Methane is responsible for around 30% of the rise in global temperatures since the Industrial Revolution, according to the International Energy Agency. The oil and gas industry, agriculture and waste management all contribute to the total methane footprint. Whilst large leaks or ‘super-emitters’ make the headlines, a staggering number of smaller fugitive emissions, from ageing or defective infrastructure, occur continually across the globe. To tackle this, it is imperative to understand the emissions location, number and leak rate.
Big Sky Theory Limited, a UK start-up founded by drone experts, aims to provide emissions intelligence from airborne platforms by quickly, effectively, and safely mapping small leaks within large and complex gas infrastructure of industrial sites, in order to inform ground-based inspections and repairs.
They have developed a capability that offers confidence in airborne sensor technology and their deployment via Remotely Piloted Air Systems (RPAS), or drones. By documenting and prioritising fugitive emissions, Big Sky Theory hopes to inform both industry and the regulator to work towards Net Zero targets.
Big Sky Theory approached NPL via the Measurement for Business (M4B) programme with the aim of ensuring that their scientific and aviation innovations were matched by rigorous validation of the hardware and deployment techniques.
The project involved an initial literature review of the different emission sensing techniques that could achieve Big Sky Theory's desired levels of accuracy and assurance, helping them to make an evidence-based decision on which sensor and configuration route to take. As a result of this, Big Sky Theory decided on Tuneable Diode Laser Absorption Spectroscopy (TDLAS) as their technique of choice. This approach fires a tuned laser to intersect a methane plume. The laser is reflected off the ground and the returning laser energy is measured. This reading is used to calculate a parts-per-million-metre (ppm.m) figure that represents the concentration of methane directly beneath the drone. Multiple measurements taken this way can then visualise the plume and create an accurate 2D mapping of the search area.
Rather than attempt to design and build their own TDLAS capability, Big Sky Theory employed an off-the-shelf sensor, chosen from a list of sensors that met the baseline requirements, provided by NPL.
NPL and Big Sky Theory began bench testing and investigating the sensor’s strengths and weakness. “We knew the manufacturer's specifications would have limitations, so the aim of the first phase was to expand the operating threshold beyond the reported capability through controlled testing” says Ben Lunnon-Wood, Founder at Big Sky Theory.
The lab-based work included measuring calibrated closed gas samples to better understand the reported measurements and document background noise, a critically important figure in TDLAS data capture. This provided essential knowledge into the laser sensor, helping to optimise the capability for the operational test and evaluation phase.
The next phase consisted of outdoor controlled release trials. Accurately controlled gas release was managed by NPL to simulate fugitive leak levels found in oil and gas environments. Comparing sensor measurements to known gas parameters allowed the accuracy of the TDLAS technique to be assessed in near real-world conditions – leading to further optimisation. Performing these tests outdoors also introduced the meteorological real-world variables which allowed further optimisation. The fieldwork concluded with the analysis and modelling of data sets that could be used for mission planning and to understand the impact of weather variables.
The M4B project laid the groundwork for building Big Sky Theory’s business by identifying the initial sensing approach that they would take forward.
“We have since had other funded projects through the Innovate UK Analysis for Innovators (A4I) programme,” says Ben “and this initial project allowed us to get the most from those, because we weren’t going in blind.”
Subsequent projects have investigated emission flow rates in industrial settings – the amount of methane escaping from a specific source over a given period – improving the intelligence Big Sky Theory can bring to its customers. Together, the work with NPL over multiple projects has enabled them to create their 'LaunCH4 and Locate™' service, which provides detection and geolocation of methane emissions sources to an accuracy of three metres. Subsequent projects are now investigating methane plume mapping in 3D using weather models and exploring using the technology for hydrogen detection.
“We have gone through several R&D projects on our journey to provide the safest, fastest and most accurate methane detection and mapping service possible,” says Ben. “It all started with an M4B project. Innovation, without validation, will always be challenged. M4B has allowed Big Sky Theory to meet this challenge head on and create confidence in the emerging world of drone-borne intelligence collection”
“NPL helped us identify and refine the right measurement technologies to offer the quality of methane measurements we were looking for, providing a tangible and trusted foundation to our business. Big Sky theory prides itself on being experts, and working with experts, to create the very best technological solutions. The relationship with NPL adds a huge amount of credibility in the eyes of our customers, since NPL’s acumen in this space is well known across the world”.
Without M4B, the capability (LaunCH4 and Locate™) would have fallen short of the standards we strive for every day. The direct support of the team at NPL has also been matched by the gravity and recognition the NPL relationship brings to business development engagement and the reputation we now hold within the industry. NPL and M4B facilitated the very best in scientific research and development.
Ben Lunnon-Wood, Founder - Big Sky Theory