Biological Ammonia Production
Ammonia is a large volume chemical, which is predominantly used in agricultural fertilizers. Other current and emerging uses include synthetic organic chemistry, cleaning products, and fuels. Ammonia is produced from hydrogen and nitrogen by an energy intensive process referred to as Haber-Bosch (HB) synthesis. In order to be profitable, traditional ammonia production requires large capital investments for reactors operating at high pressure and temperature, baseload power to keep the process running continuously, and distribution infrastructure to ship the resulting chemicals around the world. These requirements severely limit the opportunity to deploy industrial ammonia production at small scale and in a distributed manner around remote resources. Methane is also a potent greenhouse gas (GHG) 25 times more harmful than an equivalent amount of CO2. Methane is emitted from a number of sources, including oil and natural gas extraction and waste decomposition in landfills and wastewater treatment. Vented and flared natural gas are major sources of GHG emissions in the U.S., responsible for approximately 300 billion cubic feet of natural gas released annually, and growing. A method to capture and process methane from small-scale isolated sources into ammonia would both significantly reduce GHG emissions, lower the costs of ammonia production, and potentially expand ammonia production to locations that are underserved by current ammonia markets.
Project Innovation + Advantages:
Rice University will develop a first of its kind biocatalyst to synthesize ammonia from small–scale isolated methane sources. The microorganisms will be engineered to maximize simultaneous diazotrophic and methanotrophic capabilities. Diazotrophs are organisms that can fix nitrogen gas in the air into a biologically usable form, such as ammonia. Methanotrophs are organisms that metabolize and use methane as an energy and carbon source. Rice University’s technology will combine these capabilities, and develop a one-step ammonia synthesis that will operate at low temperature and pressure. These process characteristics will significantly reduce the technical complexities relative to HB synthesis and in turn enable small-scale deployment. Methane can be harvested from natural gas production sites, landfills, and biogas facilities. Bioreforming of this methane will produce CO2 and energy. The diazotrophic nature of the microorganisms will use the nitrogen, combined with energy derived from methane, to produce ammonia. Methane and air will be the only sources of energy, carbon and nitrogen, respectively. If successful, this highly mobile, low-cost ammonia synthesis process will turn previously wasted methane resources into a valuable product, while also significantly reducing U.S. GHG emissions.