A rugged LiDAR system for the remote detection of fugitive emissions of methane from shale gas and landfill sites.

We have developed a laser-based instrument that can scan the lower atmosphere and measure the concentration of greenhouse gases such as carbon dioxide and methane. The technology is known as Differential Absorption LiDAR (DIAL) and its finely-tuned scanning laser detects the atmospheric concentration of greenhouse gases at a number of distances in a hemisphere to about 5 km. Immediate applications of the system range from measuring fugitive emissions from fracking wells in the shale gas industry, landfill emissions of methane, national compliance with the Kyoto Protocol, measuring changes in the global carbon cycle and observing the impact of Cap and Trade schemes of the type just passed in Californian legislation. The DIAL can be extended to measure other atmospheric compounds such as the aerosol loading of the air in megacities, something which is rising towards the top of many political agendas.

Our DIAL fires an eye-safe laser into the atmosphere at a wavelength which is known to be absorbed by the gas of interest; the laser also fires a second beam (a reference beam) at a different wavelength that is not absorbed by the gas of interest. The difference in the backscatter return signals together with accurate time resolution is used to calculate the GHG concentration profile at ranges up to typically 5km. Our system produces profiles and maps of the concentration of the GHG of interest and, using our modelling software, we are able to pinpoint just where the GHG came from.

Our DIAL has been in development for three years and we are at a point where we need to take it from a laboratory-based device to a field demonstrator. Our experience with the system at the moment is that it needs to be made more rugged before it could be taken to the field - the focussing telescope is attached to the outside of the telescope and it turns out that pressing on the skin of the telescope moves the laser beam in space and thus affects the sensitivity of the instrument; we plan to redesign the telescope so it is more rigid by inclusion of an exoskeleton. The laser itself was built for a different, lab-based environment and we used it as proof-of-concept. We have designs to fit the more sensitive parts of the laser (the Optical Parametric Oscillator (which tunes the laser) and the receiver) into single machined blocks to help reduce thermal and vibration effects. Once we have ruggedised the system, we will undertake field trials at a landfill and shale gas (fracking) site in cooperation with our project partners. Our Business Opportunity is to offer the system as a whole - we would manufacture the telescope and its laser/detector system and we would offer a data processing option to customers of the telescope.

This project will demonstrate a working DIAL instrument in industrial settings - a landfill and a shale gas drilling site. A demonstrator instrument shown to be rugged and capable of high-resolution methane measurements at a low cost will be transformative in the market place. It is not possible to purchase such an instrument from any manufacturer around the world. The landfill community are well aware of DIAL and have expressed an interest in using that technology but the presently available truck-borne systems are expensive to hire and difficult to obtain time with. The shale gas industry faces enormous community resistance before they are allowed to frack for gas; having a state-of-the-art and robust methodology to observe for any leaks of methane and conversely to show they are small, could make the difference between given the licence to drill or not - in a multi-billion dollar industry, proving that fracking is not a major polluter will be essential for operators and regulators alike. Given there are a few thousand current and closed landfill sites in the UK and potentially a few hundred fracking wells in the UK means the market for monitoring with DIAL even in one relatively small country is great. The scientific market really needs a DIAL system to be available to probe the atmosphere for carbon - it will be a game-changer in environmental monitoring. Evidence is mounting that inventory methods of accounting for carbon are inadequate yet society needs to have faith in national and global carbon budgets in order to deal with the issues of mitigation and adaptation in global change. DIAL closes the loop between the low temporal and low spatial resolution of satellite systems and the high temporal and high spatial resolution of ground-based systems. Environmental science will benefit enormously from much more information on atmospheric constituents of concern.