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From tracking the spread of pollution to monitoring global warming, there are a number of reasons to want to monitor methane, carbon dioxide, and other hydrocarbon gas concentrations even in the most remote, or dangerous places. For example, leaks in oil pipelines are not only dangerous because of their explosion risk, but they are also estimated to cost companies around $30 billion per year.1
One of the early warning signs that an eruption may be imminent is rising CO2 concentrations above volcanoes.2 Agriculturally, measurements of gases such as CO2 and methane can be beneficial for indicating crop health or monitoring emissions from livestock that may be spread over vast areas of land.
In all of these scenarios there is an obvious requirement and advantage of possessing a scope of reliable gas sensors on site to carry out these measurements. The challenge is transporting the sensors to these locations for monitoring, as they could be very remote (in the case of oil pipelines), or too hazardous for humans to access.
Mount sensors on drones, or unmanned aerial vehicles (UAVs) as they are also known, could be the answer. These can be flown into remote places and kept in location for as long as measurements are needed, then be returned and re-used at a later date.
Sampling can be executed at a number of different locations in a single excursion because of the mobility of drones, which can be helpful for situations like tracking the spread and evolution of a hydrocarbon gas leak. This would not be easily possible using a fixed sensor station.
Agriculture has benefited immensely from the utilization of drones, it is estimated that this global market will be worth over $1 billion by 2024.3
Whilst mounting sensors on drones provides some clear advantages in terms of the possibilities and flexibilities of the locations which can be monitored, there are some unique challenges when employing drones in this way.
One of the key issues is mounting sufficient power storage to allow the drone a reasonable operating range and to keep all the on-board sensors recording, and if needed, to permit live transmission of data from the sensors to a fixed receiver for online analysis.
The heavier and bulkier the device, the more propulsion is needed for the drone to be able to fly and so the greater the power consumption in flight – so weight and space also come at a premium for drone units. The effective operating range of the drone is critical for some applications.
For many applications, where the sensors and drone would be operating in more extreme environments that may involve volcanic emissions or bad weather, all of the components must also be able to endure whatever humidity and temperatures are thrown at them.
Thankfully, Edinburgh Sensors provides a wide scope of devices which are suitable for utilization with drone units. These are a series of infrared-based devices with low power draw and very high sensitivity that can be employed not only for methane detection, but also other hydrocarbon gases including carbon monoxide and carbon dioxide.
Depending on the exact demands of the application, a number of products are available. The Gascard NG has infrared based sensors that are sensitive enough to detect methane concentrations between 0 – 3000 ppm for example, meaning it can be utilized to detect even the smallest of leaks from oil pipes.4
It also has a number of choices for data logging, including RS232 connections for control and logging and Edinburgh Sensors’ provided data logging software that can be utilized for real-time data recording.
The onboard pressure correction in the 800 to 1150 mbar range plus extensive temperature correction mean that you can be confident of the reliability of your measurements in the multitude of environmental conditions that the drones may be utilized in. With a long-term (one year) zero stability inside 2%, the Gascard NG is adequately robust for field applications with minimal interference.
Where a low-cost solution is necessary or sensors with even smaller footprints are desired, Edinburgh Instruments offers two additional solutions, the IRgaskiT5 and the GasCheck CO2 sensor.6 The IRgaskiT is easy to integrate into existing systems and is designed with no moving parts, ideal for utilization with drone vehicles.
It is possible to log current output and voltage from the sensor simultaneously and it can operate in temperatures between 0 – 50 °C, with measurements that are completely unaffected by 0 – 95% humidity. Weighing just 125 g and consuming only 0.9 W, it is perfect for integration with small vehicles and can be re-calibrated easily at the press of a button, ensuring accurate sensing over long time periods.
Utilizing all analog electronics to create an affordable device with similar low power consumption to the other sensor options, the GasCheck takes a slightly different approach to the IRgaskiT. The detection range is between 0 – 3000 ppm, it has an impressive accuracy of within 3% and will keep a 3% zero stability over a year. It can be utilized for even the most demanding of applications with no compromise on accuracy because of its robust construction.
References and Further Reading
- P. Patel, ACS Cent. Sci., 2017, 3, 679−682
- A. J. S. McGonigle, A. Aiuppa, G. Giudice, G. Tamburello, A. J. Hodson and S. Gurrieri, Geophys. Res. Lett., 2008, 35, 3–6.
- Report: Agriculture Drone Market, https://www.fractovia.org/news/industry-research-report/agriculture-drones-market, (accessed January 2019)
- The GasCard, https://edinburghsensors.com/products/oem/gascard-ng/, (accessed January 2019)
- IRgaskiT, https://edinburghsensors.com/products/oem/irgaskit/, (accessed January 2019)
- The GasCheck, https://edinburghsensors.com/products/oem/gascheck/, (accessed January 2019)
This information has been sourced, reviewed and adapted from materials provided by Edinburgh Sensors.
For more information on this source, please visit Edinburgh Sensors.