An Autarkic Wireless Sensor Network to Monitor Atmospheric CO2 Concentrations

In this study an autarkic low-cost wireless network infrastructure suitable for areas spanning a couple of hectares is introduced. Open source hard- and software components make up the infrastructure's core, rendering it very scalable in terms of cost and deployment density. The network is designed to operate continuously throughout the year in a wide range of weather conditions.Four different embedded, low-cost Sensirion SCD30 non-dispersive infrared (NDIR) CO2 sensors are evaluated under laboratory conditions and tested for cross-sensitivity on water vapour and linear characteristics, of which the Sensirion SCD30 sensor exhibits the best overall performance. An in-field comparison of eleven Sensirion sensors with an eddy-covariance station verifies its outdoor applicability. The network's suitability to monitor natural CO2 emissions was tested at a site in the upper Neckar Valley in southwestern Germany. A station with a single Sensirion sensor observed a strong diurnal cycle of the near-surface CO2 concentration over the course of several months. While only slightly elevated CO2 levels above 400 ppm prevailed during the day, concentrations reached the sensor's output limit of 40 000 ppm during the night when wind speeds are low.