Tech10 alternatives to the gasoline-powered engineThere's no shortage of greener ways to run a car. How viable they are is another story.Alex Taylor IIINovember 1, 20131. Gas-electric hybrids 2. Plug-in hybrids 3. Electrics 4. Ethanol and flex fuel 5. Biodiesel 6. Propane 7. Liquefied and compressed natural gas 8. Fuel cells 9. Solar 10. Steam