This article (posted today by @krnel) may be of interest as well:

A new remarkable type of rechargeable battery has been developed, called a flow cell. This flow cell can be recharged with a water-based solution containing dissolved carbon dioxide that was emitted from fossil fuel power plants.

The concentration of CO2 differs between the emissions from fossil fuel power plants compared to the ambient air. Each can be made into a pH solution of varying level that is used to generate electricity. .. Previous flow cells are less efficient, with this version producing 200 times higher values. The other CO2 conversion technologies require expensive catalyst materials and very high temperatures.

Link: Flow Cell Rechargeable Battery Converts Waste CO2 into Electricity