Carbon dioxide has few friends. The colorless gas is produced by combustion and unfortunately also causes global warming. But 140 million metric tons of it is used every year as a raw material, primarily by the fertilizer industry in the production of urea. Now researchers, companies and government institutions, including the German research ministry, are looking for other industrial applications for the climate killer.
The ministry’s Carbon2Chem project is a joint attempt by companies and research institutes to turn exhaust gases from industrial furnaces into a raw material not just for fertilizers, but for fuel and plastics too. The ministry has provided €60 million ($70 million) in research funding.
One of the partners is ThyssenKrupp, which wants to turn its exhaust gases, of which CO2 makes up 21 percent, into methanol in a project supported by scientists from the Max Planck Institute for Chemical Energy Conversion in Mülheim. “We want to emulate nature by closing the carbon dioxide cycle,” the institute’s director, Robert Schlögl, said at the launch of the project last year. However, it will be a long road: The steel company estimates it will be 15 years before it can use CO2 industrially.
Meanwhile, chemicals group Covestro already uses CO2 to produce polyol, which is in turn used to make polyurethane for high-quality foam materials. Formerly known as Bayer MaterialScience, Covestro integrates up to 20 percent of CO2 into the polyol, which means it requires less propylene oxide, an oil derivative.
The CO2 comes from the exhaust fumes of a nearby chemical company. “By using CO2 as a new source of carbon, we’re broadening the raw materials base of the chemical industry and promoting the recycling economy,” said Markus Steilemann, the Covestro management board member in charge of innovation, marketing and distribution. His company has launched an EU-backed project called Carbon4PUR that aims to make mixtures of carbon dioxide and carbon monoxide, produced as exhaust gases from steel production, to produce polyols.
And the research ministry is sponsoring a program called Kopernikus to produce methane, liquid fuels and base chemicals with the help of CO2. It’s also backing Coral, a program looking for ways of using CO2 found in the air, which is far more technically challenging than using the concentrated CO2 in exhaust fumes.
Some companies are even working to return CO2 to the combustion cycle. In Dresden, Sunfire is producing a synthetic substitute for oil called “blue crude.” Electrolysis is used to separate water into its components, hydrogen and oxygen. CO2 is then added to the hydrogen to produce liquid hydrocarbon. Sunfire wants to launch the commercial production of blue crude in 2020 in Norway.
But many of the projects have major drawbacks. For one, they tend to consume too much energy. The University of Stuttgart examined the Sunfire process and found that it generated more emissions than traditional diesel. Synthetic fuels only help the environment if they are produced exclusively using renewable energy, the university found. “Processes to produce energy sources from CO2 are only suitable for the time when we no longer have coal-fired power in the grid,” said Axel Liebich, an expert at the Institute for Energy and Environmental Research in Heidelberg.
In environmental terms, it doesn’t make sense to emit a lot of CO2 by firing coal to generate electricity that is then used to turn CO2 back into a carbon product. A lack of reliable data is also an issue. “At present, there’s no systematic overview of the processes with regard to their climate effectiveness,” said Peter Markewitz, a scientist at the Jülich Research Center.
There are also question marks over how much economic sense the various processes make. It currently costs €40 to €70 to separate a metric ton of CO2 from exhaust gases, said Mr. Markewitz. As long as companies are paying less than €8 to emit a metric ton of carbon dioxide into the air — the current price of an emissions certificate — there’s no economic incentive to capture and process the CO2.
So far, the industrial use of CO2 isn’t making a major contribution towards protecting the climate. The 140 million metric tons of CO2 that factories use each year as a raw material only account for half a percent of global emissions. Mr. Markewitz doesn’t think the new technologies will be able to solve the problem on their own: “But they can make sense as an additional component of climate protection.”
Bernward Janzing is a freelance journalist in Freiburg. To contact the author: Bernward.Janzing@t-online.de