EDAR
Emissions Detection And Reporting, commonly known as EDAR, is a state-of-the-art remote-sensing technology invented and developed by Hager Environmental & Atmospheric Technologies (HEAT).
This technology is an eye-safe laser-based technology capable of remotely detecting and measuring infrared absorption of environmentally critical gases coming out of a moving vehicle.
EDAR: A Touchless Emissions-Testing Solution
EDAR contains a multi-patented system of hardware and software, enabling a multispectral 3D image of the entire exhaust plume from a moving vehicle. As part of an unmanned system, EDAR’s technology collects vehicle emissions data on various gases such as CO, CO2, NO, NO2, NOx, HC and PM. Additionally, EDAR provides increased sensitivity, in some cases of over 2,000%, and resolutions of a million times greater than existing technologies in use today.
Utilizing the same footprint for light- and heavy-duty vehicles, EDAR can quickly identify the difference between clean and high-emitting vehicles on-road in a
real-world, natural operating environment.
Many key aspects set EDAR apart from traditional RSD technologies.
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The EDAR technology uses principles similar to space satellites to detect and quantify gases in the earth’s atmosphere using lasers and the Differential Absorption Spectroscopy LiDAR (DiAL) method.
EDAR's R2 Accuracy: An “r squared” of one means a perfect fit and, an "r squared" of zero indicates no fit.
EDAR's r-squares show excellent fit:
CO = 0.996
NO = 0.998
HC = 0.996
CH4 = 0.983
PM = 0.937
View Colorado Presentation here.
View UK/Colorado Comparison here.
The EDAR system uniquely uses infrared spectroscopy methods to measure the temperature of the exhaust as it exits the tailpipe. For each vehicle, the EDAR unit detects and measure the temperature of the exhaust at the moment the plume becomes visible as it exits the tailpipe.
The temperature of the exhaust relative to the ambient temperature is an indication of whether vehicle is in a warmed-up or cold start state. When a vehicle is in a cold start state, it will appear to be a high emitter due to emissions caused by a cold catalyst. However, EDAR’s unique ability to detect exhaust temperature enables these vehicles to be identified correctly instead of falsely categorizing them as a high emitter.
A report is generated by EDAR for every vehicle detected and evaluated. EDAR captures a 2D image of the vehicle and plume as well as the license plate, date, time, speed, acceleration, temperature, barometric pressure, humidity, wind speed and a real-time pass or fail indication.
The laser-based EDAR device captures a 2D image and a 3D multispectral image of the entire exhaust plume, while license-plate-recognition technology identifies the subject vehicle as it passes by the EDAR unit. Specialized imaging is a capability unique to the EDAR technology that is unavailable with alternative remote-testing technologies.
EDAR detects interfering plumes using a specialized automated algorithm that detects the correlation of pollutants to CO2. If the correlation coefficient is relatively high, the measurement is considered valid, which signifies that there are no interfering plumes. A lower correlation coefficient indicates a possible interfering plume, as interfering plumes usually have different ratios of pollutants to CO2.
Due to EDAR’s unique capability of imaging the plume and integrated interfering plume algorithm, HEAT identifies vehicles with evaporative emission leaks. In simple terms, associating HC with CO2 leads to the identification of evaporative emissions. Typically, HC related to evaporative emissions will likely not have CO2 in the same location. EDAR’s specialized algorithms identify the areas of these gases relative to each other and the tailpipe.
EDAR has been tested and proven to be an accurate and effective technology by multiple agencies and research groups throughout North America and Europe.
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No Calibration Required
The EDAR device does not require calibration to guarantee proper function. Due to the absolute nature of EDAR’s spectroscopic measurements, it can measure the targeted pollutants without explicit field calibration and remain within standard specifications. EDAR utilizes the DiAL method, a well-known method used in satellite technologies where direct calibrations are not possible. The DiAL method uses lasers locked into a particular wavelength and with narrow bandwidths to differentiate between extremely narrow absorption features. The lasers continuously subtract out the background radiation, changes in ambient conditions and instrument noise.
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Unlike competing technologies that use a much less reliable and imprecise method of non-laser light sources - the non-dispersive infrared (NDIR) technologies, EDAR does not require calibration. NDIR technologies require calibration due to changes in ambient conditions, instrument drift and noise. In a blind study performed by the Eastern Research Group (ERG) and the U.S. Environmental Protection Agency, (USEPA), the EDAR system proved to have no drift and continuously collected accurate data without a need for calibration. Therefore, EDAR operates 24 hours a day, seven days a week, unmanned and without calibration.
Graph showing drift results from the USEPA, ERG, & CDPHE blind study
What is Remote Sensing?
Remote sensing is a powerful tool for emissions testing. Using the principles of inelastic scattering of infrared to ultraviolet light, it can detect the presence, relative concentrations and quantities of specific gaseous compounds in a tailpipe plume. Hager Environmental & Atmospheric Technologies (HEAT) used these principles to develop the innovative technology known as Emissions Detection And Reporting (EDAR).
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EDAR utilizes a LiDAR system similar to existing satellite platforms such as the Active Sensing of CO2 over Nights, Days, and Seasons, or ASCENDS. Lessons learned from the research and development of such space-based platforms have been applied at a distance of 10 meters as opposed to 690,000 meters (Sun-synchronous orbit). EDAR measures total column abundances in the same method as active remote-sensing satellite platforms. Retrievals are more sensitive, more accurate and more reliable using lasers instead of a broadband system. Lasers simultaneously measure CO2, CO, NO, NO2, NOx, HC and PM. EDAR scans the entire exhaust plume to retrieve absolute amounts of these gases and to find the optically thickest part of the plume to maximize Signal-to-Noise Ratio (SNR) for relative amount retrievals.
The International Council on Clean Transportation (ICCT) and the The Real Urban Emissions (TRUE) Initiative put together the video below that explains how remote sensing works.
Source: https://www.trueinitiative.org/