As of 2019, only ten percent of the energy sources that humans utilize are wind and solar powered. These have been proven to be the most environmentally friendly compared to the common fossil fuels like gas and coal, as they do not produce nitrogen oxides that get released into the environment. Nitrogen oxides are a precursor to smog which has proven to be an issue in larger cities in parts of India.
The shift from fossil fuels to a more sustainable source of energy has been explored for a few generations by now. If human consumption of fossil fuels doesn’t slow down soon, they will not be able to be replenished. While it is a cheaper alternative and easier to store and transport, the long term effects of burning fossil fuels have proven to have negative effects on air quality and need to be switched to something more sustainable.
Lithium ion batteries have also been heavily relied upon and are able to be cost effective at several hours when the solar panels aren’t receiving any sun or if the wind turbines aren’t turning. With all of the benefits of solar and wind energy, scientists are trying to figure out a way to store this energy collected for days where the environment isn’t at its ideal conditions. Communities that rely on just these two sources of energy will experience power shortages on a cloudy day or when the wind isn’t blowing. The mining of the lithium that is required to power these batteries also required a massive amount of water which has caused some adjacent communities to experience a drought that has led to famine.
The future of renewable energy has been found in Somerville, Massachusetts in the form of rusting iron pellets. Rust is caused by the oxidation of iron or steel when it is exposed to water and oxygen. When the exposure happens, the iron particles become oxidized, resulting in the formation of Fe(OH)3. This results in a product of hydrated iron (III) oxide. Rust typically does not serve any useful purpose and it is seen as a negative byproduct when it comes to machinery and cars. Rust can occur at any rate, it is all dependent on the surrounding environment.
4Fe + 3O2 + 6H2O → 4Fe(OH)3
Scientist Matteo Jamarillo believes that the rust that is found on these old iron pellets may form the basis of a battery that is one tenth the cost of a lithium battery and is able to hold the energy storage for more than one hundred hours. The lithium batteries are currently only able to hold energy storage for a few hours at most. The batteries are able to discharge energy from the pellets of iron as they go through controlled oxidation in an air and moisture rich environment. Oxidation typically occurs on the side of the cell that contains the anode. The reverse chemical process, also known as “derusting” uses an electric current to convert the rust back into its pure iron state. This can be done through the process of electrolysis where the bond is broken between the oxygen and iron atoms. Oxidation itself is a reversible process but the only problem with tht is that there is no guarantee that the shape of the material will remain the same as it was before oxidation. Jamarillo is in the process of figuring this out.
The Fe/FeO redox reaction can be used to create hydrogen during the oxidation of iron. These hydrogen atoms can then be consumed by a fuel cell in conjunction with the oxygen from the air to create electricity. When this energy needs to be stored, the hydrogen generated by the water by operating the fuel cell in reverse is then consumed during the reduction of the iron oxide to the metallic iron. The combination of these two processes make this battery a rechargeable system.
(Fe + H2O ⇌ FeO + H2)
Figure 2: Diagram depicting the reversible process of the oxidation of iron to form rust.
While discharging, the battery “breathes” in oxygen from the air and converts iron metal to rust. While charging, the electrical current converts the rust back to iron and the battery then “breathes” out oxygen.
The idea of iron-air batteries isn't a new concept as it has been explored before by other companies. It has previously been overlooked because they have been too heavy to be portable and would work best as stationary storage. The appeal of iron-air batteries is that it involves rust which is an environmentally friendly, nontoxic component. The controversy that follows this new idea is the fact that switching over from a fossil fuels based world into renewable energy is a long and expensive process.
Figure 3: A picture of the iron-air battery. They are typically the size of a washing machine.
Works Cited:
Battery technology. Form Energy. (2021, July 28). Retrieved September 21, 2021, from https://formenergy.com/technology/battery-technology/.
Metcalfe, T. (2021, August 6). Rust? Trains? Why clean energy is turning to exotic ideas to fix its storage problem. NBCNews.com. Retrieved September 21, 2021, from https://www.nbcnews.com/science/environment/rust-trains-clean-energy-turning-exotic-ideas-fix-storage-problem-rcna1613.
In the original article the title begins "Rust? Trains? ...". The "Rust?" refers to the battery based on iron oxidation. The "Trains?" refers to a method of storing energy that involves using energy to push a train up a hill thus storing that energy as gravitational potential which can be retrieved by letting the train roll back down. The point of the title is that people are using some apparently unlikely approaches to energy storage. It would be worth emphasizing that among the pollutants produced by burning fossil fuels is carbon dioxide, a greenhouse gas that is the major contributor to global climate change. It is true that in oxidizing an iron electrode in aqueous media hydrogen may be released from water in a process competing with iron oxidation. That would reduce the electrical energy obtainable by discharging the battery. The hydrogen produced could be collected and used to produce additional energy to compensate for the lower battery output. But this process is not mentioned in your sources. In fact it is not clear that such a process is a feature of Form Energy Battery that is the subject of the article. The article is very interesting and emphasizes the importance of innovative chemistry in solving emerging societal problems and maintaining our energy intensive living standards. Good choice.
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