NGVs and the Hydrogen Transportation Future
The use of alternative fuel vehicles (AFVs) is a key strategy for cities throughout the world to improve air quality. Today, natural gas vehicles (NGVs) are the leading type of commercially available low-emissions AFV. Over the longer term, fuel cell vehicles (FCVs) operating on hydrogen offer promise to deliver zero emissions, while also providing a wide variety of other environmental and societal benefits.
Currently, FCVs exist only as prototype technology, developed and demonstrated by the automotive industry at very high cost. Fortunately, tremendous synergy and continuity exists between deployment of today’s NGVs and tomorrow’s hydrogen-fueled FCVs. As further described, NGVs and related technologies are moving America towards commercially sustainable FCV markets – faster and more affordably than would otherwise be possible. Examples include the following:
- Natural gas is the leading feedstock for hydrogen production in the U.S. today.
- The first fueling stations along California’s hydrogen highway will likely produce hydrogen onsite by reforming pipeline natural gas.
- Some of these will be advanced “energy stations” that use hydrogen from natural gas to power fuel cell vehicles, generate electricity for buildings, and produce usable hot water (“tri-generation”).
- Technologies and products developed for NGVs and natural gas stations over many years are now “jumpstarting” fuel cell vehicles and hydrogen stations.
- Many “lessons learned” for NGVs and natural gas directly apply to fuel cell vehicles and hydrogen.
- Most investments already made in NGVs and natural gas fueling stations (capital, institutional, educational, organizational, etc.) are directly or indirectly applicable to America’s emerging hydrogen fueling system..
Natural Gas is a Key Feedstock for Hydrogen Production
America’s long-range plans to improve air quality and energy independence call for a gradual transition towards zero-emission modes of transportation and away from petroleum-based fuels. The “ultimate” fuel and technology combination for meeting these objectives will be FCVs using hydrogen that has been produced locally from renewable energy sources, such as solar power, wind power, or even landfill gas.
Fuel cells and associated technologies are steadily advancing, but many challenges remain. Perhaps the most formidable of these are associated with the costs and use logistics of hydrogen itself. Although hydrogen is nature’s most abundant element, on Earth it largely exists in forms that are chemically bound into water molecules or hydrocarbon compounds such as methane. A major challenge to commercializing FCVs involves developing a process that can economically “free” hydrogen into its pure elemental form (H2) at minimal impact to the environment.
Fortunately, natural gas provides a near-term, widely available feedstock with a proven technique for separating out hydrogen molecules. Specifically, most hydrogen in the United States today, and about half of the worldwide supply, is produced by steam reforming of natural gas. In part, this is because methane (the main constituent of natural gas) has the highest hydrogen-to-carbon ratio of any hydrocarbon fuel. During the initial “launch” of hydrogen-fueled vehicles (both FCVs and internal combustion engine vehicles, or ICEVs), it is highly likely that demand for hydrogen fuel in the transportation sector will be met through this type of traditional steam reforming of natural gas.
Still, this method of producing hydrogen is prohibitively expensive when compared to today’s transportation fuels such as gasoline and compressed natural gas (CNG). The U.S. Department of Energy (DOE) has adopted a goal to reduce the cost of hydrogen produced from natural gas by 25 percent within a decade. According to DOE, “low-cost technology for hydrogen production from natural gas can be the bridging technology . . . to the hydrogen economy,” while also helping to commercialize “technologies such as fuel cell vehicles in a shorter period of time.”
NGV Technologies Are Facilitating the Transition to Fuel Cell and Hydrogen Vehicles
In a wide variety of ways, technologies used on NGVs themselves are facilitating the transition to tomorrow’s ICEVs and FCVs fueled by hydrogen. Some of these ways are highlighted below:
Until major breakthroughs in hydrogen storage technologies are realized, hydrogen will most likely be stored on-board vehicles as a compressed gas or a cryogenic liquid. Progress is well underway, because today’s prototype hydrogen vehicles are able to use existing tank technology for CNG or liquefied natural gas (LNG) vehicles as base technologies for hydrogen storage. However, to achieve commercialization objectives (e.g., driving range comparable to gasoline vehicles), FCVs and other types of hydrogen vehicles will require ongoing advancements in on-board hydrogen storage technology. Simply put, fuel storage capacity must be safely increased, while reducing cost and weight.
Because of the many similar materials and manufacturing issues, several companies that make NGV tanks are also designing improved fuel-storage systems for hydrogen vehicles, applying their vast experience from years of developing onboard CNG and LNG tanks. Some of these companies serve as “Tier 1” suppliers for major automobile manufacturers that market NGVs today, and plan to sell hydrogen vehicles in the future. These types of relationships will become increasing important as the market for hydrogen vehicles moves into the commercialization phase. In this critical way, investments in on-board fuel tanks for NGVs are also advancing and expediting hydrogen storage technology.
Fuel Management and Safety Systems
As with fuel storage technologies, commonality exists among companies working on fuel management systems for NGVs and FCVs. Generally, advancements made for natural gas systems also have application to hydrogen systems. Onboard safety technology designed for NGVs (e.g., gas detection and fire suppression) are also being applied to hydrogen vehicles.
Today’s Network of CNG Stations and Natural Gas Pipelines Are “Jump Starting” the Hydrogen Era
Fuel cell vehicles will deliver the greatest benefits (zero emissions, highest system efficiency) if they are designed to operate on “direct” hydrogen, rather than operating on hydrogen produced onboard the vehicle by reforming a hydrogen-rich fuel. This means that FCVs will need access to hydrogen fueling stations. While no such network currently exists, this is expected to gradually change. In California, Governor Schwarzenegger has announced plans to develop a “hydrogen highway” featuring up to 200 hydrogen fueling stations in California by 2010.
It is unlikely that hydrogen for these stations will be produced at large methane-reforming plants, and transported to the pumps via trucks or pipelines. A far more likely scenario is that the hydrogen will be reformed in relatively small volumes at the local station using pipeline natural gas. Pre-existence of the necessary pipeline infrastructure makes this feasible. The U.S. has more than 1.3 million miles of transmission and distribution lines carrying natural gas to almost every part of the country. This makes reforming of natural gas at existing gasoline stations a convenient, relatively cost-effective option for producing hydrogen.
Hydrogen Dispensing and Metering Technology
Today’s natural gas dispensers are “bridge” technology to pumps that will fuel tomorrow’s vehicles using either compressed or liquefied hydrogen. Much commonality exists between systems that dispense and meter these two fuels, whether in gaseous or liquid form. Consequently, today’s natural gas dispensers are “blazing the trail” for affordable, user friendly hydrogen dispensers.
Consider the case of pay-at-the-pump card reader systems now becoming increasingly common at CNG stations. Even though no technological barriers existed, economic and institutional barriers had to be overcome before card reader systems accepting major credit cards could be installed at CNG stations. New business alliances had to be formed among CNG providers, fuel card providers, and banks that facilitate credit card transactions. The alliances that have emerged for CNG stations will help expedite user-friendly payment options at hydrogen stations in the early years of deployment, when dispensed fuel volumes are especially low.
Home Refueling of Hydrogen Vehicles
NGVs can be refueled overnight at home – a major advantage compared to gasoline vehicles. Today’s “home refueling appliances” (HRAs) that dispense CNG are also being designed for longer-term capability to refuel FCVs in the residential setting. In this way, home refueling of NGVs provides a clear pathway to the longer-term scenario of fueling FCVs at home.
Natural Gas / Hydrogen Blends
Compressed hydrogen can be blended with CNG to produce an exceptionally clean transportation fuel. With relatively minor vehicle modifications, this blend can be used in today’s heavy-duty NGVs. For example, transit buses at SunLine Transit Agency in the Coachella Valley are operating in revenue service on a blend of CNG and hydrogen. This is helping SunLine to gradually transition its bus fleet to 100% operation on hydrogen. Similar efforts are underway in other areas, such as Las Vegas. Many members of the Natural Gas Vehicle Coalition are cooperating in efforts to develop and demonstrate vehicles that operate on this type of hydrogen-natural gas mixture, for a variety of applications beyond transit buses. These include refuse collection and airport shuttle buses – where harmful emissions can be greatly reduced.
Siting new hydrogen stations will involve many challenging issues. These include considerations for safety and set-backs; spacing and layout; permitting, codes and standards; financing; utility hookups; and arranging public access. Fortunately, many important lessons have already been learned through deployment of natural gas stations. Each new natural gas station represents another site that has already overcome similar types of problems. Each station has helped to educate local authorities on issues associated with gaseous or cryogenic alternative fuels. Much foresight and knowledge has been gained that can directly or indirectly be applied to siting hydrogen stations.
It is also true that every natural gas station is a potential hydrogen fueling site. Co-locating hydrogen refueling stations with existing natural gas refueling stations has the potential to enhance the logistics and economics of FCV fueling in the early years of deployment. It is even possible that existing natural gas station hardware, with certain upgrades and modifications, can be used to fuel hydrogen vehicles (fuel cell or internal combustion engine). Further research is needed to determine how many station components can be used in common in a natural gas/hydrogen station, and to determine how cost-effective such stations would be versus stand-alone natural gas and hydrogen stations. Members of the Natural Gas Vehicle Coalition have taken a lead role on this issue, as further described below.
Transition Teams Have Been Assembled
With clear synergy between today’s NGVs and tomorrow’s hydrogen vehicles, collaborative efforts are already underway to facilitate the necessary transitions. For example, the California’s South Coast Air Quality Management District has assembled a Hydrogen Compatibility Study Team to develop and assess NG to H2 synergies related to fueling stations and vehicle issues. This team has made a preliminary assessment of major natural gas stations in the Los Angeles area to determine if and how existing natural gas stations could potentially also dispense hydrogen. While only a start, this effort clearly accentuates the commonality of fueling station programs for today’s NGVs and tomorrow’s FCVs.
Human Training Programs
As hydrogen transportation technologies gradually move from the demonstration phase into commercial deployment, a new structure of human support services will be needed. This includes specialists such as mechanics, inspectors, and fire marshals who are familiar with FCVs, hydrogen fuel, and fueling stations. The NGV industry is already helping to create such a support structure. To serve today’s well- established markets for NGVs and natural gas fueling stations, thousands of people have been trained in related jobs. This support structure continues to grow, serving as a harbinger for training of America’s future hydrogen workforce – the people who will be responsible for deploying hydrogen vehicles and fueling stations on a commercial scale.
As hydrogen becomes a common transportation fuel, specialty buildings such as maintenance garages and fueling facilities will need to be modified to safely house hydrogen vehicles. Examples of modifications that will be needed include: increased building ventilation; installation of explosion-proof fixtures and switches; elimination of ceiling-mounted open-flame heaters; and installation of hydrogen detectors and fire suppression systems. Thanks to the progress already achieved for similar issues involving NGV fueling stations, this process will be significantly less costly and difficult for hydrogen fueling stations than “starting from scratch.” With each new structure designed and built to support NGV deployment and fueling, the prospects for making similar buildings safe and affordable for hydrogen are enhanced.
Public Awareness and Acceptability
Significant behavioral and institutional changes will be needed for America’s motoring public to understand and accept hydrogen as a mainstream transportation fuel. Although people are very familiar and comfortable with liquid transportation fuels, most have no real experience using gaseous transportation fuels. The NGV industry is very familiar with this challenge, and has worked hard to overcome perception issues associated with alternative, non-conventional fuels. As NGV use continues to grow, the public is becoming more familiar with and accepting of gaseous transportation fuels. This “laying of the groundwork” for public acceptance of hydrogen vehicles and fuel is an important contribution made by today’s NGV industry.
Natural Gas “Energy Stations” Will Help Pave the Hydrogen Highway
Beyond the many immediate benefits offered, natural gas presents a compelling continuum towards sustainable energy systems in America. Most stationary fuel cells in commercial operation today use natural gas as the hydrogen source. This type of system is emerging as the foundation for an “energy station” concept – a leading new approach to energy management that integrates transportation and building applications. Initially, each of these small stations will perform on-site reforming of pipeline natural gas into hydrogen, which will generate electricity in a stationary fuel cell when not being used to fuel vehicles. In addition, the system waste heat can be used for local heating (e.g., hot water for hotels, swimming pools, etc.).
This “tri-generation” approach creates synergies that greatly enhance the economics of deploying hydrogen fueling stations and using fuel cells to generate power and electricity. Over the longer term, renewable energy sources such as solar power, wind power, and “gas-to-liquid” technologies using waste gases will supplement pipeline natural gas as the feedstock for making hydrogen in energy stations.
For all the reasons highlighted above, today’s growing NGV market is quickening the pace for tomorrow’s hydrogen FCV industry. NGVs and natural gas fueling stations are major stepping stones along the pathway to a hydrogen transportation future.