If I remember correctly, the process of recycling iron oxide into iron involves carbon monoxide and results in carbon dioxide, so, I’m not sure this would be as carbon neutral as they claim. There are other ways of course, but this is only for storage and recycling uses a lot of energy.
Iron oxide contains no carbon. So if there is any carbon monoxide forming that would have to come from somewhere else. Like the co2 in the atmosphere.
Iron fuel shows its mettle
221–227 of 227 posts
Re: Iron fuel shows its mettle
#222Re: Iron fuel shows its mettle
#223Earlier quoted context omitted.
The proposal is clearly for energy storage , not as a primary energy source . To that extent, it resembles other synfuel concepts. The principle difference being that iron-as-energy-storage entails reduction rather than synthesis , in the chemical sense, for hydrocarbon synfuels. There's a lot to be said for options which provide long-term, "shelf-stable", environmentally-benign, high-volume energy storage with conve…
The challenge of using synthesized chemicals for energy storage exists for quite some time indeed. For aviation and marine there may be no other option outside of synthetic fuels, I agree. Can this scale up? Or is this a small scale only solution? Transportation. How much energy would a truck be able to move? How does it compare to a tank truck? Weight is absolutely relevant here. Also, production. Consider that redu…
I became aware of the prospect of synthesis from captured CO2 + hydrogen (from electrolysis) from a US Naval Research Lab study around 2015. Those papers had ... misleadingly-truncated citations, dating back only to the 1990s. It turns out that hydrocarbon synfuels were first proposed in the 1960s, by M. King Hubbert and studied at Brookhaven National Labs and M.I.T.
Google had an X Project devoted to the idea as well, though ran into insurmountable cost barriers.
Scaling seems to be a major concern, though the process does work at experimental scales, and produces usable fuel. It seems worth continued research based on the potential advantages, even if costs remain higher than fossil fuels. (The USNRL research suggested "competitive" costs, particularly for in situ military fuel generation, notably in aircraft carrier task groups which have ample supplies of nuclear energy, but need fuel for aircraft.)
Battery storage has numerous limitations: low energy density by both volume and weight, and the fact that whilst fuel burns off during flight (and accounts for 50% or more of take-off weight), batteries don't. In the case of metal-air batteries (iron and aluminium have both been proposed), as the redox reaction progresses, the battery gains mass as oxygen from the atmosphere is bonded to it. This poses problems for flight, and even ground-based transport tends not to work well with batteries at large scale.
Re: Iron fuel shows its mettle
#224Earlier quoted context omitted.
> My gut feeling is that transmission lines would still be cheaper Transmission lines are great for moving electricity, but only if there's demand for that electricity _right now_. Otherwise, you have to store it - which is a problem, because battery tech right now isn't great (or rather, it's not good enough for grid-scale requirements) . This iron powder could be thought of as a "battery". It might be harder to mov…
> or rather, it’s not good enough for grid-scale requirements I disagree with this point. LFP batteries are cheap, high density, and have huge cycle life. The big drawback of LFPs is manufacturing is just starting to ramp up on them. That is, they aren’t available. LFPs just came out of patent protection last year and you are already starting to see them everywhere. The biggest problem with LFPs today is demand is ou…
Current worldwide lithium production is at 3% of what it needs to be to electrify every car, which is a use case that has strict weight requirements. Ramping up lithium production by a factor of 30 is a big deal, and that's before we use any of it for grid storage!
Grid batteries are static so weight is not a concern, using the chemistry whose main advantage is weight for this purpose is a waste of resources. Heavy battery chemistries have largely been ignored because traditionally batteries have always been for mobile purposes, so we can expect an even better learning curve from low energy density but cheap battery technologies such as iron-air.
Re: Iron fuel shows its mettle
#225> “Places that have excess energy could make iron, and others can buy it. This way, you could commodify renewable energy so it can be globally distributed without the need for transmission lines. Metals can solve a big problem in the renewable energy transition: long-duration energy storage.” My gut feeling is that transmission lines would still be cheaper. That being said long-term storage seems to be the value prop…
Iron is not a good solution for moving energy because it is so heavy. Aluminium would be a much better solution.
See interesting chart of energy densities by weight and volume.
https://en.wikipedia.org/wiki/Energy_density#/media/File:Ene...
Re: Iron fuel shows its mettle
#226Lithium (Li): 3,860,000 joules/kg Aluminum (Al): 31,500,000 joules/kg Copper (Cu): 13,100,000 joules/kg Iron (Fe): 20,000,000 joules/kg Nickel (Ni): 9,800,000 joules/kg Titanium (Ti): 10,500,000 joules/kg Zinc (Zn): 3,700,000 joules/kg Lead (Pb): 2,040,000 joules/kg Silver (Ag): 10,490,000 joules/kg Gold (Au): 9,700,000 joules/kg
It has the highest density per joules/kg.
Re: Iron fuel shows its mettle
#227first off.... WTF? Transporting iron is cheaper than transmission lines? I call BS.