Mark Naples reports on an enabling technology for methane and CO₂ detection.
In September 2023, satellites detected methane leaking from a pipeline in Cheltenham, UK, at a rate of over 200kg per hour.
The detection was the first such incident recorded in the UK. It was also an accident. Researchers from the University of Leeds had been using satellite imagery to monitor methane escaping from landfill sites when they spotted the distinct signs of methane coming from a nearby gas pipeline. The leak, which had been occurring for 11 weeks, had released enough gas to power the equivalent of 7,500 homes for a year.
Leaks such as this are regrettably common in the oil and gas sector. With companies responsible for vast networks of pipelines stretching over thousands of miles, when a leak occurs, it can easily go unnoticed, letting vast quantities of heat-trapping gas escape into the atmosphere.
The need for action on methane leaks is clear. Methane has 28 times the heating potential of gases like CO2 and is responsible for approximately a third of the rise in global temperatures. Satellite monitoring presents one method of improving the visibility of leaks, but conditions such as high humidity can limit its accuracy – not to mention the expense of running it.
Enhanced gas detection will be critical if oil and gas suppliers are to make a difference in the fight against climate change. As the industry grapples to make the invisible threat of methane visible, other technologies have emerged that can provide a solid foundation of real-time data on where leaks are occurring.
How big a problem are methane emissions?
In terms of its effect on the environment, methane is often compared to other gases like CO2, but the differences in chemical structure between the two substances mean their true impact differs significantly.
Unlike the centuries-long lifespan of CO2, methane persists in the atmosphere for around 10-12 years. However, it is also much more potent at trapping heat due to a molecular structure that makes it very effective at capturing infrared radiation. As a result, when methane is first released, it can trap between 80-100 times more heat than the equivalent amount of CO2.
This means that tackling methane emissions is one of the most effective ways to address global warming – a statement that is backed up by the oil and gas industry. Ipieca, the International Association of Oil and Gas Producers, and the Oil and Gas Climate Initiative, have issued joint guidance stating that the elimination of methane emissions in the upstream oil and gas industry presents one of the best opportunities for combating climate change.
However, in the downstream segment, achieving this may not be so simple. Flaring and venting are common activities that regularly see large quantities of methane released into the atmosphere. Even if these practices cease to be used, the problem of leaking infrastructure would remain, and without technology to provide a clear picture of where leaks are occurring, locating them requires a major investment of both time and money in the form of manual surveys.
But there is a solution to this. High levels of emissions need not be inevitable. Through a robust combination of operational standards, policy action, and employing proven technologies, oil and gas producers can make a real difference to their environmental impact.
The technologies to prevent emissions are already well established. Through existing solutions, the International Energy Agency believes methane emissions from oil and gas could be cut by 40% at no net cost to producers. This is due to the high resale value of the captured material; potential profits that are currently being allowed to disappear into thin air. Chief among these technologies is laser absorption spectroscopy.
What is laser absorption spectroscopy?
Due to methane’s high infrared-trapping properties, the gas is easy to detect with infrared spectroscopy sensors – often at a sensitivity of parts per billion. What’s more, because these gases are characterised by many different spectral lines in the infrared, multiple features in the spectra can be used to identify chemical species with great accuracy.
Laser absorption spectroscopy works due to the way light is absorbed when it is passed through a medium. Beams of infrared light are sent through a sampling chamber containing a filter that only lets certain wavelengths that are reflected or emitted by the gas in question through. Using different filters changes the wavelengths of light that can reach the detector and, as a result, the equipment can be used to detect a variety of different gases and distinct particles.
Certain gas analyser instruments incorporate laser diodes mounted on a thermo-electric cooler. This enables the laser’s wavelength to be tuned to match the absorption wavelength of a particular molecule, resulting in enhanced sensitivity and discrimination. These instruments benefit from a lower risk of false alarms, which can plague other common gas detection technologies.
Action through detection
Advanced gas detection systems deployed at local and national levels will be instrumental in improving leak detection in the oil and gas sector. Although satellite imaging paints a partial picture of where methane leaks are occurring, localised methane sensors distributed across pipelines, storage facilities, and transport hubs, would provide a more accurate view of whether emissions are occurring, empowering the industry to begin addressing the problem.
The need for a clear, measurable strategy on methane is increasingly clear. Without a foundation of accurate data, action on this will be impossible. Laser absorption spectroscopy makes this data accessible and could provide the answer to turning the corner on climate change.
Mark Naples is general manager at Umicore.
