Re-formulating with re-refined

The re-refining of used motor oil is a great example of a circular economy in action. Waste engine oils are collected at the end of their life and reprocessed into fuel oils, base stocks and used as raw materials for the petroleum industry. The base stock fraction is used in the formulation of new engine oils, which at the end of their life can be collected and re-refined again.

The characteristics and quality of the base stock produced depends on the feedstock and production process methods used.  Generally Group I and Group II products are being produced. However, the improvement in quality of automotive engine oils is impacting the quality of used oil, making re-refineries a potential new source of Group III and Group III+ base stocks. 

Clearly the re-refining approach has a number of sustainability benefits. Firstly it has higher yields than the initial refining of crude oil.

Secondly, according to the American Petroleum Institute, it uses 50-80% less energy than is required for refining crude oil to produce base oil and it also means less non-renewable virgin oil is consumed. In addition re-refining also helps to reduce the significant outlay and well head emissions created in extracting crude oil.

Given the various collection, transportation, and processing methods, the carbon footprint for every re-refined base oil will be different. However, overall re-refined base oils will have a significantly lower carbon footprint than crude derived base oil – anywhere from 50-90% being reported. Our experience of using re-refined base stocks in lubricant formulations has demonstrated significant CO₂ savings in the finished lubricant vs lubricants formulated with conventional base stocks derived from virgin mineral oils.

In our view re-refined base stocks should be of particular interest to lubricant formulators where base stocks contribute significantly to their overall carbon footprint. Something clearly endorsed by the re-refiners.

But, the benefits of re-refined base stocks go beyond their ability to reduce the carbon footprint of finished lubricants.

Other benefits include the fact that they do not directly compete for feedstocks that could be used for food production. Also, the collection process resolves the disposal issues associated with used lubricants. And, as their quality improves, they could potentially be used as a substitute for PAO, which typically has a much higher cradle to gate carbon footprint than other base stocks. In addition, price volatility in the virgin base stocks market – particularly around Group III look set to continue. In terms of reliability of supply, re-refined products can offer some advantages, – making them increasingly attractive to formulators.

A growing market

Each year the world produces some 40 million tons of lubricating oil. Some is burnt in combustion, consumed during use or spilled, which theoretically leaves some 22 million tons/annum (t/a) available as a feedstock. Currently, around the world, about 68% of this oil is collected – with high regional variations, primarily driven by local legislation. Of this collected oil, 40% can be re-refined into new products, generating about 4 million tons of re-refined base stocks annually. These re-refined volumes are minor in comparison to conventional base stock production, although we have seen a number of announcements about capacity increases, which means that re-refined production is likely to increase, driven by:

• The impact of sustainability drivers on the lubricants market
• Improved used oil collection rates.
• The introduction and enforcement of legislation
• Supply and price issues regarding virgin base stocks

Forecasts suggest that re-refined base stock capacity will grow to 5 million t/a by 2025, with Asia Pacific and North America being the two largest suppliers. However, it should be noted that much of the supply from Asia Pacific is low quality Group I and not suitable for most crankcase applications.

However, the regulations driving used oil use and the prevention of waste oil combustion will be important to support the growth of the market.

And the availability of used oil feedstock is vital to the future health of the industry.

Reducing carbon emissions

Infineum has explored a wide range of re-refined products, which in combination with our robust additive packages can create lower carbon fluids that meet the performance requirements for applications including passenger cars, heavy-duty trucks, transmissions, two-wheelers and large marine and stationary gas engines. Their use not only reduces the cradle to gate carbon footprint of these finished lubricant products but also helps to contribute towards sustainability aspirations.

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