Part III: Feedstocks of the Circular Economy
Credit: Dall-E
Part III: Feedstocks of the Circular Economy
Written by Noah Helman, PhD, CEO. Industrial Microbes invents new sustainable manufacturing methods using synthetic biology and partners with the world’s leading chemical producers to bring them to market.
The issue of climate change is forcing us to restructure the most basic elements of our economy. People will continue to want (1) the same (or better!) products that we have today, (2) made with minimal carbon footprint, and (3) at equal or lower prices. We must recognize that our current system is incapable of reaching these three goals together. To have cost-competitive carbon-neutral products inevitably requires a fundamental rewiring of our chemicals and materials supply chain, from feedstock to product. Ninety-five percent of manufactured goods rely on chemicals, with petroleum the main raw material. In our first post, we discussed how oil supply will shrink, leading to higher petrochemical prices. Here, we tackle the question of ‘feedstocks of the future’: If we’re not using oil, we will have to make everything starting from different raw materials. Where will we get the atoms from which to build our materials? Given the size of the chemicals and materials markets, this is, quite literally, the trillion-dollar question.
Today’s Linear Economy Will Be Replaced by a Circular Economy
Every Monday night, I put 3 bins on the curb outside my house. They are headed to a landfill, a recycling center, and an industrial composter. Of course, my family tries to minimize what’s in the garbage bin, destined to be buried in a giant hole in the ground, but NPR and others have reported that only about 5% of plastic is recycled, while the rest ends up in a landfill anyway.
My home is a microcosm of the larger economy. To support our first-world lifestyle, we consume all sorts of things – food, clothing, toys, gasoline, natural gas, plus many plastic-wrapped items that arrive in gas-powered trucks – and we generate a spectrum of waste including garbage, recycling, and compost, plus the wastewater and carbon dioxide. This is the Linear Economy we have today: a mix of raw materials harvested from the Earth, made into finished products (using mostly fossil fuel-derived energy), and then thrown away, flushed down the toilet, or belched into the atmosphere.
At a global level, this is obviously unsustainable – we can’t dig stuff out of the ground forever. At some point, we must shift to a Circular Economy, in which we recycle nearly all of our waste back into raw materials (a.k.a. “feedstocks”), using renewable energy. Given the scale of our global economy and the degree to which petroleum and its derivatives touch every industry, it would be difficult to overstate the size of the challenge and the corresponding economic opportunities this will create.
In imagining a Circular Economy, we can take inspiration from Nature. A cherry tree produces hundreds of blossoms to make another tree; these blossoms are not waste, they are beautiful and they decompose into nutrients for other living things. The “waste” products of one organism are the food for another, with sunlight being the ultimate source of input energy. Just as the living world had evolved natural cycles before modern society disrupted the balance, we must learn to reconstruct our material economy to become more circular. What is the lowest cost way to use renewable energy and waste materials as the inputs to our factories?
The Circular Economy Requires More than Just Recycling
In a Circular Economy, wastes are converted to new products, ideally with the minimum energy input and at minimum cost. Isn’t that what we are doing with my recycling bin – sending off used objects to be turned into new products? Recycling glass, metals, and paper seems to work. But unfortunately, recycling most other materials doesn’t pencil out financially. For example, there’s no practical way to deal with mixed waste. Sorting it into pure streams kills the economics. A second problem is the quality of the recycled product. Some plastics can only be recycled a few times before the material properties are so impaired as to be nearly useless.
The pragmatic solution is to break down the large number of complex molecules into a small number of simple molecules. Creating just a handful of feedstocks as the building blocks of the Circular Economy will standardize the system, simplifying logistical issues and resulting in more flexibility and lower cost. In fact, to a certain extent, we are already implementing the breaking-down process. A few proven techniques deconstruct the diverse waste stream into C1 molecules (i.e. those with only one carbon atom). Let’s walk through the different methods and resulting feedstocks.
Mixed Organic Waste Degrades Naturally into Methane and CO2
In the absence of oxygen, a process called anaerobic digestion breaks down diverse complex organic molecules into just two simple C1 molecules, methane (CH4) and carbon dioxide (CO2). Unfortunately, these gases cause global warming when released to the atmosphere, so many landfills, farms, and wastewater treatment plants are emitting GHGs.
The IEA estimates that the world potential supply of biomethane is about 700 million metric tons per year. If it were possible to convert this back into petrochemicals, it alone could supply about ⅓ of the total renewable chemicals demand. Most of this resource is currently being wasted and contributes to global warming. When it is captured at all, biogas is almost exclusively used for heat and/or electricity, an approach that will be less economically competitive as renewable electricity and heat pumps continue to decrease in cost. Generally speaking, burning stuff is a low-value use.
Mixed Garbage Can Be Converted to Syngas, Methanol, and even Ethanol
For diverse municipal solid waste (MSW), engineers have designed “gasification” reactors to break down the diverse mix of garbage into syngas, a mixture of carbon monoxide, carbon dioxide, and hydrogen. Syngas can be converted into fuel (e.g. linear alkanes) using the Fischer-Tropsch reaction or methanol with the addition of hydrogen. Syngas fermentation can produce ethanol, a technique commercialized by companies such as Lanzatech.
Putting Carbon Dioxide To Work
Carbon dioxide is the waste product of so many industrial processes. Since we do not want it polluting the atmosphere, it would be great to use as a chemical feedstock. However, making useful products from CO2 requires added energy and hydrogen atoms. Just as plants need the energy from sunlight to capture CO2 via photosynthesis, chemical syntheses need to add energy to build carbon-carbon and carbon-hydrogen bonds.
Several approaches use hydrogen to chemically reduce CO2 to a more useful feedstock such as formate, CO, methanol, or methane. In fact, the process of combining CO2 and H2 into methane and O2 was invented in 1897 by Sabatier and Senderens. Sabatier reactors are so robust that the International Space Station tested one to recycle CO2 back into O2 for the astronauts to breathe using this chemistry. The methane was vented into space as a waste product.
Electrochemical approaches to convert CO2 to syngas or methanol are also under development. If catalysts can be developed that can achieve high selectivity and high energy efficiency, then electrochemistry may rapidly change the landscape of feedstock options.
C1 Molecules are the ‘Rebuilding Blocks’ of the Circular Economy
Using existing technologies, a huge fraction of our waste can be turned into C1 molecules. These C1’s will be the common currency of the waste processing arm of the circular economy – the ‘rebuilding blocks’ from which complex molecules are made.
This vision for circularizing the economy has focused on the question of how we can take society’s waste products and turn them into chemicals and materials. Breaking our wastes down into C1 rebuilding blocks gets us part of the way there, by converting complex mixed waste into simple molecules. From there, we can build back up – from C1 molecules to the myriad of chemicals and materials we use today.
How Will We Make Products from C1 Molecules?
The convergence of these three megatrends – the global macroenvironment (Part I), the electrification of chemical synthesis via biocatalysis (Part II), and C1 molecules as the feedstocks of the Circular Economy (Part III) – is backdrop against which we have built Industrial Microbes.
Although there are chemical methods that use C1 molecules, these suffer from high energy use and high cost. Fermentation using microbes is a newer alternative. Technoeconomic modeling convinced us that C1 fermentation will win on cost and GHG footprint.
Our platform technology enables the fermentation of methane and methanol into dozens of drop-in replacement chemicals that can reduce carbon emissions and lower costs at the same time. In order to maximize our impact (i.e. the amount of avoided emissions), we must develop a low-carbon technology that can win head-to-head on cost. By focusing on reducing the two main costs of industrial bioprocessing (feedstock and purification), methane fermentation can become an important force for dramatically reducing the emissions of the chemicals and materials industry. In doing so, we will leverage our platform to capture a significant fraction of the $200B total addressable market.
Methane Fermentation Already Works at Scale
Methane has rather low solubility in water, so many folks in the fermentation industry are worried that it cannot work. In fact, it has been proven to work at scale multiple times, and in the next article, we’ll dive into those stories to understand how they overcame the challenges.
Loved or hated this post? Tell Noah at hello@imicrobes.com.
About us
Industrial Microbes is developing carbon-negative materials to enable the transition to a circular economy and to reduce the carbon footprint of the chemical industry. We build microorganisms that make chemicals and materials from methane, a greenhouse gas 81x as potent as CO2. Our team has been working to decarbonize chemical production for decades and this series of articles will share our perspective on the massive changes we see coming.