Methane Detection
TDLAS-based methane sensing for leak detection and quantification.
Sensor Technology
BL-CH4 TDLAS Sensor
| Specification | Value |
|---|---|
| Technology | Tunable Diode Laser Absorption Spectroscopy |
| Wavelength | 1.65 µm (CH4 absorption band) |
| Sensitivity | 5 ppm·m (path-integrated) |
| Range | Up to 100m |
| Response Time | <1 second |
Detection Principle
TDLAS measures methane concentration along the laser path:
- Laser tuned to CH4 absorption wavelength
- Absorption measured as function of wavelength
- Concentration calculated from absorption profile
- Path-integrated value (ppm × meters)
Flight Patterns
Different patterns for different detection scenarios:
Grid Pattern
Use: Area coverage, baseline surveys
- Systematic coverage of target area
- Consistent altitude and spacing
- Good for identifying emission sources
Transect Pattern
Use: Downwind detection
- Perpendicular to wind direction
- Cross plume for concentration profile
- Locate source by peak detection
Spiral Pattern
Use: Plume profiling
- Centered on suspected source
- Decreasing radius spirals
- Quantify emission rate
Wind Compensation
Critical: Wind significantly affects readings
| Wind Speed | Error Without Compensation | Mitigation |
|---|---|---|
| < 3 m/s | ~50% | Acceptable for detection |
| 3-7 m/s | 100-200% | Requires correction |
| > 7 m/s | 300%+ | Multi-sensor validation essential |
Compensation Approach
- Onboard anemometer - Real-time wind measurement
- Flight heading correlation - Adjust for aircraft motion
- Multi-pass averaging - Reduce single-reading variance
- Multi-sensor fusion - Thermal + visual confirms source
Multi-Sensor Correlation
Methane detection is most reliable when correlated with other sensors:
| Secondary Sensor | Correlation Value |
|---|---|
| Thermal | Heat signature confirms active emission |
| Visual | Source identification (valve, tank, flare) |
| GPS/Asset DB | Link reading to specific equipment |
| Historical | Compare to baseline readings |
Use Cases Addressed
| # | Use Case | Methane Role |
|---|---|---|
| 3 | Liquid/gas leak detection | Primary gas detection |
| 4 | Methane (CH4) detection | Primary |
| 11 | Hot spots correlation | Secondary validation |
| 16 | Valve/tank status | Emission correlation |
SLA Compliance
| Metric | Target | Approach |
|---|---|---|
| Detection sensitivity | 5 ppm·m | Sensor specification |
| False positive rate | <20% | Multi-sensor correlation |
| Localization accuracy | ±10m | GPS + wind model |
| Processing latency | <20 min | Batch processing pipeline |