Revolutionary approach to carbon storage and utilization and impressive efforts to achieve this goal

As global emissions continue unabated, climate change is progressing at a staggering pace. However, a team of scientists from UC Santa Barbara and RWTH University in Aachen, Germany, has in mind a new and new destination for all carbon dioxide emissions into the atmosphere: chemicals.

The production of chemicals emits astonishing amounts of greenhouse gases through the energy it consumes and the carbon-based raw materials it uses. Sangwon Suh, a professor at the Bren School of Environmental Science & Management at the University of Santa Barbara, and fellow researchers, see an opportunity to divert billions of tons of CO2 from smokestacks to the supply chain in chemicals, if the world can create enough renewable energy effort is worth it. Their analysis appears in the Proceedings of the National Academy of Sciences.

According to the team's findings, chemical production – an industry encompassing sectors as diverse as lubricants, paints and plastics – accounts for more than 3.3 billion tonnes of CO2 a year, which is the largest single source of energy. equivalent of other greenhouse gases. Suh recently released the first comprehensive report on carbon emissions from plastics, in which he and his co-author discovered that plastics alone accounted for the equivalent of 1.8 billion tonnes of emissions. of CO2 per year.

"On the one hand, this massive amount of plastic and chemicals poses a problem," said Suh, a researcher in industrial ecology, "because it requires a tremendous amount of energy for production and, a once the products are used, a huge amount of waste will be generated. "

"On the other hand," he continued, "this is an opportunity because these raw materials are largely carbon-based.If we can use carbon dioxide as a carbon source for these plastics and chemicals, we can capture and store a large amount of carbon dioxide. " amount of CO2 in the plastics and chemicals that would have been emitted, while creating value. "

The application of carbon capture and utilization to the chemical industry is a new idea. It would be a renewable source of carbon compounds and would have the added benefit of removing CO2 from the atmosphere. The UCC also produces a large amount of pure water as a by-product, a potential benefit, as water safety becomes a more serious problem. In addition, the use of captured carbon partially offsets the cost of capture, a major economic challenge for carbon sequestration efforts.

But the team wanted to know if it could be practical. It's a new territory, so the researchers had to work from scratch. They looked for the possibility for the CCU to significantly reduce greenhouse gas emissions, and found that this was the case. This technique could eliminate up to 3.5 billion tons of CO2, or the equivalent in other greenhouse gases per year.

However, this process would increase the total energy demand of the industry, mainly because it also needs hydrogen, which is usually produced from water by electrolysis. Renewable energy would help to meet these demands, otherwise the process would emit more carbon than the simple fact of traditionally supplying material through fossil fuel reserves.

The question then became: how much renewable electricity is needed to reach this technical potential of 3.5 gigatons?

The answer: 126 to 222% of the world's renewable energy targets by 2030. And these goals already seem very ambitious in the context of current policies and trajectories.

"We were surprised by the amount of electricity needed to reduce greenhouse gas emissions through the CCU," said Suh. "Some people may think that the renewable energy production figures we've tested are unrealistic – well, that's the problem."

Time and effort

Many scientists have been interested in CCU – as well as in carbon capture and storage – as they were concerned about the possibility that various proposals and strategies to reduce carbon emissions could be addressed. greenhouse gases do not prove to be effective. LED lights and electric cars produce less greenhouse gases, but to avoid a climate disaster, reducing emissions is not enough, Suh said.

"Scientists are beginning to feel that these efforts will not keep us at an increase in global average temperature of 1.5 to 2 degrees Celsius," he said. These are the goals set by the United Nations following the report of the Intergovernmental Panel on Climate Change (IPCC) to prevent climate disasters. To meet these goals, it is necessary to reduce net emissions to zero by the second half of the century, said Suh, who was one of the lead authors of the group 's 2014 report. experts.

This leads to the concept of carbon budget, which is the maximum total amount of greenhouse gases that humans can emit and continue to heat below 2 degrees Celsius. Scientists have produced many estimates of this budget, but one of the most influential figures is 763 billion metric tons of CO2, the equivalent in other gases. At present, we emit about 50 billion tons of CO2 a year, said Suh. This does not leave much room for maneuver or time to solve the problem.

"We need to significantly reduce our greenhouse gas emissions immediately," said Suh.

However, he thinks that it is also dangerous to have an overly optimistic view of the potential for carbon capture. "Our study represents the first global assessment of CCU's potential for carbon mitigation, and we found that it took a lot to save the world," Suh ​​said. Humans can not continue as if nothing has been assuming that carbon capture solves the problem even if we miss our goals.

"More than anything else, this study shows the huge scale of renewable energy needed for the CCU to make sense," Suh ​​said. He suspects the readers of the study of complying with the requirements, saying that we can not direct all this renewable electricity only to the CCU.

"I agree," he says. "It's the goal."

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If we add the huge amount of renewable electricity detailed in the study, this raises the question of whether the UCC is the best application of this extra power. The team compared the CCU to more effective alternatives.

It turns out that CCU is not currently the most efficient use of renewable electricity for reducing carbon emissions. Investing this energy in heat pumps, rather than using natural gas for heating, would allow the largest reduction in emissions per kilowatt hour, followed by things like electrification of transportation and water heaters. In fact, the team has calculated that we could invest about 5 petawatt hours (5,000 billion kilowatt hours) of additional renewable energy in heat pumps before they become saturated. It is only when all these other more efficient uses of renewable electricity have been exhausted that it would make sense to invest green energy in the capture and recovery of electricity. use of carbon.

However, if additional capacity is generated, the UCC could prove to be a valuable tool for reducing greenhouse gas emissions, according to scientists. The tonnage of carbon-based compounds circulating in the chemical industry gives the CCU the potential to have a disproportionate effect on reducing emissions.

"We have not found CCU as a savior of the global environment," Suh ​​said, "though it may have local potential, where there is an oversupply of electricity. renewable electricity without apparent use ".

In this case, however, the bulky plastics and chemicals produced should be shipped to the market, thereby generating more emissions. Instead, excess electricity could be used to process data, which is much more efficient to pass around the world, said Suh. He and his colleagues are now studying the role that data centers and outsourced computing could play in reducing emissions by optimizing the use of available energy sources.