(CN) — When it comes to stopping or even reversing climate change, most experts agree that not only does the world need to curb greenhouse emissions — halving them by 2030, as the recent Intergovernmental Panel on Climate Change report suggested — but it also needs to start developing the capacity to sequester tons of carbon. Make that gigatons: 1 billion metric tons.
We're already doing that. The world's largest direct-air capture facility, which opened last year in Iceland, sucks in 4,000 tons of carbon every year. But that's a tiny fraction of what's needed. And plants like that are expensive. They also take up land which means obtaining permits and, more often than not, fighting neighborhood opposition. The process also requires energy.
"It takes vast amounts of energy to take dilute carbon dioxide and concentrate it," says Geoffrey Ozin, a professor of chemistry at the University of Toronto, and co-author of the book "The Story of CO2."
In a paper published Wednesday in the scientific journal Joule, Ozin and a team of researchers lay out an alternate proposal: rail-based direct-air carbon capture. The idea is to convert tanker cars, typically used to transport petroleum, into direct-air capture cars that would pulled along by trains and suck in air, capture carbon dioxide, and store it. The process can be powered by the energy from the train's brakes — energy that is currently wasted.
"We’re talking an enormous amount of energy," said the paper's lead author, E. Bachman, founder of CO2 Rail. "Take the energy produced by the Hoover Dam, multiply it by 105. That's how much is put to waste. Imagine 105 Hoover Dams devoted exclusively to direct-air capture. The scaling potential is enormous."
Bachman imagines putting two to five of these carbon capturing rail cars on every train in America — "just hitching a ride," he said. He thinks that if his system is fully implemented, the cars could be sucking in 2.5 gigatons of carbon dioxide every year by 2050.
“The projected cost, at scale, is less than $50 per ton, which makes the technology not only commercially feasible but commercially attractive," says Bachman.
The technology for such cars already exists and, perhaps best of all, so does the infrastructure.
“All you need to do is take advantage of what is already available," Ozin said.
Of course, the carbo- capturing rail cars are no substitute for eliminating greenhouse gas emissions.
"We absolutely need to decarbonize," Bachman said. "We need to move to renewables. No amount of direct-air capture will amount to anything unless we decarbonize."
Should the world manage to become carbon neutral by 2050 — a possibility, though something of an uphill climb, given the current political situation — Earth will still be left as much as 1.8 degrees Fahrenheit hotter than it is now. That would have a range of environmental consequences, including melting icecaps, thawed permafrost and rising sea levels. Which is why most scientists agree we need to both decarbonize and develop our capacity to capture and store carbon.
"The first step is to stop the bleeding, the second step is to repair the damage," Bachman said.
Once captured, carbon can be stored either underground or in aboveground reservoirs. It can also be put to use — recycled, as it were. Some even hope to turn the captured carbon into fuel.
In another paper published on Wednesday in Joule, a team of researchers outline a process for making jet fuel out of sunlight, water and recycled carbon dioxide using what they call a solar tower. While burning the fuel releases the same amount of carbon that burning regular old jet fuel does, the fuel uses recycled carbon and is therefore said to be carbon neutral. It also claims to have a host of other environmental benefits.
"Solar kerosene from water and CO2 is cleaner than fossil-derived kerosene," said the paper's lead author, Aldo Steinfeld of the University of Zurich, in an email. Burning the new kind of fuel, he said, would result in "dramatic reductions in soot emissions compared to fossil-based jet fuel. And soot emissions are responsible for the contrails, which are also detrimental for the climate."
The company Synhelion is currently building the first solar fuel plant in Germany, and it's scheduled to start operating sometime next year.
Charles Mann is the author of "The Wizard and the Prophet," a book about the two sides of the environmental movement: innovation and conservation. In a direct message exchange over Twitter, Mann said recent technological innovations are encouraging, but only to a point.
"There's more engagement now from the innovation sector with climate change," Mann said, but added that governments aren't doing nearly enough to support the implementation of those new technologies. "I don't mean just subsidies, important though they are. But things like building code revision, insurance reform, revamping banking regulations [and] infrastructure reconfiguration.
"Innovation is critical, but can't function in a vacuum."
Read the Top 8
Sign up for the Top 8, a roundup of the day's top stories delivered directly to your inbox Monday through Friday.