DOE seeking feedback on findings of hydrogen production and delivery workshops

29 October 2014

The US Department of Energy’s Fuel Cell Technologies Office has issued two requests for information (RFIs) seeking feedback from the research community and relevant stakeholders about electrolytic hydrogen production (DE-FOA-0001188) and hydrogen delivery research, development, and demonstration (RDD) activities (DE-FOA-0001187) aimed at developing technologies that can ultimately produce and deliver low-cost hydrogen.

The purpose of these RFIs is to solicit feedback from industry, academia, research laboratories, government agencies, and other stakeholders on issues related to electrolytic hydrogen production pathways and hydrogen transmission and distribution, specifically with respect to reports developed at workshops on the topics convened by the DOE in February.

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• The first workshop focused on hydrogen transmission and distribution and was held at DOE’s National Renewable Energy Laboratory (NREL) 25-26 February 2014. The purpose of the workshop was to share information and identify the RDD needs to enable low-cost, effective delivery of hydrogen from centralized production facilities to the point of use (e.g., retail, light-duty vehicle stations and other applications).

• The second workshop also was held at NREL 27-28 February 2014, and focused on electrolytic hydrogen production. The purpose was to discuss and share information on the RDD needs for enabling low-cost, effective hydrogen production from all types of water electrolysis systems, both centralized and forecourt.

Based on the results of these workshops and discussion between DOE and the workshop participants, the reports were published in July 2014.

DOE is also interested in the community’s opinion of the technologies that have the most potential to meet DOE goals of producing low-cost hydrogen at $2.30/kg for forecourt (1,500 kg/day) and $2.00/kg for centralized (50,000 kg/day) by 2020, and reducing hydrogen delivery from the point of production to the point of use in consumer vehicles to

Electrolytic Hydrogen Production

Electrolysis systems could provide a relatively simple, scalable and easily-deployed source of hydrogen for smaller retail and commercial uses near the point of consumption. Water electrolysis uses many technologies with different levels of commercial readiness and attributes that make them suited for particular applications. The dominant technologies in commercial installations are alkaline and PEM, with the others in pre-commercial development in laboratories.

The February workshop was attended by experts from industry and national laboratories representing polymer electrolyte membrane, traditional liquid alkaline, solid oxide electrolysis, alkaline exchange membrane, and reversible systems.

Highlights of the workshop by topic area included:

• Commercial. The top RDD needs—all considered to be near term—were improved stack performance; scale up to megawatt size; grid integration; high pressure operation; and a variety of market issues. All of these needs relate directly to increased participation of electrolysis systems in hydrogen markets.

  Stack performance needs include improved membranes and catalysts. Megawatt scale-up (required for 1,500 kg/day forecourt stations) needs include reducing capital costs by 50% on a per kilowatt basis, manufacturing issues (discussed later), demonstration and low cost testing.

• Pre-commercial. Pre-Commercial RDD needs had an emphasis on materials development at the cell component level. Some pre-commercial technologies such as alkaline exchange membrane (AEM) systems have the potential to put electrolysis on a completely new cost reduction curve; reductions of 50% in membrane thickness (increases efficiency) and 90% in catalyst loading (reduces cost) are feasible.

  High temperature technologies have the potential to use 20-25% less electrical power per kilogram of hydrogen produced. This is significant as electricity costs are often the largest cost contribution component to hydrogen cost. Additionally, heat is usually a lower cost form of energy on a kWh basis than electricity.
  

  Participants saw improving the durability of cell materials, including obtaining a better understanding of degradation mechanisms, as important. (Current high-temperature and reversible systems have degradation rates on the order of 2-4%/1000 hours.) AEM systems have been tested up to 2000 hours, and have identified improved voltage stability as a need.

  Participants identified improving the performance of catalysts, especially with respect to more efficient electrolysis cell operation, as a significant need. One presenter noted that efficiencies of high temperature systems can reach 75%. Scale up to larger cell and stack sizes was a common theme for the Pre-Commercial Technologies breakout session. Longer-term RDD needs identified include integrated system durability testing, identification of lower temperature SOEC materials, and demonstration of pressurized electrolysis stack operation.

• Additional Market Opportunities. Participants identified the following high priority markets to investigate: power-to-gas; ancillary grid services; renewable hydrogen for petroleum refining; and fuel for material handling equipment.

• Manufacturing Scale-Up. To build markets for electrolysis technologies, the consensus among participants was that the systems must grow to the megawatt scale while reducing manufacturing costs. The investment in this scale of product and manufacturing development could consume a significant percentage of company annual revenues. The challenge is to balance these needs (high capital intensity) with the realities of the markets that exist today (low volume, localized).

  Participants identified RDD needs including: support for megawatt stack development; increased material purity and reduced cost; system validation; limited availability of BOP components; and development of advanced manufacturing processes and analysis techniques which can yield high quality, low cost parts at modest volumes. Additive manufacturing was suggested as a possible direction for this last need.

  In order to meet DOE cost targets for electrolytically-produced hydrogen, participants suggested is important to pursue four simultaneous approaches: (1) improve efficiency at the stack and system level (by 15-20%); (2) make use of low-cost stranded electricity in available markets; (3) develop scaled up (multi-megawatt) systems which can enable alternate revenue streams and markets such as ancillary support and power-to-gas; and (4) reduce capital costs by 50%.

Hydrogen Transmission and Distribution.

This workshop drew on experts from the industrial gas and energy industries, national laboratories, academia, and the National Institute of Standards and Technology to explore two main topics: pipelines and over-road distribution. These two topics were further divided into breakout sessions on compression and materials for the pipeline topic, and on gaseous distribution and liquid and hybrid distribution for the over-road topic.

Pipeline. More than 1,200 miles (1,931 km) of steel hydrogen pipeline are in use in the United States today, operating at constant line pressures between 30 and 80 bar. In a high-volume market scenario, such as today’s natural gas market, pipelines become a cost-effective way to move large quantities of gas. Costly centrifugal compressors, chosen for their high throughput at relatively low output pressures, are used to maintain the line pressure in this scenario. Currently, redundant compressors are often installed due to the poor reliability of these machines and the high availability requirements for the application. These redundant machines add significantly to the cost.

The challenges in this distribution pathway can be broken into the two main areas addressed by the breakout groups: those relating to compression and those relating to the pipeline material and construction.

• Compression. The primary needs identified by the Pipeline Compression group include the development of a system-level pipeline network modeling and optimization tool for pipeline design and operations. This tool would be used to perform the technoeconomic analysis needed to determine the optimal operating pressure for transmission and distribution lines as well as the size and distribution of lines required to meet the modeled market demand.

  Also identified was the need for the development of integrated systems for purification, cooling, and compression of hydrogen gas and investigation of novel compressor drive systems in order to reduce the cost and improve the reliability of pipeline compression. The development of a compressor capable of line packing was also identified as a long-term research and development (RD) need to support a mature market where demand can be predicted.

• Materials. The primary needs identified in this area include research into the microstructures of pipeline steels, weld qualification, and the demonstration of Fiber-Reinforced Polymer (FRP) pipelines.

  Research is needed to define the relationship between the microstructure of different steels and the resistance to hydrogen-induced fatigue crack growth. This work is particularly relevant at and around pipeline welds where there are changes in the microstructure of the weld fusion and heat-affected zones. Such a model, validated with targeted testing, could accelerate progress in identifying and creating optimal steels for hydrogen pipelines.

  Another key area identified is the development of methods and procedures for qualifying welds and heat-treating processes for pipelines used in hydrogen service.

  A third need is for the demonstration of FRP pipelines as an alternative to traditional welded steel pipelines. FRP pipelines are an attractive alternative to steel pipelines because their materials of construction are not subject to hydrogen embrittlement, and because labor costs on installation are lower due to the fact that FRP can be spooled in lengths of up to a half-mile.

Over-Road Transport and Distribution. Over-road transport and distribution of hydrogen via gaseous tube trailer or liquid tanker is the most commonly used method. Hydrogen tube trailers are currently limited by the US Department of Transportation to pressures of 250 bar except by special permit. The pressure limitation results in payloads between 250 and 550 kilograms (kg).

Cryogenic liquid tankers can carry payloads of up to 4,000 kg at nearly atmospheric pressure; however, boil-off can occur during transport. The challenges and needs relevant to over-road transport were captured within the two main areas of the breakout sessions: high-pressure gaseous transport and other over-road transport, which includes liquid and alternative delivery methods.

• Gaseous Tube Trailer. The Gaseous Tube Trailer group identified that lower costs can be achieved through higher payloads and pressures. To achieve the higher payload and delivery pressure, the following needs were identified: permitting for high-pressure trailers; polymer degradation; trailer light-weighting; and the development of a high-pressure test facility.

• Other Over-Road Delivery. Stringent setback distances for liquid hydrogen storage were noted as a barrier to the use of liquid delivery. In order to reduce the setback distances, both at the terminal and at the station, data are needed on the risk associated with liquid hydrogen releases in order to inform codes and standards. Further, the energy required for the liquefaction of hydrogen adds significant cost and greenhouse gas emissions to the liquid delivery pathway.

  The group identified the need for lower-cost, high-efficiency liquefaction technologies that could be applied to existing plants as well as new ones. Additionally, the group noted the need for small-scale, modular liquefaction machines that could have low capital cost and, unlike fixed liquefaction assets today, be re-deployed as the market for hydrogen vehicles matures and expands.

Resources

• Electrolytic Hydrogen Production Workshop, 27-28 February 2014

• Hydrogen Transmission and Distribution Workshop, 25-26 February 2014