Automakers drive toward a hydrogenpowered future

Feb. 17, 2005
Hydrogen-powered vehicles are speeding off the drawing board and on to test tracks.

Research and Advanced Engineering Team
Ford Motor Co.
Dearborn, Mich.

Visible in this transparent view of the Escape hybrid are the four-cylinder ICE and 70-kW electric motor in front and the nickel-metalhydride battery pack under the rear load floor.

Ballard's fuel-cell stack is the heart of the Focus FCV.

The Ford hydrogen internalcombustion-engine (H2ICE).

The Hydrogen Hybrid Research Vehicle (H2RV) boasts zero emissions.

Electric vehicles couldn't quite cut it. Hybridelectric vehicles are already on the road. Automakers are now concentrating on the next eco-friendly trend: hydrogenpowered vehicles.

Ford Motor Co. projects hydrogen fuel-cell vehicles will hit the mass market in a big way in about 10 years or so. In the meantime, the company is rolling out vehicles that provide a substantial glimpse into the future.

The 2005 Escape Hybrid is the world's first full hybrid SUV, meaning it has a high-voltage storage battery and can drive on electric power alone. Full hybrids are said to see improvements in fuel economy up to 50% during stop and go driving where the electric motor is most efficient.

The Escape Hybrid is said to be the cleanest and most fuel-efficient sport-utility vehicle on the market today. It uses a combination of gasoline and electric power to deliver 36 mpg in city driving. It can travel more than 400 city miles on a single tank of gasoline, without compromising performance or versatility.

The hybrid system also meets the strictest emissions standards. At the heart of the Escape Hybrid powerplant is a modified Zetec four-cylinder engine that runs on the Atkinson cycle. The Atkinson-cycle engine is up to 10% more efficient than a conventional four-stroke Ottocycle engine. The increase in efficiency comes from controlling pumping losses, defined as the power expended on the induction of the fuel/air charge into a gasoline engine.

There is a small amount of the fuel/air mixture that goes from the cylinder back into the induction system without being burned, reducing the effective displacement of the engine. Also, the expansion ratio is greater than the compression ratio so as to take as much heat as possible from the exhaust gas instead of pumping it into the exhaust system, thereby increasing efficiency.

The Atkinson cycle — also called the " fivestroke cycle" — works like this: intake, backflow (partial expulsion to eliminate pumping losses), compression, expansion, and exhaust. The combustion chamber volume is adapted to maintain a constant compression ratio to avoid knock while increasing the expansion ratio to optimize efficiency. Engineers convert the Zetec I-4 engine to an Atkinson cycle by changing the intake camshaft to one with a very late valve closing and installing pistons that decrease combustion clearance volume. These changes result in a higher, 12.3:1 compression ratio.

The drive system combines a 70-kW permanent-magnetic electric motor (equivalent to 94 hp) and 28-kW generator with the Atkinsoncycle engine. The electric drive motor makes up for the low-end torque losses characteristic of five-stroke engines, making the Atkinson cycle ideal for hybridization. An electronic controller continuously adjusts the contributions of all these power sources to maximize fuel efficiency.

In place of a conventional transmission is an electronically controlled planetary gear set that includes a traction motor and power-management electronics in one compact assembly. The planetary gear set acts as an electronically controlled continuously variable transmission (eCVT) and varies the distribution of power between the gasoline engine, electric motor, and the vehicle's wheels. Because of this capability, the Escape Hybrid is known as a "full" hybrid, meaning it automatically switches between electric power, gasoline engine power, or a combined operation to maximize efficiency and performance.

The Escape Hybrid does not need to plug in to recharge. Energy normally dissipated as heat during braking gets recaptured as electric energy and stored in the 330-V nickel-metal-hydride battery pack located beneath the rear load floor. The hybrid storage battery consists of 250 D-sized cells in a sealed enclosure.

"Ford has a history of introducing vehicles that change our industry and our world," says Bill Ford, Ford chairman and CEO. "Escape Hybrid is one of those vehicles. It is our first production vehicle powered by anything other than an internal-combustion engine. It's the first, but it won't be the last."

The Ford Focus sedan combines hybrid-electric vehicle technology with an advanced fuel cell to create highly efficient, zero-emission power. The Focus Fuel Cell Vehicle (FCV) is Ford's most advanced environmental vehicle. It also is one of the industry's first "hybridized fuel-cell vehicles" — which combines the improved range and performance of hybrid technology with the overall benefits of a fuel cell.

The Focus FCV uses a fuel-cell engine from Ballard Power Systems, Burnaby, B.C., that converts chemical energy into electrical energy using hydrogen and oxygen. The electrical energy then powers the vehicle's electric-drive motor, producing water and heat as the only by-products.

The Focus FCV has been "hybridized" with the addition of a Sanyo battery pack and a brake-bywire electrohydraulic series regenerative braking system. Both of these technologies also are found on the Escape Hybrid. In addition, the Focus FCV has an advanced hydrogen storage tank, which can handle 5,000 psi of hydrogen. Together, the new battery pack, regenerative braking, and storage tank get the driving range of the four-passenger Focus FCV to between 184 and 200 miles. The hybrid-electric power system also gives the vehicle the "off-the-light" zippiness of a more conventional sedan and a top speed governed at 80 mph.

"This latest technology brings us one step closer to making fuel-cell vehicles viable for consumers," says Mary Ann Wright, director of Sustainable Mobility Technologies and Hybrid Vehicle Programs. This group at Ford is responsible for research and development of fuel-cell products. "While we are still years away from mass production and sales, we believe that eventually we will be able to give customers the efficiency and environmental benefits of a fuel cell without compromising on today's performance and functionality."

Ford has fielded a fleet of 25 Focus FCV engineering vehicles around the globe, helping to prove out, develop, and demonstrate the technology. Ford and BP this year also announced a major initiative aimed at moving the U.S. even closer to a hydrogen economy. Ford plans to produce up to 30 more hydrogen-powered vehicles, while BP will build a network of fueling stations in California, Florida, and Michigan to support them.

The Ballard Mark 902 fuel-cell system at the core of the Focus FCV has better power density than earlier cells. The 900 Series also was designed in a smaller package to be compatible with the overall system requirements of vehicles, including the Focus FCV. The stack is more reliable and designed for better manufacturability and service than previous-generation devices. It delivers 85 kW, equivalent to 117 hp. In comparison, the base Ford Focus sedan with a gasoline engine has 110 hp.

The hybridized Focus FCV's battery pack is made up of 180 individual D-sized batteries packaged between the rear seat and the hydrogen fuel tank. It is a "mild" hybrid, meaning the battery pack aids vehicle performance, but cannot power the vehicle by itself. The battery is used during launch and assists the fuel-cell system to improve performance and drivability.

The regenerative braking system works to recapture energy in the form of electricity as the brakes are applied. This electric energy — which is normally lost in the form of heat generated by the brake pads in conventional systems — goes into charging the battery. That additional energy helps give the vehicle its substantially increased range.

Brake-by-wire means there is no mechanical connection between the brake pedal and the brakes during normal operation. This lets the system electronically optimize braking between regeneration and friction for maximum fuel economy and braking performance.

The Focus FCV's highly pressurized hydrogen gas tank also contributes to the vehicle's added range. Tank technology used on board the Focus FCV came from breakthroughs in Ford's natural-gas vehicle programs. Further range gains come from using lightweight materials throughout the vehicle, such as magnesium, aluminum, titanium, and composites.

"Ford is the only automaker with a product plan and a development effort in place to move all of us to a hydrogen-powered future," claims Ford's Vice President, Environmental and Safety Engineering, Sue Cischke.

Ford is developing what is claimed to be the world's cleanest internal-combustion engine, along with a host of technologies that could lead from the present hybrid vehicles now available to zero-emissions, hydrogen fuel cells.

The new 2.3-liter hydrogen engine, with Lean NOx Trap (LNT) aftertreatment, meets the stringent Sulev-Bin 2 emissions standards. Ford engineers are in the process of optimizing its calibration to give performance similar to a gasoline-powered engine. Limited production for real-world demonstration could come within the next two years.

The first tests of the new hydrogen engine with LNT aftertreatment produced nitrogen oxide results below the Sulev or Tier2-Bin 2 standard, the world's cleanest. Subsequent tests were just as promising. Ford's target is to meet these challenging emissions requirements, produce virtually no CO2, and deliver gasolinelike performance.

"This is exciting news," says Cischke. "No company has ever demonstrated a hydrogen internalcombustion engine that can meet these standards and have near zero carbon-dioxide emissions. Another important chapter in environmental history has been written."

Ford is also showcasing its Hydrogen Hybrid Research Vehicle (H 2 RV), a technology that could be offered for sale today if a hydrogen-fueling infrastructure was widely available. The H2 RV combines a 2.3-liter internal-combustion engine powered by hydrogen, boosted by a supercharger, with a patented Modular Hybrid Transmission System. These vehicles, based on the Ford Focus wagon, now travel the roads in southeast Michigan and are generating thousands of miles in real-world conditions.

Emissions of all pollutants, including carbon dioxide, are nearly zero. The electric motor and advanced controls let the H2RV stop the internalcombustion engine when the vehicle is at rest and start it again quickly and smoothly, offering extra power for acceleration.

"H2RV is proven technology — it could be put into production," says Ford's Vice President, Advanced Research and Engineering Gerhard Schmidt. "What we are lacking are the other two legs of this three-legged stool — a fueling infrastructure for hydrogen, and uniform laws and regulations that will allow its use across the nation," he adds.

"The hydrogen internal-combustion engine in the H2RV has reliability proven to be similar to a gasoline-fueled engine," says Bob Natkin, group leader for hydrogen ICE development, Ford Research and Advanced Engineering. "Maintenance is much the same (as conventional ICEs), as is longterm durability."

Natkin says hydrogen ICE engines have logged thousands of hours on dynamometers, and more than 10,000 miles on the road under the hood of Ford Focus vehicles.

In the H2RV, the hydrogen-powered engine mates to a Modular Hybrid Transmission System. As the name suggests, the MHTS system can be used interchangeably in various vehicle structures. MHTS is a full hybrid system using a single 300-V electric motor, upgraded automatic transmission, and modified hydraulics.

Ford will place a fleet of four hydrogen fuel-cell Focus vehicles on the streets of Vancouver, B.C., for evaluation later this year.

The basis for the H2RV is its hydrogen-powered internal-combustion engine. The engine is regarded as a transition or "bridging" strategy to stimulate the hydrogen infrastructure and related technologies. These include on-board hydrogen fuel storage, hydrogen fuel dispensing, and hydrogen safety sensors.

The H2ICE engine has many benefits. H2ICEs are all-weather capable, requiring zero warm-up and have no cold start issues. They are highly efficient (52% peak indicated efficiency).

H2ICE's can easily hit Sulev emissions, or better, and more than 99% reduced CO2 vehicle emissions. Performance is comparable to gasoline, while fuel economy increases up to 25% with the engine only and up to 50% better with an aggressive hybrid-electric strategy.

"The transition of where we are today to a hydrogen economy is going to be a huge national and international challenge that is going to require coordination between governments, fuel providers, and ourselves in a scale that we have never seen before," says Schmidt. "Whether we want to take that step is a decision for public and government — but Ford is ready with product today."

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