Fighting global warming by photocatalytic reduction of CO2 using giant photocatalytic reactors

Over the last decades, fighting global warming has become the most important challenge humanity has to face. Therefore technologies of carbon dioxide capture, sequestration and recycling are equally important in order to tackle the global climate change stakes. Among recycling technologies, photocatalytic processes reducing CO2 with H2O back to fuels or to other useful organic compounds, have the potential to be part of a renewable energy system. Indeed these processes can help to control CO2 emissions and eventually eliminate CO2 in excess. This perspective paper describes a large size device, able simultaneously: •to proceed to direct air capture (DAC) of CO2; •to transform part of it into useful chemicals, like hydrocarbons or syngas; •and to produce renewable energy, thus preventing future CO2 emissions. Synergies between solar chimney power plants (SCPPs) and semiconductor photocatalysis in order to create giant photocatalytic reactors for artificial photosynthesis are discussed, as well as scale economies for unconventional carbon capture directly from the atmosphere. This paper presents a carbon negative emission technology obtained by coupling SCPPs with DAC systems which allows many scale economies, and also synergies to proceed to solar-to-chemical energy-conversion process by photocatalytic reduction of atmospheric CO2 under sunlight.