HUNTSVILLE, Ala. - At the end of a cul-de-sac called Fresh Way, two bright green structures the size of shipping containers gleam in the warm sunlight, quietly sucking from the air the carbon dioxide that is warming the planet.
One structure houses computer monitors and controls. Atop the other, large fans draw air through slabs made of honeycomb-style ceramic cubes. The cubes hold proprietary chemicals that act like sponges, absorbing carbon dioxide at room temperature. Every 15 minutes, the slabs rotate and the cubes are heated, releasing a stream of 99 percent pure carbon dioxide into a shiny steel pipe.
This is Global Thermostat, one of just three companies at the leading edge of the hunt for ways of skimming carbon dioxide from the air. It is a tiny step, but a hopeful one, toward reducing global warming. Amid a steady drumbeat of grim news about climate change, more and more people are captivated by the idea that a feasible process can help offset decades of damage to the atmosphere.
Some big deep-pocketed corporations - including oil companies - are looking, too. They are lured not so much by the virtues of fighting climate change but by the prospects of making money. Though long a prohibitively expensive technology, carbon capture has become a tantalizing possibility thanks to technological advances - and new generous government incentives.
There's little time to spare. The Intergovernmental Panel on Climate Change has written that any hope to meet the 2 degree Celsius goal for global warming "will require measures to reduce emissions, including the further deployment of existing and new technologies."
For a decade, the three companies - Carbon Engineering, Climeworks and Global Thermostat - have experimented with technologies such as the shape and chemical makeup of the spongelike membranes in an effort to reduce the towering cost of capturing carbon dioxide directly from thin air.
Now their work is poised to move beyond the lab tables and prototypes.
"Our business plan is to show that cleaning the atmosphere is a profitable activity," said Graciela Chichilnisky, a Columbia University economics professor and one of the co-founders of Global Thermostat who estimates that CO2 could become a trillion dollar market.
Over the past several years, the firms have vied to make technological progress. The cost of carbon capture has fallen from $600 a ton to as low as $100 a ton - and lower if a cheap or free source of heat or energy is available.
Federal subsidies are just as important. New U.S. federal tax credits provide as much as $50 for every ton of carbon dioxide captured and stored underground in well-sealed geological formations.
Oil companies can use the credits to pay for turning captured carbon dioxide into transportation fuels, essentially recycling the CO2. That would help Big Oil meet California regulations requiring lower amounts of carbon in motor fuels.
And the oil giants can also claim a $35-a-ton credit for enhanced oil recovery - injecting carbon dioxide into the ground to increase well pressure and boost oil production in old fields like the Permian Basin in west Texas. Oil companies currently extract natural carbon dioxide from natural reservoirs before pumping it back into the ground.
The federal tax credits, known as 45Q credits, were slipped into the 2018 federal budget in the wee hours of Feb. 9, 2018, after a nine-hour government shutdown. It attracted support from both parties, with leading roles played by Sen. John Barrasso, R-Wyo., whose state relies heavily on oil, gas and coal production, and Sen. Sheldon Whitehouse, D-R.I., who has spoken almost weekly on the Senate floor about the urgency of climate change and the danger of burning fossil fuels.
One reason they agree: It's politically more appealing to give away money through a tax credit than it is to impose a carbon tax that takes money away. A carbon tax is levied on the carbon content of hydrocarbon fuels such as coal, oil or natural gas that emit carbon dioxide and it raises prices for products such as gasoline or electricity.
Environmentalists are divided on the tax credits. Most want to bury captured carbon dioxide in geological formations underground rather than using it to produce more fossil fuels.
"We concluded that it was not possible to square it with our work to end fossil fuel subsidies," said David Hawkins, director of climate policy at the Natural Resources Defense Council, which stayed neutral on the measure.
But of the 65 million tons of carbon dioxide that is pumped underground in the United States every year, about 60 million tons is for enhanced oil recovery, said Sally Benson, co-director of Stanford University's Precourt Institute for Energy. And demand is growing.
Whitehouse said "at this point, the only revenue proposition for carbon capture is enhanced oil recovery."
"As angry and frustrated I am at the behavior of these companies," he said, "if that's what it takes to save the planet I'm willing to make that investment."
And Republican senators joined in the name of "innovation," and seemed unbothered that by putting a price on the credits they were flouting the Trump administration's effort to stymie any form of carbon tax.
"People now understand the need for addressing climate change," Carbon Engineering's chief executive Steve Oldham said in an interview after testifying before a Senate committee. "When you don't have a solution, it's a scary thought."
"We're trying to get the message out that there is a solution here," he added, "and it is not forcing everybody to buy a new car or stop taking airplanes."
A new skill set
Oldham himself is a sign that carbon capture is closer to becoming a business. He only recently took the helm at the 10-year-old Carbon Engineering, which has built a prototype on a scenic spot near an old lumber town about 30 miles north of Vancouver. Oldham wasn’t an expert on carbon capture, but he had worked at a big Canadian tech company raising money from government and commercial sources for complex projects such as large satellites and robotics.
Carbon Engineering "has been R&D focused," Oldham said. "Now, they need a different skill set."
The Squamish, British Columbia-based firm's early investors included Bill Gates. And Carbon Engineering recently raised $68 million with investments from tar sands financier and Calgary Flames co-owner Murray Edwards, Occidental Petroleum's Low Carbon Ventures, Chevron Technology Ventures, and BHP, an international mining and resources giant.
Oldham said the firm will use the money to design a full-size commercial plant and that it has already identified fives sites in the United States and two in Canada.
Drawing on research at the University of Calgary and Carnegie Mellon University, Carbon Engineering converts carbon dioxide into transportation fuels. It does that by combining CO2 with hydrogen - creating a carbon neutral cycle. That could help oil companies meet California's requirement to reduce the carbon intensity of motor fuels by 20 percent by 2030.
Harvard University engineering and public policy professor David Keith, acting chief scientist and a board member at Carbon Engineering, estimated in a paper last year that using current know-how and existing components, the company could capture carbon dioxide at $94 to $232 a ton. Even if Carbon Engineering's technique is expensive, it might still be cheaper than alternative methods of meeting the California standards.
In addition, by producing fuel, Carbon Engineering could make air travel carbon neutral without having to turn to biofuels or electrification that would be difficult to use in aircraft.
"It gives you choices," Oldham said.
Selling some fizz
Climeworks, based in Switzerland, was founded by two engineering graduate students, Christoph Gebald and Jan Wurzbacher. It became the first company to extract CO2 from the air and sell it to a commercial customer, albeit on a tiny scale. It sells about 900 tons a year - the equivalent of emissions from 200 cars - to a commercial greenhouse near Zurich that grows vegetables. The company has erected a vertical array of 18 fans, each the size of a full-grown adult that helps speed the capture process. The CO2 increases the greenhouse’s crop yields by 20 to 30 percent.
Climeworks has also forged an agreement to sell carbon dioxide to Coca-Cola HBC in Switzerland for sparkling drinks. Economics could drive future decisions. Last year Europe suffered carbon dioxide shortages when some British fertilizer plants that produce CO2 as a byproduct unexpectedly closed down for maintenance and Coke's CO2 supplies were threatened.
Like Global Thermostat, Climeworks traps CO2 simply by exposing a filter to air. The filter contains amines, a derivative of ammonia. Once the filter is saturated, it is heated with steam past the boiling point of 100 degrees Celsius, hot enough to free the carbon dioxide so it can be pumped into pipes or storage tanks. Currently, the Climeworks uses free waste heat from a local incinerator, reducing its costs.
Farming the sky
Global Thermostat has a somewhat different model than the other two.
The company is the brainchild of two Columbia University professors: Chichilnisky, an economist and mathematician who took part in the 1990s climate conference in Kyoto, and Peter Eisenberger, an applied physicist who has worked at Bell Laboratories, Exxon, Princeton and now Columbia University. With his flyaway hair, he bears a passing resemblance to Dr. Emmett Brown from the film "Back to the Future."
"When Peter and Graciela first talked about this, people thought it was crazy," said Miles Sakwa-Novak, the plant's young engineer. He says that Carbon Engineering essentially takes two mature processes and combines them in a new way, but that Global Thermostat is developing something new.
"We literally farm the sky," Chichilnisky says in a company video.
The company's early investors included the Canadian tycoon Edgar Bronfman and the utility NRG, one of the biggest U.S. emitters.
The company's process uses devices called monoliths that look like sponges to maximize surface area. That area is covered with amines, the nitrogen based chemical that naturally absorbs carbon dioxide from the air. The monoliths are similar to those used in catalytic converters and Chichilnisky says that the manufacturer Corning has provided key materials.
The next step - prying the carbon dioxide loose - is harder and more expensive. Yet Global Thermostat only needs to heat up its amine cells to 80 degrees Celsius, less than what it takes to boil a cup of tea, lower than its competitors and thus relatively cheaper.
This is the dark secret of virtually all carbon capture techniques: They tend to use large amounts of energy, which adds to carbon emissions and costs. Some say they can be combined with solar installations. So far, Carbon Engineering has tapped into cheap Canadian hydro power.
Many analysts wonder why the direct air capture companies don't place their devices near the exhaust of a natural gas or coal plant. Chichilnisky explains that sometimes lower concentrations work better, just as gasoline in a combustion engine needs oxygen. She said that their process requires less energy and works best at concentrations found in the air at 400 parts per million, 300 times more diffuse than in power plant smokestacks.
The compact size of the Global Thermostat project could be part of its appeal, Chichilnisky says. Companies with modest CO2 needs - such as soft drink bottlers or oil field service firms - can move Global Thermostat's equipment to a site without having to worry about building pipelines. Global Thermostat is already in talks with a soft drink maker and a major oil company.
Chichilnisky is optimistic about Global Thermostat, but she’s worried carbon capture will be too little too late. “The real problem with climate change is time,” she says.
Time and scale. The carbon capture enterprises are minuscule compared to the global crisis.
In 2018, mankind pumped about 37.1 gigatons of carbon dioxide into the air. One of Global Thermostat's container size units would capture just 4,000 tons; to offset all global emissions would take 9 million of the units.
Climeworks says it can manufacture 100 to 150 CO2 collectors a year, each one capable of sucking up the emissions of 250 cars. A unit with six Climeworks filters would fit in a shipping container. In order to meet its goal of capturing 1 percent of growing global emissions, Climeworks would need to fill up 750,000 shipping containers.
Arguing that is doable, Climeworks notes that it is equal to the number of shipping containers that pass through Shanghai harbor every two weeks.
Carbon Engineering is planning on much bigger projects, each costing close to $600 million, about the same as a coal-fired power plant. Oldham estimates that it would take 5,000 of his company's plants to offset U.S. carbon emissions - 5.3 gigatons - at a cost of $3 trillion. That's why, he says, "the real answer is a combination" or cutting emissions and building carbon capture.
What that means, Chichilnisky says, is that the fight to reduce emissions must continue. The danger of progress on carbon capture is that people will see it as a reason to relax their efforts.
Until now, carbon capture has been a bad bet financially. Since 2010, the Energy Department spent about $1.1 billion to help nine carbon capture and storage demonstration projects, the General Accountability Office said in a report. Private industry chipped in $610 million. But most found the cost way too high and abandoned the projects; only one power plant was still active at the end of 2017, GAO said.
Many coal companies see the federal carbon credits as a new lease on their lives. "The coal lobby was always in our office" seeking credits, said a former Energy Department official from the Obama administration who spoke on the condition of anonymity. But, he said, "carbon capture and storage makes coal more expensive, not less."
Dan Kammen, professor of energy and public policy at the University of California at Berkeley, says that carbon capture is diverting attention from cheaper and more scalable ways to taking carbon dioxide out of the air.
"The prices [of carbon capture] would have to fall a huge amount for it to be part of our near-term portfolio, meaning 2050 or sooner," Kammen says. Carbon capture from the air "can be an arrow in the quiver," he says. But he adds that changing land use and forestry, using known techniques for taking CO2 from the air and storing it, "would be the best investment in carbon capture today."
"I recommend the boring Charlie Brown strategy," he says. "When is the best day to plant a tree? Yesterday. Second best? Today."
New carbon capture technology is “the shiny new object on the table,” he says, but “with the 30-year clock more than ticking we have to scale up technology. We absolutely need to invest in carbon capture because we will have to do a good deal more of it.”