Dear EarthTalk: How is it that hydrogen can replace oil to run our cars? There seems to be a lot of controversy over whether hydrogen can really be generated and stored in such a way to be practical? -- Stephane Kuziora, Thunder Bay, ON

The jury is still out on whether hydrogen will ultimately be our environmental savior, replacing the fossil fuels responsible for global warming and various nagging forms of pollution. Two main hurdles stand in the way of mass production and widespread consumer adoption of hydrogen “fuel cell” vehicles: the still high cost of producing fuel cells, and the lack of a hydrogen refueling network...