The Nitrogen Economy: The Feasibility of Using Nitrogen-Based Alternative Fuels

We present herein a techno-economic feasibility for implementation of nitrogen-based fuels. Firstly, we compared the nitrogen- and carbon-based routes for chemical hydrogen storage. The above hydrogen carrier routes were evaluated on an energy basis, under defined system boundaries by comparing seven alternative fuels. Ammonia was found to be the best energy vector, followed by methane, methanol, and aqueous ammonium-hydroxide urea. Secondly, we evaluated the economic feasibility of a model nitrogen-based fuel by using levelized cost of storage analysis. The results indicated that a nitrogen-based fuel is competitive with other storage technologies under development. Furthermore, a decrease in the hydrogen cost can lead nitrogen-based fuels to be competitive with currently-used mature technologies. Thirdly, the utilization of the nitrogen-based fuel route was demonstrated. The auto-ignition process of a model fuel, aqueous urea ammonium nitrate (UAN) was described. The results indicate that this fuel is safe to use, store and handle under ambient pressure. We studies potential storage and reaction vessel materials, pointing out favorable metal alloys for these purposes. In addition, a catalyst screening study aimed at pollution reduction during batch combustion of this fuel is reported, as are preliminary results for continuous catalytic combustion. This work demonstrates the feasibility of catalytic pollution abatement for UAN combustion and the clean utilization of this fuel.