Oil Majors Look to Co-processing as a Rapid Route to Producing Sustainable Aviation Fuels at Scale

by Susan van Dyk (GreenAir Online) The demand for SAF is high but supply remains limited as facilities are still under construction, and production in many cases is years away. But since last year, several oil companies have started producing SAF through co-processing, which is giving SAF supply a boost. In July 2021, NetJets Europe became the first customer to purchase Air bp’s ISCC PLUS certified SAF produced through co-processing of waste fats and used cooking oil in bp’s Castellon refinery in Spain. Other oil companies have followed in rapid succession to announce SAF production through co-processing, including Phillips 66 (UK), TotalEnergies (France), OMV (Austria), Eni (Italy) and bp (Germany). Phillips 66 has just supplied British Airways with a first batch of SAF produced at its Humber Refinery in the UK under a multi-year agreement. Why are the big oil companies choosing this route? Susan van Dyk takes an in-depth look at co-processing, what it means, who is doing it and what volumes of SAF are produced this way.

Co-processing is the simultaneous processing of biobased material, such as fats, oils and other feedstocks, with fossil-based feeds in refinery infrastructure. Using an existing refinery can offer benefits in terms of cost savings and carbon reduction as it removes the need to build dedicated processing units. The high market demand for SAF is playing a role in refinery decisions to co-process.

Explained Fabian Wedam, Head of Aviation at OMV Group: “Market demand for sustainable products is increasing sharply in the short to mid term and large scale dedicated SAF production units require a significant lead time for construction.” Co-processing is a stepping stone since existing assets can be used and only limited investments are needed, he said. Co-processing allows OMV to access the growing market for sustainable products in the short term using existing assets and infrastructure in OMV’s refineries. Last December, OMV signed an agreement to supply Austrian Airlines with 1,500 tonnes of SAF produced at its Schwechat Refinery during 2022.

The potential volumes of SAF that a refinery can produce through co-processing is currently limited by ASTM D1655. The standard only permits co-processing of 5% vegetable oils or waste oils and fats, and Fischer-Tropsch synthetic liquids for SAF production. Although 5% may seem a small amount, it could still be considerable if the scale of refinery operations is considered. Bp’s Castellon and Lingen refineries each have a capacity of about 100,000 barrels per day, so 5% amounts to 5,000 bpd (about 200-250 million litres per year).

However, indicated Steve Csonka, Executive Director of the Commercial Aviation Alternative Fuels Initiative (CAAFI) in the US, the 5% “current maximum co-processing volumetric limits are being assessed by a standing ASTM Task Force for possible increase, with broader voting to be accomplished upon the Task Force’s completion in the coming months.”

SAF produced through co-processing can be certified as sustainable and is also recognised under CORSIA as an eligible fuel.

ISCC has developed a guidance document on the certification of co-processing to assist companies. Various methods or a mixture of methods are permitted to calculate the bio-yield, including radiocarbon 14 analysis, to ensure that only the renewable content is counted.

All the co-processing activities mentioned used fats and oils feedstocks, in most cases waste fats and used cooking oils (UCO). The types of feedstock are currently restricted under ASTM D1655 and limited to fats and oils, and Fischer-Tropsch synthetic liquids. FT syncrude is not currently used in co-processing as it is not commercially available at this time. Other feedstocks may be permitted in future if ASTM certification is achieved, usually a very rigorous process.

The challenge with future availability of waste oils and fats feedstock for SAF production has been confirmed in an ICF report, ‘Fueling net zero’. Renewable diesel and biodiesel compete for the same feedstock, and significant expansion of renewable diesel facilities will soon place a constraint on supply.

According to Moyes, bp recognises that “increasing feedstock availability is an important part of increasing overall SAF production and there are two elements to this. Firstly, as most commercial production today uses HEFA feedstocks, increasing these in the short-term is key. In support of this, bp recently entered into a 10-year strategic agreement with Nuseed enabling Nuseed to accelerate the expansion of its Carinata sustainable production programme.

“Secondly, bp plays an ongoing role in researching and developing the technologies required to bring the different SAF production technology options to commercial production. This widens the feedstocks that can be used. For example, bp and Johnson Matthey have developed a simple-to-operate and cost-advantaged Fischer-Tropsch technology that can operate both at large and small scale to economically convert synthesis gas, generated from sources such as municipal solid waste and other renewable biomass, into long-chain hydrocarbons suitable for the production of SAF. Using all technology options, we believe there is enough feedstock availability to meet the industry’s SAF requirements.”

Other feedstocks that have great potential for co-processing are bio-oils/biocrudes produced through technologies such as fast pyrolysis (bio-oils), catalytic pyrolysis or hydrothermal liquefaction (HTL, biocrudes). Unlike fats and oils, these biocrudes can be produced from wastes such as forest or agricultural residues that are available in far greater volumes. However, these technologies are at various stages of technology readiness.

The recently completed Pyrocell plant in Sweden, using BTG Bioliquids’ fast pyrolysis technology, has started producing bio-oil, which will be co-processed by Preem at the Lysekil refinery in Sweden to produce renewable diesel and gasoline. Note that the feedstock limitations under ASTM D1655 for SAF production do not apply to other fuel products. Preem, considered the leader in co-processing activities, has co-processed 30% tall oil methyl esters into drop-in fuels for more than a decade. Following a revamp last year, Preem’s Gothenburg refinery is currently able to co-process 95% tall oil methyl esters and tallow, according to Fredrik Hellesöy, Strategic Business Development Manager at Preem. This highlights the unlimited potential of co-processing to produce significant volumes of low-carbon intensity fuels. READ MORE