Carbon capture has received a lot of attention as a climate change-fighting tool. If private companies can find a way to make profitable products from captured carbon, then free enterprise will leverage the marketplace toward climate action instead of against it. Proposed uses have been emerging across a vast array of products and materials, whether in new ways to make traditional materials or in entirely new materials and products.
THE NATURAL CYCLE OF CARBON dioxide in the atmosphere is predictable. The concentration goes up in the Northern Hemisphere winter and goes down in the summer, tiedto the annual growth of vast forests and grasslands. Over the course of a year, the fraction of CO2 in the atmosphere shows a peak-to-troughswing of 6 parts per million.
On top of that cycle there is a trend: The carbon dioxide that is emitted into the air by industriesand other human activity at a rate faster than natural processes can clear it. From the pre-industrial average concentration of 280 parts per million,these activities have added another 135 ppm tobring the average in 2021 to around 415 ppm. Thatexcess 135 ppm in the atmosphere equals just over1 trillion tons of carbon dioxide, or a carbon massof 288 billion tons.
All that excess carbon in the atmosphere is a problem—a crisis, actually. It is also an opportunity. Companies are looking at how to pull downthat carbon and use it to make products.
“Carbon utilization is actually the holy grail of climate action if we can get it to work at scale,”said Peter Minor, a mechanical engineer whooversees innovation at Carbon180, a Washington, D.C.-based think tank. “Instead of thinking ofemissions as pollution, we can turn them into asource of value. That completely changes the incentives around how we deal with CO2.”
Until now, actions to slow the rising concentration of carbon dioxide in the atmosphere have exacted a cost penalty. Wind and solar powerwere more expensive than coal, and methods ofcarbon capture were not only expensive, but alsorequired a sequestration infrastructure to be builtand maintained forever.
Regardless of the science of climate change, as well as the urgency, the market argued for the status quo.
Recently, though, the economics have begun to change. For instance, renewable power is nowcheaper to build in many places than fossil power.If private companies can find a way to make profitable products from captured carbon, then freeenterprise will leverage the marketplace towardclimate action instead of against it.
While the technology of carbon capture and reuse is still very much in its early stages, the scope and breadth of innovation is truly breathtaking.Proposed uses have been emerging across a vastarray of products and materials, whether in newways to make traditional materials or in entirelynew materials and products that are emerginginto the space created by shifting priorities.
The potential resource is also vast. That 288 billion tons of excess carbon in the atmosphere? It is roughly the same as the world proven oil reserves,available for the taking from any point on Earth.Important changes in agriculture also show greatpromise as a means of transferring carbon fromthe atmosphere into the earth.
Getting at the excess carbon dioxide can be easy if you have time. Plants have been using photosynthesis to convert CO2 into solid mass for fueland function for millions of years. Now, a growing number of companies are looking to replacecarbon-intensive materials with biologicallyderived ones to lock up carbon for the lifetime ofthose products, potentially decades or longer.
For instance, small buildings such as singlefamily houses are made of carbon-storing wooden two-by-fours while larger multistory structuresare built from carbon-intensive steel and concrete. Now, however, engineered wood productssuch as cross-laminated timber (CLT) and glulamproduced by several companies are staking aclaim to be negative-carbon alternative to steeland concrete in construction. CLT and glulam arestructural beams made of layers of wood glued together with either parallel or perpendicular grainorientations.
Research has found that engineered wood is strong enough to support taller buildingsthan was previously thought possible. A recentlifecycle assessment study comparing twoidentical five-story building designs, one usingwood and the other concrete for the frame,found that while the two buildings took the sameamount of energy to build, the wood laminatebuilding embodied 44 percent more captured carbon.
Other plant-based building materials include structural insulating panels made of compressedwheat straw by Agriboard of Vernon, Texas, andWillows, Calif.-based CalPlant’s fiberboard madefrom rice straw. JustBioFiber of Airdrie, Alberta,makes a hemp-based insulating structural blockthat’s far less expensive than concrete with amuch lower carbon footprint. Similarly, severalcompanies produce hempcrete, which containshemp and mineral binders that absorb carbonduring its curing process. It can be cast in place, purchased as blocks, or used as insulation.
There are carbon-negative opportunities indoors as well. Apart from traditional wood andplant-based furniture and textiles, Green Island, N.Y., startup Ecovative is making insulation andsynthetic leather (as well as food and packaging)from processed mushroom mycelium. Flooringmanufacturer Interface has reduced the carbonfootprint of its carpet to the point wherebysimply adding some bio-based materials to theirbacking, they are now selling the world’s firstcarbon-negative carpet tile.
Newlight Technology is going even further back in the evolutionary scale, while gettingmore high-tech. The Huntington Beach, Calif.,company has spent the past decade developinga means to harvest polymers from bioreactor-grown microbes.
“In the ocean, there are microorganisms that eat both methane and carbon dioxide as theirfood source. In fact, these organisms played a keyrole in cleaning up the methane from the Gulf oilspill,” said Mark Herrema, Newlight’s CEO. “Theorganisms produce PHA (polyhydroxyalkano-ates) in their cells for energy storage. We use ahigh-pressure filtration system to separate thebiomass from the polymer. The polymer is thendried and extruded into pellets.”
An independent evaluation by Carbon Trust to calculate and certify the cradle-to-gate productcarbon footprint of the polymer, marketed asAirCarbon, found that “for every kilogram ofAirCarbon produced in Newlight’s productionprocess, 88 kilograms of CO2e (obtained frommethane seeping from abandoned coal mines) aresequestered.”
The company recently opened a 40,000-sq.-ft. factory to produce the ocean-degradable plasticfor use in food ware, straws, eyeglass frames, and a leather-like material that can be used for wallets, phone cases, and other consumer products.
“It’s exciting to have a product made from greenhouse gas in people’s hands where they cansee that carbon doesn’t have to go into the air,”Herrema said.
Other engineered systems skip biology altogether and start with physics and chemistry. Carbon dioxide gas is already a commercial product, created as a by-product of industrial processes,such as the conversion of methane and atmospheric nitrogen into ammonia or as the resultof fermentation of corn into ethanol. It is soldfor use in carbonated beverages or enhanced oilrecovery. According to a recent market researchreport, the global carbon dioxide market was$9.68 billion in 2020.
Capturing that CO2 is good because it avoids venting it directly into the air. Drawing from thecarbon reserve in the atmosphere requires developing a human-made method of harvesting it.Companies such as Carbon Engineering, GlobalThermostat, and Climeworks have been workingon direct-air capture machines for some time, butthe technology is still expensive and inefficient.
The promise is great, however, as Klaus Lack-ner, a professor at Arizona State University in Tempe has said, “An artificial tree can collect carbon 1,000 faster than a real tree.” That’s a crucialfactor when you consider the time scale needed,the fact that available land for tree-planting hasnumerous constraints, and the fact that those “trees” could potentially be mass-produced andthen placed anywhere.
If direct-air capture is difficult and fast, the further challenge lies in what to do with thatgas. For decades, the default has been to sequester it in geological formations. Using a differentapproach, Planetary Hydrogen in Ottawa electrolyzes seawater for hydrogen, but then addsa mineral salt to the electrolysis cell to make amineral hydroxide. That chemical will absorbatmospheric CO2—as much as 40 kg for every 1kg of hydrogen produced, the company says. It’sa speeded-up version of a naturally occurringprocess for scrubbing out atmospheric carbon.
If the electrolysis is powered by clean energy, the process results in carbon-negative hydrogen. In the end, though, the by-product wouldstill need to be dumped. Finding a market for itwould transform carbon capture from remedia-tion—which is a cost to be borne by polluters orsociety—into a type of mining.
Since there’s only so much soda that people can drink, chemical companies are looking for newways to convert carbon dioxide into products. Forinstance, Calgary-based Carbon Upcycling takesgaseous CO2 and embeds it into inorganic powders. “It’s a low-temperature batch adsorptionprocess, produced in a rotating pressure vessel,”said Madison Savilow, the company’s chief of staffand the venture lead of its commercial arm, Expedition Air. Because the process does not requirebreaking the CO2 bond, she said, their processrequires less energy than many others.
The company offers polyethylene, graphitic nanoplatelets, and talc with embedded CO2 content as high as 25 percent.
Other companies are also producing materials from recycled CO2 rather than other carbon feedstock. Richmond, Calif.-based Saratoga Energyuses a molten carbonate electrolysis process toconvert carbon dioxide into carbon nanotubesand oxygen. According to the company, theprocess cuts costs dramatically and would havea negative carbon footprint once it is powered byrenewable energy. German chemical companyCovestro produces cardyon, a precursor materialin the manufacture of polyurethane foam, via aprocess that uses CO2 as a feedstock; the materialis up to 20 percent carbon dioxide.
Perhaps the biggest opportunity to utilize CO2 is in the building sector. Some 12 percent of human greenhouse gas emissions are the result ofconstruction and the materials incorporated inbuildings. Little wonder that builders are underpressure to reduce the carbon footprint embodied in buildings.
But the size of the challenge in the building sector also points to the magnitude of the opportunity. After all, due to their mass and relativepermanence, buildings made from carbon-storing materials could lock up a great deal of carbondioxide.
Concrete is likely the biggest opportunity for carbon utilization, since the constructionindustry uses so much of it. Some companies thatare processing concrete in ways that absorb CO2include Carbon Cure, Solidia, LafargeHolcim,and Blue Planet. (See “Cutting the Carbon fromConcrete,” February 2020.)
One recent development has been hybrid concrete. Wil Srubar, a civil engineer at the University of Colorado, has created a scaffold fromsand and a nutrient-rich hydrogel that supportedthe growth of cyanobacteria. As the bacteriagrow, they deposit the minerals that form “livingmaterials” not unlike coral. Srubar’s researchteam said the material demonstrates strengthsimilar to cement-based mortar. According toone press report, if you break one of these livingbricks apart, the bacteria can use additional sand,hydrogel, and nutrients to essentially grow twocomplete bricks.
BioMason of Research Triangle Park, N.C., takes a similar approach to make a bio-cementfrom limestone grown in ambient temperature;the company sells a carbon-neutral, fully recyclable limestone tile that it claims is three timesstronger than concrete block.
Realistically, though, such materials would be used as an offset for carbon-intensive processes.Chris Magwood of the Endeavour Center, asustainable building school in Peterborough, Ontario, said that to achieve the net-zero target thatso many builders are now striving for, “you needto balance the carbon-storing materials withthose that inevitably have emissions.”
A major tool that has recently been developed to help builders with this is the Embodied Carbon in Construction Calculator (EC3) createdjointly by the Carbon Leadership Forum and theinternational construction firm Skanska. TheEC3 tool provides detailed information on theembodied carbon of more than 16,000 materials,including concrete, steel, wood, glass, aluminum,insulation, gypsum, carpet, and ceiling tiles, allbased on environmental product declarationspublished by their manufacturers.
Before the EC3 tool, Magwood said, designers “would need to obtain lifecycle analysis data foreach material selected, often relying on costlyconsultants. LCA is essential for understandingembodied carbon.” Now, this information is readily available.
“This is a journey,” said Stacy Smedley, director of sustainability at Skanska. “We’re probably on the second leg of a multi-leg journey when itcomes to carbon-storing products in the buildingindustry.”
Climate change is a problem of unprecedented scale and complexity. There is no single silver-bullet solution. The best chance of success willinvolve not simply walling off a set of climateactions, but incorporating solutions into everyaspect of what we do, including buying everydayitems. That train has already left the station andis gathering speed with each passing day.
The level of carbon dioxide in the atmosphere has been increasing relentlessly since the beginning of the Industrial Revolution, an unintendedoutput of our economic engine. To bring thoselevels down, industry must find ways to use thatwaste stream as an input.