Hydrogen Production and Distribution
Although abundant on earth as an element, hydrogen is almost always found as part of another compound, such as water (H2O), and must be separated from the compounds that contain it before it can be used in vehicles. Once separated, hydrogen can be used along with oxygen from the air in a fuel cell to create electricity through an electrochemical process.
Hydrogen can be produced from diverse, domestic resources including fossil fuels, biomass, and water electrolysis with electricity. The environmental impact and energy efficiency of hydrogen depends on how it is produced. Some projects are underway to decrease costs associated with hydrogen production.
There are a number of ways to produce hydrogen:
Natural Gas Reforming/Gasification: Synthesis gas, a mixture of hydrogen, carbon monoxide, and a small amount of carbon dioxide, is created by reacting natural gas with high-temperature steam. The carbon monoxide is reacted with water to produce additional hydrogen. This method is the cheapest, most efficient, and most common. Natural gas reforming using steam accounts for the majority of hydrogen produced in the United States annually.
A synthesis gas can also be created by reacting coal or biomass with high-temperature steam and oxygen in a pressurized gasifier, which is converted into gaseous components—a process called gasification. The resulting synthesis gas contains hydrogen and carbon monoxide, which is reacted with steam to separate the hydrogen.
Electrolysis: An electric current splits water into hydrogen and oxygen. If the electricity is produced by renewable sources, such as solar or wind, the resulting hydrogen will be considered renewable as well, and has numerous emissions benefits. Power-to-hydrogen projects are taking off, where excess renewable electricity, when it's available, is used to make hydrogen through electrolysis.
Fermentation: Biomass is converted into sugar-rich feedstocks that can be fermented to produce hydrogen.
A number of hydrogen production methods are in development:
High-Temperature Water Splitting: High temperatures generated by solar concentrators or nuclear reactors drive chemical reactions that split water to produce hydrogen.
Photobiological Water Splitting: Microbes, such as green algae, consume water in the presence of sunlight, producing hydrogen as a byproduct.
Photoelectrochemical Water Splitting: Photoelectrochemical systems produce hydrogen from water using special semiconductors and energy from sunlight.
The major hydrogen-producing states are California, Louisiana, and Texas. Today, almost all of the hydrogen produced in the United States is used for refining petroleum, treating metals, producing fertilizer, and processing foods.
The primary challenge for hydrogen production is reducing the cost of production technologies to make the resulting hydrogen cost competitive with conventional transportation fuels. Government and industry research and development projects are reducing the cost as well as the environmental impacts of hydrogen production technologies. Learn more about hydrogen production from the Fuel Cell Technologies Office and the National Renewable Energy Laboratory.
Most hydrogen used in the United States is produced at or close to where it is used—typically at large industrial sites. The infrastructure needed for distributing hydrogen to the nationwide network of fueling stations required for the widespread use of fuel cell electric vehicles still needs to be developed. The initial rollout for vehicles and stations focuses on building out these distribution networks, primarily in southern and northern California.
Currently, hydrogen is distributed through three methods:
Pipeline: This least-expensive way to deliver large volumes of hydrogen is limited—because there is only about 700 miles of U.S. pipelines for hydrogen delivery currently available. These pipelines are located near large petroleum refineries and chemical plants in Illinois, California, and the Gulf Coast.
High-Pressure Tube Trailers: Transporting compressed hydrogen gas by truck, railcar, ship, or barge in high-pressure tube trailers is expensive and used primarily for distances of 200 miles or less.
Liquefied Hydrogen Tankers: Cryogenic liquefaction is a process that cools the hydrogen to a temperature where it becomes a liquid. Although the liquefaction process is expensive, it enables hydrogen to be transported more efficiently (when compared with using high-pressure tube trailers) over longer distances by truck, railcar, ship, or barge. If the liquefied hydrogen is not used at a sufficiently high rate at the point of consumption, it boils off (or evaporates) from its containment vessels. This fact requires that the hydrogen delivery and consumption rates are carefully matched.
Creating an infrastructure for hydrogen distribution and delivery to thousands of future individual fueling stations presents many challenges. Because hydrogen contains less energy per unit volume than all other fuels, transporting, storing, and delivering it to the point of end-use is more expensive on a per gasoline gallon equivalent (per-GGE) basis. Building a new hydrogen pipeline network involves high initial capital costs, and hydrogen's properties present unique challenges to pipeline materials and compressor design. However, because hydrogen can be produced from a wide variety of resources, regional or even local hydrogen production can maximize use of local resources and minimize distribution challenges.
There are tradeoffs between centralized and distributed production to consider. Producing hydrogen centrally in large plants cuts production costs but boosts distribution costs. Producing hydrogen at the point of end-use—at fueling stations, for example—cuts distribution costs but increases production costs because of the cost to construct on-site production capabilities.
Government and industry research and development projects are overcoming the barriers to efficient hydrogen distribution. Learn more about hydrogen distribution from the Fuel Cell Technologies Office.