Excessive CO2 emissions are a major cause of climate change, and hence reducing the CO2 levels in the Earth's atmosphere is key to limiting adverse environmental effects. Rather than just capture and store CO2, it would be desirable to use it as carbon feedstock for fuel production to achieve the target of "net-zero-emissions energy systems." The capture and conversion of CO2 (from fuel gas or directly from the air) to methane and methanol simply using water as a hydrogen source under ambient conditions would provide an optimal solution to reduce excessive CO2 levels and would be highly sustainable.