What they do is use solar panels to produce electricity, and use the
electricity to run an electrolyzer that turns carbon dioxide into acetic
acid. The acetate can then be fed to yeast or other fungi and algae to
produce biomass. They claim it is 4 times more efficient than
photosynthetic carbon capture.
The conversion of carbon dioxide into something useful is one of the
least efficient reactions that lifeforms do. It seems strange that in
the billions of years since photosynthesis evolved that the reaction
remains so inefficient. It isn't just inefficient, but RuBisCO often
does the wrong reaction forcing more energy to be used to correct the
mess. It works because we have that big ball in the sky that even
though it is 93 million miles away it can supply enough light so that
plants can thrive on this planet. The inefficiency is one of the reason
why RuBisCO is the most abundant protein in our biosphere.