Laser Gas Sensing for Clean Energy Science

With the rising threat of the consequences of climate change and the negative impact of air pollutants on human’s, and more widely the biosphere’s well-being, it has become ever more important to establish accurate and reliable monitoring systems of gaseous emissions released in the atmosphere. Whenever gaseous emissions occur, such systems are crucial to help answer important questions and support targeted action. What are the gasses being emitted? Where are the emission sources located? How much gas flux is being emitted? What are the processes leading to these releases? How can these emissions be reduced? Have targeted actions succeeded in reducing emissions? Field gas monitoring technologies provides quantitative information for site characterisation, legislation enforcing, decision making, mitigation assessment and transparency that supports a wiser use of natural resources.

MIRICO develops laser sensing technologies to provide new solutions for increasingly challenging gas measurement problems. The laser sensing technology underpinning MIRICO’s molecular fingerprinting systems is embodied into two different platforms dedicated to either remote sensing, or in-situ sensing. The remote sensing system enables highly sensitive and reliable quantification of gas emissions over large field areas (see video showing the technology in action). Conversely, the in-situ instrument is brought at the point of measurement to allow real time, accurate analysis of molecular gases, such as stable isotope analysis of CO2.This isotopic analysis then enables source attribution, contributing to understanding the origin of the gaseous CO2 released. Currently, both of these platforms are being developed as part of the science for clean energy (S4CE) project to add the gas emission component of the monitoring reporting and verification (MRV) of the diverse geo-energy technologies considered in the project.

MIRICO originated from the Rutherford Appleton Laboratory, one of the UK national laboratory, from the Space Science Department Spectroscopy Group, led by Damien Weidmann. The group experiments and develops spectroscopic methods and instrumentation using advanced laser sources, targeting planetary and Earth observation applications. As with many space science research and development efforts, the arch towards miniaturisation, robustness, and high specifications has opened up new “ground-based” opportunities. These opportunities are in diverse sectors, including environmental sciences, geology, healthcare, industrial emission monitoring and others. MIRICO was founded to take these platform technologies and develop them to commercial systems that support the industrial and scientific community.

Laser frequency mixing and optical heterodyning is a core long standing expertise of the RAL research group. These techniques were used to develop tunable laser dispersion spectrometers that offer unique sensing properties compared to traditional approaches using only molecular absorption. Indeed, with Laser Dispersion Spectroscopy (LDS), molecular concentration signalsare encoded in the frequency of the electromagnetic field rather than in the intensity (the latter being the case of the usual absorption approach). Using optical dispersion turns into benefits such as greater immunity to laser power fluctuations that can stem from field conditions (rain, snow, fog, particulates, etc.), and increased measurement dynamic range well suited for highly variable emis differential measurement approach, measurement sensitivity is significantly improved through common noise suppression, such as atmospheric scintillation for instance. As a result, the overall system offers highly sensitive, stable and reliable gas concentration measurements for demanding environments.

To date MIRICO has been working as part of the S4CE Consortium in developing the sensors for characterization of stray gas surface emission at geo-energy sites. Anearly prototype system for CH4 emission source mapping and quantification has been deployed during a controlled release test to successfully demonstrate the methodology. This prototype was also deployed over the Cornwall geothermal energy site to record background level of atmospheric CH4 before the start of the drilling of the wells.

More recently, simultaneous remote sensing of CH4 and CO2has been demonstrated for the first time. The system is now being further validated and ruggedized to enable field operations and the deployment to S4CE sites.The core  core technology for the isotopic in-situ instrument is also being developed with a first light anticipated in early 2019.

Figure 2: Deployment of the CH4 remote sensing prototype instrument at the Cornwall geothermal energy site before the start of drilling operation. Left, system being installed in the office block. Right, array of retro-reflectors deployed over the planned well location

 

The next key step for MIRICO within the S4CE project is to complete the first instrument demonstrators and start test deployments at the consortium field sites to begin the first in a series to field measurements. Sites includeReykjavik Energy Carbon Capture and Storage Carbfix project, where MIRICO’s instrument will be deployed to provide background atmospheric CO2 measurements over large areas, and support quantification of emission sources from fault lines and other known sources. Furthermore, CO2 isotopic measurement trials will be planned to provide real time analysis of injected CO2, to understand the injected source isotopic ratio and subsequent isotopic analysis from various depths. This will support the understanding of the method’s sequestration efficacy. The Cornwall geo-energy site will be further investigated after the drilling is completed. It will be particularly interesting to contribute to the understanding of the impact of local old mines on CH4 emissions. MIRICO will also work with a new S4CE partner, ENI, to start organizing deployment in a test industrial setting in Italy and therefore expands the technology benefits to greenhouse gas leak detection and mitigation for oil and gas operators

Authors: Mohammed Belal, Damien Weidmann