Air conditioners can capture CO2 and generate hydrogen
The problem here is that the low CO2 concentration in the air makes it necessary to filter large amounts of air, which in turn causes high electricity consumption. Scientists from the Karlsruhe Institute of Technology (KIT) have now published an article in the journal Nature Communications , which uses three examples to show that air conditioning and ventilation systems can also be used instead, since these move large amounts of air anyway.
Retrofitting air conditioning and ventilation systems enables CO2 to be captured from the air and alternative fuels to be generated from it. According to a calculation by the Karlsruhe Institute of Technology, the Frankfurt high-rise building alone could generate between 2,000 and 4,000 tons of hydrocarbon fuel per year without significantly increasing electricity consumption.
In order to limit the currently unstoppable climate change , it is necessary to prevent the increase in the atmospheric CO2 value and, if possible, to capture CO2. In addition to reducing new emissions, filtering out CO2 from the air and CO2 capture and storage (CCS) can help. The first test systems with so-called Direct Air Capture Technology (DAC) are already in operation in Switzerland and Iceland. The captured CO2 can either be stored or used to produce alternative fuels such as hydrogen .
Fuel production with renewable energy:
The scientists’ vision of the future describes a “climate control system powered by renewable energy, which not only cools or heats, but also filters CO2 and water from the air, thus producing sustainable hydrocarbon fuel as a local and decentralized source.”
The technology required for this already exists and is used in power-to-liquid plants to generate alternative fuels or synthesis gases from CO2 using catalysts. The scientists only had to calculate the profitability of the retrofitting of air conditioning and ventilation systems and the additional electricity demand, and they had to be demonstrated using three examples.
Messeturm could generate 2,000 to 4,000 tons of fuel annually:
According to the results of the study, the high-rise office building at the Frankfurt trade fair could capture between 0.75 and 1.5 tons of CO2 per hour from the air by retrofitting the air conditioning system. The energy required for this could be supplied via solar thermal or district heating, which would ensure that electricity consumption hardly increases. The conversion of the captured CO2 into hydrocarbon fuel would then be possible via Fischer-Tropsch synthesis modules or container systems. According to the researchers, the energy efficiency of the process is between 50 and 60 percent. Roland Dittmeyer explains that “this could produce 250 to 500 kilograms of fuel per hour.” Production would be between 2,000 and 4,000 tons per year.
A medium-sized house with six parties has at least 500 grams of CO2 that could be filtered out of the atmosphere every hour. Four to five kilograms of fuel could be generated from this every day. The power consumption that the conversion requires is between four and five kilowatt hours, which would cost around 1.50 euros.
The 25,000 ventilation systems operated by the three largest supermarket chains in their branches across Germany would remove around 1,000 tons of CO2 per hour from the air and generate around three million tons of fuel annually if they were technically upgraded. This corresponds to a fuel quantity of around 30 percent of the total kerosene requirement or eight percent of the diesel consumed .
Significant effects possible:
Dittmeyer and his team explain that “this technology could have a significant impact on CO2 emissions and at the same time enables the storage of renewable energy in the form of high-energy chemical fuels.” The use of synergy effects of ventilation and air conditioning technology and the CO2 capture and conversion processes can help to significantly reduce costs and power consumption. The scientists also emphasize that “mass production, 3D printing and digitization will make such systems even smaller and more economical in the future.”
The air conditioning system will supply petrol in the future:
They call it the “crowd oil” concept: German scientists have developed a new process with which air conditioning and ventilation systems can fish carbon dioxide from the air. This can be used to produce fuel for cars and planes.
On the one hand, this is a major technical challenge, because the concentration of CO 2 in the atmosphere is still very low at 0.038 percent. On the other hand, it is not yet clear what to do with the CO 2 gas extracted from the air . A dump deep in the earth or seabed has been discussed for years.
October 2018, the IPCC submitted a special report . The researchers found that the desired limitation of the global temperature increase to 1.5 degrees Celsius can no longer be achieved simply by reducing CO 2 emissions. In addition, large amounts of carbon dioxide would have to be extracted from the atmosphere. In this century, between 100 and 1000 billion tons of carbon dioxide would have to be fished from the atmosphere.
But there is great resistance to this technology, known as sequestration or CCS (Carbon Capture and Storage), at least in this country. There were protests wherever the injection of carbon dioxide into the ground was to be tested. The projects have been stopped.
Carbon dioxide becomes kerosene:
Another option is the use of carbon dioxide as a chemical raw material that can be used to produce synthetic and artificial fuels for cars and planes. Gasoline, diesel and kerosene as well as various plastics can be produced from carbon dioxide and hydrogen.
However, this also requires hydrogen and a lot of electrical energy. Both could be supplied CO 2 -neutral by wind and solar power plants . For example, the hydrogen could be produced by electrolysis of water.
However, there is a bottleneck in the large-scale production of fuel from carbon dioxide: With the technologies available today, it is not possible to continuously remove sufficiently large amounts of CO 2 from the air.
Researchers in the Karlsruhe Institute of Technology (KIT) and the University of Toronto have now suggested in the journal ” Nature Communications ” to carry out the production of fuel from carbon dioxide in a decentralized manner: Thousands of air conditioning and ventilation systems are each supposed to convert comparatively small amounts of CO 2 into fuels ,
When these fuels are burned, carbon dioxide would of course be released into the atmosphere again. But this use would be at least CO 2 neutral. This could be an interesting scenario for a transition period. If, however, net carbon dioxide is to be extracted from the air, then the carbon-containing substances produced in this way would have to be stored in a suitable manner and should not be burned.
The compact systems are designed to separate carbon dioxide from the ambient air directly in buildings and produce synthetic hydrocarbons that can then be used as renewable synthetic oil. The researchers call this the “crowd oil” concept.
The technologies required for this are essentially already available, Professor Roland Dittmeyer from KIT and Professor Geoffrey Ozin from the University of Toronto state. They calculate that the process is possible with an efficiency of 50 to 60 percent.
The researchers are currently building a pilot plant with which they want to convert 1.25 kilograms of carbon dioxide per hour. The scientists calculated that the ventilation systems of the approximately 25,000 supermarkets in Germany’s three largest food retailers alone could cover around 30 percent of kerosene requirements or around eight percent of diesel requirements in Germany.
In any case, the scientists admit that their concept, even with widespread use, cannot meet today’s demand for crude oil products. The technology they propose can only be one piece of the puzzle for many in the overall picture of the energy industry of tomorrow.