by Ray Hicks, President, CO2Meter.com
At CO2Meter, we get just as excited about science fair projects as the students. For example, over the last several months I worked with 14 year-old Matthew Siracusa on his school science fair project titled, ‘A Method for the Mobile Study of Fracking Sites.”
Matthew was looking for a way to monitor the air around shale oil hydraulic fracturing (fracking) sites from a moving vehicle. About 50% of these sites in the US are currently being monitored. His project was to create a platform using off-the-shelf technology that would reduce the cost of public monitoring of all the sites. When it comes to the environment, I believe more raw data is better, so this seemed like a worthwhile project to me.
Last month, I was pleasantly surprised when Matthew informed us that his project had been entered into the 2014 Google Science Fair. After winning a Google local award and becoming a regional finalist, he is now competing with students internationally for a $25,000 scholarship and prizes from Google, the National Geographic Society and others to further their interest in science.
For me, the project started out as a simple enough question: How do you inexpensively measure methane (CH4)? A typical non-dispersive infrared (NDIR) sensor to measure low concentrations (<1%) of CH4 are not only physically large, but are fairly expensive.
To stay within a budget, I had an alternative. Our lab testing had shown that NDIR CO2 sensors are cross-sensitive to other gases by varying degrees. For example, the COZIR CO2 Sensor is measurably cross-sensitive to methane (3.4 µm wavelength) and other gases at a similar wavelength to CO2 (4.25 µm). When methane is present, the COZIR reports it as an increase in CO2. On the other hand, the SenseAir CO2 sensor has near zero cross-sensitivity to methane because of its narrow filtering around the 4.25 µm wavelength of CO2.
Therefore, in theory one could predict that the difference between the CO2 levels reported by the 2 sensors should be an accurate measure of CH4.
To test this, we started by zero referencing both sensors to nitrogen, then span calibrating them within the working range for reference. We found that using the COZIR and SenseAir sensors in combination solved both the CO2 and CH4 environmental measurement tasks simultaneously.
During the process, Matthew developed his own calibration techniques and learned gas law principals for compensation for pressure and temperature – things you don’t think about till you are attempting to measure with some precision.
Of course, CO2 and CH4 gas measurement were only one aspect of the project. Fortunately, both Matthew and his father were great to work with, and it was both a pleasure and interesting to work with these very bright people. Whether he wins or loses another award, Matthew is already a winner. I look forward to many good things from this young man in the future.