Blending Lubricants for Biofuels
The use of biofuelsis growing in Europe, encouraged by European Union legislation aimed at reducing greenhouse gas emissions and mitigating fossil fuel extraction. David Wright looks at where lubricants fit intothis emerging trend.
Biofuels have been around for many years. In fact, people have been running diesel engines on vegetable oil much longer than they have been running them on petroleum-based diesel fuel. Over the past decade, biofuels have risen to the fore as a key way of tackling the issues of reducing carbon dioxide emissions and our dependence on the finite supply of fossil fuels.
According to the European Unions Fuel Directive of 2014, biofuels are currently the most important type of alternative fuels, accounting for 4.7 percent of the total fuels consumed in [EU] transport in 2011. They can also contribute to a substantial reduction in overall CO2 emissions if they are produced sustainably. They could provide clean power to all forms of transport.
The EUs Fuel Quality Directive requires a reduction of the greenhouse gas intensity of fuels by a minimum of 6 percent by 2020.
What is Biofuel?
Biofuel is any fuel that is generated from sustainable sources. For automotive vehicles, it can come in the form of biodiesel or biogasoline, where a quantity of the biofuel is mixed with traditional petrol or diesel. In fact, EU Directive 2009/30/DC allows for the blending of ethanol into petrol up to 10 percent by volume and for a FAME (fatty-acid methyl ester biodiesel made from natural fats) content of 7 percent in diesel. In the United Kingdom, the government set out in April 2018 its aim to double the current amount of bio-matter in diesel fuel from 4.75 percent to 9.75 percent by 2020, and then 12.4 percent by 2032. Most of the fuels put into cars already have some element of biofuel in them without us even realizing it.
Sources of biofuels include corn, sugarcane, palm oil, rapeseed oil, vegetable oil, soy beans and ethanol. Crop-based sources such as rapeseed oil offer the benefit of taking CO2 from the atmosphere as part of the growing process, helping to offset the CO2 produced when the oil is burnt. For example, bioethanol is classed as carbon neutral, because any CO2 released during production is removed from the environment by the crops themselves. However, the use of food sources for fuel does have some drawbacks. Taking land used for food production out of circulation to instead raise crops for fuel production might affect the prices of sustainable crops. Biodiesel currently uses about 30,000 square kilometers of arable land across the EU and this is expected to increase in the future.
Companies around the world are investing in and adopting biofuels in a range of ways. In the U.K., global fast food corporation McDonalds recycles used cooking oil from their kitchens into biodiesel, which they use to fuel more than half of their delivery trucks. In the United States, waste feedstock from the city of Oakland, California is being converted to Neste MY Renewable Diesel and fuels the citys fleet. In Australia, a Queensland oil refinery is making biofuel from post-consumer waste and tires. Their laboratory tests have shown this diesel is indistinguishable from fossil-fuel-derived diesel and delivers all the performance that you would expect.
Impact on Lubes
This increasing use of biofuels is having a major impact on lubricants. In any engine, a small amount of the fuel goes into the lubricant. Todays latest generation of lower-emission, higher-performance engines are running at hotter temperatures. This means that lubricants are also running at higher temperatures than in the past. Biofuels are less stable than other fuels and oxidize easily. The combination of higher temperatures and biofuels causes increased oxidation, which in turn creates carbon deposits in the engine and reduces the viscosity of the lubricant. Biodiesel, like all fuels, will find its way into the oil sump where it will contribute to oil degradation.
The European Automobile Manufacturers Association lubricating oil sequences in 2016 were revised to take account of the increasing use of biofuels. Across both the A/B and C categories, ACEA introduced a new requirement to report on high tension, high shear viscosity at 100 degrees Celsius, and a new requirement around oil oxidation for engine oils operating in the presence of biodiesel.
For lubricants, two key issues result from increased use of biofuels. The first is thickening as a result of oxidation, which restricts lubricant flow and results in increased wear and therefore shorter engine life. Secondly, increased carbon deposits from oxidation in the piston ring grooves restrict the movement of the rings and increases friction and wear in the cylinders. These deposits are also abrasive on the parts they come in contact with and result in higher rates of component wear.
As engines and fuels change, lubricants must adapt to perform in these new environments. To address the oxidation challenge presented by biofuels, engine oils are being developed using better-quality base oils and additives to increase oxidation stability. At the moment, this is covered within mainstream oils, which are designed and tested for vehicles running up to 20 percent biofuels. However, if an engine were to run on 100 percent biofuel, it would need a different lubricant entirely, as well as different oil drain intervals.
Any car engine lubricant is 70 to 80 percent base oil, so there is an opportunity for the lubricants industry to increase the use of renewable materials, just as fuel companies are. These could come from plant-based sources such as rapeseed oil or palm oil.
Recycled lubes may also have an increasing role to play. Motor oil does not wear out – it just gets contaminated by deposits in the engine. With the right collection, processing and refining procedures in place, used engine oil can be turned into high-quality base oil and blended into high-quality lubricants.
One gallon of used motor oil provides the same 2.5 quarts of [base] oil as 42 gallons of crude oil. United States Environmental Protection Agency
In the short term, the use of biofuels is expected to continue to rise. Longer term, electric vehicles will become more dominant. This will require further innovation in the lubricants industry, as electrically powered vehicles dont need standard engine oils at all. They do however need advanced cooling systems and drive-line lubricants to ensure that vehicles run effectively.
Meanwhile, the advice for users remains the same: Use the correct, high-quality lubricant from a reputable supplier that is formulated with the latest additives to combat the effects of biodiesel and meet all the needs of modern engines. The balance of each additive in a finished lubricant is highly sophisticated and the result of months, even years of research and testing. The slightest overtreatment of an element by just 0.001 percent can throw the entire balance out. Fuel additives can be helpful, but they run the risk of negatively impacting these finely tuned products.
In an increasingly complex market, users must be confident that lubricant products are being correctly prescribed and are fit for purpose. The European Engine Lubricant Quality Management System is a voluntary quality management system for automotive engine lubricants. It is designed to assist lubricant marketers in assuring the quality of their lubricants and the performance claims made for them in the marketplace.
If in doubt about the correct lubricant to use, always refer to the vehicle owners manual to comply with manufacturer guidelines on the correct lubricant to use and how often to change it. Using the most suitable, high-quality lubricant is the best approach to ensure that the engine is sufficiently protected throughout its lifetime.
David Wright is company secretary of VLS, an independent organization that verifies lubricant specifications in the U.K.