Physiologists estimate that humans have 300 million alveoli in their lungs to get rid of just one kilogram of carbon dioxide per day. At rest, they barely exchange ten liters of breathing air each minute. Macrophages are constantly lurking for dust particles or rests of small haemorrhages which immediately have to be eliminated.

It is this reliability, developed by the respiratory system in the evolution process, that inspires Hans Fahlenkamp, professor for chemical engineering at Universität Dortmund. He thinks it is the answer to the biggest challenge in environmental technology; the carbon dioxide separation from power plant flue gas.

“The technique of CO2-separation is feasible and going to be realized” Fahlenkamp states.

Fahlenkamp has developed membrane contactors that filter smoke through small plastic tubes filled with liquid detergent. The carbon dioxide gets into the detergent through microscopically small pores. That’s the same process organic membranes in the alveoli use when they separate the breathing air from the blood and still enable the efficient exchange of oxygen and carbon dioxide between the two phases.

The problem of actual flue gas scrubbing, where gas and liquid detergent directly get into contact, is the danger of gas scrubber siltation. Residual dust which can not totally be avoided even by using efficient electro filters would remain in the detergent together with CO2 and build this unwanted mud.

“In a modern large-scale plant with a rating of 1,000 megawatts three million cubic meters of flue gas are going through the chimney every hour” Fahlenkamp explains. “When there are 20 kilos of dust left, it is not much and only amounts to one third of the legal limit. But after 1,000 operating hours it already adds up to 20 tons. And this can potentially be the case after only a few weeks."

So a certain amount of care needs to be exercised. Brown coal power stations in the Rhineland produce more than half of the energy needed in North Rhine-Westphalia and cannot be shut down when a fault occurs. However, the World Wildlife Fund states that six of the ten power plants most harmful to the climate are found in Germany, four of them brown coal plants in the Rhineland.

There's a practical issue and a political one.

To replace the dirty coal-fired plants would mean substituting 200,000 megawatts over the next 20 years and an additional 100,000 megawatts if energy usage continues to ramp up.

That's 300 large power plants. So, engineers already concerned about higher efficiency due to increased power demands are now also being forced to adjust to the short-term political requirements of CO2-separation.

The German government has stated they want a 40 percent reduction in power plant emissions by 2020. More efficient power plants alone can't accomplish that. Hans Fahlenkamp's "lungs" may be the answer.