Austrian farmer uses CO2 from heating boiler to fertilize plants

One of Europe's first greenhouse carbon capture systems has been installed in Vienna. Local greenhouse operator Martin Merschl replaced his natural gas heater with an innovative biomass system.

"We burn the wood chips, we use the heat and we can use the CO2 as fertilizer in our greenhouses," the tomato grower tells CGTN.

While carbon dioxide can be a problem in the atmosphere, in greenhouses it can significantly increase vegetable yield – so Merschl installed plastic tubes that lead the CO2 from the heater to the tomato plants. 

But first the gas needs to be treated, because "the CO2 from the wood burning system is dirty," Merschl says. "We have to clean it with a complicated process."

The exhaust flue gas from the boiler first runs through tanks which filter out sulfite and other harmful substances, creating 12 tonnes of pure CO2 each day that is piped into the greenhouse.

The tomato plants absorb most of the CO2 gas, although it is eventually released into the atmosphere after the tomatoes are eaten and digested. Despite the limited environmental effect, the project shows how carbon capture technologies are further advancing.

According to Tobias Pröll, professor of energy engineering at BOKU university, the innovation lies within the filtering process – capturing CO2 from a flue gas stream that normally contains only 10 percent of carbon dioxide and concentrating it to essentially pure CO2.

"This is of course an innovative step that we will need in the future if we want to achieve net zero," Pröll tells CGTN.

The innovative step comes at a price of around $14 million – not an easy investment but worth it, says farmer Merschl. With the natural gas supply fluctuating in recent years, he can now enjoy energy security... and well-nurtured tomatoes.