Petroleum is a limited resource and if we keep using it global warming will accelerate. Since this realisation has filtered in the quest for alternatives has begun. Shale gas and natural gas are only pseudo solutions as those supplies are finite and fossil, too. The only way out are fossil-free resources, bio-based ones that is. Industry and academia are developing bio-based processes fervently and with the prerequisite that the products must not be more expensive than conventional ones. However, in late 2014 the price for crude oil dropped below $70 per barrel and has not recovered as of early 2018. The prices for the chemical building blocks ethylene and propylene have roughly halved from 2014 to 2016. The dismal prospects have made big players such as Braskem and Dow Chemical shelve their bio-based propylene development. Thyssen Krupp Industrial Solutions sent its multipurpose plant for organic acid fermentation in Leuna, Germany into hibernation in 2015 until better times, selling it subsequently to EW Biotech.
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All around the world times are hard for bio-based chemicals as they can rarely compete with their fossil counterparts pricewise and cannot even play a trump card in the matter of climate change. Of the total energy demand worldwide the chemical industry uses 30% and it is responsible for 20% of the industrial greenhouse gas emissions. In comparison, the amount of ‘C’ that ends up as part of products is marginal. Consequently energy consumption is the main area to target if CO2 emissions shall be significantly reduced. Nonetheless, support for bio-based products is firmly anchored in the policies of many governments and the targets they have set are ambitious.
Bio-based policies in Europe and the US
There is consensus in Europe and the US that guidelines on how to switch over to a bio-based economy need to be stipulated; the approaches to implement the change are quite different regarding the strategies of the different governments and the legislative conditions.
The European Union has agreed upon
- a 40% greenhouse gas reduction by 2030 (compared to 1990 levels)
- at least a 27% share of renewable energy consumption
- at least 27% energy savings.
More explicitly 20% of the chemicals and materials in the European Union will be bio-based by 2020, rising to a quarter in 2030. In the United States the Biomass R&D board envisions a billion ton bioeconomy. By 2030 one billion tons of biomass is projected to be sustainably produced. It is supposed to be the base for emerging bioproducts industries, but mainly to target “a potential 30% penetration of biomass carbon into US transportation market by 2030”. Plainly spoken this means biofuel in the forms of biodiesel or the addition of ethanol to gasoline.
Which is the most promising bio-based chemical?
When new processes and products enter the market it’s human nature to ask who does best in the competition. For the uninvolved observer it may be simple curiosity, for investors it’s a matter of money – and lots of it – to decide whether to jump on the bio-based bandwagon and which car to take.
In 2004 the US National Renewable Energy Laboratory (NREL) defined 12 top value added chemicals from biomass. These products seemed to be the most promising at that time but a lot has happened in the last decade. In the follow-up report of 2016 there is again a list of 12 promising chemicals. The overlap between the two lists is moderate and consists of glycerol, succinic acid and para-xylene.
The European Union, too, strives to identify the chemicals that are predestined to be made from biomass. RoadToBio is an EU-funded project set up in mid-2017 to deliver a roadmap by 2019 illustrating the ‘sweet spots’ for Europe’s chemical industry. In a first step, a long list with 120 chemicals at technology readiness level (TRL) of 6 or higher was compiled that show potential for the chemicals market. In parallel, the value chains of 500 petrochemicals were analyzed from a purely technical point of view. 85% of the value chains offer entry points where a petrochemical could be replaced by a bio-based one. The chemicals that were cited most often as replaceable are ethylene, propylene and methanol.
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RoadToBio analyzes the interface between bio-based and petrochemical
The NREL report and RoadToBio project have in common that they both examine products with a TRL 6 or higher meaning that the production process has reached pilot scale. Furthermore the studies so far both work along the value chain of petrochemical products. A typical product tree starts from a low value feedstock like ethylene and branches into many higher value intermediates like polyethylene, ethylene oxide and vinyl acetate. The intermediates again have multiple uses; vinyl acetate can end up in an adhesive as well as in paint.
Whenever a chemical can in theory be replaced by a bio-based one this is called an entry point in RoadToBio. Overall, of the 120 chemicals identified in the long list for further analysis, only 49 have entry points into existing petrochemical value chains, while the other 71 are dedicated chemicals. Dedicated chemicals are those which have no fossil-based counterpart and thus offer unique production routes. Lactic acid as base for the bioplastic polylactic acid is a prominent example for a dedicated chemical. In contrast, drop-in chemicals are bio-based versions of existing chemicals. A third group, smart drop-in chemicals, are also chemically identical to their fossil counterparts but provide an additional advantage compared to ordinary drop-ins. This can be a faster and simpler production pathway or less energy use.
In the NREL analysis some products such as ethylene and methanol were consciously excluded as they would compete with chemicals derived from natural gas, which is not realistic. It remains to be seen if RoadToBio researchers take a similar route in the next step, in which they will analyze drop-ins and dedicated chemicals for their market potential.
Four chemicals that appear on both the top 12 NREL list and among the 49 RoadToBio chemicals with potential entry points are succinic acid, para-xylene, 1,2-propanediol and glycerol.
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And the winner is…cooperation
If predicting the success of a bio-based product were easy governments worldwide would not employ legions of scientists and commission studies to do so. Only time will tell which of the cited bio-based chemicals will become a blockbuster and whether RoadToBio will come to the same conclusions as the NREL study. The petroleum price and governmental interventions are only two of the more unpredictable factors in the multi-parameter matrix which determines the economic success of a bio-based product. One of the commonalities of the four chemicals discussed above is that they are drop-in chemicals. They are chemically identical to their fossil counterparts and for further processing it doesn’t play a role whether they are made from petroleum or from biomass.
On closer inspection the production processes of promising drop-in chemicals are an eclectic mix of chemical and biotechnological. Fermentation steps are followed by chemical transformations; whether a metal catalyst or an enzyme is used is just a matter of what works best. Anything goes as long it is technically feasible. A process is no longer either chemical or biotechnological, cooperation is the new normal. Winners in the quest for the holy grail of bio-based chemicals are definitely the scientists from all the different disciplines involved. They have learned to look past the boundaries of their own sector and gained a whole new perspective.