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.
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.
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.
Read more »
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.
Read more »
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.
Read more »
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
Contact us
MEASUREMENTS MAKE SENSE
