Laser technology used to detect biogas leaks from metres away

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Fraunhofer scientists have developed a laser-based system that can detect methane leaks in biogas plants from up to 15 metres away. The device is based on optical emission and backscattering spectroscopy, and is anticipated to be ready for market in the next three to five years.

There are nearly 8,000 biogas plants in Germany, which produce about 17 per cent of the gross electricity generation from renewable energies. Even small leaks from the joints of the gas lines or fermenters can have huge consequences; escaping methane can result in fires, economic damage and can be harmful to the environment. Up until now, there was a lack of technology which allows operators to track down leaks in system parts quickly, inexpensively and safely.

The new contactless instrument developed by the Fraunhofer scientists, however, is capable of detecting biogas or natural gas escaping from leaks faster and with higher accuracy than previously possible.

The development was funded by the German Federal Ministry of Food and Agriculture, and involved the Fraunhofer Institute for Physical Measurement Techniques (IPM), the Fraunhofer Institute for Environmental, Safety and Energy Technology, and measuring instrument manufacturer, Schütz Messtechnik.

The optical portion of the measurement system comprises the laser, detector, camera, and range finder. It detects methane by firing a laser beam at the piece of equipment being inspected, and if present, the light from the laser will be reflected by the methane molecules into the detector. Because the wavelength of the laser is specific to the absorption spectrum of methane, only this gas is measured.

The backscattered light is then analysed, and the concentration is calculated using the data from the built-in range finder. A connected tablet PC also evaluates the data to provide information concerning the escaping methane and diplays the exact position of the leak on the screen.

Dr Johannes Herbst, measurement technology expert at the Fraunhofer IPM, expects the technology to be ready for the market in the next three to five years. Currently, the researchers are detecting methane without the backscattered light. For this purpose, the gas itself is illuminated by a strong laser. ‘In the future, the measurement team will be able to easily check the entire system from the ground. It used to be necessary to climb ladders and identify the leaks on the spot,’ Herbst said.

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