Hydrogen Holds Hope as Fuel of the Future
Research organizations and industry are quietly working on ways to power internal combustion engines and fuel cells with clean hydrogen
Spring 2008
Amine loader undergoing conversion to fuel-cell power at Caterpillar's Tech Center in Mossville, Ill., is an example of new power technology coming to construction. That research organizations and industry, prodded by toughening air-quality rules and fuel economics, are beginning to adapt big machines to alternative energy is a clear indication that big changes are in the wind for construction equipment as well.
One immediate factor driving conversion to alternatives is the rising cost of diesel fuel which powers just about all heavy equipment. Hydrogen and fuel-cell power are not likely to be cheaper than diesel power but the big drivers toward alternative energy are concerns about the environment, air quality and global warming.
The black carbon (soot) emitted by diesel engines and other sources is beginning to attract attention in Congress as a major contributor to global warming and health problems. It is "emitted from our diesel trucks, our trains, our planes, ships and even our fireplaces," said Rep. Henry A. Waxman (D-Calif.), chairman of the House Oversight and Government Reform Committee at a hearing last Nov. 18. "Black carbon may be responsible for almost 20% of the warming the planet is currently experiencing. Experts tell us that black carbon may be the second most significant global warming pollutant after carbon dioxide."
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The move to hydrogen is driven by concerns about the environment, air quality and global warming.
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A growing number of companies and research institutions are heeding that message. Examples abound of experimental or prototype machines that have been converted to either hydrogen-fueled internal combustion engines or fuel cells.
Today, the most economical industrial process to produce hydrogen usually is "steam-reforming" natural gas. Electrolysis, the process in which water is split into hydrogen and oxygen by running an electrical current through it, is used in some places where there is cheap hydropower electricity. Electrolysis is the reverse of a fuel cell where hydrogen and oxygen combine electrochemically to produce electricity, water and some heat. The great future hope is to use solar electricity to make carbon-less, emission-free hydrogen fuel.
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Vehicle Projects LLC
Caterpillar mine loader being adapted to fuel-cell power shows that the technology could be used on big construction equipment. |
Like any fuel, hydrogen has to be handled with care. It burns much faster than natural gas and the ignition energy for a hydrogen/air mixture is only about one-twelfth of that for a gasoline/air mixture. But if there is any leak or tank rupture, the very light hydrogen rises and disperses in the air. The bottom line is that it is as safe as conventional fuels, but with different characteristics.
Building hydrogen fueling infrastructure is a major concern. California now is constructing a "hydrogen highway" with about two dozen-plus stations already built and more planned. Some fueling stations have been built specifically for fleets at central locations like bus depots. Worldwide, there are only about 300 stations so far. But major industrial gas suppliers such as Air Products, Air Liquide and Linde, as well as specialized firms such as California's Quantum Fuel Systems Technologies Worldwide Inc., have developed mobile fuelers that can service construction or similar equipment onsite. The hydrogen usually is compressed gas but sometimes is cryogenic liquid.
Hydrogen is being developed as fuel for internal combustion engines. Efforts include:
More than a dozen MAN city transit buses that are taking to the streets of the German capital Berlin.
An experimental pickup truck and Caterpillar farm tractor at the University of North Dakota.
Airport-type Ford Motor Co. shuttle buses in Canada, Las Vegas and in Florida.
A research project sponsored by the European Union called HyICE (Hydrogen Internal Combustion Engine), with companies like Ford, Volvo and BMW participating and American researchers at Argonne National Laboratory, Sandia National Laboratories and the University of Wisconsin contributing.
Fuel cells are the powerplants of choice in many experimental, prototype or demonstration versions of equipment. These include forklifts by various manufacturers: Canada's Hydrogenics fuel cells are powering a Hyster forklift, Crown Equipment is using Cellex Power Products fuel-cell modules and Toyota is using its own fuel cells. In a recent collaboration announced in January, Ballard Power Systems is providing fuel-cell stacks to Danish systems integrator H2 Logic A/S.
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Basin Electric Power Cooperative
North Dakota State University student team converted a tractor to partial hydrogen power. |
Stacks developed by Ballard Power Systems also are powering Daimler's fuel-cell Citaro transit buses. About three dozen of them have been deployed in demonstration programs across Europe, Australia and Asia. The ones in Europe are supported by the European Union.
UTC Power, the fuel-cell-building subsidiary of United Technologies Corp., South Windsor, Conn., has converted a number of buses by various manufacturers such as Belgium's Van Hool (for California's AC Transit) and by the French-Italian Irisbus group to fuel- cell propulsion. Hydrogenics has equipped a New Flyer bus with its fuel cell, and Germany's Neoplan busmaker teamed with German fuel-cell developer Proton Motor Fuel Cell in an early project. Japanese truckmaker Hino built a prototype fuel-cell city bus with Toyota. And China has developed fuel-cell city buses of its own.
Fuel-cell power is regarded as the superior, if longer-term, propulsion solution because it is about twice as efficient as internal combustion engines. Fueled by hydrogen, fuel cells emit virtually no carbon dioxide or any other waste gases. Hydrogen-fueled internal combustion engines are less efficient and can emit nitrogen oxides because the air's nitrogen takes part in the combustion process. They also produce carbon dioxide, the greenhouse gas generally accepted to be the main cause of global warming. But because engine manufacturing technology is mature and inexpensive compared with still-developing fuel-cell technology, it is seen by many as a bridge technology.
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A slight oversaturation of the fuel/air mixture with hydrogen cuts NOx by more than 95% at a catalytic converter.
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Construction equipment manufacturers apparently are looking at hydrogen internal-combustion or fuel-cell technology as something for the future, but not now. John Deere is "presently not conducting any fuel-cell or hydrogen activity with immediate application," says Joe Mastanduno, product marketing manager for engines and drivetrains in Deere's Construction and Forestry Division. Caterpillar says only that it "continues to explore hydrogen fuel-cell technologies."
Thus, whatever work is going on typically is initiated or led by others. A Caterpillar tractor with a turbocharged 173-hp Perkins diesel engine was converted to partial hydrogen operation last year by a student team at North Dakota State University in Fargo as a proof-of-concept exercise. A carbon-fiber tank with an aluminum liner holds 5,000-psi compressed hydrogen gas and is mounted in front of the radiator. The gas is blended into the diesel fuel to improve power and reduce emissions.
Five years ago, Hydrogenics adapted a Deere Pro-Gator work vehicle to use a 40-kW fuel-cell system, complete with standard power outlets in the rear to operate power tools in the field. But that apparently was as far as the project went.
The Caterpillar 160-kW, 23-ton hybrid fuel-cell mine loader is an effort by a 17-member consortium that includes Caterpillar USA and Caterpillar Australia. The effort is led by Vehicle Projects LLC, an offshoot of the FuelCell Propulsion Institute, Denver. The machine is based on Caterpillar's R1300 123-kW diesel loader. The 90-kW PEM (Proton Exchange Membrane) fuel cell is provided by Nuvera Fuel Cells Europe, Milan, Italy, and is augmented by a HERA 70-kW nickel metal hydride battery in a hybrid configuration. The machine is finished and is awaiting shakedown testing and debugging at Caterpillar's proving grounds in Tucson, Ariz., Vehicle Projects says.
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Peter Hoffmann
Fuel-cell conversion of work vehicle was successful, but that is as far as the project went. |
Another project currently under way by the FuelCell Propulsion Institute is the biggest land fuel-cell vehicle yet, a 127-ton, 250-kW hybrid railyard switch locomotive. It is a joint development with BNSF Railway Co. (a subsidiary of Burlington Northern Santa Fe Corp., Topeka, Kan.) and nine other consortium members. The fuel cells are made by Ballard Power Systems, Vancouver. (The only fuel-cell craft more powerful is a submarine developed by a German shipyard using Siemens fuel cells of about 300 kW as an auxiliary powerplant for underwater loitering.) The locomotive is expected to be completed later this year. There are plans for a bigger version with twice the fuel-cell power and three times the onboard hydrogen storage capacity for a "road switcher" locomotive that can operate outside a railyard.
The switcher is an interesting example of technological cross-fertilization. Both the Ballard fuel-cell modules as well as the 5,000-psi compressed-gaseous-hydrogen fuel tanks made by Dynetek Industries, Calgary, Canada, essentially are the same as the ones used in Daimler's Citaro buses.
In terms of hydrogen fuel for large internal combustion engines, two examples stand out: Ford's airport-type E-450 shuttle buses that are being deployed for two to three years of evaluation in Canada, Las Vegas and Florida; and the MAN transit buses that are conversions of the company's natural-gas-fueled engines. MAN also is working on fuel-cell versions.
Ford delivered the first five of a 30-vehicle test fleet to Ottawa and Vancouver in late 2006, and the first four of eight buses to Florida in May 2007. Two of the Florida fleet are for the Orlando Airport Authority and two for the Orlando Convention District. They will be refueled at a hydrogen station near the Orlando airport built by Chevron and Air Products.
Ford began work on hydrogen-fueled engines in 1997 as a transition strategy toward a hydrogen economy. Based on the natural-gas version of Ford's 6.8L V-10 235-hp engines, modifications include supercharging and a number of special components. Others, such as BMW and Mazda, have opted for dual-fuel technology as transition strategy, permitting drivers to choose between gasoline and hydrogen.
MAN started developing hydrogen-fueled buses in 1992 and the first four of a fleet of 14 started cruising Berlin in 2006. Part of EU-supported HyFLEET:CUTE (Clean Urban Transport Europe), the four buses are normally aspirated. The other 10 in various states of readiness will be turbocharged. All will be up and running by the end of this year for a test scheduled to run through the end of 2009. After that, busses with more advanced technology will likely be added, says a MAN spokesman.
Adapted from MAN's natural-gas versions of its diesel engines, the hydrogen 12.8L in-line six-cylinder engines are rated at 150 kW/204 hp in their naturally aspirated version and at 200 kW/272 hp in the turbo version. Compression is 8.5:1 and 11:1, respectively. For the standard natural- gas engine, compression is 11:1, and 12:1 for the turbo. Hydrogen gas injection pressures are 5 bar and 10 bar, respectively.
Other modifications include external mixture formation via a butterfly valve, and spark ignition. To prevent incandescent explosion, backfiring and knock, other modifications include hydrogen injection into the arms of the intake manifold directly ahead of the inlet valves using electromagnetically actuated valves. A slight oversaturation of the fuel/air mixture with hydrogen cuts NOx by more than 95% at a downstream catalytic converter.
