Today, the majority of U.S. oil consumption is accounted for by the transportation sector, which includes more than 220 million privately owned vehicles. Soaring oil prices, unstable energy supplies and a vulnerable environment have made alternative energy vehicles a plausible solution to reducing the nation’s dependence on gasoline and protecting the environment. While several types of alternative energy vehicles, such as alternative fuel and hybrid electric vehicles are now available on the market, models utilizing fuel cells and promising even more energy efficiency are still in development. The continuing challenge for researchers is to create these types of energy efficient vehicles while keeping the technology cheap enough to be commercially viable.
Some alternative fuels can only be used in alternative fuel vehicles, or flexible fueled vehicles (FFV). An FFV contains a single fuel tank, fuel system and engine. The vehicle runs on a blend of unleaded gasoline and an alcohol fuel, generally ethanol. Due to the corrosive nature of ethanol, the engine and fuel system must be slightly adapted. The vehicle also needs a sensor in the fuel line to read the fuel mixture and control the fuel injection and timing, which are dependent on the fuel blend. Today, FFVs can run on up to 85 percent ethanol.
Hybrid electric vehicles, or hybrids, are clean, quiet, fairly independent of imported petroleum, and open to using wind or other renewable forms of power generation. Hybrids utilize both internal combustion engines (ICE) and electric motors. Some hybrid vehicles use regenerative braking systems that capture the energy from deceleration, store it, and then convert it to electricity to help propel the vehicle, which ultimately increases overall efficiency.
Hybrid-electric technology has made further strides in combating the main problem with electric vehicles by expanding their range. Adding extra batteries and a way to charge it externally, or “plug-in” the vehicle have afforded hybrids the ability to drive most of their daily mileage on clean, less expensive electricity. An easily refillable fuel tank adds security for longer trips. Some hybrids have been converted to plug-ins, and many automobile manufacturers are working on making more plug-in models available.
However, plug-in hybrids can be problematic, as their batteries are costly and extremely heavy. The Department of Energy’s National Renewable Energy Laboratory (NREL) has been extensively researching thermal management, modeling, and systems solutions for energy storage technology. The NREL feels that even at today’s battery costs, plug-ins may be able to repay their costs within a few years. NREL is also researching improved power electronics, which are critical to hybrid efficiency, conducting analyses to illustrate the economic viability of plug-ins and identify key areas for improvement, and looking into the future possibilities of reversible plug-ins, which would allow vehicle owners and local utility companies to utilize the extra electrical storage capacity in the vehicle batteries to meet peak residence and business demand for electricity.
While hybrids have gained a solid foothold in the auto industry, fuel cell technology and fuel cell vehicles (FCV) are starting to make ground. Fuel cells produce electricity through a chemical reaction between hydrogen and oxygen yet release no detrimental emissions. Similar to hybrid models, the electricity supplies a storage battery, which powers the electric motor. In fact, FCVs resemble hybrids because both of their electric batteries are charged by a separate onboard system.
The NREL feels this emphasizes the importance of advancing current hybrid technology and will ultimately help reduce petroleum consumption and encourage clean, environmentally safe transportation methods. However, it may take a few more years before FCVs are as cost-competitive as traditional gasoline vehicles and even hybrids. According to some industry experts, extended tax incentives and tax credits would help reduce costs for consumers and bring FCVs to the market more quickly.
The DOE has been working to improve the technology of alternative energy vehicles through their FreedomCAR and Vehicle Technologies Program and their 21st Century Truck Partnership. They have been conducting research on advanced automotive and truck technologies that will provide the transition to hydrogen-powered fuel cell vehicles.
Sources: National Renewable Energy Laboratory (NREL), U.S. Department of Energy (Energy Efficiency and Renewable Energy), U.S. Environmental Protection Agency and “Americas Untapped Depths”, The American Legion Magazine, April 2006