Method and an unmanned aerial vehicle for determining emissions

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.