Real-Time, in situ, Process-Based Soil Gas Analyzers

Biological, chemical and geological activity of soils and groundwater impact agriculture, hydrology, and climate. Sophisticated computer models now include a multitude of interactions that can simulate the complex nature of near, subsurface regions. Improved measurement methods are needed both to provide accurate data to those computer models and to test model predictions. Ideal instruments will be easily deployed at field sites for long term, fully automated operation. Given the current advanced state of modeling experiment, new measurement capabilities are needed quickly. How This Problem is Being Addressed: This project is a collaboration between Mesa Photonics and the Bureau of Economic Geology (BEG) at the University of Texas. The BEG researchers showed that vadose-zone biogeochemical activity can be characterized by looking at the relative concentrations of four common gases: nitrogen, oxygen, carbon dioxide, and methane. Mesa Photonics recently demonstrated that the four gases can be detected simultaneously using Raman spectroscopy of gas samples flowing through a hollow-core, photonic crystal fiber. The process-based analysis method can be implemented using gas concentrations measured with the Raman technique. The proposed work includes evaluation of the process-based method over a wider range of soil types, improvements to the Raman instrumentation, and soil modeling to determine the full benefits of the combined approach. What is to be done in Phase I? The Phase I STTR project includes confirming the generality of the process-based gas analysis approach, improving Mesas benchtop ERGS instrument, and head-to-head tests of the ERGS instrument against gas chromatography on grab samples from playa lakes or engineered sites that are set up for adding selected gas to soils. Commercial Applications: Two markets will be served: a small research market plus a much more lucrative market for process-based leak detection at carbon capture and storage sites. The products will be nearly identical for both. Commercial gas analyzers will be fully automated and self-sufficient. They will not require any consumable supplies and will be self-calibrating. Installation and operating costs will be minimal. Each analyzer will be powered by a small solar panel and battery, and the analyzers will be connected to a wireless network for data transfers and maintenance logging.