Hydrogen delivery through liquid organic hydrides: Considerations for a potential technology

The purpose of this project was to investigate and evaluate the attractiveness of using a magnesium chemical hydride slurry as a hydrogen storage, delivery, and production medium for automobiles. To fully evaluate the potential for magnesium hydride slurry to act as a carrier of hydrogen, potential slurry compositions, potential hydrogen release techniques, and the processes (and their costs) that will be used to recycle the byproducts back to a high hydrogen content slurry were evaluated. A 75% MgH2 slurry was demonstrated, which was just short of the 76% goal. This slurry is pumpable and storable for months at a time at room temperature and pressure conditions and it has the consistency of paint. Two techniques were demonstrated for reacting the slurry with water to release hydrogen. The first technique was a continuous mixing process that was tested for several hours at a time and demonstrated operation without external heat addition. Further work will be required to reduce this design to a reliable, robust system. The second technique was a semi-continuous process. It was demonstrated on a 2 kWh scale. This system operated continuously and reliably for hours at a time, including starts and stops. This process could be readily reduced to practice for commercial applications. The processes and costs associated with recycling the byproducts of the water/slurry reaction were also evaluated. This included recovering and recycling the oils of the slurry, reforming the magnesium hydroxide and magnesium oxide byproduct to magnesium metal, hydriding the magnesium metal with hydrogen to form magnesium hydride, and preparing the slurry. We found that the SOM process, under development by Boston University, offers the lowest cost alternative for producing and recycling the slurry. Using the H2A framework, a total cost of production, delivery, and distribution of $4.50/kg of hydrogen delivered or $4.50/gge was determined. Experiments performed at Boston University have demonstrated the technical viability of the process and have provided data for the cost analyses that have been performed. We also concluded that a carbothermic process could also produce magnesium at acceptable costs. The use of slurry as a medium to carry chemical hydrides has been shown during this project to offer significant advantages for storing, delivering, and distributing hydrogen: • Magnesium hydride slurry is stable for months and pumpable. • The oils of the slurry minimize the contact of oxygen and moisture in the air with the metal hydride in the slurry. Thus reactive chemicals, such as lithium hydride, can be handled safely in the air when encased in the oils of the slurry. • Though magnesium hydride offers an additional safety feature of not reacting readily with water at room temperatures, it does react readily with water at temperatures above the boiling point of water. Thus when hydrogen is needed, the slurry and water are heated until the reaction begins, then the reaction energy provides heat for more slurry and water to be heated. • The reaction system can be relatively small and light and the slurry can be stored in conventional liquid fuel tanks. When transported and stored, the conventional liquid fuel infrastructure can be used. • The particular metal hydride of interest in this project, magnesium hydride, forms benign byproducts, magnesium hydroxide (“Milk of Magnesia”) and magnesium oxide. • We have estimated that a magnesium hydride slurry system (including the mixer device and tanks) could meet the DOE 2010 energy density goals. During the investigation of hydriding techniques, we learned that magnesium hydride in a slurry can also be cycled in a rechargeable fashion. Thus, magnesium hydride slurry can act either as a chemical hydride storage medium or as a rechargeable hydride storage system. Hydrogen can be stored and delivered and then stored again thus significantly reducing the cost of storing and delivering hydrogen. Further evaluation and development of this concept will be performed as follow-on work under another project. However, since the cost of reducing magnesium from magnesium oxide makes up 85% of the cost of the slurry, if hydrogen can be stored many times in the slurry, then the cost of storing hydrogen can be spread over many units of hydrogen and can be significantly reduced from the costs of a chemical hydride system. This may be the most important finding of this project. If the slurry is used to carry a rechargeable hydride, the slurry can be stored in a conventional liquid fuel tank and delivered to a release system as hydrogen is needed. The release system will contain only the hydride needed to produce the hydrogen desired. This is in contrast to conventional designs proposed for other rechargeable hydride systems that store all the hydride in a large and heavy pressure and heat transfer vessel.

Impact of Hydrogen Integration and Implementation on Costs in Glass Production

Distributionally robust planning method for expressway hydrogen refueling station powered by a wind-PV system

While aircraft account for less than 10% of United States (U.S.) transportation energy consumption, it is the only mode expected to see sustained growth in energy demand through 2050. Currently, commercially available aircraft rely heavily on either jet fuel or leaded aviation gasoline. Over the past few decades, concerns have grown over the contributing effects that greenhouse gases, which are produced from fossil fuels, have on the environment. Due to these concerns, many aircraft manufacturers are pursuing the development of new generation aircraft that can leverage alternative, renewable fuels. The Federal Aviation Administration (FAA) is presently working toward certifying multiple novel aircraft and developing an environment to safely support this innovation. For airports and aircraft original equipment manufacturers (OEMs) that choose to be early adopters of hydrogen technology, the FAA needs to provide guidance for the associated support infrastructure. The FAA is collaborating with the National Renewable Energy Laboratory (NREL) on this research project to evaluate the impact of the anticipated demand for hydrogen as a fuel source on existing airport infrastructure. This study is intended to help reduce market barriers involving uncertainty in standards and operational requirements of hydrogen technology and airport infrastructure. By defining system-wide best practices in refueling systems and facility layouts, manufacturers, airports, and communities can be better prepared to participate in this emerging industry. Section 2 of this document is the culmination of a literature review that describes the current state and the anticipated future of hydrogen-related technology across various government organizations, industries, and academia. This work identifies existing goals and the maturity level of the industry to help define a realistic strategy and approach to implement hydrogen systems into the airport environment within a realistic timeframe. The technology areas cover production, storage, transport, and fueling as a supply chain of hydrogen. This report also briefly investigates hydrogen propulsion systems, such as fuel cell and combustion engines. Furthermore, this work organizes safety codes and standards to identify gaps in our current understanding. Presently, there are detailed standards regarding hydrogen technology, airport safety, and aircraft fueling. However, they are not consolidated as a unified set of codes and standards suitable for the airport environment. Preventive safety measures and emergency procedures must be identified as hydrogen will begin to be transported on to airport sites. These safety requirements must continue to mature as the airports adopt hydrogen technology in their proximity. Sections 3 and 4 of this study focus hydrogen aircraft demands, and airport infrastructure needed to support hydrogen technology. The examination of hydrogen production, storage requirements, delivery methods, refueling services, and safety requirements are critical to accommodate novel hydrogen aircraft in the airport environment. Learnings are applied to the LAX, SEA, PDX, and SFO airports to gain insight on: 1) space requirements for hydrogen infrastructure, 2) airport hydrogen infrastructure placement, and 3) cost and economic impacts of hydrogen infrastructure at each airport. Results show that each airport has space for hydrogen infrastructure, especially at hydrogen demand levels of around 1,000 kg/day. We also find that both hydrogen infrastructure cost and economic impacts become more favorable as hydrogen demand at the airports scale. This study is intended to provide a comprehensive understanding of hydrogen infrastructure that will enable energy-savings and emissions-reductions while illuminating pathways to transition from legacy systems to next generation aviation. The study should be used as a guide by airport and government officials, as well as industry leaders, to gain insights on how hydrogen and hydrogen infrastructure can be utilized for advance air mobility applications.

Hydrogen production from surplus solar electricity as energy storage for export purposes can push towards large-scale application of solar energy in the United Arab Emirates and the Middle East region; this region’s properties of high solar irradiance and vast empty lands provide a good fit for solar technologies such as concentrated solar power and photovoltaics. However, a thorough comparison between the two solar technologies, as well as investigating the infrastructure of the United Arab Emirates for a well-to-ship hydrogen pathway, is yet to be fully carried out. Therefore, in this study we aim to provide a full model for solar hydrogen production and delivery by evaluating the potential of concentrated solar power and photovoltaics in the UAE, then comparing two different pathways for hydrogen delivery based on the location of hydrogen production sites. A Solid Oxide Cell Electrolyzer (SOEC) is used for technical comparison, while the shortest routes for hydrogen transport were analyzed using Geographical Information System (GIS). The results show that CSP technology coupled with SOEC is the most favorable pathway for large-scale hydrogen from solar energy production in the UAE for export purposes. Although PV has a slightly higher electricity potential compared to CSP, around 42 GWh/km2 to 41.1 GWh/km2, respectively, CSP show the highest productions rates of over 6 megatons of hydrogen when the electrolyzer is placed at the same site as the CSP plant, while PV generates 5.15 megatons when hydrogen is produced at the same site with PV plants; meanwhile, hydrogen from PV and CSP shows similar levels of 4.8 and 4.6 megatons of hydrogen, respectively, when electrolyzers are placed at port sites. Even considering the constraints in the UAE’s infrastructure and suggesting new shorter electrical transmission lines that could save up to 0.1 megatons of hydrogen in the second pathway, production at the same site with CSP is still the most advantageous scenario.

The growing concern about climate change and the contemporary increase in mobility requirements call for faster, cheaper, safer, and cleaner means of transportation. The retrofitting of fossil-fueled piston engine ultralight aerial vehicles to hydrogen power systems is an option recently proposed in this direction. The goal of this investigation is a comparative analysis of the environmental impact of conventional and hydrogen-based propulsive systems. As a case study, a hybrid electric configuration consisting of a fuel cell with a nominal power of about 30 kW, a 6 kWh LFP battery, and a pressurized hydrogen vessel is proposed to replace a piston prop configuration for an ultralight aerial vehicle. Both power systems are modeled with a backward approach that allows the efficiency of the main components to be evaluated based on the load and altitude at every moment of the flight with a time step of 1 s. A typical 90 min flight mission is considered for the comparative analysis, which is performed in terms of direct and indirect emissions of carbon dioxide, water, and pollutant substances. For the hydrogen-based configuration, two possible strategies are adopted for the use of the battery: charge sustaining and charge depleting. Moreover, the effect of the altitude on the parasitic power of the fuel cell compressor and, consequently, on the net efficiency of the fuel cell system is taken into account. The results showed that even if the use of hydrogen confines the direct environmental impact to the emission of water (in a similar quantity to the fossil fuel case), the indirect emissions associated with the production, transportation, and delivery of hydrogen and electricity compromise the desired achievement of pollutant-free propulsion in terms of equivalent emissions of CO2 and VOCs if hydrogen is obtained from natural gas reforming. However, in the case of green hydrogen from electrolysis with wind energy, the total (direct and indirect) emissions of CO2 can be reduced up to 1/5 of the fossil fuel case. The proposed configuration has the additional advantage of eliminating the problem of lead, which is used as an additive in the AVGAS 100LL.

Utilizing Probabilistic Analyses to Explore Performance Margins of Natural Gas Infrastructure for the Transport and Delivery of Hydrogen and Hydrogen Blends

Hydrogen production has become an emerging technology and offered a pathway to sustainable energy utilization in transportation systems. In this paper, we propose a coordinated planning of the electricity network and hydrogen refueling and production station planning strategy for hydrogen fuel cell electric vehicles (FCEVs). In the proposed system structure, a hydrogen supply chain for FCEVs mainly composes hydrogen refueling stations (HRSs), hydrogen production stations (HPSs), hydrogen storage, and hydrogen delivery network. To enhance the system's flexibility, hydrogen delivery combines both gas pipeline delivery and truck logistics delivery. In the mathematical models, the synergistic effect and coupling relationship of the electricity network, gas network, and transportation network are presented. To ensure the efficiency and effectiveness of the hydrogen refueling system, a quality of service (QoS) and reliability assessment method is presented. The proposed methodology is verified in case studies. It is found out that compared with the single delivery methods, the proposed multi-network coordinated planning has the lowest total cost with less unserved energy. Besides, through QoS and reliability assessment, enough hydrogen reserves can be maintained to cope with contingencies.

A cooperative research and development agreement was made between Linde, LLC and Sandia to develop a plan for modifying the Turbulent Combustion Laboratory (TCL) with the necessary infrastructure to produce a cold (near liquid temperature) hydrogen jet. A three-stage heat exchanger will be used to cool gaseous hydrogen using liquid nitrogen, gaseous helium, and liquid helium. A cryogenic line from the heat exchanger into the lab will allow high-fidelity diagnostics already in place in the lab to be applied to cold hydrogen jets. Data from these experiments will be used to develop and validate models that inform codes and standards which specify protection criteria for unintended releases from liquid hydrogen storage, transport, and delivery infrastructure.

Powering squarely into the future: A strategic analysis of hydrogen energy in QUAD nations

The United States Department of Energy's high temperature, low relative humidity membrane program

With the imminent threat of global warming, the international energy industry has sought out alternative fuels to reduce greenhouse emissions. Hydrogen, a clean fuel, has been identified as a promising alternative to carbon-based fuels. When utilized, hydrogen produces no harmful exhaust emissions. Blue hydrogen, also known as low carbon intensity hydrogen, is generated via the reaction of hydrocarbons and steam under heat and pressure [steam methane reforming (SMR)] to create hydrogen-enriched syngas. The hydrogen is then purified via a Pressure Swing Adsorption (PSA) unit. The blue hydrogen production process includes carbon capture, utilization, and/or storage technologies. In this paper, a proprietary blue hydrogen production process is presented. This technology offers certain valuable differentiators described further in this paper. The proprietary process integrates the waste heat from the hydrogen generation process with the heat demand from the carbon capture process. The heat integration scheme is optimized resulting in no auxiliary boilers or drastically reducing auxiliary boiler capacity for the carbon capture process, reducing CAPEX and OPEX. Moreover, the design reduces the footprint of the facility and increases CO2 capture efficiency by eliminating or reducing the boiler's carbon footprint. Hydrogen transportation and subsequent use is also reviewed. Hydrogen suffers from a low density even in liquid state. As such, the use of chemical carriers is necessary for practical transportation. Ammonia is the predominant chemical carrier for hydrogen as its transport via maritime vessels is well-established. Nonetheless, the use of ammonia as a chemical carrier entails additional processing. Ammonia production predominately uses the Haber-Bosch method, an exothermic process. Upon transportation to the end user, hydrogen recovery is achieved via catalytic cracking of ammonia over a ruthenium or a nickel-based catalyst. Direct combustion of ammonia in maritime vessel engines is also feasible but requires high pressure ratios or the use of co-fuels.

A novel cryo-pressurized hydrogen storage and delivery system for internal combustion engine vehicles

A comparative economic study of nuclear hydrogen production, storage, and transportation

Hydrogen extraction characteristics of high-temperature proton conductor ceramics for hydrogen isotopes purification and recovery