Hydrogen(H2) has held the interest of scientists as a source of energy since the 1800s, due to its abundance in the environment and high energy per unit of mass. Most of the hydrogen in nature exists as water or bonded in organic compounds, however, and its high vapor pressure means significant compression is required to take advantage of the energy density.
Hydrogen also has additional infrastructure challenges associated with its small molecular size and negative effects on material fatigue resistance. While the application of hydrogen as an energy source results in zero emissions, the production of hydrogen relies primarily on steam methane reforming, which is energy-intensive and releases carbon dioxide (CO2) to the atmosphere, Fig 1. The steam reforming reaction produces 10 tons of CO2 for every ton of H2.
Hydrogen shot. The U.S. Department of Energy’s (DOE’s) Energy Earthshots Initiative aims to accelerate breakthroughs of more abundant, affordable and reliable clean energy solutions within the decade. The first Energy Earthshot, launched June 7, 2021—Hydrogen Shot—seeks to reduce the cost of clean hydrogen by 80% to $1 per 1 kilogram in 1 decade (“1 1 1”).
The Hydrogen Shot establishes a framework and foundation for clean hydrogen deployment in the American Jobs Plan (whitehouse.gov), which includes support for demonstration projects. Industries are beginning to implement clean hydrogen to reduce emissions, yet many hurdles remain to deploying it at scale.
Right now, hydrogen from renewable energy costs about $5/kg. Achieving the Hydrogen Shot’s 80% cost reduction goal can unlock new markets for hydrogen, including steel manufacturing, clean ammonia, energy storage, and heavy-duty trucks. This would create more clean energy jobs, reduce greenhouse gas emissions, and position America to compete in the clean energy market on a global scale. These efforts would ensure that environmental protection and benefits for local communities are a priority.
To address these goals, the U.S. Department of Energy (DOE) and its National Energy Technology Laboratory (NETL) are researching hydrogen production (https://www.netl.doe.gov/node/10875) and the integrity of hydrogen production, delivery and storage systems, with ongoing activities in fuel cell development, manufacturing, systems analysis and integration, safety, standards and education.
Fossil fuels currently provide the lowest-cost pathway for producing hydrogen, according to cost data in a recent DOE Hydrogen Strategy Document (https://www.energy.gov/sites/prod/files/2020/07/f76/USDOE_FE_Hydrogen_Strategy_July2020.pdf).
To further the advancement of technologies for hydrogen production, DOE recently selected 11 projects to help recalibrate the nation’s vast fossil-fuel and power infrastructure for decarbonized energy and hydrogen production. The selected projects will develop technologies for the production of fossil-based hydrogen, with progress toward net-zero carbon emissions.
The National Energy Technology Laboratory (NETL) will manage the hydrogen production projects, which fall under three areas of interest. The first focuses directly on Solid Oxide Electrolysis Cell (SOEC) Technology Development for Hydrogen Production, per the following items.
Durable and High-Performance SOECs Based on Proton Conductors for Hydrogen Production. The Georgia Institute of Technology (Atlanta, Ga.) will assess the degradation mechanisms of the electrolyte, electrode and catalyst materials under electrolysis conditions to gain insights for rational design of better electrode and catalyst materials.
Improving Durability and Performance of Solid Oxide Electrolyzers by Controlling Surface Composition on Oxygen Electrodes. The Massachusetts Institute of Technology (Cambridge, Mass.) will research the degradation pathway that couples surface chemistry to impurity poisoning on perovskite oxygen electrodes.
Development of Stable Solid Oxide Electrolysis Cell for Low-Cost Hydrogen Production. OxEon Energy LLC (North Salt Lake, Utah) will operate a solid oxide electrolysis cell stack in a laboratory test bed. It will show improved performance over baseline stacks, exhibiting robustness, reliability, endurance, H2 purity, and producing H2 at elevated pressure of 2 to 3 bar.
Development of Novel 3D Cell Structure and Manufacturing Processes for Highly Efficient, Durable and Redox-Resistant Solid Oxide Electrolysis Cells. The Regents of the University of California, San Diego (La Jolla, Calif.) will evaluate and demonstrate a highly efficient, durable and reduction-oxidation (redox)-resistant solid oxide electrolysis cell technology for H2 production. This project focuses on the development of a novel cell design and its corresponding manufacturing processes. It will culminate in the demonstration of a scaled-up SOEC, featuring a design with improved performance, enhanced redox resistance and increased durability under conditions suitable for H2 production from steam.
Development of High-Performance Metal-Supported SOECs and Innovative Diagnostic Methodologies. The University of Louisiana at Lafayette (Lafayette, La.) will develop high-performance metal-supported solid oxide electrolysis cells and innovative diagnostic methodologies to achieve net-zero or negative emissions. The team plans to fabricate metal-supported solid oxide electrolysis cells (MS-SOECs) to improve the electrolysis performance while maintaining mechanical strength for the stack assembly; develop accelerated test protocols for SOECs and apply theoretical analysis to improve its stability and suppress oxygen electrode delamination; and use machine learning to study the dependence of electrochemical performance on microstructural details of an electrode.
Developing Stable, Critical Materials and Microstructure for High-Flux and Efficient H2 production through Reversible Solid Oxide Cells. The University of South Carolina (Columbia, S.C.) will advance RSOC technology for stand-alone or hybrid power and H2 production by addressing critical and unsolved issues through foundational materials and microstructure innovations. The impact of the project could assist the commercialization course of RSOC technology and expand it to utility markets, such as distributed stand-alone or hybrid power and H2 generation as a means of energy storage
Designing Internal Surfaces of Porous Electrodes in Solid Oxide Electrolysis Cells for Highly Efficient and Durable Hydrogen Production. The West Virginia University Research Corporation (Morgantown, W.V.) will develop and implant highly active and robust nano-scale coating layers to the internal surface of a porous electrode. The coating layer will be developed, using the additive manufacturing process of atomic layer deposition (ALD) and will be implanted on the internal surface of porous electrodes of the as-fabricated commercial cells directly. The project will provide a simple solution to various materials challenges at the cell level and could further enable extensive and more efficient SOEC stacks and systems.
Heterostructured Cr-Resistant Oxygen Electrode for SOECs. Worcester Polytechnic Institute (Worcester, Mass.) will design, test and validate oxygen electrode materials for SOECs that maintain high-performance and low-degradation rates in the operation conditions with the presence of Cr-containing gas impurities, using a combined integrated computational materials engineering (ICME) and lab-scale testing approach. The recipient believes that when fully optimized, this oxygen electrode material would have an intrinsic, long-term degradation rate of less than 0.3%/1000 hours at 700oC.
Further DOE-funded research projects focus on a tangential, but serious, problem. As noted above, the current production of hydrogen relies primarily on steam methane reforming, which is energy-intensive and releases CO2 to the atmosphere, thus exacerbating the CO2 greenhouse gas problem. To address this, DOE also has authorized funding of approximately $4 million for three projects focused on carbon capture, utilization and storage (CCUS), in response to Area of Interest (AOI) 3, Carbon Capture. The AOI’s objective is to complete the initial design of a commercial-scale, carbon capture, storage, and utilization (CCUS) system that separates and stores more than 100,000 tonnes/year, net carbon dioxide of 95% purity, with 90%+ carbon capture efficiency, from a steam methane reforming (SMR) or autothermal reforming (ATR) plant producing 99.97% H2 from natural gas.
These projects are described in the following three summations.
Engineering Study of Svante’s Solid Sorbent Post-Combustion CO2 Capture Technology at a Linde Steam Methane Reforming H2 Plant. Linde Inc. (Danbury, Conn.) will complete an initial engineering design of a commercial-scale CO2 capture plant for a steam methane reformer (SMR), using the Svante VeloxoTherm™ solid adsorbent CO2 capture technology to make blue H2. The overall system would be designed to capture approximately 1,100,000 tonnes/year net CO2 with 90% or greater carbon capture efficiency while producing H2 with 99.97% purity, from an existing Linde SMR H2 plant along the U.S. Gulf Coast. The project is intended to achieve the overall DOE performance goals of a 90% CO2 capture rate with 95% CO2 purity from a SMR plant producing 99.97% H2 from natural gas.
Initial Engineering Design Study for Advanced CO2 Capture from Hydrogen Production Unit at Phillips 66 Rodeo Refinery. Phillips 66 (Houston, Texas) will complete an initial engineering design of a commercial-scale, advanced CO2 capture and sequestration (CCS) plant that separates and stores ~190,000 tons/year net CO2 with more than 90% carbon capture efficiency from an existing steam reforming plant at the Phillips 66 Rodeo Refinery, California. The goal of this project is to advance the CCS technology for commercialization in a steam reforming plant application.
Blue Bison ATR Advanced CCUS System: Initial Engineering of a 1.66-MTPY CO2 Capture Unit from Tallgrass Planned Blue Bison ATR Producing 220 MMscfd of Pure Hydrogen. Tallgrass MLP Operations LLC (Johnson, Kans.) will design a commercial-scale carbon capture unit capable of separating and storing 1.66 million tonne/year of 95% pure CO2 with more than 97% carbon capture efficiency. As designed, the Blue Bison plant will, for the first time, combine carbon capture, pure H2 production (220 MMSCFD at 99.97% purity), and H2 combustion in auxiliary burners. This project would act as a precursor to the proposed development of a replicable world scale ATR blue H2 plant that could produce a cost-competitive, carbon-neutral fuel that can significantly decarbonize the energy economy while simultaneously capitalizing on the nation’s vast natural resources.
Hydrogen produced by the electrochemical splitting of water, using renewable electricity, has seen some decline in baseload cost of production, but this approach remains significantly more expensive than hydrogen produced from steam methane reforming of natural gas, even when the cost of capturing and storing CO2 is included. However, reforming with capture and storage is still significantly more expensive than current reforming operations without capture and storage, and only limited pipeline infrastructure exists to transport CO2 to suitable geological storage sites within the U.S.
Therefore, an alternative interest to DOE is the direct conversion of methane into hydrogen gas and solid carbon. Preliminary analyses indicate that such a process can be more efficient and potentially less expensive than steam methane reforming with CO2 capture and storage. Solid carbon can be transported easily by truck or rail to an appropriate storage location and, depending on the morphology of the carbon produced (e.g., amorphous carbon, activated carbon and carbon fibers), it may be sold for beneficial applications. ARPA-E is currently managing four research and development projects aimed at directly producing pure hydrogen from flared methane through conversion of that gas to hydrogen and solid carbon.
NETL is also exploring ways to mitigate flaring of natural gas through the development of modular conversion solutions that produce higher value chemicals; some of these processes also produce hydrogen as a side product. These projects began in 2019 under a Funding Opportunity Announcement (FOA) directed at advanced natural gas infrastructure technology development. The projects are summarized in Table 1.
DOE/NETL has explored other methods of hydrogen production, including microwave active metal oxides for CO2 dry reforming of methane. This patent-pending technology establishes a novel system and method for the microwave-assisted dry reforming of methane. The technology is available for licensing and/or further collaborative research from DOE/NETL.
Traditional steam reforming of methane to produce hydrogen, which is then reacted with carbon (CO) to produce methanol and other industrial commodity chemicals, is an energy- intensive process with a large carbon footprint. Methane dry reforming uses an alternative reaction that uses CO2 as a soft oxidant to produce CO and H2 from methane, which can be further processed into methanol or hydrocarbons.
Further, using CO2 to produce commodity chemicals, such as H2 and CO, can generate revenue to offset carbon capture costs, reduce the carbon footprint of fossil-fuel powered processes, and allow sustainable use of fossil fuel resources. Traditional dry reforming techniques are extremely energy-intensive and require very high temperatures (>800o C) that make it unpractical economically, compared with the lower-temperature, carbon-positive, methane steam reforming.
Microwave-assisted catalysis has been demonstrated as an enabling technology to promote high-temperature chemical processes. Unlike traditional thermal heating, microwaves can rapidly heat catalysts to extremely high temperatures without heating the entire reactor volume. This reduces heat management issues of conventional reactors and enables rapid heating/cooling cycles. Ultimately, this can allow reactors to utilize excess renewable energy on an intermittent basis (load follow) to promote traditionally challenging, thermally-driven reactions for on-demand chemical production.
Microwave absorption is a function of the electronic and magnetic properties of the material, and a properly designed catalyst may function as both a microwave heater and a reactive surface for driving the desired reaction. Microwave absorption is extremely sensitive to the catalyst’s chemical state and electronic structure, and effective catalysts must maintain microwave activity across a wide range of temperatures in both oxidative and reductive environments.
As countries seek to reduce their greenhouse gas (GHG) emissions while providing cost-effective energy to businesses and consumers, hydrogen is emerging as a key technology. It could soon be a multi-billion industry in the United States. Indeed, two scenarios in the Forbes Energy Policy Simulator (EPS–https://www.forbes.com/sites/energyinnovation/2019/10/07/how-hydrogen-could-become-a-130-billion-us-industry-and-cut-emissions-by-2050/?sh=4eb239752849) illustrate pathways in which hydrogen becomes a major part of the U.S. energy mix, earning revenues of $130 billion to $170 billion per year by 2050 while lowering greenhouse gas (GHG) emissions by 20—120 million metric tons (Mt) of CO2 equivalent annually.
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