Leaving It (Oil) Behind

The U.S. Department of Energy's alternative fuel initiatives and partnerships are starting to produce results in the search for a cleaner way to move around

• By Edward J. Wall
• Sep 01, 2005

As competition for the world's oil resources increases with the advance of developing economies, the United States must seek out ways to reduce its petroleum usage or put its economic security at risk. The era of "cheap oil" may well be over, and as our imports increase we become more and more dependent on resources from such politically unstable regions of the world as the Middle East, Central Africa, and South America. Currently, some 60 percent of the oil we use is imported from these regions at a staggering cost of $200 billion per year. Having doubled in the past two years, this spending affects our inflation rate and our domestic productivity. Less oil at higher prices will mean fewer jobs and a reduced standard of living.

Against this backdrop, the U.S. Department of Energy's (DOE) Office of Energy Efficiency and Renewable Energy's (www.eere.energy.gov) mission to strengthen America's energy security, environmental quality, and economic vitality has never been timelier. The mission's top priority is to dramatically reduce or, perhaps, end our dependence on foreign oil. Because transportation consumes two-thirds of all U.S. oil (consuming more than five times as much oil as the next largest sector), and is also the fastest growing sector, DOE and industry have joined together to create two major partnerships, the FreedomCAR and Fuel Partnership and the 21st Century Truck Partnership, directed toward enhanced energy efficiency in light and heavy vehicles, respectively.

The FreedomCAR and Fuel Partnership is an expansion of the FreedomCAR Partnership, announced in January 2002 by then Secretary of Energy Spencer Abraham and senior executives of DaimlerChrysler Corp., Ford Motor Co., and General Motors Corp. The CAR in FreedomCAR stands for Cooperative Automotive Research.

The FreedomCAR and Fuel Partnership pursues pre-competitive, high-risk research in component and infrastructure technologies necessary to enable a full range of affordable cars and light trucks, along with the fueling infrastructure to support them. Successful research will reduce the dependence of the nation's personal transportation system on imported oil and minimize harmful vehicle emissions, without sacrificing freedom of mobility and freedom of vehicle choice.

The long term vision of the FreedomCAR and Fuel Partnership is a clean and sustainable transportation energy future. This will be achieved with the widespread adoption of fuel-cell vehicles running on hydrogen, especially hydrogen produced from renewable energy and other emissions-free energy sources. In the interim, before fuel-cell vehicles are widely available, renewable fuels, such as ethanol, biodiesel, and clean carbon-based fuels used in advanced internal combustion engines, can make a significant contribution toward reducing future petroleum consumption and vehicle emissions. Many interim technologies, such as lightweight materials, power electronics, electric motors, and batteries, are shared components between an internal-combustion, hybrid-electric, and hybrid fuel-cell vehicles. Successful research and development in these areas will contribute to progress in both vehicles.

The 21st Century Truck Partnership was first announced on April 21, 2000, in Romulus, Mich., at a gathering of representatives from the U.S. trucking and supporting industries, concerned environmentalists, and federal agencies. The ultimate goal of 21st Century Truck Partnership is safe, secure, and environmentally friendly trucks and buses, using sustainable and self-sufficient energy sources that enhance America's global competitiveness. The 21st Century Truck Partnership brings together 15 industrial partners and four federal agencies to help the heavy vehicle industry focus on promising technologies, build on each other's research, and spotlight the role trucks can play in reducing oil consumption and air pollution.

DOE has funded a number of different research initiatives in support of the goals of these partnerships, and some of those initiatives are beginning to pay off.

Research, Developments, Results
The FreedomCAR and Fuel Partnership examines and advances pre-competitive research and development (R&D) of technologies to enable high-volume production of affordable hydrogen fuel-cell vehicles, and to establish the national hydrogen infrastructure necessary to support them. These technologies include fuel cells, hydrogen production, hydrogen distribution, and hydrogen storage. The Partnership also examines and promotes pre-competitive R&D for other advanced automotive technologies that directly assist in the development of fuel-efficient internal combustion engine (ICE) and hybrid electric vehicles (HEVs). The research areas include: advanced internal combustion engines, alternative fuels, lightweight materials, advanced batteries, power electronics and electric motors, and systems analysis. The Partnership has established aggressive technology-specific goals for 2010 and 2015 to promote R&D innovation. These detailed goals pertain to the critical components for technologies ranging from lightweight materials to fuel-cell system performance.

Fuel-cell vehicles very likely will be hybrids, supplementing the fuel cell stack with a battery in the same way as ICE hybrids. Because of this fact, advanced batteries, power electronics, and electric motors are key technologies for both ICE and fuel-cell hybrids. Developing and incorporating new lightweight materials without compromising crashworthiness or vehicle durability is a key challenge, as a 10-percent reduction in weight results in a 6-percent increase in fuel economy. Supported research in these areas benefits advanced fuel efficient hybrid vehicles of today, as well as ensures the technologies are adequately developed and cost effective for the hybrid fuel-cell vehicles of the future.

DOE also tests and evaluates system components and advanced vehicles. Over a million miles of data already have been collected on HEVs. Validation projects are starting to evaluate the performance of hydrogen and fuel-cell-powered transit vehicles and the necessary supporting infrastructure. DOE's ADVISOR, GREET and Powertrain Systems Analysis Toolkit (PSAT) models are being used to develop control strategies and well-to-wheel analysis of fuel pathways for advanced HEVs and fuel-cell vehicles.

The 21st Century Truck Partnership focuses on technologies to support energy efficiency improvements in the heavy duty truck and bus industry. In order to decrease fuel consumption and emissions, research is directed toward advanced compression ignition engines, reducing idle time and parasitic losses, and advancing heavy-hybrid drive systems. In addition, fuel-cell-based auxiliary power units are being developed for heavy vehicles.

Some Accomplishments
Homogeneous Charge Compression Ignition (HCCI) combustion offers the possibility of greatly improved efficiency over conventional spark-ignition combustion with lower nitrogen oxide emissions than Compression Ignition Direct Injection combustion. In HCCI combustion a homogeneous mixture of fuel and air is ignited by compression heating without a spark. Difficulties arise at low load limits, resulting in poor combustion efficiency and high carbon monoxide (CO) and hydrocarbon (HC) emissions. Studies conducted by Sandia National Laboratory have identified injection timing, which minimizes emissions and improves stability. A late, direct injection of fuel at approximately 290 degrees crank angle dramatically reduces CO and HC emissions and increases stability and efficiency. The studies have made HCCI engines feasible at lower loads. Researchers continue to work on the remaining challenges, such as transient operation and varying loads.

An essential component of an energy-efficient fuel cell is high hydrogen conductivity through the membrane electrolyte. Conductivity suffers with increased temperature and decreased humidity, requiring large, inefficient radiators in fuel-cell vehicles. A new polymer electrolyte material has been developed that demonstrates high hydrogen conductivity at 120 degrees Celsius and less than 25 percent relative humidity. This breakthrough will allow for the use of conventionally sized, efficient radiators.

Today's 5,000-pounds per square inch (psi) compressed-hydrogen gas tanks do not have a sufficient energy density to power a vehicle for 300 miles between refueling. Researchers have designed and tested a 5,000-psi cryo-compressed tank that uses an insulated pressure vessel. The tank is capable of being filled with liquid or compressed hydrogen with no performance losses. A cryo-compressed hydrogen gas tank is more compact than a conventional compressed-gas tank, requires less energy than liquefaction, and has less evaporative losses than liquid hydrogen tanks. Cryogenic cycling and burst testing was performed with positive results. The cryo-compressed tanks have an estimated system volumetric efficiency that is 80 percent of the Partnerships' 2010 goal.

Through the More Electric Truck project, 21st Century Truck partners are introducing new technology that uses electrically powered accessories instead of mechanical ones in a prototype class 7/8 truck. This allows accessories like water pumps, oil pumps, and air compressors to run independent of the engine at the precise speed, pressure, or flow rate required. Tests show that the fuel economy of the More Electric truck improved by 8 percent overall -- 2 percent in over-the-road driving and almost 6 percent from not idling the main engine overnight. The reduction in engine idling alone could save more than 600 million gallons of diesel fuel every year and annually reduce carbon dioxide emissions by 9.8 million tons ("Analysis of Technology Options to Reduce the Fuel Consumption of Idling Trucks," Center for Transportation Research Argonne National Laboratory, 2000). The technology is expected to become commercially available to truck equipment manufacturers and fleets nationwide in late 2005.

With the combined effort of the two partnerships, the United States will be able to reduce its dependence on imported oil and minimize harmful vehicle emissions without sacrificing freedom of mobility and freedom of vehicle choice. This work is paving the way for a clean and sustainable transportation future.

This article originally appeared in the 09/01/2005 issue of Environmental Protection.