Thousands of chemicals are used by consumers and businesses every day. At the base of most of their supply chains lie petrochemicals.
These petrochemical raw materials are partly why the chemical industry today is responsible for around 6% of global carbon dioxide-equivalent emissions.
After a century of fossil dominance, the hunt is on to develop cost-effective renewable industrial inputs.
The search for biobased all-rounders
Petroleum is the most important raw material in today’s chemicals industries due to one basic trait: its chemical versatility. Plant-based replacements must be able to mimic oil’s shape-shifting properties.
The hunt for suitable biobased candidates began in earnest over the 2000s. In 2004, the US Department of Energy systematically listed 30 plant-based chemicals that could replace fundamental chemical derivatives for industry, all organised into six groups according to their number of carbon atoms: C1 through to C6.
A follow-up report in 2007 whittled this down to just twelve biobased substances, selected for their high versatility as synthetic building blocks and their lower costs of production. By 2012, researchers had reduced the list of potential biological replacements to ten.
It is one thing to identify which plant-based chemicals could work. However, the stumbling block is figuring out the best way to manufacture them at scale for a reasonable cost. In the years that have followed these early scoping exercises, many of the candidates proposed – and more – have gone into R&D and commercialisation.
Next, we look at some key industrial chemicals where bio based alternatives are needed or have been developed.
Isoprene: on the road
Isoprene is used to produce polyisoprene rubber, thermoplastic elastomer, and butyl rubber. These technical-sounding names are present in all manner of essential sectors: in transport, they fill our car tyres while in health, they are used to make surgical gloves. However, it’s the lucrative auto tyre market that’s behind why the chemical has a market value of around $1-2 billion a year.
Biobased isoprene has reached the market in pockets but companies are still figuring out ways to develop more cost-effective manufacturing processes. In the US, Amyris was an early mover in developing a way to produce the substance, announcing collaborations with buyers through the 2010s around its biobased rubber.
As with many early experiments in the commercialisation of biobased chemicals, Amyris never managed to boost isoprene yields from microbes to profit-turning levels. The company went bankrupt last year.
Still, other companies are trying to become the ones that will tap the market for lower-carbon tyres with a cost-effective manufacturing pathway for biobased isoprene. Last year, it was announced that Ginkgo Bioworks and Visolis were working on a microbial biomanufacturing process for the material. In 2019, US clean tech company Gevo developed a process of converting waste alcohol into renewable isoprene.
Lactic acid: born to be bio
Lactic acid, a global production capacity of over 600, 000 tonnes in 2019,
Is a good example of the kind of chemical that industry should turn bio because so many secondary materials could be derived from it including green solvents, poly-acrylate, specialty chemical intermediates, poly acrylamide, and phthalate polyesters.
A major use for lactic acid is as a food preservative but it is also a vital industrial feedstock for many other industries. One of the major industrial ones is as a feedstock for acrylic acid, an input for superabsorbent polymers, plastics, synthetic rubbers, coatings, paint formulations and leather finishing. It is normally made using petrochemical feedstocks.
One of lactic acid’s highest-growing end-use segments is as an input in the production of biodegradable polymer polylactic acid (PLA) used in food packaging. Commercialisation is in full swing with NatureWorks in Nebraska, USA as well as Corbion in the Netherlands being leading producers.
Ethylene: the chemical industry’s chemical
Ethylene is the chemical industry’s highest-volume molecule worldwide meaning cost-effective biobased options could help support sector-wide decarbonisation efforts.
The substance is used in making high-volume plastics including polyethylenes, the biggest end use for the chemical, as well as polyvinyl chloride, and polyethylene terephthalate (PET). Its production in 2021 was 175 million tonnes globally.
McKinsey estimates that ethylene made from sugar biomass achieves significant reductions in carbon intensity compared to those made from fossil naphtha.
The commercialisation of bio-based ethylene has been relatively smooth as production has been able to piggyback off the bioethanol industry, whose byproduct bio-naphtha is one potential feedstock for the chemical. The major producer here is Braskem which launched a bio-based polyethylene produced from sugar cane-derived bioethanol.
Fumaric acid: it’s everywhere
Fumaric acid is an intermediate for chemical production used in food, chemicals, agriculture and pharmaceuticals. Around 300, 000 tonnes were produced in 2023 making it one of the world’s top workhorse chemicals.
The chemical key to its versatility is that it can be polymerised and made into esters, as well as being nontoxic, a boon for food uses. However, manufacturing it currently involves huge amounts of energy since isomerisation, a step in the petrochemical method, demands very high temperatures.
The biobased production route for fumaric acid has the potential to solve the problem of high energy usage in conventional manufacturing routes, especially if renewable energy sources power the whole process. This is because it uses microbes to ferment some basic biomass into the target chemical – a metabolic process rather than a thermomechanical one.
So far, finding an economically viable way to ferment the substance has been challenging.
BASF is looking into a biobased alternative made using living bacteria from cow stomachs that could turn sugar and carbon dioxide into the substance.
Propylene: a major-league petrochemical
Overall, we can say that biobased propylene is on the cusp of wider commercialisation. It is no surprise why this is the case. The chemical, usually made as a byproduct of petroleum refining, is the second largest petrochemical produced globally by volume and is used to produce many other chemicals that a wide variety of industries depend on including polypropylene (a plastic used in cars, packaging, and medicine) and acrylonitrile (used to make clothing and upholstery fibres).
Shell Chemicals recently started to supply Braskem with bio-attributed and bio-circular propylene feedstocks, based on a mass balance approach and independently certified by a third party.
In 2023, LG Chem signed a Joint Development Agreement with Gevo, Inc., a North American renewable fuel company to develop bio-propylene using bio-ethanol produced from corn and sugarcane. Gevo will supply the source technology with LG Them to advance and verify it through scale-up and commercialisation.
1,4-butanediol: the base of the global apparel industry
This is a spandex precursor that is usually made using coal, another widely used chemical that has acquired major backers to fund the development and commercialisation of biobased alternatives.
Geno pioneered intellectual property aimed at the scale-up of biobased versions of this chemical, having developed a metabolically engineered strain of E. coli suitable for making the chemical. Novamont is the leader in making biobased alternatives now after licensing the strains from Geno.
Other large companies working on the chemicals are Cargill and Helm whose joint venture Qore is also set to scale production at Cargill’s biotech campus in Eddyville, Iowa. In September 2023 it was announced that BASF obtained long-term access to More’s 1,4 butanediol made from renewable feedstock.
Maximising the benefits of biobased chemicals
As well as working with new renewable materials, the chemical industry will need to increase energy efficiency, adopt renewable energy, and implement more recycling to meet net-zero goals.
Moreover, biobased materials have to be used in the right sectors. This is because natural resources – even biobased ones – are limited. To maximise decarbonisation impacts then, biobased chemicals should be encouraged in sectors where they can make the biggest environmental impact. For producers, it also makes sense to target applications with the highest value proposition.
Opinions vary on how far we can replace all existing petrochemical derivatives with biobased ones. Some believe that technological advances and favourable policy developments could soon unlock vast feedstock reserves that are currently unusable, including woody matter or algae, allowing almost every industry to partially or wholly switch to bio.
However, a general rule for formulating environmental policy is to err on the side of caution. If the sluggishness of decarbonisation policy so far is anything to go by, we should assume that biobased manufacturing will continue to draw on a relatively limited pool of biomass as it does today – some field crops like corn and sugarcane, certain kinds of agricultural and urban waste, and certain kinds of third generation feedstocks like algae.
There is also a case to be made against giving over the precious biomass feedstock pool towards high-volume applications such as jet fuel altogether. The Royal Society estimated that half of the UK’s land would be needed to meet its sustainable aviation fuel needs. In many other regions, the supply of sustainable biomass will simply not be big enough for bio-based materials to offer the sole, or even the most significant, tool for attaining net zero in all chemicals industries, stretching from fuels to pharmaceuticals.
Given this, we are much more likely to see biobased chemical growth remain confined to speciality and luxury markets (pharmaceuticals and high-end personal care).
Making the speciality chemicals sector go bio would still be a feat. Today, the bio-based chemicals market comprises less than 10% of the global market by volume and less than 5% of the estimated $4.7 trillion overall global chemicals market, meaning huge potential for growth.
