Up in the Air

The search for cost-effective ways of capturing and repurposing carbon in the atmosphere

According to a 2018 report published by the National Oceanic and Atmospheric Administration (NOAA), the amount of carbon dioxide in the atmosphere hit a new high of 405 ppm (parts per million). The report further states, “The annual rate of increase in atmospheric carbon dioxide over the past 60 years is about 100 times faster than previous natural increases, such as those that occurred at the end of the last ice age 11,000 to 17,000 years ago.”

As a “greenhouse gas,” carbon dioxide absorbs heat, which it slowly releases over time. While it’s true that in the right amounts, it’s precisely such greenhouse gases that make earth habitable rather than freezing, an imbalance leads to rising global temperatures and ocean acidification (when carbon dioxide dissolves in the ocean, causing a chemical reaction that produces carbonic acid and lowers the ocean’s pH).

In short, the rapidly increasing levels of carbon dioxide in the atmosphere are a threat to life on land and in the sea, which is why many across the globe are looking for ways to decrease carbon dioxide emissions. Innovative thinkers and entrepreneurs alike are taking such efforts a step further and looking at ways to remove carbon from the atmosphere and finding new uses for it.

The Center for Negative Carbon Emissions

Arizona State University’s Center for Negative Carbon Emissions (CNCE) focuses on developing technology that collects and reuses carbon while cleaning the air. Klaus Lackner, a particle physicist who works at CNCE and is a leader in the carbon capture movement has been working with his colleagues on several options for carbon sequestering.

One of the more intriguing machines that the research center has created at first appears to be a simple large metal container. When activated, it opens to unleash three rectangular metal frames that in turn expand to reveal large polymer sails that are treated with a resin that pulls CO₂ from the air as the wind blows through. The strips release the CO₂ when wet, so the greenhouse gas can be harvested when the strips are cleaned.

The efficacy of CNCE’s machines is yet to be determined as the cost of building them may be too high and finding the space for enough machines to make a dent in atmospheric carbon levels could be tricky. Such concerns don’t dissuade Lackner, as he puts it, “We have to demand cleanup. And the neat thing of having many different options is that the markets can then figure out which of these options are the most cost-effective and which ones we follow.”

Trees and Artificial Trees

Dr. Thomas Crowther, professor of Global Ecosystem Ecology at ETH Zürich and founder of the Trillion Tree Campaign, claims that planting three trillion trees could capture 400 gigatons of carbon. His plan, which sprang out of the United Nations’ Billion Tree Campaign, has led to the planting of 17 billion trees worldwide on abandoned or devalued land.

It can take a long time for trees to grow, so the idea of using artificial trees to reduce carbon pollution has become intriguing. Last summer, scientists in Germany published a study that suggested the use of artificial photosynthesis, which is five times more efficient than natural photosynthesis. Artificial trees could solve the problem of finding free land to plant three trillion trees, unfortunately the cost of such tree-like machines is currently prohibitive — in 2011, a group of Boston scientists developed artificial trees that would cost $350,000 per tree.

Perhaps just developing photosynthesis-capable artificial leaves could be a more affordable option? In February, a team of researchers at the University of Illinois at Chicago (UIC) published a report in the ACS Sustainable Chemistry & Engineering journal suggesting methods that could produce artificial leaves that capture carbon dioxide and convert it to fuel 10 times more efficiently than natural leaves.

So far, other artificial leaves have only existed in laboratories, taking in pressurized CO₂ from tanks. The leaves proposed at UIC would be inside a capsule of water that, when heated by sunlight, evaporates and traps CO₂. The artificial leaf converts the CO₂ into oxygen which is released into the atmosphere, and carbon monoxide which is removed and stored and can later be used to create fuel.

New Fuel

Speaking of creating fuel, Canadian company Carbon Engineering is using its AIR TO FUELS™ technology to collect CO₂ from the air and combine it with hydrogen to create synthetic fuel. The new fuel will ideally either be used on its own as a carbon-neutral fuel which only emits the same CO₂ that was used to create it, or combined with gasoline, diesel or jet fuel for a more eco-friendly fuel.

Last June, the company’s CEO, Steve Oldham, told National Geographic, “(The synthetic fuel) costs more than a barrel of oil right now, but in places with a price on carbon of $200 a ton, like what’s enabled through California’s Low Carbon Fuel Standard, we’re competitive.” As more states and provinces apply and raise carbon prices, Carbon Engineering’s fuel will become even more appealing. Similarly, Carbon Engineering believes that once its operations are scaled up, its fuels can be produced for as little as $1 per liter which would put it on par with biodiesel.

Carbon Farming

Currently, the cost of pulling carbon from the air is a bit prohibitive for those looking to make some money — or break even — from the process. This has caused an interest in using plants, which already extract carbon dioxide from the air, to do the job.

More than one-third of Earth’s land that isn’t covered in ice is used for agriculture, so proper management of that land is critical. According to the New York Times, agriculture and animal husbandry have led to the release of 135 gigatons of carbon into the atmosphere since the Industrial Revolution.

The Carbon Cycle Institute explains that agriculture is the only sector “that has the ability to transform from a net emitter of CO₂ to a net sequesterer of CO₂.” Such an accomplishment would be done through carbon farming, which captures some of the carbon released into the air from farming and puts it back in the soil where it can benefit the pedosphere (the outermost layer of Earth, composed of soil).

Compost plays an important role in carbon farming, specifically compost made from manure along with other organic materials. Treating farmland with a layer of organic compost has been shown to increase the amount of occluded carbon in soil, which can stay underground for hundreds of years. Not only that, proper use of compost can promote the absorption of carbon by plants which then deposit carbon deep in soil as tiny rootlets die.

Those with mid-size farms allow cattle to graze on fields not currently in use, where their manure naturally combines with soil and dead plants. Farmers and even home gardeners working on a much smaller scale can purchase organic cow manure, such as that from Black Kow, to make their own compost. The full benefits of carbon farming are yet to be universally determined, but at the very least it helps reduce greenhouse gases by keeping cow waste out of manure lagoons where nitrous oxide and methane are released into the atmosphere.

Forward Thinking

Clearly there is much to be done in terms of carbon capture and more than likely it will take multiple solutions to achieve the atmospheric carbon levels necessary to keep the planet safe and inhabitable. However, some of the previously mentioned strategies — along with the prospect of additional breakthroughs — provide hope for Earth’s future.