December 2021 /// Vol 242 No. 12)
A look into future hydrogen storage, distribution and transportation
Researchers at NETL and its partners are advancing technologies capable of improving the performance, reliability and flexibility of methods to produce, transport, store and use hydrogen
Hydrogen is useful in many industries. It is used as a chemical feedstock in the petroleum and petrochemical industries, as well as for the hydrogenation of oils and fats and the production of fertilizer. Its ability to scavenge oxygen is used to advantage in metallurgical processes. Hydrogen 721 is used as a fuel in the space industry because of its high energy per unit mass.
Over the last decade, there has been persistent interest in hydrogen as an automotive fuel, because it has zero point-of-use greenhouse gas emissions; high combustion efficiency; compatibility with efficient fuel cells; improved safety compared to other fuels; and the ability to be generated from domestic energy sources. The need for large quantities of hydrogen will increase dramatically, if even a minute portion of the vehicles in the United States begin to use hydrogen fuel.
Hydrogen transportation, distribution and storage remain the primary challenges for integrating hydrogen into the overall energy-economy system. On a mass basis, hydrogen has nearly three times the energy content of gasoline. While hydrogen has high energy density per unit mass, it has low volumetric energy density at room conditions (around 30% of methane at 15 °C, 1 bar) and an ability to permeate metal-based materials, which can present operational and safety constraints. This makes transporting hydrogen a challenge, because it requires high pressures, low temperatures, or chemical processes in order to be stored compactly.
Hydrogen has an active electron, and thus behaves somewhat like a halogen (halogens are a group in the periodic table consisting of five chemically related elements: fluorine (F), chlorine (Cl), bromine (Br) iodine (I), and astatine (At). The name “halogen” means “salt-producing.” When halogens react with metals, they produce a range of salts, including calcium fluoride, sodium chloride (common table salt), silver bromide and potassium iodide. All halogens form acids when bonded to hydrogen. The combination of behaving like a halogen, combined with a high acidic content when bonded with halogens, makes hydrogen combinations highly corrosive, with a tendency to also embrittle metals, which can lead to catastrophic results, as in Fig. 1.
For this reason, hydrogen pipes and containers have to resist corrosion. The problem is compounded, because hydrogen can easily migrate into the crystal structure of most metals. For process metal piping at pressures up to 7,000 psi (48 MPa), high-purity stainless steel piping with a maximum hardness of 80 HRB (Rockwell Hardness) is preferred.
Gaseous hydrogen is usually transported by either tube trailers or (in limited concentrations) by pipelines, while liquid hydrogen is moved by road tankers, Fig. 2. Blending hydrogen into natural gas pipeline networks is the standard option for delivering pure hydrogen to markets, using separation and purification technologies downstream to extract hydrogen from the natural gas blend near the point of end-use. However, existing pipelines can handle only a 15% to 30% mix of hydrogen with natural gas. Higher percentages of hydrogen in the mix can lead to corrosion and embrittlement. Hydrogen may also be transported by railcar, barge or ship. Any of the above methods will use metal as the primary containment element.
Liquid hydrogen (LH2) is the liquid state of the element hydrogen. To exist as a liquid, H2 must be cooled below its critical point of 33 K. However, for it to be in a fully liquid state at atmospheric pressure, H2 needs to be cooled to 20.28 K (−252.87°C; −423.17°F). Liquid hydrogen is typically used as a concentrated form of hydrogen storage. As for any gas, storing it as liquid takes less space than storing it as a gas at normal temperature and pressure. However, the liquid density is very low compared to other common fuels. Once liquefied, it can be maintained as a liquid in pressurized and thermally insulated containers, most typically used for transport via trucks.
U.S. DOE HYDROGEN RESEARCH FOCI
The U.S. Department of Energy’s (DOE) Office of Fossil Energy (FE) has focused on developing and advancing technologies that will enable and expand a domestic hydrogen (H2) economy. Carbon-neutral or even carbon-negative H2 can be produced from fossil fuels, biomass, and waste plastics. H2 unites the nation’s natural gas, coal, nuclear, and renewable energy resources, and H2 produced from fossil fuels can play an important role in the transition to clean, low-carbon energy systems, Fig. 3.
Transition to a hydrogen economy. DOE is well-positioned to accelerate a transition to an H2 economy, and FE is committed to advancing technology solutions that utilize the nation’s vast fossil energy resources. FE’s research and development (R&D) programs can be divided into four major focus areas: 1. Carbon-Neutral Hydrogen Production, using Gasification and Reforming Technologies; 2. Large-Scale Hydrogen Transport Infrastructure; 3. Large-Scale Onsite and Geological Hydrogen Storage; and 4. Hydrogen Use for Electricity Generation, Fuels, and Manufacturing.
Hydrogen production and costs. Currently, the U.S. produces more than 10 million metric tons (MMT) of hydrogen annually, with 95% produced from natural gas via steam methane reforming (SMR), 4% by coal gasification, and 1% by the electrolysis of water. Global H2 production is approximately 70 MMT, with 76% from SMR, 22% from coal gasification, and 2% from electrolysis, Fig. 4. Through the use of carbon capture, storage, and utilization (CCUS) technologies demonstrated by FE, fossil fuels are the lowest-cost source of carbon-neutral hydrogen. H2 production from fossil resources is readily scalable, using existing technologies. At present, H2 generation from gasification and reforming are the only ways to generate the necessary quantities at reasonable costs.
Emerging markets for hydrogen. As we get closer to a decarbonized world, H2 presents long-term potential in many sectors beyond existing industrial applications. If the cost of H2 production and utilization can be made significantly lower, compared to the cost of other fossil fuels, it could be used to run transportation, buildings, and power sectors. Some of the emerging uses of H2 include electric grid management, energy storage and fuel cell vehicles, as well as blending H2 into existing natural gas pipelines and decarbonizing industrial processes, such as steel production, cement production, and other chemical engineering applications. All these uses would eventually create major increases in H2 demand, and they would potentially require foreign markets to be opened for H2 exported from the United States.
At DOE, the offices of Fossil Energy, Energy Efficiency and Renewable Energy, and Nuclear Energy, are collaborating on research areas and technologies for H2 production, transport, delivery and storage, along with power production via fuel cells, electrolysis and turbines.
The focal areas of collaborative research are numerous. Within Area of Interest (AOI) 1 (Subtopic A), here are “Design Studies for Engineering Scale Prototypes (hydrogen-focused).”
Reversible SOFC Systems for Energy Storage and Hydrogen Production—Fuel Cell Energy Inc. (Danbury, Conn.) and partners will complete a feasibility study and techno-economic analysis for MW-scale deployment of its reversible solid oxide fuel cell (SOFC) energy storage technology, in combination with hydrogen production, as an additional source of revenue or use in a power plant during peak periods.
Hydrogen Storage for Flexible Fossil Fuel Power Generation: Integration of Underground Hydrogen Storage with Novel Gas Turbine Technology—Gas Technology Institute (Des Plains, Ill.) will complete a conceptual feasibility study for innovative hydrogen energy storage and production as part of an integrated, fossil-based, power generation system at the University of Illinois. The objective is to advance the commercialization of an energy production system using hydrogen storage (subsurface and above ground) and carbon dioxide sequestration that demonstrates the ramping and dispatch capabilities of traditional electricity generating units powered by natural gas turbines.
Hydrogen Storage for Load-following and Clean Power: Duct-Firing of Hydrogen to Improve the Capacity Factor of NGC—Gas Technology Institute (Des Plaines, Ill.) will demonstrate technology to store greater than 150 MWh of energy as “blue” hydrogen and its use for load-following in an existing natural gas combined cycle (NGCC) plant with a hydrogen-fired duct burner. Hydrogen storage and discharge rates will be coupled to follow daily power demand fluctuations from variable renewable energy, thus increasing the plant capacity factor while reducing emissions. Objectives include establishing a project plan to conduct a preliminary front end engineering design study at an NGCC plant owned by Southern Company.
Integrated Hydrogen Energy Storage System (IHESS) for Power Generation—Gas Technology Institute (Des Plaines, Ill.) will lead a project team to determine the economic and technical feasibility of providing hydrogen energy storage and delivery to natural gas-based combined heat and power generation plants for blending in natural gas fuel streams, for electricity production using an IHESS. The system comprises hydrogen production, transportation and storage assets, a blending module or apparatus, existing natural gas supply networks, and an on-site power generation facility with blended hydrogen/natural gas compatible turbines.
Clemson Hydrogen Combined Heat and Power Storage System—Siemens Energy Inc. (Orlando, Florida) will work toward energy storage integration with Clemson University’s combined heat and power facility in Clemson, S.C. Siemens and project partners will complete a conceptual study to develop an advanced hydrogen energy storage system for a greater-than-50-MWh hydrogen energy storage system. The proposed system would be designed and sized to ensure adequate supply for daily and/or seasonal demand, as well as provide key grid support functions as an active electricity generating unit.
Hydrogen Energy Storage Integrated with a Combined Cycle Plant—Siemens Energy Inc. (Orlando, Florida) and partner will develop a concept design for a hydrogen energy storage system integrated into an advanced-class combined cycle power plant (CCPP). The goal is to maximize efficiency and reliability of the CCPP, mitigating inefficient or off-design operation by complementing it with the dynamic response characteristics of a hydrogen energy storage system.
Hydrogen-Based Energy Storage System for Integration with Dispatchable Power Generator, Phase I Feasibility Study—University of California, Irvine (Irvine, Calif.), researchers will seek to advance the capability of an existing fossil asset serving the campus microgrid to store energy in the form of hydrogen produced through electrolytic or micro-steam [JB1] methane reformation and to consume hydrogen as fuel with the production and use cycles optimized, based on market, operational and demand conditions. The project has the potential to establish the capability for the gas turbine to operate on high-hydrogen-fraction natural gas/hydrogen blends and to dynamically vary the hydrogen fraction to optimize economic and operational dispatch.
H2-SALT: Storing Fossil Energy as Hydrogen in Salt Caverns—University of Kansas Center for Research Inc. (Lawrence, Kans.) will assess the feasibility of storing excess energy from a gas power plant as hydrogen in an underground salt cavern. The proposed concept will leverage an electrolyzer to produce hydrogen from excess power at a gas combined cycle power plant, for storage in a salt cavern below the electricity generating unit.
Economically Viable Intermediate to Long Duration Hydrogen Energy Storage Solutions for Fossil Fueled Asset—WE New Energy Inc. (Knoxville, Tenn.) and partners will design and engineer a cost-effective hydrogen energy storage prototype to synergistically integrate with existing or new coal- and gas-fueled electricity generating units (EGUs). A synergistically integrated hydrogen energy storage system would enable EGUs to operate at optimal baseload conditions via a sufficiently large hydrogen energy storage system to manage the dynamic changes in electric grid demand and electricity price.
Advanced Hydrogen Compressor for Hydrogen Storage Integrated with a Power Plant—Siemens Energy Inc. (Orlando, Florida) will focus on an advanced compressor concept that significantly reduces the number of stages required for cost-effective hydrogen compression and storage. The project will include progressing the design of the compressor, manufacturing a prototype, and testing it to verify its performance in relevant operating conditions. Testing will aim to provide validation of the efficiency and operating range and advance the technology.
Development of an Advanced Hydrogen Energy Storage System Using Aerogel in a Cryogenic Flux Capacitor—Southwest Research Institute (San Antonio, Texas), along with partners, will study a high-density cryogenic flux capacitor (CFC) for hydrogen energy storage. CFC modules can accept gaseous hydrogen at ambient conditions, such as from an electrolyzer, and “charge up” over time. On the discharge step, controlling heat input into a CFC storage cell can pressurize the system and regulate the flow of hydrogen gas, as it is released.
Advanced Oxygen-Free Electrolyzer for Ultra-Low-Cost H2 Storage for Fossil Plants—T2M Global LLC (Danbury, Conn.) will develop advanced oxygen-free electrolyzer technology for low-cost, long-duration hydrogen energy storage for fossil fuel plants. The proposed technology would upgrade stranded fossil assets (waste syngas streams, excess electricity, and waste heat) to a higher-value pure hydrogen for additional revenue and greater sustainability. The technology also will reduce greenhouse gas and generate additional revenue from stranded/underutilized resources.
Durable Low-Cost Pressure Vessels for Bulk Hydrogen Storage—WireTough Cylinders LLC (Bristol, Va.) will complete a near full-scale demonstration model of its patented technology for low-cost, durable, and damage-resistant cylinders to store hydrogen for hydrogen fueling stations and to be optimized for use in fossil-fueled power plants. A liner for the model vessel will be manufactured, and a detailed design analysis of the wire-wrapped cylinder will be performed.
Scalable Boron Nitride-Based Sorbents with Balanced Capacity-Kinetics-Thermodynamics for Hydrogen Storage in Fossil Fuel Power Plants—C-Crete Technologies (Stafford, Texas) seeks to demonstrate the feasibility of a new class of scalable, low-cost sorbents with a balance of capacity-kinetics-thermodynamics for hydrogen storage and integration with fossil fuel power plants. The core fabrication of the sorbent leverages the unique properties of emerging nanomaterials, followed by strategic coupling with functional groups and dopants to optimize porosity and deliver a stable, long-term energy storage solution for the grid.
Speaking at the Hydrogen Shot Summit, a U.S. Department of Energy (DOE) event to accelerate the development of breakthrough technologies that can expand the use and lower the cost of this clean-burning fuel, NETL Director Brian Anderson, Ph.D., noted that “researchers at NETL and our partners are advancing technologies capable of improving the performance, reliability and flexibility of methods to produce, transport, store and use hydrogen. The summit provides opportunities to share the steps we are taking to develop hydrogen as viable zero-emission fuel to fight climate change.”
The Hydrogen Shot Summit is the first undertaking in DOE’s Energy Earthshots Initiative, which was established in June by Secretary of Energy Jennifer M. Granholm as an all-hands-on-deck call for innovation, collaboration and acceleration to drive development of clean energy solutions within the decade. The Hydrogen Shot Summit convened thousands of stakeholders online to introduce the 0 Hydrogen Shot, which seeks to reduce the cost of clean hydrogen (H2) by 80% to $1 per 1 kilogram in 1 decade (“1 1 1”), solicit dialogue, and rally the global community on the urgency of tackling the climate crisis through concrete actions and innovation.
Currently, hydrogen from renewable energy costs about $5 per kilogram. Achieving the Hydrogen Shot’s 80% cost reduction goal can unlock new markets for hydrogen, including uses in steelmaking and energy storage, production of clean ammonia, and other applications. Hydrogen produced from natural gas with carbon capture can be produced for about $1.50/kg H2, so fossil energy is the most affordable route to clean hydrogen.
- Factory after rupture and explosion of a hydrogen storage tank, Hydrogen Storage: State-of-the-Art and Future Perspective, E. Tzimad, et. Al., European Commission, Joint Research Centre, 2003.