Hydrogen Distribution and Delivery Infrastructure Basics
Most of the hydrogen used in the United States is produced at or very near where it is used—typically at large industrial sites. As a result, we do not yet have a cost-effective and energy-efficient infrastructure for delivering large quantities of hydrogen over long distances. Before hydrogen can become a mainstream energy carrier used widely by consumers, we must build the infrastructure needed to distribute it.
How Is Hydrogen Delivered Today?
Suppliers currently transport hydrogen by pipeline or road using tube trailers and cryogenic liquid hydrogen tankers. For special purposes, liquefied hydrogen is transported by barge. Hydrogen also can be moved using carriers—chemical substances that incorporate atoms of hydrogen and other elements—such as ethanol or ammonia.
Pipelines
Pipelines are the least expensive way to deliver large volumes of hydrogen, but the current U.S. hydrogen pipeline infrastructure is very small (approximately 700 miles, compared to more than one million miles of natural gas pipelines). Hydrogen pipelines currently exist in just a few regions, near large petroleum refineries and chemical plants in Illinois, California, and the Gulf Coast.
Short-Distance Road Transport: High-Pressure Tube Trailers
Transporting compressed hydrogen gas over the road in high-pressure tube trailers is expensive and used primarily for short distances; it becomes cost-prohibitive when transporting the gas farther than about 200 miles from the point of production.
Long-Distance Road Transport: Liquefied Hydrogen
Liquefied hydrogen (cooled to -253°C) is denser and has a higher energy content than gaseous hydrogen in a given volume (such as a tank), so it's preferred for delivery over long distances when compared to delivery by tube trailer. Liquefaction is costly and takes a great deal of energy, but because current pipeline transport has limited availability, hydrogen is often transported as a liquid in super-insulated, cryogenic, over-the-road tankers and then vaporized for use at the customer site.
What Are the Challenges?
Building a national hydrogen delivery infrastructure is a big challenge. It will take time to develop and may include various combinations of technologies. Delivery infrastructure needs and resources will vary by region and type of market (e.g., urban, interstate, or rural). Infrastructure options will also evolve as the demand for hydrogen grows and as delivery technologies develop and improve. Specific technology challenges include:
Low Volumetric Energy Density
Hydrogen has a low volumetric energy density. It contains a relatively small amount of energy by volume compared to other fuels such as natural gas and gasoline, so its transportation, storage, and final delivery to the point of end-use are costly and result in some of the energy inefficiencies associated with using it as an energy carrier.
High Pipeline Construction Costs
The high initial capital costs of new pipeline construction are a major barrier to expanding hydrogen pipeline delivery infrastructure. Technical concerns related to pipeline transmission include the potential for hydrogen to embrittle the steel, the welds used to construct pipelines, and the need for lower cost, more reliable, and more durable hydrogen compression technology. Also, because hydrogen atoms are very small, preventing permeation and leakage from pipeline and other containment materials is a challenge.
Central Versus Distributed Production: Transportation and Production Cost Trade-offs
How hydrogen is produced also affects the cost and method of delivery. Producing hydrogen in large, central plants (as far as several hundred miles from the point of end-use) results in longer transport distances that increase delivery costs. Distributed production at the point of end-use, such as refueling stations or stationary power sites, eliminates transportation costs but results in higher production costs.
Research Directions
Researchers are working to better understand the options and trade-offs for hydrogen delivery from central, semi-central (25 to 100 miles from the point of end-use), and distributed production sites.
Research is also focused on developing:
- Lower-cost, more reliable hydrogen compression technology
- More cost-effective bulk hydrogen storage technology
- New materials for lower-cost hydrogen pipelines
- More energy-efficient and lower-cost hydrogen liquefaction processes
- Integrated production, delivery, and end-use technologies.