Making Light Work NOAA GMAC 2018 Open-Path Laser Dispersion Spectrometer for Methane Emissions Mapping and Quantification Dr Graham Leggett VP, Business Development
OUTLINE 1. 1. Abo bout ut M MIRICO 2. 2. Tec echno hnology • Laser Dispersion Spectroscopy (LDS) 3. 3. Em Emissions M Mappi pping a and nd Qua uantification • CH 4 release trials in collaboration with Shell Global Solutions International B.V. • Mapping derived using Shell LightSource software • Collaboration with NPL 4. 4. Conclus usions ns 2
ABOUT MIRICO • Developer of rugged, high performance spectrometers for gas analysis • Space science technology developed at Rutherford Appleton Labs • Instruments offer precision, sensitivity, accuracy, and reliability • Headquarters in Oxford, UK Serving Multiple Rugged & High Robust Space Technology Industries performance Analysers for the field 3
LASER DISPERSION SPECTROSCOPY ABSORBTION LDS I 0 I t • Signal encoded in intensity of • Signal encoded in phase of beam emitted beam Linear response over broad dynamic range • Non linear after 10% absorbance Maintains sensitivity in “dirty” • • Useful signal limited by intensity – environments • susceptible to dust, water vapour, Immune to intensity fluctuations • etc. 4
LASER DISPERSION SPECTROSCOPY QCL/ICL Acousto-optic Mid-infrared modulator Detector laser (AOM) Absorption • Each frequency experiences different refracted index • Results in different propagation LDS time to detector 5
SET-UP 500 m 500 m Tripod-mounted c Tr corner cube re retro re reflector LDS 1 100 OP OP prototyp ype CH CH 4 • 1 km km t tot otal al p path-len ength ( (transmit a and return) • Manual al align gnmen ent using v g visible l e laser • ~1 1 hour d dep eployment p t process ss 6
OPEN-PATH LDS – CH 4 MAPPING SIMPLE CASE OF POINT EMITTER TEMPORAL EVOLUTION OF CH 4 7
OPEN-PATH LDS – CH 4 MAPPING SIMPLE CASE OF POINT EMITTER TEMPORAL EVOLUTION OF CH 4 8
MULTI-PATH CH 4 EMISSIONS MAPPING Fast galvo mirror Laser Detector AOM 9
MULTI-PATH CH 4 EMISSIONS MAPPING 19 releases of ~1 hour each • 2x2m diffuse area sources at ground level • four release schemes of 1 or 2 sources • emission rates: 1.2 to 1.6 kg/hr per source • <2m/sec wind -data excluded • 1 minute data averaging used • 10
MULTI-PATH CH 4 EMISSIONS MAPPING 11
MULTI-PATH CH 4 EMISSIONS MAPPING Temporal evolution of integrated CH 4 concentration over 7 paths Release Location 2 1s resolution - ~10 ppb precision - ~1 ppm.m/ √ Hz 7 min background 40 min release 7 min background (1 of 5 datasets used for analysis) Path switching 10 milliseconds Paths 5, 6, and 7 upwind so no reaction to release ~200 meters 0-14 ppm Wind direction 120 ms/beam 12
MULTI-PATH CH 4 EMISSIONS MAPPING Location 2 1.38 kg/hr actual Location 1 1.35kg/hr actual Location 3 Location 3&4 1.47 kg/hr actual 2x 1.24 kg/hr actual 13
NPL TRIAL Purpose: Test at different heights, emission scenarios and release rates. 14
NPL TRIAL 15
CONCLUSIONS • Suc Succes essfully t y tak aken LDS f S from l laboratory to fiel eld • Co Confirmed ed pa path th-leng ngth a and s nd sensitivity • Co Confirmed ed o oper perati tion in n variable a e atmosp spher eric condi nditions • De Demons nstrated s ed scanni nning ng techni hniqu que f for l large-area ea mapp pping ng 16
ACKNOWLEDGEMENTS 17
THANK YOU QUESTI TIONS? graham@mirico.co.uk www.mirico.co.uk +44 7715 676751
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