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This diagram illustrates the role that hydrogen plays as an "energy carrier" and identifies the major subsystems that make up the overall hydrogen energy system - production, storage, delivery, and end-use applications. In the diagram, the end-use is transportation, however, hydrogen is also used for portable and stationary power generation. Hydrogen may be used in fuel cells or internal combustion engines. Each subsystem requires the development of many technologies and related products that provide research and business development opportunities for Hawaii universities and businesses. In Hawaii, there is a major focus on producing hydrogen from renewable energy sources as a means of transforming from fossil fuels to increased use of Hawaii's plentiful indigenous renewable energy resources such as biomass, geothermal, wind, and solar. Hydrogen production technologies of interest in Hawaii include conversion of biomass utilizing gasification and reforming technologies, and utilization of geothermal, wind, and solar electrical power using electrolysis. Hydrogen storage technologies in Hawaii include pioneering chemical hydride technology being developed by the University of Hawaii Manoa's Department of Chemistry. HNEI, at the Hawaii Fuel Cell Test Facility is leading a major effort aimed at understanding the effects of impurities in hydrogen and oxygen on the performance and durability of fuel cells that is enabling a deeper understanding of the fundamentals of how fuel cells work which can lead to the development of advanced fuel cell technologies and products. Links to additional information on the hydrogen energy system components are provided in the sub-menu on the left. Hydrogen Production
 Hydrogen does not occur naturally as a separate element. It is bound to other atoms - primarily oxygen and carbon. Energy must be applied to break the chemical bond and separate the hydrogen atoms. Hydrogen-containing compounds such as fossil fuels, biomass, or even water can be a source of hydrogen. Thermo-chemical (heat) processes can be used to produce hydrogen from biomass and from fossil fuels such as coal, natural gas and petroleum. Electrical energy generated from sunlight, wind, geothermal, ocean, and nuclear sources can be used to produce hydrogen electrolytically. Sunlight alone can also drive photolytic production of hydrogen from water, using advanced photoelectrochemical and photobiological processes.
For more information about hydrogen production technologies, visit the following links: A sampling of hydrogen production research: Hydrogen Storage
 Hydrogen storage is a key enabling technology in transportation, stationary, and portable power generation applications. Hydrogen has the lowest gas density and the second lowest boiling point of all known substances, making it a challenge to store as gas or a liquid. As a gas it requires very large storage volumes and pressures, and as a liquid it requires a cryogenic storage system.
Storing enough hydrogen onboard a vehicle to achieve a driving range of greater than 300 miles is a significant challenge. On a weight basis, hydrogen has nearly three times the energy content of gasoline. However on a volume basis the situation is reversed.
Where and How Will Hydrogen be Stored? Hydrogen storage will be required onboard vehicles and at hydrogen production sites, hydrogen fueling stations, and stationary power sites. Possible approaches to storing hydrogen include: Physical storage of compressed hydrogen gas in high pressure tanks (up to 10,000 pounds per square inch); Physical storage of cryogenic liquid hydrogen (cooled to -253°C) in insulated tanks; Storage in advanced materials – within the structure or on the surface of certain materials, as well as in the form of chemical precursors that undergo a chemical reaction to release hydrogen.
For more information about hydrogen storage technologies visit the following links: A sampling of hydrogen storage research: Hydrogen Delivery
 Hydrogen must be transported from the point of production to the point of use. It also must be safely compressed, stored and dispensed at refueling stations or stationary power facilities. Due to its relatively low volumetric energy density, transportation, storage and final delivery to the point of use can be one of the significant costs and energy inefficiencies associated with using hydrogen as an energy carrier. For an overview of hydrogen delivery technologies and R&D programs visit the following links: Fuel Cells
 A fuel cell is an electrochemical device that combines hydrogen (or hydrogen-rich fuel) and oxygen to create electricity. Fuel cells are more energy efficient than combustion engines. The hydrogen used to power them can come from a variety of sources. If pure hydrogen is used as a fuel, fuel cells emit only heat and water, eliminating concerns about air pollutants or greenhouse gases.
Fuel cells are key enabling technologies for a future hydrogen economy. They have the potential to replace the internal combustion engine in vehicles and to provide power in stationary and portable power applications because they are energy-efficient and clean. For transportation applications, the research and development (R&D) focus is on direct hydrogen fuel cells, in which on-board storage of hydrogen is supplied by a hydrogen generation, delivery, and fueling infrastructure. The hydrogen may be produced using reforming of liquid or gaseous fuels, or by the electrolysis of water. For distributed generation fuel cell applications for the production of electrical power, the R&D focus is on near-term fuel cell systems that can reform natural gas or liquid fuels. Renewable energy sources can be used to provide hydrogen from a wide range of fuel types for both transportation and distributed generation including portable, back-up, or utility power. For more information on fuel cells, visit the following links:
Hydrogen Safety
 In many ways, hydrogen is a fuel like gasoline and propane. As with most fuels, hydrogen can be used safely with appropriate sensing, handling, and engineering measures. These are some of the relevant properties of hydrogen: Hydrogen is less flammable than gasoline. The self-ignition temperature of hydrogen is 550 degrees Celsius. Gasoline varies from 228 – 501 degrees Celsius, depending on the grade. Hydrogen disperses quickly. Being the lightest element (fifteen times lighter than air), hydrogen rises and disperses quickly in the atmosphere. Should a leak occur, any escaping hydrogen gas quickly becomes so dispersed that it cannot burn. If ignited before dispersion, hydrogen will burn upward, and be quickly consumed. In contrast, materials such as gasoline and diesel vapors, as well as natural gas, are heavier than air and will not disperse, remaining a flammable threat for much longer. Hydrogen is non-toxic. Hydrogen is a non-toxic, naturally-occurring element in the atmosphere. By comparison, all petroleum fuels are toxic to humans. Hydrogen combustion produces only water. When pure hydrogen is burned in pure oxygen, only pure water is produced. Compared with the toxic compounds (carbon monoxide, nitrogen oxides, and hydrogen sulfide) produced by petroleum fuels, the products of hydrogen combustion are much safer. Hydrogen can be stored safely. Tanks currently in use for storage of compressed hydrogen (similar to compressed natural gas tanks) have survived intact through extensive testing by various means including being subjected to gunshots, dynamite, and fire at 1500° F. A typical gasoline tank would not meet these tests.
For more information on hydrogen safety visit the following links: Codes and Standards  To enable the commercialization of hydrogen in consumer products, new model building codes and standards are being developed and recognized by federal, state, and local governments. For a more information about hydrogen codes and standards click on the links below: Hydrogen – “The Physics”  Hydrogen is the simplest and lightest element. Although hydrogen is all around us and accounts for 75% of the entire universe’s mass, on earth it is found only in combination with other elements. Once separated through the application of energy to break the chemical bond, hydrogen exists as a gas under normal conditions, although it can be supercooled (-423° F) into its liquid form. In either case, hydrogen fuel consists of two hydrogen atoms bound together (H2). For more information on the properties of hydrogen, please visit the following links:
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