21st Century Problems Require 21st Century Solutions
Petrochemicals will remain a stubborn source of carbon emissions, regardless of the contribution from burning fossil fuels and attempts to divest away from this practice. Oil extraction alone can result in the release of 50-70 kg of carbon dioxide per barrel - the equivalent of 4.75-6.65 megatons, annually. In order for sustainable alternatives to displace petrochemicals they must reach price parity, until then they will only be eligible for the exclusive eco-lifestyle market. In order to reach price parity, production methods will have to become much more efficient by becoming continuous, intensive, and reliant on scalable feedstocks independent of arable land.
The earliest form of bioprocess technology
Beer and wine fermentation is an ancient process. The Mesopotamians are thought to be the first to brew beer in around 6000 BC. The earliest evidence for wine production in pottery jars comes from the village of Areni in modern day Armenia dating back to 6100 BC. The process is dependant on agricultural feedstocks, some mechanical pre-processing (pressing grapes, malting barley and subsequent boiling to produce the malty sweet wort) before fermenting under anaerobic conditions to convert the sugars to ethanol, a result of the presence of alcohol fermenting yeast species.
Many differences, essentially the same…
Today, bioreactors are much more sophisticated, generally constructed from stainless steel and paired with a variety of sensors and actuators to precisely control growth conditions, ensuring reproducibility of optimised product yields. They are used to produce a range of products including, beer and wine, but additionally, industrial solvents and fuels, food additives, fragrances, antibiotics, and biopharmaceuticals such as antibodies and vaccines. Crucially, their basic design has remained intact over millennia. Modern bioreactors are essentially still a large tank into which a feedstock is placed followed by a microbial fermentation process - with the exception of biopharmaceuticals, which are often produced using an immortalised cell line originating from a multicellular organism. The fermentation processes used in industrial biomanufacturing can be either batch or fed-batch, both of which impose significant limitations on process unit metrics.
The future is continuous and intensified bioprocesses
The continuous production line for car assembly was introduced at Ford’s Highland Park, Michigan, plant in 1913. This innovation significantly reduced assembly time, boosted production, and played a crucial role in making cars more accessible by lowering costs, bringing the price of a Model T from $850 to $260. This revolutionised manufacturing and the approach was applied to the assembly of many other products. Clearly the revolution did not penetrate industrial fermentation technology. Synthetic biology will allow us to take inspiration from Ford’s assembly process. We can engineer microbial species so that they will be amenable to continuous and more intensive processes, speeding up production, and lowering prices so that the use of green petrochemical alternatives will become widespread throughout society.