A Literature Review of Nox Emissions in Current and Future State-of-the-art Gas Turbines

Abstract Current U.S. government policy seeks to achieve a carbon-free economy by 2050, with a carbon-free electricity sector by 2035 (per executive orders #14008 and #14057). To address these goals, the U.S. Department of Energy is evaluating technologies that support the production, utilization, transport, and storage of hydrogen (via initiatives like DOE's Energy Earthshots and various DOE funding opportunity announcements). A carbon-free fuel like hydrogen is valuable for a dynamic electric energy sector seeking to decarbonize. One of the most important technologies needed to achieve this carbon-free electricity sector is a 100% hydrogen-fueled gas turbine. Accommodating hydrogen fuels has been a key goal for various original engine manufacturers (OEMs) for many years, but more research and development (R&D) is needed. The purpose of this paper is to highlight the current state-of-the- art of hydrogen turbine technology, especially regarding nitrogen oxide (NOX) emissions, compared to natural gas turbines. NOX is the primary criteria pollutant from thermally-driven combustion turbines and should be controlled to levels that are below current standards. This paper provides an overview of hydrogen as a fuel and various NOX control techniques that are relevant for hydrogen-based fuels. A conclusion from this overview is that, with some level of R&D, NOX emissions from hydrogen-fueled gas turbines can be controlled to levels similar to those produced by state-of-the-art natural gas-fueled combustion turbines while remaining competitive in terms of performance and efficiency.