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Introduction

What is Continuous Monitoring?​

Continuous Emissions Monitoring involves the use of fixed point sensors, often found at the fenceline of a facility that record and transmit environmental data, including wind direction, wind speed, and methane gas concentration at that specific location through time. Point sensors operate autonomously, powered by their own batteries and solar panels, transmitting data to the cloud using their own LTE connections. The Qube Platform runs on a cloud server and uses all the combined collected data for a facility in tandem to localize and quantify emissions for that facility.

Point Sensors​

  • Point sensors are devices that measure the concentration of methane at a specific, fixed location.
  • As a plume of methane drifts past the sensor's location, the sensor detects an increase in the methane concentration in the air.
  • The sensor records this concentration over time, providing a time series of methane levels at that point.
  • Point sensors operate autonomously and transmit data to the cloud using each device's independent LTE connection.

Localization​

  • Multiple point sensors are often deployed in a network around a facility.
  • The Qube Platform analyzes data from all point sensors around a facility to model emissions at the facility.
  • By analyzing the concentration data from all sensors together in conjunction with wind direction, it's possible to triangulate the specific location of the methane source.
  • By analyzing time periods where a sensor should see methane based on the wind direction but is not, it is possible to rule out specific potential sources.

Quantification​

Quantifying a leak using point sensors can be done by modeling a methane plume as a gaussian distribution using:

  • Magnitude of the concentration spikes
  • Wind speed
  • Distance to the suspected leak source
  • Wind variability
  • Atmospheric conditions (temperature, pressure & humidity)

Using the concentration readings at the device along with wind speed, we are able to determine what volume of methane is passing by the instrument.

Wind variability and the atmospheric conditions tell us how a plume would disperse through space. With a model of the plume, along with the distance to the suspected leak source, we are able to solve for what size of leak would be required to produce that magnitude of reading the sensors are seeing.