Carbon conundrum: cooling the planet will entail recapturing plenty of CO2

For decades we’ve been pumping massive amounts of carbon dioxide into the planet’s atmosphere, thereby irreversibly altering Earth’s climate for the worse. This needs to be stopped, yet that alone will no longer suffice. Given the massive amounts of CO2 already in the atmosphere, we’ll also need to suck plenty of that excess carbon out and lock it away safely.

Scientists have been working on plausible ways of doing that. Several carbon capture and sequestration processes are proving to be highly promising, at least in theory.

Take one example: researchers at the Georgia Institute of Technology developed a technique for capturing, storing and recycling carbon emitted by vehicles in order to prevent it from escaping into the atmosphere via exhaust pipes. Thanks to a fuel-processing device that can separate out carbon and store it in liquid form inside a vehicle, carbon in your car could one day be captured before it is emitted so that it could later be processed at a fueling station with no harm to the environment. The liquid carbon could then be transported to a processing plant where it could be turned back into liquid fuel.

“Presently, we have an unsustainable carbon-based economy with several severe limitations, including a limited supply of fossil fuels, high costs and carbon dioxide pollution,” explains Andrei G. Fedorov, who is Woodruff Professor of Mechanical Engineering at the university and was a lead researcher in the project. “We wanted to create a practical and sustainable energy strategy for automobiles that could solve each of those limitations, eventually using renewable energy sources and in an environmentally conscious way.”

Fedorov’s research team developed a fuel processor, called CO2/H2 Active Membrane Piston (CHAMP) reactor, which can produce hydrogen and separate liquefied CO2 out of a liquid hydrocarbon or synthetic fuel used by an internal combustion engine. Once CO2 is separated from hydrogen, carbon can be safely stored in its liquefied form, which is much more stable and transportable than in its gas form.

Such inventions, if implemented on a large enough scale, could go a long way towards reducing global carbon footprints. That could make a whole lot of difference since nearly two-thirds of global carbon emissions are produced by small emitters, including automobiles and other vehicles.

Yet that does not mean that scientists’ work is done. “The current technologies will have to be improved and engineered/tested for different scales of carbon capture needs (transportation vs industrial power vs centralized power generation),” Fedorov tells Sustainability Times. “But fundamentally they are capable of addressing the needs for managing CO2 emissions over the long term.”

CO2 capture, Fedorov says, “is the only technologically feasible solution that we have in hand for mitigating the impact of CO2 emissions on climate change, and we are terribly mistaken by not adequately investing in CO2 capture technology development, validation and deployment on all scales.”

Yet such technologies won’t come cheap, especially when applied on an industrial scale. “It will be costly, very costly,” Fedorov concedes. “But it is the only path forward given the unprecedented scale of the problem, level of maturity of renewables and lack of supporting infrastructure to mitigate their intermittency, economic realities of emerging economies, and very slow turnover rate in capital intensive assets that define power generation,” he adds.

Encouragingly, promising lines of research abound. In another breakthrough researchers at the California Institute of Technology (Caltech) and the University of Southern California have come up with a new way that can make it up to 500 times faster to sequester atmospheric carbon. They have done so by adding a simple enzyme to the process.

The researchers, who published their findings in the Proceedings of the National Academy of Sciences, set out by measuring how long it takes for calcite to dissolve in seawater. Calcite is a mineral made of calcium, carbon, and oxygen. On the floor of the oceans calcite deposits are formed from the shells of organisms like dead plankton that sink to the bottom.

Meanwhile, the surface of oceans naturally absorb carbon dioxide contained in the air in a sort of natural buffering process that serves to contain vast amounts of carbon dioxide. Right now, the planet’s oceans contain about 50 times as much carbon dioxide as its atmosphere. However, this buffering doesn’t come without a cost: extra carbon leads to acidification in the ocean water, which is harmful to marine lifeforms like corals. Over time carbon from the surface circulates down to the calcite sediments.

The process, however, was poorly understood. The researchers decided to rely on isotopic labeling and add the enzyme carbonic anhydrase, which helps balance pH levels in blood, into the mix and found that the naturally slowly occurring process could be speeded up considerably. The scientists “engineered a sample of calcite made entirely of the rare carbon-13, and then dissolved it in seawater,” a Caltech news release explains.

“By measuring the change in the ratio of carbon-12 to carbon-13 in the seawater over time, they were able to quantify the dissolution at a molecular level,” the statement adds. “Their method proved to be about 200 times more sensitive than comparable techniques for studying the process.”

What slows down the reaction is the conversion of carbon dioxide and water to carbonic acid. By tweaking the chemistry, scientists can accelerate that process. They can now also set about finding more effective and faster of ways of sequestering carbon naturally from the atmosphere before our planet’s temperature reaches a boiling point.

While no single solution can work wonders, several carbon capture and sequestration technologies used in creative combinations will be able to bring about tangible results in mitigating climate change. “There is no one single technology/silver bullet. It depends on the particular sector of economy and all technologies must be developed and pursued in parallel,” Fedorov observes in an interview with Sustainability Times.

What’s also important is that even as we continue to transition towards low-carbon power sources, we must use energy more judiciously through improved practices and new technologies.

“We must deploy renewables at the largest extent and scale possible in parallel to the incorporation of CO2 capture/sequestration on a massive scale, along with continuous improvement in energy efficiency of existing power generation, energy conversion and utilization systems to reduce overall energy consumption,” Fedorov explains. “Both supply and demand sides must be addressed at the same time.”