Metallic nanoparticles as alternative energy carriers & their combustion feasibility under ICE-like conditions

The possibility of utilizing metals as energy carriers and/or fuels for Internal Combustion Engines (ICE) has first been considered a few decades ago. The idea lies on two main characteristics: some metals contain significantly higher energy content per unit volume than the conventional fuels, while -under certain conditions- the only product derived from their combustion is the respective metal oxide. In principle, the latter makes metals excellent candidate fuels towards the implementation of zero-emission combustion engines. The environmental friendliness of the concept can be further strengthened under the prerequisite that the metal oxide (spent fuel) is recycled so that the metal is recovered and reused. 2Fe + 1.5O2 = Fe2O3, ?Ho = - 826.2 kJ/mol (1) 2Al + 1.5O2 = Al2O3, ?Ho = - 1675.7 kJ/mol (2) The fundamental problem, when considering such metals in coarse form is the fact that their ignition is difficult. However, upon ignition the combustion process proceeds in an uncontrollable way, thus resulting to extremely high temperatures which make the whole process unsuitable for ICE-like applications. The most suitable way of achieving control of a metallic fuel combustion process is by tuning the size of its primary particles. Recent advances of nanotechnology in the manufacturing of metallic nanopowders with specific tailored characteristics have opened new pathways in the exploitation of such candidate energy carriers.