Natural gas powered cars

Home refueling units, which tap into a house natural gas main and compress the fuel so it can fill a vehicle tank overnight, have been available for years.

But even though the fuel is cheap and units have to meet safety standards like other household appliances, home refilling is uncommon in the United States, held back by the upfront expense of buying and installing new units, and a lack of natural gas cars. The cars themselves generally cost about $10,000 more than comparable conventional vehicles. (Reuters)