While hybrids typically are associated with electric batteries acting in a supporting role, other cleaner-burning energy sources can feed or work in parallel with gasoline-powered engines. Natural gas (in either compressed or liquid form) is one alternative. As new underground gas supplies reduce prices, additional investment may be made in a wider distribution network for delivering natural gas to vehicles. Biofuels derived from biomass or crops, while contributing to higher global food prices, offer another option.

Hydrogen fuel cells provide a third alternative energy source for hybrid vehicles. These fuel cells act as a storage medium similar to a battery. If the hydrogen is produced from renewable sources, the use of hydrogen fuel cells causes the least environmental impact. While currently expensive to produce, store, and distribute — requiring significant investment in new infrastructure — such costs are trending downward as energy players and automakers seek to commercialize this clean technology.

Fortunately for automakers and related service providers, global vehicle sales are expected to increase dramatically, with the current estimate of about 800 million cars on the roads doubling in the next 20 to 25 years. Most of this increase will occur in developing countries that cannot afford the higher pollution levels caused by the burning of traditional fuels for transport. As these new car buyers come to market, alternative energy vehicles will face greater opportunities to overcome the current bumps on the road toward higher sales.

In time, the electric car may break free from the carbon-based pack.

Scott Mortman is former director of global business development at the electric vehicle services company Better Place. He is now a shareholder with Miami-based Greenberg and Traurig, in the law firm’s Tel Aviv office. The views are strictly his own.