The world today is facing great environmental challenges: global warming, limited natural resources and pollution of the environment. Not everyone knows, however, that tribology – the science of interacting moving surfaces, friction and lubricants – may play a significant role in handling them.
What´s the point of lubricants? Why we need lubricants?
In cars, trucks, locomotives, pumps and a lot of other machinery where metal parts move against each other, energy is lost to friction. At the same time, the metal parts wear upon each other and thus reduce the lifespan of the machinery.
Both this energy loss and waste is reduced by lubricants. These are most often oily liquids which facilitate the movement of metal parts relative each other, and thus reduce friction.
Lubricants can also serve other purposes: In refrigerators, freezers and air condition, they cool the refrigerant gas and seal against gas leakage. Often in electrical equipment (generators in power stations, transformers, subway cars …), they act as insulators and take up heat generated by the electric processes.
What are lubricants made of?
Usually, lubricants are oil based, which help the surfaces to move smoothly against each other. A number of other substances can be added in small amounts for purposes such as protecting the oil from chemical modifications and to help small particles that have entered the system to stay suspended in the oil and not form larger, more disturbing particles.
Currently, about 90 percent of lubricants are based on mineral oils. An increasing share of the market is however made up of non-fossil lubricants and lubricants produced chemically from different sources – non fossil or fossil. Such synthetic lubricants can be designed to have technically and environmentally desirable properties.
Reducing greenhouse gases
Lowering emissions of greenhouse gases is vital for limiting future climate change. This can only be done by decreasing the use of energy from fossil sources, and that demands a reduction in energy consumption. By limiting friction, considerable reductions can be achieved. In heavy transport, for example, we know that two thirds of energy is lost to the surroundings, and only one third goes to physically moving the vehicle.
In transportation, housing, manufacturing and power generation, current advances in tribology – if implemented – has been calculated to have a potential to save 40% of energy used during a 15 year period. In total, a savings of 9% of global energy consumption is estimated to be possible .1 This alone would of course not solve the issue of global warming, but is an important part of reduction of greenhouse gas emissions.
Saving natural resources
Another significant concern is to reduce the use of limited natural resources. Here tribology can help in two ways. First, better lubricants and improved design that limits wear would increase the lifespan of equipment, thus saving on natural resources used in its production. A hint of the extent to which that could be achieved is given by the fact that 70% of equipment failure has been attributed to lubrication breakdown and wear. That wear, repair and maintenance equals to approximately 10 percent of the GDP in industrialized economies.
Also, the lubricant itself could be chosen to save on scarce natural resources and be made from non-fossil renewable sources and recycled material. Therefore, many manufacturers – among them Perstorp – aim to develop productions systems where all materials used should be either renewable or recycled.
Non-toxic and biodegradable lubricants
It is almost impossible to avoid lubricants leaking into the environment; different studies have estimated that between 15 and 40% of lubricants end up in nature. Therefore, there is an increasing interest in designing lubricants that are environmentally friendly by being non-toxic, not accumulate in nature or living organisms, and being easily degradable in the ecosystems.
In this respect, so called synthetic lubricants are superior to lubricants based on mineral oils. Mineral oils degrade slowly in nature and are often toxic. Synthetic lubricants, made from biological or other materials, can, in contrast, be designed to combine desirable technical features with low toxicity, and a high ability to be broken down in nature and thus low ability to accumulate.
Currently, about 90 percent of lubricants are made from mineral oils. Synthetic lubricants have around 10 percent of the market, but the share increases: Its market grows with 5-10 percent a year, compared to 3-5 percent for lubricants in general.
The unique possibilities of polyol esters
Among synthetic lubricants, polyol esters (POE) offer unique possibilities to be tailor made for a wide variety of needs. This has to do with the chemistry of esters. Esters are formed when compounds called alcohols and organic acids bind to one another. In a polyol ester, the alcohol has many sites where an organic acid can bind (and is thus named polyol), and the organic acids come in many variants, sizes and forms. They may be longer or shorter, branched or unbranched, and branched in different places.
Because of the many ways different organic acids can be linked to the binding sites on the polyol, there are huge possibilities to design various polyol esters with different properties, tailor made for different needs and purposes.
They can for example be given di-electrical properties to function as oils in transformers and insulating fluids in electrical switch gears. Their fluidity at low temperatures can be adapted for aircraft gas turbines. Heat stability can be adapted for compressors or use in chain oil. Their compatibility with non-ozone depleting and low global warming potential refrigerant gases can be adapted for use in refrigeration systems. Lubricants that may come in contact with food can be designed to further minimize toxicity, and those that might leak into nature could be made with optimal biodegradability in mind.
A wide range of different polyols and organic acids (and combinations thereof) are provided by Perstorp. Such a portfolio makes it possible for our customers to produce tailor made synthetic lubricants for a wide variety of purposes, including refrigeration and air conditioning, automotive, aviation and use as di-electric insulators.
In summary, by developing and choosing more efficient, purpose designed and biodegradable lubricators that are based on non-fossil sources, industry, transport and housing can significantly reduce their environmental footprint, including emissions of greenhouse gases.