Integrated CO2 sequestration and seasonal underground blue hydrogen storage: a model-based technoeconomic evaluation

3.15 - Solar-Assisted Heat Pumps

The goal of this study was to assess the potential for storing hydrogen underground in depleted gas fields in Northern California. We considered the potential amount of hydrogen generated from the electrolysis of California's curtailed solar and wind energy. We then determined the fields with the best geological and reservoir properties to support secure underground hydrogen storage. We developed a three-stage set of criteria for selecting potential hydrogen storage sites. In stage 1, our screening approach combines integrated geoscience and environmental factors to identify the fields to exclude from consideration for hydrogen storage. In stage 2, we applied a numerical simulation-based site selection criteria to the fields that passed the stage 1 screening criteria. We started the screening with 182 depleted and underground storage fields in Northern California, of which 147 fields were disqualified in the first stage. We scored and ranked the remaining 35 fields based on their potential to maximize storage and withdrawal of hydrogen using the numerical simulation-based site selection criteria. The top-ten high scoring sites for underground hydrogen storage and production were reservoirs with dips between 5° and 15°, reservoir porosity above 20%, reservoir flow capacity above 5000 mDm, and reservoirs at depths between 430 m to 2400 m. The total estimated hydrogen storage capacity for the ten high-scoring sites was 203.5 million tonnes of hydrogen. Our set of site selection criteria has a stage 3 that requires detailed site characterization. With stage 3, we gather additional rock and fluid properties of high-scoring sites that enable detailed modeling of the processes related to hydrogen storage and withdrawal. We did not cover stage 3 in this paper. We estimated the potential hydrogen recovery from a hypothetical depleted field in California and evaluated the efficiency of converting the renewable energy to hydrogen and back to power. The results show that depleted gas fields in Northern California have sufficient storage capacity to support the seasonal underground storage of hydrogen derived from renewable energy electrolysis. However, recovery is limited to the amount of fluid that can be injected, the mixing between hydrogen and the in-situ gas, and the lateral spread of hydrogen. The round-trip efficiency of power to hydrogen to power conversion maxed at 36% for the system under study.

Thermal energy storage strategies for effective closed greenhouse design

A simulation was performed, which concerns the feasibility of great-scale seasonal underground thermal energy storage in Tianjin, China. The investigated system consists of a 1000m2 flat plate solar collector (FPSC) and a underground storage. In summer, solar thermal energy is collected and emitted into the soil surrounding borehole heat exchangers, through which the stored heat is extracted in winter with a GSHP to provide a proper heating temperature. According to the experimental data about a GSHP system in Tianjin and local meteorological conditions and soil properties, a simulation study was performed for the influence of system operation modes on heat emitting and extracting. Results indicate different features of temperature distribution in the storage field under different running modes. For a more share provided by clean and free energy, an operation mode was presented based on both less loss and better thermal recovery in the soil storage.

In response to Governor Brown’s January 2016 state of emergency proclamation regarding the Aliso Canyon gas leak, SB 826 (Leno, 2016) requested that the California Council on Science and Technology (CCST) provide the State with up-to-date information on all currently operating underground natural gas storage fields in California. CCST was instructed to provide an independent technical assessment answering three key questions about: The risks California’s underground gas storage facilities pose to health, safety, environment, and infrastructure; Whether California needs underground gas storage to provide for energy reliability through 2020; and How implementation of California’s climate policies changes the future need for underground gas storage. From a statewide field of leading energy researchers, CCST selected Jens T. Birkholzer, PhD, and Jane C.S. Long, PhD, to serve as co-chairs of the 12-member CCST Report Steering Committee – which supervised 21 Report Authors with expertise spanning hydrogeology and reservoir engineering, risk assessment, public and occupational health, greenhouse gas (GHG) emissions, and energy analysis and economics. Each report chapter was subject to a peer review process by independent experts, while another independent expert served as Report Monitor to oversee the process, ensuring that peer review comments were sufficiently addressed in the final report. An additional Oversight Committee reviewed the entire process, including conflict-of-interest declarations. The report’s findings and conclusions are based on a review of published literature and official and voluntary databases, which the Report Authors compiled between January through September 2017, and delivered to the California Public Utilities Commission in January 2018. Key findings and conclusions include: Safety: The risks associated with underground storage (UGS) facilities can be managed, and, with appropriate regulation and safety management, may become comparable to risks in other types of energy facilities found acceptable in California, such as oil refineries and natural gas power plants. At each UGS facility, the State should ensure timely and thorough implementation of the new regulations coming into force in 2018 set by the California Department of Conservation’s Division of Oil, Gas, and Geothermal Resources (DOGGR). Those regulations emphasize new and safer well completions, risk and safety management plans, and requirements for well integrity testing and monitoring. The report recommends that the State go further and require more quantitative risk assessment activities, including consideration of human and organizational factors affecting risk. The State should also implement an independent and mandatory review program to evaluate the effectiveness of these new regulations and the rigor of their application in practice, with opportunity for public comment and public dissemination of the review results. Facility-by-Facility Evaluation: Any industrial operation involves some risk to health, safety, and environment. This report assessed various risk-related characteristics across UGS facilities in California, and found a small list of facilities had relatively higher potential risk compared to others. Reliability of Natural Gas Supply: California’s energy system currently requires natural gas and UGS facilities to run reliably, primarily because many residential and commercial buildings in California rely on natural gas for heating during the winter, and because natural gas provides electricity when solar and wind power are not available. The peak demand for natural gas during the winter currently exceeds the ability of pipelines to bring natural gas into the State of California, so natural gas must be stored during periods of low demand in order to have it available to meet peak demand. Near-Term Alternatives to UGS: Closing any or all UGS facilities in the near term would involve replacing UGS facilities with new pipelines or natural gas storage capacity, and require very large investments. Such new natural-gas-related infrastructure would bring its own risks and would further obligate the State to the use of natural gas for decades. The risks, costs, and benefits associated with alternatives to UGS storage should be evaluated accordingly. Long-Term Need for Underground Gas Storage: California’s climate policies in future decades could still necessitate the continued use of natural gas. Also, energy systems that meet the climate goals may require underground storage of natural gas, biogas, or hydrogen, as well as sequestration of carbon dioxide. The State should develop a more complete and integrated plan to understand how the role of natural gas might evolve; assess possible energy portfolios that both meet GHG emission constraints and achieve energy reliability; and consider the potential need for UGS facilities in the future.

The requirement for energy is increasing worldwide as populations and economies develop. Reasons for this increase include global warming, climate change, an increase in electricity demand, and paucity of fossil fuels. Therefore, research in renewable energy technology has become a central topic in recent studies. In this study, a solar-assisted house heating system with a seasonal underground thermal energy storage tank is proposed based on the reference system to calculate the insulation thickness effect, the collector area, and an underground storage tank volume on the system performance according to real weather conditions at Jeju Island, South Korea. For this purpose, a mathematical model was established to calculate its operating performance. This mathematical model used the thermal response factor method to calculate the heat load and heat loss of the seasonal underground thermal energy storage tank. The results revealed that on days with different weather conditions, namely, clear weather, intermittent clouds sky, and overcast sky, the obtained solar fraction was 45.8%, 17.26%, and 0%, respectively. Using this method, we can save energy, space, and cost. This can then be applied to the solar-assisted house heating system in South Korea using the seasonal underground thermal energy storage tank.

Techno-economic analysis of long-duration energy storage and flexible power generation technologies to support high-variable renewable energy grids

Comparison of control strategies for a solar heating system with underground pit seasonal storage in the non-heating season

The design of underground gas storage systems requires the selection of optimal values for several interacting variables. Some of these variables are related by nonlinear functions so that frequently used optimization techniques, such as linear programming, are less than precise and cumbersome to apply. precise and cumbersome to apply. A method of optimizing the variables, subject to the operating and physical constraints, has been developed and programmed for solution by digital computer. A Fibonacci Search routine is used for efficient convergence on the optimal solution. The relationships between the variables are preserved in original form, nonlinear where this is the case. The storage system includes the underground storage reservoir, the wells, the gathering system, the purification facilities, and the compressor station. purification facilities, and the compressor station. Because the gathering system is analyzed separately, only the average pressure loss from wellhead to compressor suction is entered into this system. The solution selects optimum horsepower for the withdrawal cycle. The reservoir is represented by the pressure-withdrawal relationship, and the producing ability of the wells by the back-pressure relationship. The variables subject to optimization are the volume of in storage, the producing rate of the wells, the number of wells, the size of the casing, the size of the purification system, and the size of the compression equipment used for withdrawal. The optimal solution is the set of values for the variables that will minimize investment. When the purification equipment is sized for the peak day volume, and the number and casing sizes of the peak day volume, and the number and casing sizes of the wells are temporarily considered fixed, the optimum-seeking computer program can be formulated as a two-variable, unimodal function that lends itself to efficient solution by the Fibonacci Search convergence technique. The program is designed to evaluate several casing sizes for any number of wells. By using the Fibonacci Search, the original range of uncertainty can be reduced to less than one percent in ten iterations. A tolerance of .001 percent can be achieved in 25 iterations. Introduction Variation in rates of gas consumption requires the use of some form of gas storage in conjunction with transmission and distribution facilities. Storage is used to supply additional volumes on peak demand days. it also permits the more efficient use of facilities during summer permits the more efficient use of facilities during summer months. Usually underground storage is the most practical means of gaining seasonal gas storage. An underground storage system contains several subsystems: the well casing, gathering, purification and compression facilities and the reservoir. The optimum design is the best combination of these subsystems. Gas transmission facilities should be operated at a high load factor. Interruptible sales are one method of accomplishing higher load factors.

Compared to fossil fuel-based energy sources, renewable energy sources are gaining momentum worldwide due to climate control agreements. The Hydrogen Energy Roadmap proposes to generate hydrogen using renewable energy sources such as hydro, biomass, and solar. However, renewable energy source like hydrogen often has an unstable flow of energy supply, which can lead to temporary underproduction of the required supply. Underground storage options like depleted gas or oil reservoirs, aquifers, and salt caverns are used to address this issue. These underground gas storage alternatives have been used for various applications, including hydrogen storage. Underground hydrogen storage is possible in two geological sites: porous media and cave storage. Salt caverns are suitable for seasonal hydrogen storage at high pressures, while aquifers have the potential for hydrogen storage due to their widespread distribution. However, it is crucial to note that adequate reservoir properties and an impermeable layer are necessary for hydrogen storage in underground structures to prevent gas migration. Microbial and geochemical activities, often overlooked but crucial in hydrogen storage, can pose challenges due to their existence.

Thermal and economical analysis of a central solar heating system with underground seasonal storage in Turkey

Storage of hydrogen, natural gas, and carbon dioxide – Geological and legal conditions

The value of diurnal and seasonal energy storage in baseload renewable energy systems: A case study of Ras Ghareb – Egypt

Underground hydrogen storage: Characteristics and prospects

The problem of carbon dioxide utilization is of increasing concern to the public, since measures to reduce greenhouse gas emissions are no longer sufficient to prevent a global increase in temperature on the planet. Most modeling scenarios show that a significant deployment of negative emission technologies is required. Carbon dioxide is often used as an agent for enhancing hydrocarbon production in the development of oil and gas fields, which is technologically consistent with projects for its utilization and underground storage in depleted reservoirs, saline aquifers, and shale rocks. For the successful implementation of such sequestration projects, it is necessary to conduct a complex of experimental, modeling, and field studies. It is necessary to understand the characteristic physical and chemical changes that occur in a subterranean formation during sequestration processes, such as dissolution, chemical reactions, convective mixing, advective processes, and dispersion. Computer modeling of ongoing processes is seen as a very important task for the correct functioning of such projects. The article deals with topical problems of computer modeling of processes associated with underground injection and storage of carbon dioxide, and also presents the results of laboratory studies on the utilization of carbon dioxide through its catalytic conversion into useful energy resources—hydrogen and hydrocarbons. The findings of this study can help to better understand physicochemical mechanisms that can occur in subterranean formations when carbon dioxide is injected. © 2022 Society of Chemical Industry and John Wiley & Sons, Ltd.