Best technology for coal electricity capture costs $10/watt (close to new on budget nuclear plants), and only captures 65% of emissions. A better “free” climate strategy would be to put them in “backup peaker” mode for renewables and run them at far less than 35% of year.
DAC can work only if price of carbon is $300/ton ($3/gallon gasoline). Still, 100% renewables is cheapest path to avoiding those taxes, but afterwards, DAC can hope to pay for itself.
I think the designs all end up as big combined wing aircraft to give more storage. Can work, but so many new techs and challenges that no one is really investing in it…
Airport expansions like at Gatwick and Heathrow in the UK (both very contentious) should have carbon caps to encourage investment in this kind of stuff.
There shouldn’t be further expansion at Heathrow in particular, it’s already a blight on southwest London as it is.