biobased lubricants give quite satisfactory performances in many applications, high load and speed performance properties may not perform as well as mineral oils in some applications.
- Higher cost as compared to synthetic lubricants and typically costlier than mineral base oils.
Biobased lubricants are used in a variety of industrial and vehicle applications
- Lost oil applications (chainsaw chain oils, 2-stroke engine oils, form oil, open gears, and greases.
- Application where oils may leak accidentally in sensitive environments.
- Mandated requirements by regulations such as those from state or federal agencies.
- Requirements may also come from specifications defined by equipment manufacturers, especially if the machine is still under warranty or operated in public areas.
When choosing a lubricant, price may not always be the first consideration when it comes to selecting the proper product for a work environment. Performance characteristics requirements should be noted, such as compatibility for the work application, biodegradability, compatibility for the work environment, performance in the equipment application.
End of life and disposal of biobased lubricants have some considerations. There are no facilities dedicated to re-refining biobased lubricants due to their relatively low volumes. Petroleum re-refiners are reluctant to accept greater than 2% biobased used lubricants in their incoming mixtures, due to a concern for degrading the oxidation stability of the base oil they produce by re-refining. There are some alternative disposal and reuse applications other than re-refining. Used oils are commonly used as a low cost fuel feedstock for industrial furnaces. Applications such as a dust control and as a once-through lubricant for oven bearings and chains are options when end of life service in the original application has been reached.
David Doyle, CLS, OMA I, OMA II
Key Accounts and Special Projects