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EP-4285197-B1 - A METHOD AND AN UNMANNED AERIAL VEHICLE FOR DETERMINING EMISSIONS

EP4285197B1EP 4285197 B1EP4285197 B1EP 4285197B1EP-4285197-B1

Inventors

  • KNUDSEN, JON

Dates

Publication Date
20260506
Application Date
20220127

Claims (12)

  1. A method for determining emissions (104) from at least one source (102), the method comprising the steps of: - providing an unmanned aerial vehicle (UAV) (103) comprising: - an electronic control system for controlling the vehicle's flight; - a positioning system for determining the position of the UAV (103); - at least one emissions sensor for determining the presence or concentration of at least one gas and/or particles; - at least one wind sensor (110) for determining measured wind speed and measured wind direction (113) in a horizontal direction; - at least one positioning structure (109) for positioning the at least one wind sensor (110) relative to a centre of the UAV (103), the at least one positioning structure (109) comprising an elongated structure attached to the UAV at one end, and where the at least one wind sensor (110) is attached to an opposite end of the elongated structure, the positioning structure defining an axis extending from the UAV to the at least one wind sensor , wherein a size of the positioning structure is larger than a rotor radius of the UAV to position the at least one wind sensor outside a rotor radius of the UAV; - a data interface for collecting data during flight, the data interface being configured to store said data onboard the UAV (103) and/or pass said data to an external data collection unit, said data comprising at least one of: a first output signal from the electronic control system representing the position of the wind sensor (110), a second output signal from the positioning system representing the position of the UAV (103), a third output signal from the at least one emissions sensor, a fourth output signal from the at least one wind sensor (110) representing the measured wind speed and measured wind direction (113); - controlling the UAV (103) to: - fly through an inspection area along a flight trajectory (107); - collect data by use of the data interface during flight, and/or transmitting said data to an external data collecting unit for further processing thereof; characterised by controlling the UAV (103) to position the at least one wind sensor (110) at an offset position relative to the centre of the UAV and to position the positioning structure (109) with said axis substantially perpendicular to the measured wind direction (113) by moving the at least one positioning structure (109) relative to the centre of the UAV, wherein the at least one wind sensor (110) is repositioned during flight by moving the at least one positioning structure (109) based on the measured wind direction (113) by rotating the UAV (103) including the positioning structure (109) relative to a yaw axis of the UAV (103), and determining said emissions (104) by combining data from the at least one emissions sensor with data from the at least one wind sensor (110), and with data from the positioning system, the data from the at least one emission sensor, the at least one wind sensor (110), and the positioning system being collected during movement of the UAV (103) along the flight trajectory (107), wherein the data from the at least one wind sensor (110) and the speed and direction of the moving UAV (103) is used in wind triangulation for calculating true wind, and wherein the true wind is used to determine emissions (104).
  2. A method according to claim 1, wherein the data are continuously collected.
  3. A method according to any of the preceding claims, further comprising a step of determining a tilted position of the UAV (103), where the tilted positioned is defined as a position of the UAV (103) relative to a horizontal plane, and a step of tilting the wind sensor (110) in response to the tilted position.
  4. A method according to any of the preceding claims, wherein the step of positioning the at least one wind sensor (110) is continuously repeated during flight.
  5. A method according to claim any of the preceding claims, further comprising a step of determining the flight trajectory (107) prior to take off.
  6. A method according to any preceding claims, wherein the flight trajectory (107) is formed at least partly in a predetermined, substantially vertical plane (100).
  7. A method according to claim 6, wherein the predetermined, substantially vertical plane (100) is located at a predetermined distance to the at least one source (102).
  8. A method according to claim 6 or 7, wherein the predetermined, substantially vertical plane (100) is formed by substantially horizontal transects (115), where each transect (115) is traversing the vertical plane (100) at a determined altitude or height above ground.
  9. A method according to any of claims 6-8, wherein the predetermined, substantially vertical plane (100) at least partly forms a curved inspection area, partially or fully surrounding the at least one source (102).
  10. A method according to any of claims 6-9, further comprising a step of determining a mean wind direction prior to take off, and a step of arranging the substantially vertical plane (100) downwind from the at least one source (102).
  11. A method according to any of the preceding claims, wherein the step of collecting data during flight is carried out by sampling data sets at a determined frequency, wherein each data set comprises a time mark and at least one of: (a) a first output signal from the electronic control system representing the position of the wind sensor (110), (b) a second output signal from the positioning system representing the position of the UAV (103), (c) a third output signal from the at least one emissions sensor, and (d) a fourth output signal from the at least one wind sensor (110) representing measured wind speed and measured wind direction (113).
  12. An unmanned aerial vehicle (UAV) (103) for determining emissions (104) from at least one source (102), the UAV (103) comprising: - an electronic control system for controlling the vehicle's flight; - a positioning system for determining the position of the UAV (103); - at least one emissions sensor for determining the presence or concentration of at least one gas and/or particles; - at least one wind sensor (110) for determining measured wind speed and measured wind direction (113) in a horizontal direction; - at least one positioning structure (109) for positioning the at least one wind sensor (110) relative to a centre of the UAV (103), the at least one positioning structure (109) comprising an elongated structure attached to the UAV at one end, and where the at least one wind sensor (110) is attached to an opposite end of the elongated structure, the positioning structure defining an axis extending from the UAV to the at least one wind sensor , wherein a size of the positioning structure is larger than a rotor radius of the UAV to position the at least one wind sensor outside a rotor radius of the UAV; - a data interface for collecting data during flight, the data interface being configured to store said data onboard the UAV (103) and/or pass said data to an external data collection unit, said data comprising at least one of: a first output signal from the electronic control system representing the position of the wind sensor (110), a second output signal from the positioning system representing the position of the UAV (103), a third output signal from the at least one emissions sensor, a fourth output signal from the at least one wind sensor (110) representing the measured wind speed and measured wind direction (113); the UAV (103) being controllable to: - fly through an inspection area along a flight trajectory (107); - collect data by use of the data interface during flight, and/or transmitting said data to an external data collecting unit for further processing thereof; characterised in that the UAV (103) is controllable to position the at least one wind sensor (110) at an offset position relative to the centre of the UAV and to position the positioning structure (109) with said axis substantially perpendicular to the measured wind direction (113) by moving the at least one positioning structure (109) relative to the centre of the UAV, wherein the at least one wind sensor (110) is repositioned during flight by moving the at least one positioning structure (109) based on the measured wind direction (113) by rotating the UAV (103) including the positioning structure (109) relative to a yaw axis of the UAV (103), wherein said UAV (103) is configured to determine said emissions (104) by combining data from the at least one emissions sensor with data from the at least one wind sensor (110), and with data from the positioning system, the data from the at least one emission sensor, the at least one wind sensor (110), and the positioning system being collected during movement of the UAV (103) along the flight trajectory (107), wherein the data from the at least one wind sensor (110) and the speed and direction of the moving UAV (103) is used in wind triangulation for calculating true wind, and wherein the true wind is used to determine emissions (104).

Description

TECHNICAL FIELD The present invention relates to a method for determining emissions from at least one source by inspection at an inspection area, said emissions comprising the presence or concentration of at least one predetermined gas and/or particles. The invention also relates to an unmanned aerial vehicle (UAV) for determining emissions from at least one source. BACKGROUND OF THE INVENTION Emissions impact both climate and air quality significantly, yet many emissions remain sparsely documented due to the lack of cost-efficient and accurate methods for determining their location and contributions to climate change and air pollution. This is particularly true for fugitive or diffuse emissions from e.g., fossil and/or bio energy production, landfills, wastewater treatment, animal production, other surface area emissions, fires, flares, or other similar drifting emission scenarios. Some of these emissions may also be caused naturally, such as the release of methane through soil layers or similar discharges into the atmosphere from natural deposits. Even in the case of certain stack emissions, such as from vessels at sea or in port, or from land-based facilities, the emissions impact can be hard to determine without reliance on in-stack emissions data which may or may not be available. With an increased global focus on climate change and air pollution, and an urgent need to counter harmful emissions through the effective application of mitigating strategies and reduction technologies, the ability to reliably and cost-effectively measure the quantity and source origin of fugitive and diffuse emissions becomes central to curbing negative climate and environmental impacts. In particular, accurate monitoring of gaseous emissions of methane (CH4), ammonia (NH3), carbon dioxide (CO2), nitrous oxide (N20), sulphur dioxide (SO2), and nitrogen oxides (NOx), as well as particle emissions, is of growing concern because of their potent nature or increasing occurrence, although other gases with potential climate and environmental impacts are also relevant. Determining quantity and source origin of emissions involves the reliable measurement of atmospheric concentrations (of gases or particle size and count), wind speed and direction in a substantially vertical surface downwind from a target source, effectively documenting a vertical cross-section ("inspection area") of the drifting emissions plumes to determine the emission rate and directional location of the source (or sources). Other methods and technologies documented in prior art have attempted to do this using various airborne techniques. US 4,135,092 describes a method involving the use of, among other techniques, manned aircraft to map gas concentrations in a vertical plane of inspection downwind from a source, in combination with independent measurements of speed and direction of (mean) wind at an index point near the plane of inspection, using portable masts or balloons. EP 2 625 500 B1 describes the use of a UAV equipped with a remote detection optical instrument to fly over an inspection area, sufficiently above the emissions plume, to remotely detect mean vertical concentration values, while mean wind speed and direction is measured using diagnostic meteorological models that process data from meteorological stations placed at strategic points in the field to be monitored. WO 2019/246280 A1 describes a system and a method by which an UAV is used to measure methane concentrations along a vertical plane of inspection downwind from a source, while one or more weather stations, distal from the UAV, in combination with a standard wind speed model, are used to establish the mean wind speed in the area at various heights (vertical wind profile). The vertical wind profile in combination with the concentrations on the plane of inspection is subsequently used to derive an integrated mass flux through the plane. WO 2019/246283 A1 describes a method by which an UAV is used to locate emission sources using a combination of gas sensors on an UAV, local meteorological data, and an inverse stochastic dispersion model to determine the probable location (back trajectory) of the source or sources based on wind statistics measured separately during each plume event. WO 2020/086499 A1 describes a system comprising an UAV equipped with a gas sensor for detecting gases of methane, carbon dioxide, hydrogen sulphide, water, ammonia, sulphur oxides and nitrogen to generate a map of atmospheric greenhouse gas concentrations but without the inclusion of a wind component. US 2018/127093 A1 describes an Unmanned Aerial System (UAS) for use in the detection, localization, and quantification of gas leaks. A gas sensor is mounted to a UAS such that the sensor is positioned in a region unaffected by prop wash that is relatively undisturbed by the effects of the propeller(s) and other environmental conditions when in use. The location for the gas sensor is selected where the static and dynam