How Drones Can Be Used to Monitor Methane

Edinburgh Sensors: From monitoring global warming to tracking the spread of pollution, there are many good reasons to want to be able to monitor carbon dioxide, methane and other hydrocarbon gas concentrations even in the most remote, or dangerous, of locations. Leaks in oil pipelines, are not just dangerous because of the explosion risk they pose, but are also estimated to cost companies $30 billion a year.¹ Rising CO2 concentrations above volcanos are one of the early warning signs that an eruption may be imminent.² In agriculture, measurements of gases such as methane and CO2 can be useful for indicating crop health or monitoring emissions from livestock that may be spread over very large areas of land.

There is an obvious need and advantage then in all of these scenarios to having a variety of reliable gas sensors on site to perform these measurements. The challenge is how to get the sensors to such locations for monitoring, as they may be very remote, in the case of oil pipelines, or too dangerous for humans to access.

The answer to these problems is to mount sensors on drones, or unmanned aerial vehicles (UAVs) as they are also known. These can be flown into remote locations, stay in location for as long as measurements are required, then be returned and re-used later. The mobility of drones also means that sampling can be performed in a variety of different locations in a single excursion, which can be useful for situations such as tracking the spread and evolution of a hydrocarbon gas leak, which would not be easily possible with a fixed sensor station. Agriculture has benefitted immensely from the use of drones, with estimates being that this global market will be worth over $1 billion with 2024.³

Suitable Sensors

While mounting sensors on drones offers some clear advantages in terms of the flexibilities and possibilities of the locations that can be monitored, there are a few unique challenges to using drones in this fashion. One of the main problems is mounting sufficient power storage to give the drone a reasonable operating range and to keep all the on-board sensors recording, and if required, also to allow live transmission of data from the sensors to a fixed receiver for online analysis.

Weight and space also come at a premium for drone units as the bulkier and heavier the device, the more propulsion is required for the drone to be able to fly and the greater the power consumption in flight. This would reduce the effective operating range of the drone, which is crucial for some applications. For certain applications, where the drone and sensors will be operating in more extreme environments that may involve bad weather or volcanic emissions, all the components also need to be able to withstand whatever temperatures and humidity are thrown at them.

Efficiency Savings

Fortunately, Edinburgh Sensors offer a range of devices that are suitable for use with drone units. These are a series of infrared-based devices with very high sensitivity and low power draw that can be used not just for methane detection, but also other hydrocarbon gases including carbon dioxide and carbon monoxide.

There are a range of products depending on the exact demands of the application. For example, the Gascard NG has an infra-red based sensors this sensitive enough to detect methane concentrations between 0 – 3000 ppm, meaning it can be used to pick up even the smallest of leaks from oil pipes.4 It has a series of options for data logging, including RS232 connections for control and logging and Edinburgh Sensor’s provided data logging software that can be used for real-time data recording. The onboard pressure correction in the 800 to 1150 mbar range and extensive temperature correction ensure that you can be confident of the reliability of your measurements in a variety of environmental conditions that the drones may be used in. With a long-term (12 month) zero stability within 2 %, the Gascard NG is sufficiently robust for field applications with minimal interference.

Small Sensors

Where sensors with even smaller footprints may be desirable, or a low-cost solution is necessary, Edinburgh Instruments offers two addition solutions, the IRgaskiT5 and the GasCheck CO2 sensor. 6 The IRgaskiT is designed with no moving parts and is easy to integrate into existing systems, ideal for use with drone vehicles. It is possible to log voltage and current output from the sensor simultaneously and can operate in temperature from 0 - 50 °C, with measurements completely unaffected by 0 – 95 % humidity. Weighing only 125 g and consuming 0.9 W, it is perfect for integration with small vehicles and can easily be recalibrated at the press of a button to ensure accurate sensing over long periods.

The GasCheck takes a slightly different approach to the IRgaskiT, using all analogue electronics to make for an affordable device with similar low power consumption to the other sensor options. The detection range is between 0 – 3000 ppm and it has an impressive accuracy of within 3 % and will maintain a 3 % zero stability over 12 months. The robust construction means it can be used for even the most demanding of applications with no compromise on accuracy.

References

1. P. Patel, ACS Cent. Sci., 2017, 3, 679−682 
2. A. J. S. McGonigle, A. Aiuppa, G. Giudice, G. Tamburello, A. J. Hodson and S. Gurrieri, Geophys. Res. Lett., 2008, 35, 3–6.
3. Report: Agriculture Drone Market, https://www.fractovia.org/news/industry-research-report/agriculture-drones-market, (accessed January 2019)
4. The GasCard, https://edinburghsensors.com/products/oem/gascard-ng/, (accessed January 2019)
5. IRgaskiT, https://edinburghsensors.com/products/oem/irgaskit/, (accessed January 2019)
6. The GasCheck, https://edinburghsensors.com/products/oem/gascheck/, (accessed January 2019)