Written by Zachary Gray, B.Eng.Biosci., Chemical Engineering & Bioengineering
Motor oil changes are a sacrament in our car-obsessed modern life, while the mechanics working in the auto shops are their enforcers and evangelizers. Every 5,000 to 8,000 kilometres, car owners begrudgingly schedule an oil change between busy work days and weekend errands.
Primer of Motor Oil
During the 20-minute oil-change procedure, mechanics bleed the blackened, viscous motor oil from the bowels of the engine and replace it with pristine liquids from bright plastic packaging – eye-catching to some, but a far cry from the painted metal containers that furnish collector’s shelves.
While the myriad of car oil brands available might suggest a wide variance in products, they differ only in the precise mixing of additives. Motor lubricant is essentially 70-80% base oil with the remaining 20-30% consisting of supplements such as antioxidants, detergents, and viscosity enhancers, as well as rust inhibitors.
The quality of the motor oil degrades over time in a motor vehicle. The build-up of debris blackens the oil, while the additive properties deteriorate over the driving cycle, dissipating heat and lubricating contact points between metal parts with less efficiency as time marches onward. Water entrainment and oxidation of the base oil are also contributing factors.
Changing one’s motor oil frequently, as the chorus drones on, ensures the longevity of the engine. One question remains as the mechanics dispense with the last of the used oil: what happens to it afterward? Nothing much is often the answer.
Motor Oil Re-refining
There are over 300 million registered vehicles in Canada and the United States alone, contributing to the nearly 2.5 billion gallons of motor oil disposed of annually throughout North America. Of the almost 60% recovered, a mere 8% is recycled. The remainder feeds the 12 billion of gallons of lubricant reduced to toxic waste yearly.
Catastrophizing about the volumes quoted and their impact is not productive in and of itself. Exploring ways to improve oil recycling figures is a better use of time.
In 2009, when the revered Scientific American explored whether motor oil could be recycled, the editors profiled Universal Lubricants (“UL”). The Wichita-based company uses conventional refining techniques from upgrading crude oil when recovering the spent lubricant. They essentially re-refine the used motor oil
UL processes over 45.4 million litres of used motor oil, or 28,600 barrels, per day. In the re-refining process, used oil passes through a vacuum distillation unit which removes water from the base oil, accounting for 5-7% of the incoming volume. Next, contaminants are removed using an evaporation press. In the final step, UL hydrotreats the decontaminated oil.
Hydrotreating consists of applying high temperature and pressure (700 deg-F and 1,100 PSI) and enriching the carbon-backbone of the oil with hydrogen molecules in the presence of catalysts that aid in the chemical reactions.
The final product resembles base oil, ready for lubricant merchants to add their additive concoctions and branding power.
Re-refining efforts, much like those by UL, accounts for only 10 percent of used oil management market. The majority of used motor oil is either burned or dumped, depending on the jurisdiction and level of enforcement. The emergence of re-refining technologies has done little in altering the outcome for spent motor oil — but why?
Barriers to Recycling
There are two main barriers to a broader adaptation of re-refining used motor oil. The first is the capital expense in building and operating a facility on UL’s scale. Investors should expect a final bill of tens of millions of dollars in replicating UL’s plant in Canada. Recovering their investment is another issue: refineries derive their profits either from large volumes, amplifying small gains per unit of measurement, or upgrading cheaper base stocks. With respect to the latter point, one could argue that the used motor oil would be a commodity instead of merely a waste product with broader market adaptation. Such a classification diminishes the facility’s economic viability.
The second barrier to re-refining is the plant’s environmental impact. A re-refiner has a similar environmental impact as an oil refinery. To understand how difficult it is to get environmental approval for an oil refinery, one need to realize that the newest oil refinery in Canada is over 30 years old.
Besides re-refining, there are innovative and arguably more feasible solutions for recycling motor oil in development. The Ottawa-based MemPore Environmental Technologies Inc. (“MemPore”) is one such example, scaling their locally-minded, membrane-based process.
MemPore’s solution is this: the used motor oil is kept in 5,000-gallon settling tanks and periodically shipped to their regionally-based operation. The central locations reduce the amount of pollution from transporting oil over longer distances and eases logistical challenges. After removing contaminants during the pretreatment process, consisting of a filter, centrifuge, and flash evaporators, the oil is sent to the membrane unit. Once polished to a quality consistent with a regular base oil, lubricant mixers take the final product and infuse it with their additives.
Cement kilns take the waste sludge separated by the membrane. The 15 metric tonnes, or 148 barrels, per day system operates at low temperatures and pressures, thus reducing its running costs and environmental impact.
Alastair Samson, MemPore’s CEO, eloquently summarizes the company’s position and value proposition:
“The MemPore System can, for the first time, recover and recycle this base oil with 71% reduction in pollution, from localized systems, using low energy, and at low capital and operating cost. This is an important contribution to the clean technology movement and the preservation of earth’s natural resources.”
MemPore’s community-centric and scalable solution, with the potential for handsome profit margins, offers a tangible solution to the endemic squandering of used motor oil. They also provide the mechanics a new hymn during drivers’ reluctant excursion to the auto body shop.