Round-Trip efficiency some 40%? If so is this a good idea to waste over half the renewable energy? Li-ion has already two times this Round-Trip and much easier to realize.
I believe the question posed was 'How can individuals and corporations manage and reduce their carbon contributions?'
They are proposing to use CO2 sequestered from air to create syn-gas, which will not only reduce their carbon contributions but will also make useful products, to be used or stored. Batteries are with no doubt a more mature technology with higher efficiency for now, but storage is not the main point of this project, as I understand.