Conversion of CO2 to saturated carbon chains is a highly endothermic (energy-using) process - we know this because the reverse (burning anything with carbon chains, including butter) gives off gobs of heat - exothermic to such an extent that it’s our main source of useful energy.
That’s why we mostly let plants turn CO2 into useful organic compounds, and then let animal turn those plants into stuff we can convert to butter.
So unless these folks have found a cheap, readily-available, environmentally-friendly source of unused energy, I’m not real sure why they’re so excited.