Compact High Precision Field Instrument for All Major Greenhouse Gases

The purpose of this project is the development of a compact, high precision and fast response instrument that can simultaneously measure all four major greenhouse gasescarbon dioxide, methane, nitrous oxide, and water vapor. By selecting different lasers the same instrument can measure other sets of gases. The precision and response speed will be sufficient for emission measurements by means of correlation with wind fluctuations (eddy correlation method), or by correlation with a tracer gas. Rapid, precise and simultaneous measurement of all the major greenhouse gases allows researchers to gain a comprehensive picture of emission processes in the natural environment, and to distinguish natural from industrial sources. Measurement of tracer gases, such as ethane and nitrous oxide along with methane, can be used to quantify emissions during natural gas drilling and production operations. The instrument is based on quantitative spectroscopy with a pair of mid-infrared lasers. This development draws upon and extends trace gas measurement technology developed at Aerodyne Research, Inc that has yielded the most precise field-ready trace gas instruments presently available, which define the state of the art. We can routinely measure gases at the part-per-trillion level and observe changes in the concentration of gases with a precision of one part in 10,000 (0.1 per mil) in 1s. This new instrument will have reduced size optics and electronics, allowing operation of two lasers in the space currently needed for one. The new instrument will be smaller, more capable and less costly than present instruments. During Phase 1 we explored several approaches to reduce the size of the instrument optical system, and have outlined an innovative optical design that will be implemented in Phase 2. During Phase 1 we have learned how to operate two lasers of different types (quantum cascade and 3 m diode) in the same instrument and have gained experience with new 3 micron wavelength lasers that allow very sensitive measurement of hydrocarbons. During Phase 1 we have employed such a 3 micron laser in a field measurement of methane and ethane, in order to identify the source of methane in an urban area. During Phase 2 we will complete the detailed design of the new compact two laser instrument for multiple gases. We plan to produce two different versions and employ them in two different field measurements, in collaboration with Harvard University. Commercial Applications and Other Benefits: The availability of a field-ready compact high precision instrument for the simultaneous measurement of four greenhouse gases (or the isotopologues of two greenhouse gases) will find wide use in research on the carbon cycle and greenhouse gases. We can change the lasers and measure other sets of gases for other research and monitoring purposes. The same instrument will have other applications in the energy sector, such as measuring emissions of methane in natural gas production, or on-site isotopic analysis during drilling operations.