Development of a low cost, field portable imaging FTIR to detect and differentiate between biogenically and thermogenically derived hydrocarbon gas.

The detection and quantification of methane gas emissions is a critical component of a wide range of environmental science processes and applications. Acquisition of sampling datasets with the essential spatial and temporal resolution and detection sensitivity to address the requirements of the key science questions, climate models and commercial users is a significant environmental challenge and poses a critical market need. A diverse range of researchers, interest groups, commercial and regulatory organisations require the detection, quantification and differentiation of hydrocarbon gases (methane, propane, butane, & ethane) at spatial scales ranging from point source to landscape scale.

Identification of the sources and fluxes of methane into the atmosphere is a critical component of climate change research. A significant challenge to accurately quantifying the methane contribution is the spatial and temporal variability in methane emissions of many of the environmental processes, e.g. melting of boreal peatland, combined with the exceptionally large size of the affected areas. Fugative methane emissions are also of critical interest to a wide range of commercial and regulatory organisations. Gas emissions from landfill sites are a common environmental issue faced by councils and the environment agency while fugitive emissions from pipelines are a very expensive and inconvenient problem for many commercial organisations ranging from domestic supply to large-scale petro-chemical facilities.

Detection of on-shore microseeps is a key objective of exploration hydrocarbon geoscientists as they are highly indicative of the presence of a hydrocarbon-rich basin. Microseeps are characterised by the emission of thermogenically derived hydrocarbon gas which usually contains significant concentrations of ethane, propane, butanes and condensate. Thermogenic gas geochemistry differs from biogenic gas, which consists almost entirely of methane, providing a direct, remote methodology for microseep identification. This detection capability could also be utilised to quantify the environmental impact of the exploitation of unconventional gas deposits (shale gas & coalbed methane). The volume, composition and duration of fugitive thermogenic hydrocarbon gas emissions from well sites is poorly understood. Continuous, complete, accurate measurements of hydrocarbon emissions over the entire well site could inform discussion of the environmental impact and influence decisions on future developments.

All these applications require the acquisition of accurate, continuous measurements of hydrocarbon gas emissions over prolonged periods (night and day) over scales ranging from site to landscape. Current field-based methods for detecting hydrocarbon gas emissions cannot meet the requirements of researchers and users as they are time-consuming, costly and produce very sparse spatial datasets Remote-sensing based methods offer a potential solution however current techniques are either inaccurate (e.g. reflectance spectroscopy) or very costly and impractical (e.g. LiDAR).

Currently available imaging based gas monitoring instruments are not capable of resolving the hydrocarbon gases with sufficient accuracy. Imaging Fourier Transform Interferometers (FTIRs) have the potential to detect and quantify hydrocarbon emissions but the current design of imaging FTIRs make them prohibitively expensive and cumbersome for operational deployment by environmental scientists.There is an urgent need for the development of a low-cost, highly portable, highly sensitive imaging system. The aim of this project is to undertake a laboratory-based study to develop, and validate a low cost, lightweight, compact imaging Fourier Transform InfraRed (FTIR) spectrometer with sufficient spectral resolution and radiometric sensitivity to detect, quantify and differentiate between biogenically and thermogenically derived hydrocarbon gas.

The high spectral resolution imaging FTIR to be developed from this project will be of potential interest to a diverse range of users. This project will develop the instrument to a TRL 4. The testing of the protptype version of the instrument at the NPL will provide potential users with a thorough, independent assessment of the performance of the instrument and give them the neccessary technical details to prepare high quality research proposals. It will also give confidence to potential commercial users the potential of the instrument. The instrument developed from this proposal will have the flexibility to undergo a range of technical development specific to particular projects and applications and be deployable in a range of configurations and on a range of platforms including a UAV. A wide range of regulatory and commercial organisations would benefit immediately from the availablity of a low cost, lightweight imaging FTIR. Potential users already identified include :

i) Environmental scientists
The capability of detecting the spatial extent of the dispersion of biogenic methane gas from landfills, sewage works and other types of contaminated land would be of immediate use to environmental scientists.

ii) Hydrocarbon exploration geologists
The ability to detect remotely on-shore micro-seeps accurately at the landscape scale would provide an exceptionally powerful first-pass exploration tool for assessing the hydrocarbon potential of basins.

iii) Enhancing Geohazard Prediction
The ability to detect methane and carbon dioxide emissions from volcanoes would assist planners in assessing the location, scale and degree of potential volcanic hazard and provide additionaly early warning capabilities.

v) Unconventional gas developers
Monitoring the hydrocarbon gas emissions from a complete well site over its entire development and production life would provide developers with means of demonstrating to opponents that the environmental affect of hydraulic fracturing (with regard to climate change) was insignificant.

v) Gas utility and petrochemical facilities
The identification of pipeline leaks is a major financial and operational concern for gas suppliers. A low cost, field portable methodology for detecting the volume, extent and source location of gas leaks would be of very significant interest to a variety of commercial organisations. Similarly detection of leaks in petro-chemical facilities would be of great health & safety as well as commercial interest.

vi) General scientific community
It is envisaged that there would be a significant degree of interest in the wider scientific community regarding use of and development of this instrument in their specific project and application. The anticipated applications range from medical, defence to agricultural.