US-12625122-B2 - Method and an unmanned aerial vehicle for determining emissions

US12625122B2US 12625122 B2US12625122 B2US 12625122B2US-12625122-B2

Abstract

A method is provided for determining emissions from at least one source by inspection at an inspection area. The emissions include the presence or concentration of at least one predetermined gas and/or particles. An unmanned aerial vehicle (UAV) and the collection of wind data is obtained by a moving UAV using at least one wind sensor.

Inventors

Jon Knudsen

Assignees

EXPLICIT ApS

Dates

Publication Date: 20260512
Application Date: 20220127
Priority Date: 20210127

Claims (14)

1 . A method for determining emission rates from at least one source, the method comprising the steps of: providing an unmanned aerial vehicle (UAV) comprising: an electronic control system for controlling the vehicle's flight; a positioning system for determining the position of the UAV; at least one emissions sensor for determining the presence or concentration of at least one gas and/or particles; at least one wind sensor for determining measured wind speed and measured wind direction; at least one positioning structure for positioning the at least one wind sensor relative to a centre of the UAV; a data interface for collecting data during flight, the data interface being configured to store said data onboard the UAV 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, a second output signal from the positioning system representing the position of the UAV, a third output signal from the at least one emissions sensor, a fourth output signal from the at least one wind sensor representing the measured wind speed and measured wind direction; controlling the UAV to: fly through an inspection area along a flight trajectory; position the at least one wind sensor substantially perpendicular to the measured wind direction at an offset position relative to the centre of the UAV, wherein positioning of the at least one wind sensor comprises a step of moving the at least one positioning structure relative to the centre of the UAV; and wherein the at least one wind sensor is repositioned during flight, if the speed of the UAV is changed, 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; determining said emissions by combining data from the at least one emissions sensor with data from the at least one wind sensor, and with data from the positioning system, the data from the at least one emission sensor, the at least one wind sensor, and the positioning system being collected during movement of the UAV along the flight trajectory, wherein the data from the at least one wind sensor and the speed and direction of the moving UAV is used in wind triangulation for calculating a true wind speed, and wherein the true wind speed is used for calculating emission rates.
2 . The method according to claim 1 , wherein the data are continuously collected.
3 . The method according to claim 1 , wherein the step of positioning the at least one wind sensor comprises a step of rotating the UAV including the positioning structure relative to a yaw axis of the UAV.
4 . The method according to claim 1 , further comprising a step of determining a tilted position of the UAV, where the tilted positioned is defined as a position of the UAV relative to a horizontal plane, and a step of tilting the wind sensor in response to the tilted position.
5 . The method according to claim 1 , wherein the step of positioning the at least one wind sensor is continuously repeated during flight.
6 . The method according to claim 1 , further comprising a step of determining the flight trajectory prior to take off.
7 . The method according to claim 1 , wherein the flight trajectory is formed at least partly in a predetermined, substantially vertical plane.
8 . The method according to claim 7 , wherein the predetermined, substantially vertical plane is located at a predetermined distance to the at least one source.
9 . The method according to claim 7 , wherein the predetermined, substantially vertical plane is formed by substantially horizontal transects, where each transect is traversing the vertical plane at a determined altitude or height above ground.
10 . The method according to claim 7 , wherein the predetermined, substantially vertical plane at least partly forms a curved inspection area, partially or fully surrounding the at least one source.
11 . The method according to claim 7 , further comprising a step of determining a mean wind direction prior to take off, and a step of arranging the substantially vertical plane downwind from the at least one source.
12 . The method according to claim 7 , further comprising a step of determining a mean wind direction prior to take off, and at step of arranging the substantially vertical plane upwind from the at least one source to determine a background level of gas and/or particles which do not originate from the at least one source, and/or to isolate said emissions from said at least one source from emissions from other sources.
13 . The method according to claim 7 , 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, (b) a second output signal from the positioning system representing the position of the UAV, (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 representing measured wind speed and measured wind direction.
14 . An unmanned aerial vehicle (UAV) for determining emission rates from at least one source, the UAV comprising: an electronic control system for controlling the vehicle's flight; a positioning system for determining the position of the UAV; at least one emissions sensor for determining the presence or concentration of at least one gas and/or particles; at least one wind sensor for determining measured wind speed and measured wind direction; at least one positioning structure for positioning the at least one wind sensor relative to a centre of the UAV; a data interface for collecting data during flight, the data interface being configured to store said data onboard the UAV 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, a second output signal from the positioning system representing the position of the UAV, a third output signal from the at least one emissions sensor, a fourth output signal from the at least one wind sensor representing the measured wind speed and measured wind direction; the UAV being controllable to: fly through an inspection area along a flight trajectory; position the at least one wind sensor substantially perpendicular to the measured wind direction at an offset position relative to the centre of the UAV, wherein positioning of the at least one wind sensor comprises a step of moving the at least one positioning structure relative to the centre of the UAV; and wherein the at least one wind sensor is repositioned during flight, if the speed of the UAV is changed, 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; wherein said UAV is configured to determine said emissions by combining data from the at least one emissions sensor with data from the at least one wind sensor, and with data from the positioning system, the data from the at least one emission sensor, the at least one wind sensor, and the positioning system being collected during movement of the UAV along the flight trajectory, wherein the data from the at least one wind sensor and the speed and direction of the moving UAV is used in wind triangulation for calculating a true wind speed, and wherein the true wind speed is used for calculating emission rates.

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) and the collection of wind data by a moving UAV using at least one wind sensor. 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 (N2O), 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. U.S. Pat. No. 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