The phrase "to capture both gases" means to collect or trap both types of gases in order to prevent them from escaping into the environment. Full definition
The new facility captures gas from the wastewater treatment and converts it to energy for the University of California San Diego campus. (newenergycapital.com)
Based on past work, they're also dubious that sources of methane such as landfills and leaky pipelines will be equipped to capture the gas before it escapes into the atmosphere. (sciencemag.org)
The knowledge gained from such research could inform the design, selection, and improvement of adsorbent materials and membranes for capturing gases such as radioactive krypton and xenon generated by nuclear power plants. (sciencedaily.com)