Researchers are exploring the novel idea of using metals as fuels. This is not some new, exotic science-fiction material, but rather plentiful, ordinary metals such as iron that could be used in a novel way for storing and transporting renewable energy. According to a McGill University article, the research being led by Professor Jeffrey Bergthorson is proposing “a novel concept for using tiny metal particles – similar in size to fine flour or icing sugar – to power external-combustion engines.” Instead of using the chemical bonds with carbon, which are currently the basis of most fuels we presently use, metal powders could be used in a similar fashion and make use of energetic reactions to release energy when and where it is needed.
The article describes the process: “Unlike the internal-combustion engines used in gasoline-powered cars, external-combustion engines use heat from an outside source to drive an engine. External-combustion engines, modern versions of the coal-fired steam locomotives that drove the industrial era, are widely used to generate power from nuclear, coal or biomass fuels in power stations.”
We already speak of the “embodied energy” in a material as par of its overall sustainability profile. Materials that are energy intensive to produce, such as concrete and steel, are less preferable from a lifecycle perspective compared to a material like wood, which needs much less energy to gather and prepare. So the idea of using iron powder (or some other metal) as a fuel is not as impractical as it might seem at first.
While we think of metal as non-combustible, fine metal can be burned (as anyone who has ever lit a piece of steel wool on fire can tell you). But transporting a load of iron dust is much less hazardous than loads of oil or liquified natural gas.
Using metals as a fuel would require capturing the spent fuel in order to re-process it. Having clouds of rust floating in the air sounds like a dystopian future. But, in theory, processing the oxidized metal back into its pure state could be carried out repeatedly, re-using the same metal over and over.
While the researchers are looking at all levels of energy use with this technology, from automotive uses on up, the idea of storing grid-scale energy or even transporting it from one location to another (refining metal near locations producing lots of energy, much the way aluminum processing presently takes place close to cheap electricity sources), and then transporting the metal to power plants for it to be burned to produce electricity.
One potential drawback that probably requires further investigation is that metal is a much heavier substrate than carbon-based fuels are. If metal dust is to be used for transportation, how heavy is the fuel that needs to be carried for ordinary travel?
But if existing combustion power plants could be adapted to use metal powder instead of coal or other fossil fuels, then much of the existing power generating infrastructure could be used, and power generation could continue to be in the same places it is now, using the same grid as is currently supplying electricity. Large scale power plants are also likely much easier to set up with the equipment necessary to do the capture of exhaust.
via: Quirks and Quarks