03.10.2022

The carbon dioxide that flows unused – and harmful to the climate – from the smokestacks of power plants, love to use as a source of energy

Burning coal, oil and gas to generate electrical energy produces about 12 billion metric tons of carbon dioxide worldwide each year. The odorless gas, together with methane, is largely responsible for climate warming. There are currently various ways to find a remedy: for example, there is talk of capturing the excess co2 at the place where it is produced and storing it somewhere. Plants breathe carbon dioxide and convert it into biomass with the help of sunlight. If this process is encouraged (e.G. By manuring the oceans), the amount of co2 in the atmosphere could also be reduced. Finally, the use of fossil fuels could be completely or partially eliminated by generating electricity from renewable sources.

The best way, of course, is to use all three at the same time. And the fourth one at the same time, which researchers have now published in the magazine environmental science technology letters propose. Scientists consider the carbon dioxide gas produced during combustion as a source of energy.

They do not use the warmth of the exhaust gas (as has already happened). Instead, an effect comes into play that, although relatively small, has gross potential over the enormous amounts of matter: when two substances mix, there is an associated increase in entropy that corresponds to a release of energy. It must then only be possible to collect this energy.

Scientists ame combustion gases with high co2 content (5 to 20 percent), which are mixed with normal air (co2 content below one per mille). To capture the energy released, the mixing takes place not in free space but in desalinated water. It turns out that, under the right conditions, a current of charge carriers (ions) is created that can be tapped from auben – and further used as electrical energy.

The potential of this technology would be enormous if it were extrapolated to the total energy production worldwide

In the experiment, the researchers achieved an efficiency of just over 12 percent, meaning that about one-eighth of the energy released during mixing could actually be captured. If monoethanolamine (which absorbs carbon dioxide better) were used instead of water, efficiency could be increased to as much as 32 percent. The co2-added liquid can then be recycled by spinning it with air. In the process, the remaining carbon dioxide is finally released – just like from the smokestack, except that it previously contributed to energy production.

On a global scale, the potential of this technology would be enormous. Depending on the co2 content in the exhaust gas (coal: 12.7%, gas: 7.5%), only 265 or 236 kilojoules are produced per kilogram of carbon dioxide. But at 12 billion metric tons per year, that adds up to 850 terawatt hours that all the world’s power plants together could then produce additionally.

If you include other co2 sources, you get 1570 terawatt hours, which is about 400 times the energy production of the hydroelectric plants at hoover dam. So all is well? Unfortunately not quite.

The process the researchers used to mix air and co2 with water consumes about 300 kilojoules per kilogram of co2 itself. So even in the best-case scenario, more energy currently has to be expended than is generated in the process. However, the researchers ame that other, less costly mixing processes had to be found that would allow the technology to be used commercially.

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