The purpose here is to develop a methodology that uses laser to identify, from a distance, leaks of methane and other volatile organic compounds.

Creation of a tool to help industry to detect leaks of components of natural gas and which enables the control and the inventory of the issues related to it: this is the main aim of the project Studies on the application of LIDAR in the measurement of atmospheric pollutants, which is one of the 28 projects that are already in progress at the Research Center for Gas Innovation (RCGI).

“We want to use the methodology known as “Light Detection and Ranging”, or LIDAR, to monitor gaseous emissions of methane and other volatile organic compounds, which pollute the atmosphere”, explains Roberto Guardani, a chemical engineer, a professor at the Polytechnic School of USP and coordinator of the Project.

Mr. Guardani and his team have already worked with LIDAR since 2008 to measure aerosols such as particles, drops and dust, together with the Lasers and Applications Center of the Institute for Nuclear and Energy Research (IPEN). “There has come a challenge of working with gaseous emissions, so we will adapt the methodology for monitoring of the gases. We have a consolidated technique for aerosols, for measurement and also for analysis of data.”

According to Mr. Guardiani, LIDAR is only used to measure gases experimentally. “Nowhere in the world is this methodology used as a technique for control. Its use in this role is therefore innovative. In Brazil, there are no other teams using this technique to measure pollutants”.

The system includes a laser source, a telescope, and signal detectors. It issues beams of light using three different wavelengths: visible, ultraviolet and infrared. “The source issues directional beams, with a pulse frequency. Then we measure the return signal: for example, if the light reaches out to particles and is scattered in several directions, then we measure the light that returns in this pattern of scattering. The system also has a telescope that detects the light that returns. Based on the speed of light, comparing the pulse that was emitted and the pulse that returned, we will know how far away the particle is. This technique offers a very good spatial resolution, as we manage, from a distance between 2 and 3 km, to measure a volume 4 meters in diameter and know what happens in it.”

Physicist Eduardo Landulfo, a head researcher at IPEN and also one of the supervisors of the project, stresses that the major challenge for measurement of methane is that of having a quick response. “In traditional measurement techniques, the gas is collected and then taken to a laboratory, where the sample is analyzed using conventional chemical techniques. However, these are not quick. In addition, the instrumental techniques for monitoring which are most commonly used can measure the presence of methane and some other gases at small distances, maybe a few dozen meters away.

In his opinion, this is another tool for control of emissions and leaks by industrial companies. “We plan to carry out measurements both in stock control and in production. In this area, there are normally sensors already installed, but stock control is the critical part, where measurement is more complicated.” Mr. Landulfo stresses that the system can make programmed searches of large areas as also be directed towards a specific source, like a chimney.

“The chemical industry in general issues very hot gases, which are often aggressive. Placing sensors in chimneys is expensive and not very reliable, as this requires constant calibration and maintenance… In a technique such as LIDAR, the equipment may be placed on the ground, pointing to the chimney, and detect any faults. We believe that this will probably be cheaper than placing sensors inside the chimney and at other critical points”, Mr. Guardani adds.

“The proposed system is compact, quick to respond, and also has constancy of time and measurement, and also a calibration which can be used for low and high concentrations. In a nutshell: it can be an excellent tool”, stresses Mr. Landulfo.