Out of Thin Air

Vox, the popular United States media site, had an insightful column this past September about what the world needs to do if it has any hope of keeping planetary warming in check. 

Step one: kick fossil fuels off the power grid. Step two: Electrify everything.

The idea is to take anything that currently relies on solid, liquid or gaseous fossil fuels and have them run on clean electrons. This means buildings, industry and transportation. According to a report from the Deep Decarbonization Pathways Project, a global collaboration of energy research teams committed to reducing greenhouse gas emissions in their own countries, 100 percent of all light-duty vehicles in Canada would need to go fully electric by 2050 if we have any hope of meeting our national commitments under the Paris climate agreement. 

Adrian Corless, CEO of Squamish, BC-based Carbon Engineering, doesn’t argue with that point. He’s all for electric cars. They’re clean, efficient and getting better every day, Corless says. But his support for electrification begins to wane when discussion turns to big trucks, big equipment and big airplanes — powerful machines that, because of their intense hunger for energy, aren’t well suited to operating on batteries alone. “There’s probably 40 to 50 percent of the transportation sector that’s unlikely ever to electrify,” Corless says.

From a climate perspective, it’s a market gap that Carbon Engineering is looking to fill. Established in 2009 by former University of Calgary professor David Keith, the company has the ambitious — and some say crazy — goal of capturing carbon dioxide out of thin air. But on top of that, it wants to use that CO₂ and, along with hydrogen generated from renewable sources, convert it into an ultra-low carbon but energy-dense synthetic fuel, the kind you can use to run semi-trucks, buses and commercial aircraft. “It would be compatible with the infrastructure that’s out there today,” says Corless, explaining it would be a “drop-in” fuel that could be blended incrementally with conventional diesel or jet fuels at any ratio.

Carbon Engineering wouldn’t be the first to attempt turning CO₂ into a useful product. In September 2015, for example, Canada’s Oil Sands Innovation Alliance (COSIA) and US power generator NRG Energy announced themselves as sponsors of a $20 million Carbon XPrize. Forty-seven teams from seven countries will spend the next four years trying to come up with the best way to use CO₂ to make high-value products, everything from fuels and plastics to fertilizers and fish food. “Such widespread interest and support demonstrates an unwavering global commitment to take a radical leap forward to address climate change,” says Paul Bunje, a senior scientist with the XPrize Foundation.

Carbon Engineering didn’t apply, nor could it. Contest guidelines required that flue gases from a coal- or natural gas-fired power plant be used as the source of CO₂ emissions. Direct-air capture didn’t count because it doesn’t perpetuate society’s reliance on fossil fuels, Corless says. “In Alberta, it’s all about doubling down on fossil-fuel assets so they can be competitive. But to us, if you’re not thinking of all fuels as a utilization of CO₂ then you’re not going to make a dent in the climate problem.” 

Carbon Engineering opened its direct-air CO₂ capture demonstration plant in Squamish, BC in October 2015. The facility is the largest of its kind and proves that it’s possible to chemically capture CO2 from the air more efficiently than trees and plants. The next step for the company: turn that CO₂ into synthetic liquid fuel. Photo credit: Carbon Engineering

Making a Dent

After seven years, and with financial backing from tech billionaire Bill Gates and Canadian oil sands mogul Murray Edwards, the company has made significant progress. At the same time, the politics around climate action — in Canada and abroad — have grown much more favourable. “I’m more excited now than when we started,” says Keith, currently a professor of advanced physics at Harvard University.

A year ago, the company flicked the switch on its first demonstration facility, showing the world that direct-air capture of CO₂ isn’t just a neat idea on paper. Chemistry, of course, lies at the heart of this multistep, continuous process. The air that we breathe contains only 0.04 percent CO₂ and to use it as a feedstock for fuel requires that it be pure. “To go from 0.04 per cent to 100 percent is three orders of magnitude of concentration and you can’t do that in one step,” says Corless. 

The company starts with a cooling, tower-type structure called an “air contactor,” which is packed with sheets of corrugated plastic designed to maximize air-surface contact. A strong alkaline solution made up of potassium hydroxide is dripped from the top of the structure onto the corrugated sheets such that the surface is completely coated.  

While this is happening, industrial fans suck in outside air and blow it across the solution-soaked sheets. The CO₂ in the air is absorbed into the solution to create potassium carbonate, which drips to the bottom of the structure and is carried away to the next step.  

At this point, the collected solution is only about two percent CO₂ by weight. To get it to 44 percent, it interacts with calcium hydroxide in a machine called a pellet reactor. Two products emerge from this reaction: potassium hydroxide, which is sent back to the air contactor for reuse, and calcium carbonate pellets (i.e. synthetic limestone), which resemble white candy sprinkles used to decorate cupcakes. “The most energy-intensive step comes next,” says Corless. This final step involves sending the pellets into another machine called a calciner, which is basically a modified cement kiln. The pellets are heated to 900 C, causing them to break down into CO₂ gas, which is collected, and calcium oxide, which is mixed with water to create calcium hydroxide that can be reused in the previous step. “When we do that final step of heating those pellets up, that’s when we get to that 100 percent CO₂,” he says.

Getting that heat comes with an additional carbon penalty — at least for now. Carbon Engineering uses natural gas to drive the calciner process. But Corless says that the demonstration plant was designed to get the most out of that gas. Waste heat from the calciner is used to generate electricity that helps power fans and pumps. As well, the CO₂ that results from burning the natural gas is mixed with the ambient air that flows through the air contactor, so it is ultimately captured and becomes part off the company’s pure CO₂ stream. Over time, this will improve. The company is also investigating using solar thermal and nuclear energy as potential zero-carbon sources of heat.

Adrian Corless, CEO of Carbon Engineering.

Carbon Engineering was founded by Harvard University advanced physics professor David Keith, a former Canada Research Chair in Energy and Environment at the University of Calgary. 

Putting CO₂ Back to Work

Indeed, when it comes to the next stage — taking all that CO₂ and turning it into fuel for today’s long-haul trucks and jets — having access to cheap, zero-carbon electricity is essential. Here, hydrogen produced through renewable-generated electrolysis of water is brought in as a dance partner for CO₂. “They’re the main ingredients necessary to create long-chain hydrocarbons like gasoline and diesel. They embody the energy in the ultimate fuel we’re producing,” says Corless. “But the first thing you need to do is knock an oxygen off the CO₂ to create carbon monoxide (CO).” 

This is done using a high-temperature catalytic process. The company is in the process of developing a reactor technology and special catalyst that would bring more efficiency to what is normally an energy-intensive step. After that, there are relatively well-established processes to turn that CO and hydrogen into a liquid hydrocarbon such as synthetic gasoline or diesel.  

One popular catalytic approach is the Fischer–Tropsch process, which petroleum-poor Germany used during the Second World War to make fuel for military and civilian vehicles. Carbon Engineering is leaning in that direction but using another modified catalyst that works more cost-effectively.

The “neat” factor to all of this is obvious but can it really compete against conventional diesel? A handful of companies in the past have tried to create “petrol from air” on a very small scale, including United Kingdom firm Air Fuel Synthesis and, more recently, a research group led by German car manufacturer Audi. “There is no question about technical viability,” writes chemical engineer Robert Rapier, author of Power Plays: Energy Options in the Age of Peak Oil. “The question boils down to economic viability.”  

On this front, Carbon Engineering has no shortage of skeptics. The fact is, it’s far easier to let the cat out of the bag than to stuff the struggling, claw-exposed creature back in. Likewise, getting CO₂ and water from diesel involves striking a match and lighting the fuel on fire. But capturing CO₂, separating hydrogen from water and then combining the two back into diesel? More energy will go into making the fuel than the energy contained in the fuel itself. Even worse, if you burn that fuel in a truck, two-thirds of it will be discarded as waste heat because of the inefficiency of internal combustion engines. It’s yet another good argument for direct electrification. “We’re not trying to pretend that’s not the case,” says Corless. Ultimately it comes down to setting priorities in a carbon-constrained world where all-out electrification has its limitations, Corless adds. The focus shouldn’t be so much on energy in versus energy out. The bottom line is, he says, can it be cost-competitive with conventional diesel in an economy that properly values low-carbon alternatives?

At large-scale production, and based on an industrial electricity rate of four cents per kilowatt-hour, Corless estimates that Carbon Engineering could produce its synthetic diesel for about $1.10 per litre, versus a wholesale cost of 50 to 60 cents for regular diesel today. But solar power could prove a game-changer, with costs expected to fall to two cents per kilowatt-hour. And if the price of oil climbs back to $100 per barrel, suddenly the economics get interesting. “Once we’re there, why would anyone bother taking oil out of the ground anymore?” Corless says. 

Carbon Engineering produces pure CO₂ from the air using a three-step process. First, it captures CO₂ existing at a concentration of 0.04 percent in air with a strong alkaline solution that after capture contains approximately two percent atmospheric CO2 by weight. It then gets to 44 percent by reacting that solution with calcium hydroxide to produce calcium carbonate pellets. Finally, it heats those pellets to 900 C, releasing 100 percent CO2 gas. Photo credit: Carbon Engineering

Political Will and Scientific Breakthroughs

Then there’s the wild card of future carbon pricing, which is currently a hot topic of debate in Canada. Asked if a price on carbon of $100 a tonne would be enough for Carbon Engineering to compete commercially, Keith replys: “That’s getting pretty damn close.” The company could also further reduce costs in other ways, through what Keith describes as “creative and effective application of existing industrial processes.” And while the path from chemistry breakthrough to practical commercial application is long, Keith certainly welcomes it. “For us, the breakthrough would be something that dropped the capital cost of water electrolysis.”

Researchers at the University of Toronto are working on it as part of an international collaboration. Earlier this year they announced success with a new catalyst made of tungsten, iron and cobalt that, when used as a booster for water electrolysis, proved three times more efficient and much more robust than the best — and significantly more expensive — precious metal-based catalysts. Their work, led by engineering professor Ted Sargent, was published in Science this past March.  

Another energy-intensive process that could benefit from a breakthrough is the reduction of CO₂ to CO. Here, the Sargent team and another U of T team led by chemistry professor Geoffrey Ozin have come up with different approaches. 

Phil de Luna, a PhD candidate who works under Sargent, says his team uses an electrochemical process to coerce otherwise inert CO₂ molecules into a reaction. To make the reaction more efficient, they developed a gold catalyst with sharp nano-sized “needles” that protrude from the surface of an electrode. “They act as lightning rods,” says de Luna, explaining that this creates a high electric field that both attracts the CO₂ and causes it to give up an oxygen more easily and faster than previous catalysts. Their work was published this past August in Nature. 

The same month, Ozin’s team described a promising photocatalyic approach in a paper published in Nature Communications. It relies on hydride-terminated silicon nanocrystals, which efficiently and selectively convert CO₂ to CO when exposed to sunlight — no external electricity or high temperatures required. “It is indeed a surprising yet welcome discovery,” the paper states. Since silicon is an abundant, non-toxic and inexpensive material, the approach could one day drive down costs for a company like Carbon Engineering.   

Corless truly believes that what his company is doing has the potential to change the geopolitics of energy, which has favoured countries that are naturally blessed with an abundance of fossil fuels. Energy-poor developing countries with strong solar assets, for example, could eventually have a way to meet their own transportation fuel needs as well as meet international climate obligations without relying on imports from Russia, the Middle East and other unstable regions. “We see this much more as a global solution,” says Corless, adding that it could also prove a strategic opportunity for Canada as a world still hungry for liquid fuels begins to transition from the fossil kind.