<instructions>Your goal is to analyze the following comment and estimate how highly it will be upvoted by the Hacker News community.</instructions><comment><author>dragontamer</author><text>1. Iron is heavy -- This means it costs more to transport iron fuel, compared to lighter fuels like methane, propane, or butane (aka: gasoline).&lt;p&gt;2. Iron is dense -- ?? Not discussed in the webpage. But something like Hydrogen (despite being very light) takes up a lot of space. Hydrogen is so light that its volume becomes a problem. Iron does seem to solve that issue at least.&lt;p&gt;3. Iron is renewable -- Iron turns into Rust, and the rust can turn back into Iron easily. This makes Iron more comparable to Redox-flow batteries or Hydrogen.&lt;p&gt;----------&lt;p&gt;Funny thing is: I was just discussing with someone else in my social circles about how Iron&amp;#x2F;Rust is exactly the same process as battery-chemistries. Just... worse. Iron-electricity has less voltage than Li-ion or Zinc, or other elements.&lt;p&gt;But the Iron -&amp;gt; Rust -&amp;gt; Iron process is a well known process for &amp;quot;storing energy&amp;quot;. We just usually don&amp;#x27;t care about the energy storage part, and more about the physical properties of Iron, and preventing it from turning into Rust (which is weaker, redder, more stains, etc. etc.).&lt;p&gt;Experimenting with Iron-based energy storage seems like it&amp;#x27;d be destined for failure? Its one of the oldest elements and the chemical process has been known for a while. However, the only way to be sure that its a bad idea is to try it. So we should experiment with it, at least a little bit, to really make sure that we didn&amp;#x27;t miss anything here. Iron is a hugely abundant element after all... if at all else, it can be used as a &amp;quot;cheap&amp;quot; energy storage mechanism as opposed to a &amp;quot;quality&amp;quot; energy storage mechanism.&lt;p&gt;After all, a lot of our energy is just wasted (ex: Solar Panels during the peak days just turn off). Instead of turning off solar panels when the grid is overloaded, maybe store the excess electricity in cheap iron? 40% round-trip efficiency is still better than 0%.</text><parent_chain></parent_chain></comment><story><title>Iron Cycle based energy storage and generation</title><url>https://teamsolid.org/</url></story>
<instructions>Your goal is to analyze the following comment and estimate how highly it will be upvoted by the Hacker News community.</instructions><comment><author>photochemsyn</author><text>Looks pretty interesting. Note this is a coupling technology, i.e. the power input is at the reduction stage when iron oxide is reduced back to metallic iron via the use of hydrogen (generating water).  To make it a non-fossil process, you have to scale up hydrogen-from-water using wind&amp;#x2F;solar:&lt;p&gt;&amp;gt; &amp;quot;The resulting iron oxide is a solid material, so it can be captured after the combustion process. It is then reused by regenerating it with green hydrogen into flammable iron fuel. In this way, iron fuel offers a revolutionary method to store energy in a circular and carbon-free fashion.&amp;quot;&lt;p&gt;It has some real advantages over shipping hydrogen, as hydrogen is tricky to work with, relative to methane.  There is an alternative process, developing direct-air-capture of atmospheric CO2 and using the hydrogen to reduce the CO2 to CH4, which has the advantage of being able to use existing natural gas pipelines for transport and distribution.  In contrast this iron process has some long-term storage advantages; it could serve as a way to store excess wind&amp;#x2F;solar power over longer periods i.e. months.  The notion it could be used to fuel long-distance shipping is also intriguing: ships could use hydrogen to regenerate their iron fuel at the end of each voyage.&lt;p&gt;However this all depends on massive scale-up of hydrogen-from-water.  That hydrogen can be used in many industrial processes, including also fossil-fuel-free steel production.  Without that, this iron process can&amp;#x27;t be run at any scale.</text><parent_chain></parent_chain></comment><story><title>Iron Cycle based energy storage and generation</title><url>https://teamsolid.org/</url></story>