Each day brings fresh news of the impact of man-made environmental collapse: floods, wildfires, rising sea levels. These are changes to the very earth and sea around us, on the largest scale imaginable.
The culprit is the dramatic rise in carbon dioxide (CO2) levels caused by the burning of fossil fuels, and the remedy currently being applied is a move to renewable energy. Oil and gas are being replaced with solar, wind, nuclear and other carbon-free sources. But society today is not only dependent on energy. We also rely on an industrial carbon economy – one that produces everything from carbon-based plastics to fibres and detergents. And it is not only the energy for this industry that comes from fossil fuels, but the carbon itself.
Thankfully, tiny helpers are at hand. Humans are finally learning from the original carbon cycle, which has governed Earth for 4 billion years. This natural cycle is regulated largely by bacteria and other microbes. Today, using what we know about the chemical wizardry of bacteria, scientists are developing processes to create carbon products from CO2, rather than from oil or gas.
Alongside the transition to renewable energy, the building of a new carbon economy could play a vital role in helping us reach net zero.
The wonders of bacteria
Let’s see how it works in more detail. Life has existed on Earth for around 4 billion years; for over 3 billion of them in the form of single-celled organisms. The machinery of life that now exists in every living creature evolved first in bacteria, whose crucial innovation was the light-harvesting process of photosynthesis, which enables biomass to be created from water, sunlight and carbon dioxide in the air. Oxygen, a by-product of that process, eventually built up in the oceans and the atmosphere, supporting multicellular, higher animal life: this was the road from single-celled organisms to us.
Incredible as it now seems, it wasn’t until the 1860s that humankind discovered the existence of bacteria. Even then, these microbes were misunderstood, being taken simply as a cause of disease. But during the 20th century it became apparent that bacteria are the basis of all life. Only microbes (a catch-all term that includes bacteria and fungi) can recycle the remains of living things when they die. In the oceans, they still produce roughly half of the oxygen in the air. They trap the nitrogen in the atmosphere and turn it into useful ammonia and nitrates which feed our plant life.
This natural ecosystem created great deposits of iron oxide, chalk from the compacted shells of decayed marine organisms, coal from decayed trees and other plants, and oil and gas from marine microbes that sank to the bottom of the ocean and were transformed by the pressure of sediments. Eventually, around 250 years ago, humans began to use these materials, laid down by early life, to develop industrial civilisation. In this period – just a quarter of a millennium – humans have burnt millions of years’ worth of fossil fuels, riding roughshod over the planet’s own geochemical and geophysical processes. The results, as we know, have taken us to the edge of climate catastrophe.
Today, however, we are finally learning from the world of microbes. Bacteria, we are discovering, possess all of the ingenious chemistry to enable the synthesis of every organic substance we need to sustain human civilisation. With the help of bacteria, companies are now producing fuel from industrial waste gases which would otherwise further pollute our atmosphere.
And while this source of carbon dioxide is still reliant on the burning of oil and gas, we can also capture CO2 directly from the air. Prohibitively expensive at present, work is ongoing to make direct air capture economically viable.
We would then be able to produce a range of chemicals needed to make plastics, fibres or even food without the need to release any further CO2. Even better, the new carbon economy could help reduce the dangerous levels already in the atmosphere. This new and virtuous industrial carbon cycle could help rectify the harm done by the old, polluting one.
Building the new carbon economy
There is much work to do. The physical damage done by the burning of fossil fuels began in earnest around the late 18th century. But the seeds were sown much earlier when, around 6,000 years after the domestication of crops and animals had become the norm, humans told themselves the story that their dominion over nature had been granted to them by God.
Since then, exercising our “dominion”, we have made the world comfortable for ourselves through a life-support system of food, energy, transport, shelter and communications by grossly coralling nature for our own ends.
Yet, as the iconoclastic biologist Lynn Margulis pointed out in her 1986 book Microcosmos: Four Billion Years of Microbial Evolution (co-written with Dorion Sagan), the machinery of life is the same in bacteria or a redwood tree or a human being. We are all bacterial assemblages. Nature only knows the trading of gases between organisms and the air, the waters and the Earth. It doesn’t matter what the outward form is:
“Life at the surface of the Earth seems to regulate itself in the face of external perturbation, and does so without regard for the individuals and species that compose it . . . The visible world is a late-arriving, overgrown portion of the microcosm, and it functions only because of its well-developed connection with the microcosm’s activities.”
So what is the connection between the microcosm and the macro environment?It can be summed up as a three-way molecular dance between carbon, hydrogen and oxygen (with a little help from a few other key elements – nitrogen, sulphur, phosphorus, etc). Carbon is either in a hydrogenated state, known chemically as “reduced” (that is all the biomass including us), or in an oxidised state as CO2. The astrobiologist Michael Russell has summed up the secret of life in one line: “The purpose of life is to hydrogenate carbon dioxide.”
That is nature’s carbon cycle, which has existed for around 4 billion years. Our own industrial fossil-based carbon cycle actually began with farming 10,000 years ago. Farming disrupts the natural ecosystem to produce our food in ways that are now deeply damaging, given the scale our population demands. It then went on to power the modern industrial economy with a vast range of manufactured materials, both mineral and organically carbon based: metals, plastics, ceramics, glass, paints, detergents and many other products.
This means that moving to a low-carbon sustainable economy is not just a matter of decarbonising electricity production, transport, home heating and cooking. The key is to use the very substance that is damaging the planet, CO2, as the source of carbon, instead of oil and gas.
This is already a viable technology on a small scale, although scaling up is hampered by difficulties in concentrating the CO2 from the air. While it is immensely damaging to the climate, the level of CO2 in the atmosphere is still relatively low – currently 419 parts per million. This makes it challenging to extract from the air at an economically viable price, compared to fossil fuels.
Luckily, there is a halfway house. Waste gases from highly polluting furnace industries – steel, cement and glass manufacture, for example – are rich in carbon oxides, both carbon dioxide and its relative, carbon monoxide. Bacteria are able to convert both carbon oxides into organic chemicals, such as ethanol, which is a substitute for petrol and a key feedstock for many chemical production processes.
The final piece of the jigsaw to create the new carbon economy is cheap (“green”) hydrogen generated by splitting water using renewable electricity. Microbes can convert carbon monoxide directly, but to reduce CO2 they need hydrogen.
Most such work is still at lab stage development. But some is up and running. After 15 years in development, the US firm LanzaTech opened a plant in China, which has been using commercial waste gases to produce ethanol since 2018. Sean Simpson, LanzaTech’s co-founder and chief scientific officer, has described the process.
First, the hot waste gases are piped into a bioreactor containing bacteria where they cool to 37C – the best temperature for bacteria to work their transformation. The carbon monoxide in the gases is the source of both carbon and the energy that the bacteria consume.
The process runs continuously. A stream of liquid is drawn off from the reactor, containing some of the bacteria, ethanol and liquid media. The ethanol is then recovered by distillation, which kills the bacteria in the liquid stream. The bacteria are also recovered and can then be used a source of animal feedstuffs. The remaining liquid, without bacteria and ethanol, is then returned to the reactor and some nutrients are added.
So, with only small additions of some nutrients (trace minerals), the bacteria continue to grow on the waste gases and the ethanol produced goes on to further processing.
Flexibility, food and scaling up
What is so promising about LanzaTech’s process is that, unlike many chemical processes that can only make one product from one starting material, the bacteria have a healthy appetite for carbon gases from different sources. Once pulling CO2 from the air becomes more economically viable, the plant could be adapted to use this process.
The flexibility of LanzaTech’s process also extends to the products. The bacteria can be genetically tweaked to produce many other chemical building blocks besides ethanol. This new form of carbon capture can be used to produce chemicals for plastics production, or fibres, or even food. This is where those headlines you might have seen come from: “Fuel from the Air” or “Food from the Air”.
The prospects are exciting. However, it’s worth remembering that when you read reports of startling innovative techniques that promise to address the world’s pressing environmental problems you’ve usually just read about a proof of principle, based on very small-scale lab work. What lies ahead is what the start-ups who try to commercialise these processes call “the valley of death”. Almost all fail. As Freya Burton, LanzaTech’s chief sustainability officer, says: “Everyone wants to be first to be second.” Scepticism is so great that everyone is waiting for the pioneer to prove it can be viable.
But LanzaTech are nevertheless scaling up at pace. Following the success of the pioneering Chinese plant, they have seven plants in construction and development globally, plus a second Chinese plant which started last year, and a third under construction.
Two key examples of how this process feeds into large-scale product production involve synthetic fibres and detergents. LanzaTech’s ethanol is being converted by the Indian company India Glycols Limited into monoethylene glycol, one of the precursors of polyester fabric yarn. The fabrics have already been used in a range of dresses by the retail fashion house Zara.
To create a detergent for washing machines, LanzaTech teamed up with the consumer products giant Unilever. Here the same intermediary company, India Glycols Limited, turns the ethanol into ethylene oxide to begin the detergent production process. This flexibility to plug into existing processes instead of using new fossil input is a great attraction of the new bacterial production techniques.
The final area in which bacterial carbon technology is coming into play is food. All our food conventionally originates from the CO2 of the air, via plants. But creating an alternative pathway could alleviate the enormous burden incurred in feeding the whole world by traditional farming.
In this case, bacteria themselves are the product, in the form of single cell protein. Bacterially sourced foods have been around for decades, but they were always produced from fossil-fuel sources. Now the bacteria are grown on CO2. Some are genetically engineered to make replicas of natural proteins such as milk proteins. Milk is an emulsion containing many ingredients, but the key ones are proteins, fats and milk sugar. The Californian company Perfect Day has been marketing synthetic milk protein products such as ice cream since 2020. The precise animal milk proteins are cloned and expressed in a fungus.
More radical still is the “electric food” pioneered by the Finnish company Solar Foods. The basis of all life is at root electricity – that is what is produced in some bacteria and all green plants by the process of capturing the sun’s radiation. But some bacteria can live directly on electricity. Solar Foods use this process to make food proteins from, as they say, “air and electricity”. The component of the air they use is, of course, carbon dioxide.
Bringing humanity back in line with nature’s carbon cycle
The elements needed to create a new carbon economy are beginning to fall into place. And the ideas behind them may not be so new, after all. They were actually predicted as far back as 1894 by the French chemist Marcellin Berthelot, looking forward to the year 2000:
“The day will come when everyone will carry their little protein tablet, their little pat of fat, their little portion of starch or sugar, their little bottle of spices, tailored to their personal taste; all these will be synthesised economically and in inexhaustible quantities in our factories.”
He didn’t envisage a role for bacteria, which he disdained for their association with disease and decay. It’s taken humanity far too long to understand the role of bacteria on Earth. We, as medium-sized creatures, have historically found it hard to imagine the world of microbes. We must now develop our understanding of the planet as a conjoined world of the very small and the very large: of microbes and the global processes to which they give rise.
The task of building the new Carbon economy deserves elevating to Moonshot or Manhattan Project scale. Alongside renewable energy, these new chemical processes can help to bring our life-support system back into alignment with planetary limits.
We can carry on as we are, but if we do, we’ll lose. An ecosystem that has run for over 4 billion years is not going to lie down before an upstart species that has tried to subvert it over a mere 10,000 years since the birth of farming. Unlike our present industrial support system, the new carbon economy would prove compatible with nature’s own carbon cycle, the one that has been governing the Earth for billions of years. Both will be run by microbes – with a little help from humanity this time, rather than hindrance.
This piece is from the New Humanist summer 2022 edition. Subscribe here.