Co-processing is the smartest way to generate a bio-content in fossil-based fuels. Why? All you need is a spare tank to store the bio-feedstock(s), some piping and pumping to feed this alternative and sustainable raw material into crude oil refinery process units, usually hydrotreaters or conversion units, the approval by your local administration to measure the bio-content by bookkeeping, and, by and large, you can get some 5% of biogenic material to contribute to your renewable obligation as a fuel marketer for a limited investment. The cost comes mostly from the price you pay for the bio-feedstock.
If you have spare capacity in the oil refinery, co-processing is a no-brainer, compared to a greenfield bio-refinery. Lipids (vegetable oils, used cooking oils, animal fats) have been co-(hydro)processed with diesel for more than a decade, but co-processing’s main limitation lies in the capability and capacity of the host process unit to deal with the non-hydrocarbon part of the bio-feedstock. This is mainly oxygen, which is not found in crude oil, thus is not featuring as something to get rid of in a crude oil refinery, at least in large volumes. Thus, the usual co-processing rate is around 5%, a significant limitation. This implies you need 95% of fossil material, acting as a carrier or a buffer, not a problem today, when most transport fuels are fossil.
Looking now at bioenergy production pathways: when legacy, first-generation, biofuels, FAME biodiesel, HVO renewable diesel and ethanol, are produced neat from mature processes like lipids esterification and hydrogenation or fermentation, and have been occasionally cost-competitive when raw materials were cheap, new pathways have emerged as a smart compromise between these well installed first-movers and the capital intensive gasification-synthesis process, that can produce any hydrocarbon from any biomass, but barely exists today at industrial level because of the huge investment cost (actually, this mature process only exists on a large scale in South Africa, on coal, and in Qatar, on natural gas).
Thus, enter innovative pathways, using thermo-chemical processes, like fast-pyrolysis and hydrothermal liquefaction, that can produce bio-oils or bio-crudes, intermediates with a large distillation range, from most types of biomass, including the residual ones allowing to eventually obtain advanced biofuels, at a much more affordable investment cost. The bio-oil or bio-crude is rather unpalatable as a commercial fuel, and has to be seriously purified and upgraded in downstream units, like crude oil refineries distillation or conversion units, in short, get co-processed: as for the early co-processing feedstocks, oxygen and water are the main contaminants, with residual metals, and hydrocarbon composition, such as the aromatics content, may not be the best suited to meet commercial fuels specifications, explaining why this “new” co-processing remains also limited around 5 %, like the “old” one.
And commercial plants have become a reality in Europe: recent examples are the Green Fuel Nordic plant in Lieksa, Finland (2020) or the Pyrocell Setra plant in Gävie, Sweden (2021), both transforming saw-dust into bio-oil using the BTG fast-pyrolysis process, the latter project a JV between Sepra and Preem, which will co-process the 24 000 tons per year of bio-oil in its Lysekil refinery.
But the prospects of crude oil refining in Europe are bleak. If the European Green Deal objectives are met in 2050, fossil fuel demand will have shrunk by a factor of 10 in thirty years, as heating fuels for home and industry have mostly been replaced by greener alternatives, cars run on electricity, trucks mostly on renewable diesel and electricity or hydrogen, air and maritime transport, harder to decarbonize, remaining the only pockets of demand, with petrochemicals, if recycling of waste plastics and bio-plastics have not taken over in this sister industry, and niche products, like lubricants and bitumen. Oil refineries may not disappear from the industrial landscape, some morphing into bio-refineries, a process already in progress in France and Italy (lipids hydrotreatment to HVO), some remaining logistical hubs, or perusing their industrial infrastructure to accommodate other renewable energy sources, like biomass (gasification-synthesis), some focusing on petrochemical feedstock supply. A sure thing is that crude oil intake will decrease, quite possibly from the 700 million tons per year of the previous decade to perhaps 100? This will severely limit the capacity to absorb “difficult” feedstocks such as bio-oils, capped at 5 million tons per year.
All experts today blame uncertainty, of regulations, of technologies, of market demand, as the biggest hurdle to finance the energy transition. If you are a project developer, once you have convinced the potential investor that the technology is mature, the raw materials are sustainable, available and affordable, in the long run, the demand for products exists, also in the long run, you still have to convince that the steel you intend to put in the ground will generate returns for several decades, the heavy industry not being usually a big supporter of fast obsolescence: well, if you want to invest in technologies that rely on the oil refining industry as a key step in your supply chain, better be a first-mover to secure the right-of-way, or think outside of Europe. Or consider investing in technologies that produce neat biofuels, rather than intermediates, like cellulosic ethanol, for cars or planes.
The fuels industry has moved from the monolithic crude oil refining of the 20th century to a variety of production pathways in the 21st, but whether all of those will last as long remains a big unknown today.
Philippe Marchand is a Bioenergy Steering Committee Member of the European Technology and Innovation Platform (ETIP).
