The Department of Energy (DOE) has issued a Request for Information (DE-FOA-0000920) seeking feedback from stakeholders for hydrogen delivery research and development activities aimed at lowering the cost of hydrogen delivery technologies in order to reach the threshold cost goal of $2-4 per gallon of gasoline equivalent (gge) produced, delivered and dispensed of hydrogen.
The RFI is not a funding opportunity announcement, although DOE said it may issue such an FOA in the future. The RFI covers two main areas of interest: Compression, Storage and Dispensing; and Liquefaction.
Compression, Storage and Dispensing (CSD). DOE’s Fuel Cell Technologies (FCT) Office would like feedback on the “2013 Hydrogen Compression, Storage, and Dispensing Cost Reduction Workshop Final Report”, with specific interest in which of the topics identified in the report are the most relevant to cost reduction at the hydrogen refueling station (forecourt).
DOE also is looking for input on topics which could address cost reduction at the forecourt which are not included.
The Hydrogen Compression, Storage, and Dispensing Cost Reduction Workshop was held at Argonne National Laboratory (ANL) on 20–21 March 2013, and featured 36 participants representing industry, government, and national laboratories with expertise in the relevant fields. The objective of the workshop was to identify the research, development, and demonstration (RD&D) needs in the areas of compression, storage, and dispensing (CSD) to enable cost reduction of hydrogen fuel at fueling stations.
The workshop was divided into sessions for compression, storage, and other forecourt issues. Among the findings:
Compression Cost Reduction Opportunities. Hydrogen compressors currently used at fueling stations are generally either diaphragm or reciprocating compressors. Poor reliability is a problem for hydrogen compressors because current standards for their design assume prolonged operation at peak pressure—an operating regime that is not representative of the operating conditions to which forecourt hydrogen compressors are exposed.
The operating and maintenance cost of in-service compressors is exacerbated by the on/off cycling of the compressors resulting from a lack of station demand.
The capital cost of the commercial hardware remains high due to low production volumes. Significant cost reductions can be achieved through high-volume production; panelists estimated that a 70% reduction in compressor capital cost is possible from a three-order-of-magnitude increase in production demand.Identified activities to decrease the cost of hydrogen compression at the forecourt include research and development (R&D) to develop design standards and tests that accurately reflect operating conditions; development of high-temperature polymer and composites that are compatible with hydrogen; identification of high-strength metallic materials that are resistant to hydrogen embrittlement; improved compressor efficiency; and collection of compressor durability and reliability data to better understand the current mean time between failures and failure modes.
Storage Cost Reduction Opportunities. The cost of on-site storage is determined by vessel requirements and durability. High-pressure stainless steel vessels are expensive due to the thickness necessary for containment and the manufacturing process requirements. Composite carbon fiber and steel vessels are a potential alternative.
To become economically competitive with steel, lower-cost, high-strength carbon fiber and improved batch-to-batch carbon fiber quality are needed. In addition, composite vessels are constrained due to the lack of non-destructive tests for recertification and the 15-year service life, which is based on glass fiber degradation. R&D to better understand the effect of partial pressure cycles on composite tank life and the design of non-destructive tests for tank recertification is needed to extend the service life of carbon fiber composite tanks, which would lower the life cycle cost.
Another low-cost alternative is a steel/concrete composite vessel projected to meet the DOE’s 2020 dollar per kilogram cost goal and is currently under development at Oak Ridge National Laboratory.
Another significant barrier to low-cost on-site hydrogen storage is the large setback distances required by facility codes and standards. The early stations are expected to be deployed in urban environments where real estate is at a premium. Requiring larger than necessary setback distances from wall openings (e.g., gas station windows) at best significantly increases the station cost and at worse precludes station placement in these settings.
Necessary activities include research to determine ideal minimal setback distances and development of underground and containerized storage to reduce cost. Analysis of other alternatives such as installing hydrogen refueling stations at retail stores or the use of high-pressure tube trailers in a “swap and drop” scenario could identify lower-cost alternatives to the traditional station design of co-locating facilities at existing gasoline refueling sites.
Cost savings could also be obtained by maximizing the use of high-pressure storage through development of the necessary balance of plant components and standardization of storage vessel capacity to increase production volumes and lower cost.
Other Forecourt Issues Cost Reduction Opportunities. Key opportunities for cost reduction outside of compression and storage were identified in hydrogen dispensing and through analysis work to optimize station designs.
Hydrogen metering requires further development to meet the required 1-2% system accuracy while also lowering costs. Other recommendations included development of high-pressure welding standards and hardware to measure the quantity and quality of the hydrogen as well as the performance of the refueling station during vehicle fills.
Opportunities to reduce cost through station optimization include analysis to establish the expected demand profiles for early and mature market demands, allowing for optimization of station design for both the near and long terms. Once these profiles are established, an analysis of the trade-off between compressor throughput and on-site storage capacity to meet station demand could be performed to optimize station design for both performance and cost. Another analysis activity identified was work to quantify the cost effects of different fueling protocols in order to provide input to code development.
Liquefaction Technologies. Current liquefaction technologies require significant capital investment and the process is energy intensive. Current liquefaction contributes ~$1.50/gge to the cost of hydrogen delivery via liquid pathway.
At 8-12 kWh/kg H2 and ~$186 million for a 300,000 kg/day plant, significant cost reduction and energy improvements are needed to reach the $1-2/gge delivery cost goal for hydrogen delivery and dispensing. The Department of Energy’s Fuel Cell Technologies (FCT) Office requests information on improved liquefaction cycles and novel approaches to both lower the cost and the energy requirement of the technology.
Of specific interest are what liquefaction process innovations can potentially reduce energy penalties and cost, as well as the potential cost reduction, the estimated kWh/kg energy requirement of the process, the kg/day capacity of the design, and the barriers to commercialization.