Cars running on metal nanoparticles
Internal combustion engines (ICEs) dominate the transportation market. Combustion or burning of fossil fuels in the presence of an oxidiser (usually air) converts the chemical energy in molecular bonds into useful mechanical energy, but – also harmful greenhouse gas (GHG) emissions. Among the many green mobility solutions on the horizon are hydrogen-powered and lithium-ion battery-powered vehicles. For the first time, scientists investigated the potential of metallic nanoparticles, particles of metals that are ten thousand times smaller than the width of a human hair, to act as clean fuel for ICEs with EU funding from the project COMETNANO (Technologies for synthesis, recycling and combustion of metallic nanoclusters as future transportation fuels). Ideally, combustion of metals produces energy and metal oxides without harmful emissions. The consortium investigated the in-principle feasibility of clean combustion together with recyclation of spent fuel via renewable technologies. Based on studies of availability, toxicity, market price and power density, investigators chose iron, aluminium and boron for further study. Results of preliminary engine-like testing highlighted the promise of iron-air combustion. Aluminium-air combustion was also investigated due to broader scientific interest, although but aluminium was found to possess less favourable combustion parameters and higher environmental impact and production costs. Comprehensive studies carried out during the project elaborated on the fundamental mechanism of iron nanoparticle combustion. COMETNANO developed customised simulation models of iron-air combustion based on experimental data describing the main principles controlling dispersion flow, injection and combustion processes. At the same time, scientists developed a process to upgrade iron-based waste from steel industries for the synthesis of iron nanoparticles, and successfully employed the synthesis procedure under laboratory-scale conditions. In addition, a novel system for the preparation of metallic nanoparticles was successfully tested as proof of concept. COMETNANO also assessed the potential hazard of nanoparticle exposure on human health. The consortium demonstrated technology for 100 % recovery of utilised nanoparticles using customised approaches of the well-established diesel particulate filters technology. An investigation of nanoparticle toxicity was initiated that included studies on partial failure scenarios regarding combustion and incorporation of simple fail-safe modules. Cost analyses indicated that under certain prerequisites metallic fuels could become competitive with CO2-taxed fossil fuels and less expensive than several other alternative ‘renewable’ fuels. COMETNANO successfully proved the in-principle feasibility of using metallic nanoparticles as fuel in ICEs. Results pave the way for further research and development with important potential benefits for the automotive and metal industries as well as for the environment.
Keywords
Metal nanoparticles, spent fuel, internal combustion engines, COMETNANO, spent fuel, iron-air combustion
