Clean coal?

Nikkei Asian Review:

Toshiba has developed technology to convert sunlight and carbon dioxide into an energy source at the highest efficiency to date, with a goal of commercializing it in 2020.

The artificial-photosynthesis technology combines a semiconductor with a gold catalyst. Oxygen and hydrogen ions are generated from water by applying sunlight to the semiconductor. The catalyst then creates carbon monoxide through a reaction between the carbon dioxide and the hydrogen ions. The carbon monoxide can be processed into such fuels as methanol.

An American article on this, using gallium phosphide with a cobaloxime catalyst, here.

So far, clean coal is a pipe dream, and not just because of CO2. Coal produces mercury and sulfur oxides among other pollutants.

But maybe some day.