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Technology

FluxSense is using a range of optical techniques/methods for gas monitoring and emission quantification for different gases and purposes.

We use both passive techniques (SOF and SkyDOAS) with external light sources (direct and scattered Sunlight respectively) and passive techniques (MeFTIR and MeDOAS) with internal light sources (lamps). SOF and SkyDOAS are categorized as remote (non-invasive) while MeFTIR and MeDOAS are extractive. Furthermore, different measurement geometries implicate different primary quantities and units, where SOF gives slant atmospheric mass column (mg/m2), SkyDOAS vertical atmospheric mass column (mg/m2) and MeFTIR and MeDOAS local concentrations (mg/m3 and ppb). They use also different part of light spectra; SOF and MeFTIR are operating in the infrared (IR) and SkyDOAS and MeDOAS are sensitive to ultra-violet (UV) light.

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Spectroscopy

What unites all our methods are absorption spectroscopy and the Beer-Lambert’s law, where the concentration of a specific gas along the measurement path (i.e. from the light source to the sensor) can be deduced from the amount of absorbed light and the absorption cross sections (i.e. the ability to absorb light) for that gas.

Since gases have unique spectral absorption features, different gases can be separated if the sensor has sufficient spectral resolution. If many absorbing gases are present, a mathematical optimization algorithm (Least Squares Fit) will be used to compute the concentration of each gas that best fit the measured absorption. Gas molecules have strong absorption features in defined regions (due quantum physics characteristics), that’s why we need different sensors/instruments to get all the gases.

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Direct Emission measurements

SOF

The SOF instrument system is designed to measure gas emissions (flux) of VOCs and other gases using direct solar IR-light.
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SkyDOAS

The SkyDOAS instrument system measures atmospheric emissions (flux) of SO2, NO2 and HCHO using zenith-scattered solar UV-light.
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Extractive Concentration Measurements

MeFTIR

The MeFTIR instrument system is designed to measure gas concentrations of VOCs and other gases in the extracted air using internal IR-light.
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MeDOAS

The MeDOAS instrument system is designed to measure gas concentrations of BTEX and other gases in the extracted air using internal UV-light.
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Tracer Correlation

The Tracer Correlation method is used for 2-dimensional mapping of concentrations and leak search on an industrial site and quantification of gas emissions from individual components, main equipment (e.g. tanks) and in some cases subareas on a site, if spatially separated.
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Indirect Flux

The indirect flux method is used for emission assessments of gases that cannot be directly measured by (SOF or SkyDOAS or other sensors). Indirect flux relies on measured gas-ratios in the same plume as quantified by SOF.
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Data Processing and Quality Control

FluxSense is following internal quality assessment protocols for measurements and the post-processing. We also apply an internal peer-review for all data analysis.
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Methods Summary

Typical Compounds Spectral Region Type Measured Quantity [unit] Reference Derived Quantity [unit] Complementary data
SOF Total alkanes
alkenes
ammonia
IR Passive, Remote Sensing Integrated slant column mass [mg/m2] Relative Background Mass Flux [kg/h] 1) Vehicle GPS-coordinates,
2) Plume wind speed and direction
Sky DOAS SO2
NO2
Formaldehyde
UV Passive, Remote Sensing Integrated vertical column mass [mg/m2] Relative Background Mass Flux [kg/h] 1) Vehicle GPS-coordinates,
2) Plume wind speed and direction
MeFTIR Methane,
Total alkanes
Alkenes
NH3
N2O (tracer)
C2H2 (tracer)
IR Active, Extractive Mass concentration at vehicle height [mg/m3] Relative Background 1) Mass concentration ratio of ground plume combined with SOF gives Indirect Flux [kg/h] and plume height information [m]
2) Mass flux [kg/h] via tracer release
1) Vehicle GPS-coordinates
2) Plume wind direction
MeDOAS BTEX UV Active, Extractive Concentration at vehicle height [mg/m3] Relative Background Combined with MeFTIR and SOF gives Indirect Flux [kg/h] 1) Vehicle GPS-coordinates,
2) Plume wind direction

Conditions and limitations

Conditions and limitations 3

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MEASUREMENTS MAKE SENSE

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Contact

+46 (0)70 30 99 669
contact@fluxsense.se

Sweden – FluxSense AB – Head Office
+46 (0)76 30 80 535
Hulda Mellgrens gata 3,
SE-421 32, Västra Frölunda

US – FluxSense Inc
+1 (775) 830 52 72
15641 Product Ln A11,
Huntington Beach,
CA 92649

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FluxSense AB was founded in 2001 to fill a need for reliable diffuse emissions measurements for the petroleum and petrochemical industry. Since then, FluxSense has conducted well over 100 measurement campaigns of industrial and agricultural emissions in Europe, America and Asia.

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