<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>Animats</author><text>I think this is the paper behind that.[1] Round trip efficiency is listed there as about 75%.&lt;p&gt;It was previously proposed at Lawerence Livermore.[2] It was apparently tried in China in 2016, at least at pilot plant stage.&lt;p&gt;It&amp;#x27;s an obvious idea. There&amp;#x27;s been lots of interest in compressed air storage, and compressed CO2 storage is in some ways easier, because you can liquify it easily. So why hasn&amp;#x27;t this come up much before?&lt;p&gt;[1] &lt;a href=&quot;https:&amp;#x2F;&amp;#x2F;sco2.eu&amp;#x2F;fileadmin&amp;#x2F;user_upload&amp;#x2F;presentations&amp;#x2F;2021&amp;#x2F;Manzoni-Adiabatic_Compressed_CO2_Energy_Storage-118_c.pdf&quot; rel=&quot;nofollow&quot;&gt;https:&amp;#x2F;&amp;#x2F;sco2.eu&amp;#x2F;fileadmin&amp;#x2F;user_upload&amp;#x2F;presentations&amp;#x2F;2021&amp;#x2F;Man...&lt;/a&gt;&lt;p&gt;[2] &lt;a href=&quot;https:&amp;#x2F;&amp;#x2F;www.forbes.com&amp;#x2F;sites&amp;#x2F;jeffmcmahon&amp;#x2F;2017&amp;#x2F;03&amp;#x2F;26&amp;#x2F;how-captured-co2-could-provide-the-energy-storage-solution-everyone-is-looking-for&amp;#x2F;?sh=4c90955fddef&quot; rel=&quot;nofollow&quot;&gt;https:&amp;#x2F;&amp;#x2F;www.forbes.com&amp;#x2F;sites&amp;#x2F;jeffmcmahon&amp;#x2F;2017&amp;#x2F;03&amp;#x2F;26&amp;#x2F;how-capt...&lt;/a&gt;</text><parent_chain></parent_chain></comment><story><title>CO2 battery could make wind and solar dispatchable at a lower price</title><url>https://www.rechargenews.com/energy-transition/new-co2-battery-will-make-wind-and-solar-dispatchable-at-an-unprecedented-low-price/2-1-1044755</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>pfdietz</author><text>The problem with this is not storing the liquid CO2, it&amp;#x27;s storing the &amp;quot;spent&amp;quot; low pressure CO2 gas.  The volume required will be very large.  The energy&amp;#x2F;volume of this will be even worse than pumped hydro.</text><parent_chain></parent_chain></comment><story><title>CO2 battery could make wind and solar dispatchable at a lower price</title><url>https://www.rechargenews.com/energy-transition/new-co2-battery-will-make-wind-and-solar-dispatchable-at-an-unprecedented-low-price/2-1-1044755</url></story>