“Fracking” (Hydraulic Fracturing) is a controversial process in Europe. By producing rock cracks, it allows the extraction of oil and gas from unconventional deposits.

Scientists from KIT, in cooperation with the National Center for Atmospheric Research and the University of Colorado, conducted field measurements to detect methane emissions from fracking in spring 2015.

In the model test, one of the two available gas cells can additionally be brought into the beam. One cell contains carbon dioxide (CO2), the other methane (CH4). The quantities of the gases are tuned in such a way that the attenuation is approximately the same as in the atmospheric observation against the sun. By inserting the cell, the characteristic signatures of carbon dioxide (or methane) visible in solar measurement are generated.

For this purpose, several of the mobile spectrometers were positioned northwest of Denver at a distance of about 70 km along the prevailing wind direction. Significant increases in methane quantities were observed downstream from the monitored area.

The greenhouse effect of methane is about 25 times greater than that of carbon dioxide:  Therefore, the environmental impact of a process that releases large quantities of methane into the atmosphere during the extraction of oil or gas is particularly unfavorable.

THE MODEL EXPERIMENT

Since an atmospheric measurement requires direct sunlight, we illustrate the measurement procedure using a weather-independent model: The source is the hot filament of a lamp.  Even on the short path between the lamp and the spectrometer, the water vapor in the air causes a noticeable attenuation of the signal at characteristic wavelengths. These areas are almost completely darkened in the solar spectrum due to the much longer atmospheric path.

EMISSINS FROM CITIES

According to a WHO survey, only 34 percent of the world’s population lived in cities in 1960, compared to 54 percent in 2014. Cities generate the largest proportion of anthropogenic carbon dioxide emissions. The quantification of urban emissions is therefore of crucial importance, including the evaluation of approaches aimed at developing a sustainable city, the “eco city.”

The use of several mobile spectrometers allows the observation of local sources by comparing the measured trace gas quantities in the Luv and Lee of the source. Scientists from KIT demonstrated this method for the first time in summer 2014 by detecting the carbon dioxide emission of Berlin.

For the spectrometers developed by KIT in cooperation with Bruker Optik, Ettlingen, a previously unparalleled level of stability of the instrumental properties was demonstrated. In May 2015, KIT, in cooperation with French partners, successfully applied the same method for the measurement of the greenhouse gas emissions of Paris.