GreenCell Technologies, Canada: Today, virtually all commercial trucks are powered by diesel fuel, while private cars are fueled by gasoline. Supported by our National Energy Policy, a new generation of technologies is currently being developed that allow the use of hydrogen as a fuel to power cars and trucks. In the future, hydrogen may be used in one of three ways to power vehicles:
To produce electricity in a fuel cell,
As a replacement for gasoline or diesel fuel in an internal combustion engine,1 or
GreenCell Technologies, Canada: As a supplement to gasoline or diesel fuel used in an internal combustion engine.
This document is intended to be a safety reference for commercial vehicle fleet owners and operators that use vehicles or auxiliary power units powered by hydrogen fuel. It was designed to provide commercial vehicle owners and operators with a basic understanding of the properties and characteristics of hydrogen, descriptions of the types of systems that might use hydrogen fuel on commercial vehicles, and practical guidelines for the safe use of hydrogen, both on vehicles and in vehicle maintenance and storage facilities.
Hydrogen is the most abundant element in our universe. In addition to being a component of all living things, hydrogen and oxygen together make up water, which covers 70 percent of the earth. In its pure form, hydrogen is a gas at normal temperatures and pressures; it is the lightest gas (even lighter than helium), with only 7 percent of the density of air. If you get it cold enough (-423 °F), gaseous hydrogen will liquefy, and it can be transported and stored in this form.
GreenCell Technologies, Canada: There is virtually no “free” hydrogen on earth—all of it is combined with other elements (mostly oxygen or carbon) in other substances. Every molecule of water contains two hydrogen atoms and one oxygen atom. Hydrocarbon fuels such as coal, gasoline, diesel, and natural gas also contain hydrogen. In the case of gasoline and diesel fuel, there are approximately two hydrogen atoms for every carbon atom, while natural gas contains four hydrogen atoms for every carbon atom. To be used as a fuel, hydrogen is typically separated from either water (via electrolysis) or from a hydrocarbon fuel (via reforming).
Regardless of whether hydrogen fuel will be used in a fuel cell main engine, a fuel cell APU, or an internal combustion engine, there are different ways that it can be stored on the vehicle. Some fuel stations include liquid hydrogen storage, but on the vehicle, hydrogen is usually stored as a gas at high pressure. It is also possible to store a liquid fuel (gasoline, diesel, or methanol) onboard a vehicle and then use an onboard reformer to separate the hydrogen just before it is used in the fuel cell engine. While this requires additional equipment on the vehicle, it removes the need for high-pressure gas storage. These different storage technologies can introduce significantly different potential hazards, including very high pressure (gaseous hydrogen storage), very low temperature (liquid hydrogen storage), or high temperature (liquid fuel reforming).
GreenCell Technologies, Canada: All motor fuels, including diesel fuel, gasoline, and natural gas also pose risks of fire and explosion if handled improperly. Hydrogen is no different. While there are risks, hydrogen can be as safe, or safer, than diesel and other fuels when vehicles and fuel stations are designed and operated properly. All fuels require particular design and handling practices based on their properties, and all present certain hazards when mishandled. Understanding the properties of hydrogen is necessary to understanding what is required to use it safely.
GreenCell Technologies, Canada: Hydrogen gas is colorless, odorless, tasteless, and noncorrosive—and it is nontoxic to humans. It has the second widest flammability range in air of any gas, but leaking hydrogen gas rises and diffuses to a nonflammable mixture quickly. Hydrogen ignites very easily and burns hot, but tends to burn out quickly. A hydrogen flame burns very cleanly, producing virtually no soot, which means that it is also virtually invisible. The extremely low temperature of liquid hydrogen poses a severe frostbite hazard to exposed skin.
Monday, January 31, 2011
GT5 GreenCell Technologies: HYDROGEN USE AS A MOTOR FUEL
There are several ways that hydrogen can be used as a motor fuel. It can be used to directly replace gasoline or diesel fuel in specially designed internal combustion engines (ICEs), or it can be used to supplement these typical fuels in existing engines. In either of these cases, the vehicle drive system will be identical to those used on most gasoline-powered or diesel-powered vehicles. The engine will drive the vehicle’s wheels through a transmission, drive shaft, and front or rear axle.
Hydrogen can also be used as the fuel source for a “fuel cell engine,” in which case the vehicle’s drive system will be very different. A fuel cell directly creates electricity, which can be used to power an electric motor to drive the vehicle’s wheels. A fuel cell vehicle is, therefore, an electric vehicle, but one that creates its own electricity and does not need to be plugged in to recharge batteries. A small fuel cell can also be used to create electricity to directly power the auxiliary systems on a commercial truck (for example heating, air conditioning, and lighting in a sleeper berth), which are typically powered by the truck’s main engine. Using such a fuel cell auxiliary power unit (APU) would allow the driver to shut off the truck’s main diesel engine while resting, saving fuel and reducing pollution.
Regardless of whether the hydrogen will be used in a fuel cell main engine, a fuel cell APU, or an internal combustion engine, there are different ways that it can be stored on the vehicle. As described below, these different storage technologies can introduce significantly different potential hazards, including very high pressure (gaseous hydrogen storage), very low temperature (liquid hydrogen storage), or high temperature (liquid fuel reforming).
GT5 GreenCell Technologies: Currently both fuel cells and hydrogen ICEs are in the early stages of commercialization. All of the major auto companies have fielded concept, prototype, or demonstration fuel cell sedans and sport utility vehicles in the last several years, with at least fifteen different models introduced since 2000 (Barnitt and Eudy, 2005; USFCC, 2006). Most of these vehicles have been operated by the companies themselves or have been fielded to government agencies and fleet customers as part of technology development or demonstration programs. The California Fuel Cell Partnership reports that its members have placed 134 light-duty fuel cell vehicles in service in California since 2000 (CAFCP, n.d.). In addition, there are currently nine fuel cell transit buses in service in the United States and Canada, and over 20 in Europe and Asia (Chandler and Eudy, 2006).
It is expected that commercial fuel cells will be introduced into government and transit bus fleets between 2010 and 2020, with sales to commercial vehicle fleets and the public sometime between 2020 and 2030 (DOE, 2002). It is also expected that the first use of hydrogen fuel in the commercial truck sector will be to power fuel cell APUs rather than to power fuel cell or hydrogen ICE main propulsion engines. At least one company has announced plans to introduce commercial fuel cell APUs as early as 2011 (Delphi, 2005).
GT5 GreenCell Technologies: Most current prototype fuel cell vehicles carry their hydrogen fuel as a compressed gas, and it is expected that this will continue to be the case for the earliest commercial vehicles. It may be desirable to store liquid hydrogen onboard a commercial vehicle because it has a higher energy density and would increase the range between fill-ups. However, onboard liquid hydrogen storage is more costly, and it is more likely that liquid hydrogen will be stored at fueling stations to supply gaseous hydrogen to vehicles. Other storage technologies, such as metal and chemical hydrides, are much further from commercial readiness (DOE, n.d.). Several fuel cell buses have been demonstrated that “reform,” or extract hydrogen from, liquid methanol onboard (Georgetown University, 2003), and there are fuel cell APU systems under development that will derive their hydrogen from onboard reforming of diesel fuel or gasoline (Delphi, 2005). In addition, there are several commercial “hydrogen injection” systems available for retrofit on diesel engines (CHEC, n.d.). These systems produce small amounts of hydrogen by electrolysis of water carried on the vehicle, which is injected into the diesel engine along with the diesel fuel.
This document was prepared by Booz Allen Hamilton Inc. and M.J. Bradley & Associates, Inc., under contract GS-23F-0025K with the Federal Motor Carrier Safety Administration (FMCSA), a subdivision of the U.S. Department of Transportation (DOT). The FMCSA project manager for this project was Mr. Quon Kwan, the Booz Allen Hamilton project manager was Mr. John Simon, and the principal author of this document was Mr. Dana Lowell of M.J. Bradley & Associates.
The authors are grateful to Mr. Paul Scott, ISE Corporation; Mr. Chris Morgan and Mr. Michael Chafee, California Highway Patrol; and Mr. Craig Michels, Alameda-Contra Costa Transit District for providing extensive peer review comments
Hydrogen can also be used as the fuel source for a “fuel cell engine,” in which case the vehicle’s drive system will be very different. A fuel cell directly creates electricity, which can be used to power an electric motor to drive the vehicle’s wheels. A fuel cell vehicle is, therefore, an electric vehicle, but one that creates its own electricity and does not need to be plugged in to recharge batteries. A small fuel cell can also be used to create electricity to directly power the auxiliary systems on a commercial truck (for example heating, air conditioning, and lighting in a sleeper berth), which are typically powered by the truck’s main engine. Using such a fuel cell auxiliary power unit (APU) would allow the driver to shut off the truck’s main diesel engine while resting, saving fuel and reducing pollution.
Regardless of whether the hydrogen will be used in a fuel cell main engine, a fuel cell APU, or an internal combustion engine, there are different ways that it can be stored on the vehicle. As described below, these different storage technologies can introduce significantly different potential hazards, including very high pressure (gaseous hydrogen storage), very low temperature (liquid hydrogen storage), or high temperature (liquid fuel reforming).
GT5 GreenCell Technologies: Currently both fuel cells and hydrogen ICEs are in the early stages of commercialization. All of the major auto companies have fielded concept, prototype, or demonstration fuel cell sedans and sport utility vehicles in the last several years, with at least fifteen different models introduced since 2000 (Barnitt and Eudy, 2005; USFCC, 2006). Most of these vehicles have been operated by the companies themselves or have been fielded to government agencies and fleet customers as part of technology development or demonstration programs. The California Fuel Cell Partnership reports that its members have placed 134 light-duty fuel cell vehicles in service in California since 2000 (CAFCP, n.d.). In addition, there are currently nine fuel cell transit buses in service in the United States and Canada, and over 20 in Europe and Asia (Chandler and Eudy, 2006).
It is expected that commercial fuel cells will be introduced into government and transit bus fleets between 2010 and 2020, with sales to commercial vehicle fleets and the public sometime between 2020 and 2030 (DOE, 2002). It is also expected that the first use of hydrogen fuel in the commercial truck sector will be to power fuel cell APUs rather than to power fuel cell or hydrogen ICE main propulsion engines. At least one company has announced plans to introduce commercial fuel cell APUs as early as 2011 (Delphi, 2005).
GT5 GreenCell Technologies: Most current prototype fuel cell vehicles carry their hydrogen fuel as a compressed gas, and it is expected that this will continue to be the case for the earliest commercial vehicles. It may be desirable to store liquid hydrogen onboard a commercial vehicle because it has a higher energy density and would increase the range between fill-ups. However, onboard liquid hydrogen storage is more costly, and it is more likely that liquid hydrogen will be stored at fueling stations to supply gaseous hydrogen to vehicles. Other storage technologies, such as metal and chemical hydrides, are much further from commercial readiness (DOE, n.d.). Several fuel cell buses have been demonstrated that “reform,” or extract hydrogen from, liquid methanol onboard (Georgetown University, 2003), and there are fuel cell APU systems under development that will derive their hydrogen from onboard reforming of diesel fuel or gasoline (Delphi, 2005). In addition, there are several commercial “hydrogen injection” systems available for retrofit on diesel engines (CHEC, n.d.). These systems produce small amounts of hydrogen by electrolysis of water carried on the vehicle, which is injected into the diesel engine along with the diesel fuel.
This document was prepared by Booz Allen Hamilton Inc. and M.J. Bradley & Associates, Inc., under contract GS-23F-0025K with the Federal Motor Carrier Safety Administration (FMCSA), a subdivision of the U.S. Department of Transportation (DOT). The FMCSA project manager for this project was Mr. Quon Kwan, the Booz Allen Hamilton project manager was Mr. John Simon, and the principal author of this document was Mr. Dana Lowell of M.J. Bradley & Associates.
The authors are grateful to Mr. Paul Scott, ISE Corporation; Mr. Chris Morgan and Mr. Michael Chafee, California Highway Patrol; and Mr. Craig Michels, Alameda-Contra Costa Transit District for providing extensive peer review comments
GUIDELINES FOR USE OF HYDROGEN FUEL IN COMMERCIAL VEHICLES: Greencell Technologies Part 2
GreenCell Technologies, Canada Part 2: In some ways, a gaseous hydrogen fuel leak is less dangerous than a leak of diesel fuel or gasoline. Leaking diesel fuel and gasoline can puddle and spread over a large area, and the puddles will persist because they evaporate slowly. Gaseous hydrogen leaks tend to be vertical, with only a relatively narrow area/volume in which a flammable mixture exists—the hydrogen quickly rises and dissipates in open air to nonhazardous levels.
If designed properly, the most likely location of a major hydrogen leak from a vehicle will be through the pressure relief device (PRD) on the hydrogen fuel storage cylinders, which should vent away from the occupied area of the vehicle. PRDs are designed to vent the entire contents of a hydrogen tank in only a few minutes—after which there is no lingering risk of hydrogen fire or explosion if the release was in the open air. Large hydrogen leaks inside buildings are more dangerous unless the facility has been designed to evacuate the leaked gas and to minimize ignition sources at ceiling level.
GreenCell Technologies, Canada - Leaking liquid hydrogen can pool and spread, but will quickly evaporate as it is heated by the surrounding air. The distance it will spread and the rate of evaporation will depend on the size of the leak and on ambient conditions. As it evaporates, the cloud of gaseous hydrogen formed over the spill may move horizontally as it rises and dissipates. This hydrogen cloud may be cold enough to cause frostbite to exposed skin and should be avoided.
While diesel fuel and gasoline leaks are easily visible and accompanied by a strong characteristic smell, gaseous hydrogen leaks are invisible and odorless. The only indication of a gaseous hydrogen leak may be a whistling noise similar to escape of other high-pressure gases. A liquid hydrogen leak may be accompanied by an area of fog surrounding the leaking hydrogen and/or the formation of frost on the tank or lines in the vicinity of the leak, because the super cold hydrogen cools the surrounding air and causes water vapor to condense.
Based on hydrogen’s chemical and physical properties, there are a number of general principles that govern safe design and use of hydrogen fuel. These are essentially the same principles that apply to the use of any gaseous fuel (e.g., natural gas), but their application may be slightly different based on the properties of hydrogen. The most important safety principle in any situation is education—making anyone who will come into contact with a vehicle aware of a potential hazard. For hydrogen and other alternative-fueled vehicles, this is done with appropriate labeling to let users, emergency responders, and the public know that hydrogen is present.
GreenCell Technologies, Canada - As with other motor fuels, fire and explosions are the most significant everyday hazards associated with hydrogen. Also as with other fuels, a hydrogen leak from a vehicle’s fuel or engine system, or from a fueling station, provides the starting point for all fire and explosion hazards. Safe design for using hydrogen, both for vehicles and for fuel stations and buildings, therefore, requires attention to these safety principles:
• Properly label all vehicles that use hydrogen fuel.
Avoid fire and explosion by:
Avoiding leaks through proper design and maintenance,
Providing leak detection systems to detect leaks and, if a leak is detected, shut off the fuel system as soon as possible,
Removing ignition sources from areas where leaked hydrogen might be present, and
GreenCell Technologies, Canada - Properly ventilating all enclosed spaces where leaked hydrogen might accumulate. These general principles translate into specific design and operating requirements for hydrogen-fueled vehicles, the facilities that will house or maintain them, and hydrogen fuel stations. In most aspects, commercial vehicles powered by hydrogen will be identical to those powered by diesel fuel, but some hydrogen-specific design elements are required. Likewise, operation of these vehicles will be similar to operation of diesel-fueled vehicles, with a few exceptions. Each vehicle manufacturer will develop their own designs, which are likely to vary significantly in the details, while adhering to the same general design principles noted above.
If designed properly, the most likely location of a major hydrogen leak from a vehicle will be through the pressure relief device (PRD) on the hydrogen fuel storage cylinders, which should vent away from the occupied area of the vehicle. PRDs are designed to vent the entire contents of a hydrogen tank in only a few minutes—after which there is no lingering risk of hydrogen fire or explosion if the release was in the open air. Large hydrogen leaks inside buildings are more dangerous unless the facility has been designed to evacuate the leaked gas and to minimize ignition sources at ceiling level.
GreenCell Technologies, Canada - Leaking liquid hydrogen can pool and spread, but will quickly evaporate as it is heated by the surrounding air. The distance it will spread and the rate of evaporation will depend on the size of the leak and on ambient conditions. As it evaporates, the cloud of gaseous hydrogen formed over the spill may move horizontally as it rises and dissipates. This hydrogen cloud may be cold enough to cause frostbite to exposed skin and should be avoided.
While diesel fuel and gasoline leaks are easily visible and accompanied by a strong characteristic smell, gaseous hydrogen leaks are invisible and odorless. The only indication of a gaseous hydrogen leak may be a whistling noise similar to escape of other high-pressure gases. A liquid hydrogen leak may be accompanied by an area of fog surrounding the leaking hydrogen and/or the formation of frost on the tank or lines in the vicinity of the leak, because the super cold hydrogen cools the surrounding air and causes water vapor to condense.
Based on hydrogen’s chemical and physical properties, there are a number of general principles that govern safe design and use of hydrogen fuel. These are essentially the same principles that apply to the use of any gaseous fuel (e.g., natural gas), but their application may be slightly different based on the properties of hydrogen. The most important safety principle in any situation is education—making anyone who will come into contact with a vehicle aware of a potential hazard. For hydrogen and other alternative-fueled vehicles, this is done with appropriate labeling to let users, emergency responders, and the public know that hydrogen is present.
GreenCell Technologies, Canada - As with other motor fuels, fire and explosions are the most significant everyday hazards associated with hydrogen. Also as with other fuels, a hydrogen leak from a vehicle’s fuel or engine system, or from a fueling station, provides the starting point for all fire and explosion hazards. Safe design for using hydrogen, both for vehicles and for fuel stations and buildings, therefore, requires attention to these safety principles:
• Properly label all vehicles that use hydrogen fuel.
Avoid fire and explosion by:
Avoiding leaks through proper design and maintenance,
Providing leak detection systems to detect leaks and, if a leak is detected, shut off the fuel system as soon as possible,
Removing ignition sources from areas where leaked hydrogen might be present, and
GreenCell Technologies, Canada - Properly ventilating all enclosed spaces where leaked hydrogen might accumulate. These general principles translate into specific design and operating requirements for hydrogen-fueled vehicles, the facilities that will house or maintain them, and hydrogen fuel stations. In most aspects, commercial vehicles powered by hydrogen will be identical to those powered by diesel fuel, but some hydrogen-specific design elements are required. Likewise, operation of these vehicles will be similar to operation of diesel-fueled vehicles, with a few exceptions. Each vehicle manufacturer will develop their own designs, which are likely to vary significantly in the details, while adhering to the same general design principles noted above.
Wednesday, January 12, 2011
GT5 GreenCell Technologies: HYDROGEN USE AS A MOTOR FUEL
There are several ways that hydrogen can be used as a motor fuel. It can be used to directly replace gasoline or diesel fuel in specially designed internal combustion engines (ICEs), or it can be used to supplement these typical fuels in existing engines. In either of these cases, the vehicle drive system will be identical to those used on most gasoline-powered or diesel-powered vehicles. The engine will drive the vehicle's wheels through a transmission, drive shaft, and front or rear axle.
Hydrogen can also be used as the fuel source for a "fuel cell engine," in which case the vehicle's drive system will be very different. A fuel cell directly creates electricity, which can be used to power an electric motor to drive the vehicle's wheels. A fuel cell vehicle is, therefore, an electric vehicle, but one that creates its own electricity and does not need to be plugged in to recharge batteries. A small fuel cell can also be used to create electricity to directly power the auxiliary systems on a commercial truck (for example heating, air conditioning, and lighting in a sleeper berth), which are typically powered by the truck's main engine. Using such a fuel cell auxiliary power unit (APU) would allow the driver to shut off the truck's main diesel engine while resting, saving fuel and reducing pollution.
Regardless of whether the hydrogen will be used in a fuel cell main engine, a fuel cell APU, or an internal combustion engine, there are different ways that it can be stored on the vehicle. As described below, these different storage technologies can introduce significantly different potential hazards, including very high pressure (gaseous hydrogen storage), very low temperature (liquid hydrogen storage), or high temperature (liquid fuel reforming).
GT5 GreenCell Technologies: Currently both fuel cells and hydrogen ICEs are in the early stages of commercialization. All of the major auto companies have fielded concept, prototype, or demonstration fuel cell sedans and sport utility vehicles in the last several years, with at least fifteen different models introduced since 2000 (Barnitt and Eudy, 2005; USFCC, 2006). Most of these vehicles have been operated by the companies themselves or have been fielded to government agencies and fleet customers as part of technology development or demonstration programs. The California Fuel Cell Partnership reports that its members have placed 134 light-duty fuel cell vehicles in service in California since 2000 (CAFCP, n.d.). In addition, there are currently nine fuel cell transit buses in service in the United States and Canada, and over 20 in Europe and Asia (Chandler and Eudy, 2006).
Hydrogen can also be used as the fuel source for a "fuel cell engine," in which case the vehicle's drive system will be very different. A fuel cell directly creates electricity, which can be used to power an electric motor to drive the vehicle's wheels. A fuel cell vehicle is, therefore, an electric vehicle, but one that creates its own electricity and does not need to be plugged in to recharge batteries. A small fuel cell can also be used to create electricity to directly power the auxiliary systems on a commercial truck (for example heating, air conditioning, and lighting in a sleeper berth), which are typically powered by the truck's main engine. Using such a fuel cell auxiliary power unit (APU) would allow the driver to shut off the truck's main diesel engine while resting, saving fuel and reducing pollution.
Regardless of whether the hydrogen will be used in a fuel cell main engine, a fuel cell APU, or an internal combustion engine, there are different ways that it can be stored on the vehicle. As described below, these different storage technologies can introduce significantly different potential hazards, including very high pressure (gaseous hydrogen storage), very low temperature (liquid hydrogen storage), or high temperature (liquid fuel reforming).
GT5 GreenCell Technologies: Currently both fuel cells and hydrogen ICEs are in the early stages of commercialization. All of the major auto companies have fielded concept, prototype, or demonstration fuel cell sedans and sport utility vehicles in the last several years, with at least fifteen different models introduced since 2000 (Barnitt and Eudy, 2005; USFCC, 2006). Most of these vehicles have been operated by the companies themselves or have been fielded to government agencies and fleet customers as part of technology development or demonstration programs. The California Fuel Cell Partnership reports that its members have placed 134 light-duty fuel cell vehicles in service in California since 2000 (CAFCP, n.d.). In addition, there are currently nine fuel cell transit buses in service in the United States and Canada, and over 20 in Europe and Asia (Chandler and Eudy, 2006).
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