Rather, it is largely a result of coal being displaced by natural gas, which emits less carbon dioxide when producing electricity. (desmogblog.com)
On - board hydrogen fuel - cells could be up to 80 percent more fuel - efficient, and emit 45 percent less carbon dioxide, than today's internal - combustion engine. (exxonmobilperspectives.com)
In a fossil fuel - fired generator, this means less carbon dioxide emissions for the same unit of electricity produced. (scientificamerican.com)