Carbon capture is becoming a major pillar in developing a sustainable bioeconomy, and companies want to partner with the major emitters of waste gas to turn their costly pollution into a valued product.
The driving force of climate change is the accumulation of greenhouse gases (GHGs). Transport and agriculture each account for just over 14% of GHG emissions, while feeding a growing population and sustaining growth are two of humanity’s biggest challenges. Waste gases like carbon dioxide, carbon monoxide and methane are the major culprits. Carbon capture is becoming a major pillar in developing a sustainable bioeconomy, and companies want to partner with the major emitters of waste gas to turn their costly pollution into a valued product.
Power from pollutants
Capturing carbon and conversion is not a new concept. First generation biofuels used plants to produce sugar first, then fermented those sugars into ethanol which in turn could be processed into biodiesel. Enter next generation biofuels made from the waste carbon itself. Lanzatech is the biggest success story in this area. They produce a sustainable next generation biofuel from steel mill waste gas called syngas. Last year the company announced its first batch of biofuel was used in a commercial Virgin Atlantic flight from Orlando to London.
The jet fuel is derived from ethanol produced by microbes using the syngas as a feedstock. The ethanol is further chemically processed into kerosene to be mixed with petrochemically derived jet fuel. Lanzatech plan to attach their technology to existing industrial processes and produce bioethanol on-site. Fuel is a difficult target product due to its competitive pricing and costly production. Another advantage to joining biotech with synthetic chemistry is the potential to produce other high value petrochemically derived compounds from biofuels, such as ketone compounds.
Pollution into protein
Dr Lisa Dyson of Kiverdi highlights the promise of technology that can convert waste gas into protein. The land equivalent of South America and Africa combined are used for agriculture and a more efficient source of protein must be found. Their technology is based on a closed loop carbon dioxide recycling originally developed by NASA to feed astronauts on long journeys. Their process doesn’t require sunlight and uses far fewer natural resources. “Around two thousand times less water than soy protein production and ten thousand times less land for the same amount of protein,” Dyson explained at the recent Kind Earth Tech conference.
Kiverdi are not the only company developing similar technology. Deep Branch Biotechnology, based in the UK, are using similar process and have partnered with renewable energy providers Drax to begin work on a pilot plant at one of their power stations. Like Kiverdi, they use waste GHGs as a feedstock for a bacterium that converts it to single cell protein. More recently on the scene is NovoNutrients, who found success through IndieBio’s accelerator program in 2018. Founded by Brian Sefton and led by CEO David Tze, the company is backed by veterans from Intrexon, Codexis, Novozymes, Solazyme, and SRI International. They are also converting carbon dioxide to fish food using bacteria.
The fish feed market is popular for several reasons: it is a valuable product for feed producers; bacteria offer immense efficiencies in protein density (around 60-70% dry weight); downstream processing of final product is relatively simple and cost effective. Current fish feeds rely on fish meal made from smaller fish which also must be caught or farmed. Other farms use plant protein which is more sustainable but can disagree with a fish’s digestion and may also cause a build-up of nutrients in the water, a type of pollution called eutrophication, leading to algal blooms and fish kills.
Methane market
Methane is the most notorious waste gas due its potent greenhouse effect. Methane is a common byproduct of oil refineries and other industrial processes, as well as a product of biological decomposition by microbes known as anaerobic digestion. Calysta use methane as a feedstock for gas-fixing bacteria called methanotrophs which turn methane into protein, like plants turn carbon dioxide into sugar for energy. They have successfully produced FeedKind, a single cell protein-based feed for farmed fish which can be manufactured to suit the end user’s need – pellets or powder.
The real manufacturing and scale up hurdles are as much engineering based as biology based. Danish company UniBio, like Calysta, produces single cell protein using methanotrophs, but are targeting the animal feed market rather than fish. Their fermentation technology is the key to their success. Gas fermentation is more difficult than standard fermentations using sugar, due to the inefficiency of gas exchange. However, UniBio’s unique U-Loop reactor technology ensures that the methane gas substrate is efficiently transferred to the bacteria during fermentation.
The field may seem crowded but the aquafeed market estimated to be about $100 B. The next hurdle for carbon capture is scaling the technology in a cost-effective manner so products, such as feed and fuels, can compete on the market. The climate crisis is not going away and novel biotech solutions are getting more attention from funding bodies and savvy investors, ahead of the already growing populations and global temperature increases. Valorization of waste gas to develop a circular bioeconomy will not only allow for more sustainable agriculture and aquaculture, but also help secure food and petrochemically-derived products in the future.
