Seasonal Energy Storage Research Articles

Demonstration study on ground source heat pump heating system with solar thermal energy storage for greenhouse heating

In this study, a demonstration project of a ground source heat pump (GSHP) heating system with seasonal solar thermal energy storage (SSTES) and diurnal solar thermal energy storage (DSTES) is constructed for greenhouse heating. In the non-heating season, the SSTES overcomes the thermal imbalance of GSHP heating for agricultural greenhouses. While in the heating season, the DSTES undertakes part of the heating load of greenhouses, reduces GSHP heating electric energy consumption and improves the annual coefficient of performance of heating system COPsys,y. The experimental data illustrate that the soil temperature of ground heat exchanger (GHE) area is about 0.3 K higher than the initial soil temperature at the end of SSTES, and the COPsys,y of the proposed heating system is 14.3 % higher than that of bank control experiment. The above results demonstrate that the proposed heating system is favorable for greenhouses in cold regions. Further, coupling DSTES can reduce the rated capacity of GSHP and the total length of GHE tube for the newly designed heating system. In addition, the recommended values of two key operating parameters are given based on the experimental data. This study can shed a light on clean and efficient heating for greenhouses in cold regions and provide data support for related research.

Inefficient Building Electrification Will Require Massive Buildout of Renewable Energy and Seasonal Energy Storage

Building electrification is essential to many full-economy decarbonization pathways. However, current decarbonization modeling in the United States (U.S.) does not incorporate seasonal fluctuations in building energy demand, seasonal fluctuations in electricity demand of electrified buildings, or the ramifications of this extra demand for electricity generation. Here, we examine historical energy data in the U.S. to evaluate current seasonal fluctuation in total energy demand and management of seasonal fluctuations. We then model additional electricity demand under different building electrification scenarios and the necessary increases in wind or solar PV to meet this demand. We found that U.S. monthly average total building energy consumption varies by a factor of 1.6×—lowest in May and highest in January. This is largely managed by fossil fuel systems with long-term storage capability. All of our building electrification scenarios resulted in substantial increases in winter electrical demand, enough to switch the grid from summer to winter peaking. Meeting this peak with renewables would require a 28× increase in January wind generation, or a 303× increase in January solar, with excess generation in other months. Highly efficient building electrification can shrink this winter peak—requiring 4.5× more generation from wind and 36× more from solar.

Power to Methane Technology for Energy Storage

Power to gas (P2G) is a technology that converts electricity into gases like H2 and O2 and is expected to meet future high-capacity energy storage needs. In this paper, we present an electric-gas system coupled with electricity and gas as well as an operational analysis to solve the energy dispatch problem in P2G technology. This paper introduces the principle of P2G technology and analyzes the advantages as well as the disadvantages of the technology. P2G technology allows for long-term, seasonal energy storage and a large amount of energy storage. However, the technology has low conversion efficiency and the risk of methane leakage when applied. A coupled electric-gas system consisting of gas-fired units and P2G facilities converts rich electricity into methane for transportation and transient storage with natural gas pipeline. Besides, natural gas power generation is economical and environmentally friendly, and the gas generator sets are responsive, which can better deepen the coupling between the power system and the natural gas system in the framework of the energy internet. This paper illustrates with examples that the P2G coupling technology has a good application prospect, and it has some implications for the future application of P2G technology.

A Molten-Salt Battery for Seasonal Energy Storage

Cost-competitive renewable energy sources, such as wind and solar energy, are more rapidly replacing fossil fuels for power generation. As their integration into the power grid increases, the inherent intermittency exposes a great challenge in maintaining the grid stability. Therefore, the development of low-cost energy storage technology suitable for large-scale manufacturing is essential for the further deployment of renewable energy. We noticed that renewable electricity production usually follows predictable seasonal trends. For example, the longer daylight in summers corresponds to more solar power generated. If any seasonal excess can be efficiently stored and redistributed in times of needs, a power grid based on 100% renewable energy is more feasible. Unfortunately, current rechargeable battery technologies have not been optimized for seasonal storage, as the self-discharge rate ranges from approximately 3–5% for lithium-ion batteries to almost 30% for nickel metal hydride batteries in the first month.In this presentation, we will demonstrate the concept of a rechargeable molten-salt battery with earth-abundant elements and simple construction that preserve the stored energy for long periods of time. Due to its unique operating mechanism, this battery can discharge most of its stored capacity (> 90%) after a period of 1 to 8 weeks. This approach brings new possibilities to seasonal energy storage and helps the grid to overcome short supply during seasonal fluctuations.

Electro-Chemical-Mechanical Coupled Modeling of Oxygen Electrodes in Solid Oxide Electrolyzer Cells

Solid oxide electrolyzer cell (SOECs), which is an electrochemical device to split water with electricity to generate hydrogen, have received widespread attention for multi-day or seasonal energy storage to integrate variable renewable energy (VRE) into the grid [1]. Even though there have been tremendous material development and performance improvement of the technology in the past decade [2], challenges remain in understanding its degradation mechanism, especially the delamination of oxygen electrode/electrolyte interface [3-5]. Developing new oxygen electrodes which could decelerate the degradation and extend the stack lifetime beyond 60,000 hours at 1.5A/cm2 would significantly drive the stack price down to $100/kW and hydrogen cost down to $2/kg [6].In the state-of-the-art SOECs, pure ionic conductor 8 mol% Y2O3 doped ZrO2 (YSZ) and Gadolinium-doped Ceria (GDC) are usually used as the dense electrolyte and the buffer layer; mixed electronic and ionic conductor (MIEC) La1-xSrxCo1-yFeyO3-d (LSCF) is widely used as the oxygen electrode [7]. Such cells still suffer from short lifetimes with current densities over 1A/cm2. To overcome the challenge, a bilayer oxygen electrode structure, consisting of a commercial LSCF-GDC porous backbone coated by a thin SrCo0.9Ta0.1O3- d (SCT10) film (denoted as LSCF-SCT bilayer design), has been proposed and demonstrated with much higher performance compared to traditional LSCF electrode (single layer design) [8]. The new oxygen electrode has an inherently fast oxygen evolution reaction (OER) electrokinetics (or high oxygen evolution rate) and can mitigate the delamination problem by minimizing the accumulation of oxygen in oxygen evoluation reaction (OER) electrode lattice and thus chemical stresses.In this study, based upon an Electro-Chemical-Mechanical coupled model, we will correlate the crack length at the oxygen electrode/electrolyte interface with the electrochemical performance of the cell, specifically the voltage-current curve (Fig.1a). We will use J-integral (Fig.1b) as the fracture criteria to evaluate the crack growth rate under different current densities and with different oxygen electrode designs. LSCF single layer design is the baseline of the study. The long-term performance improvement of LSCF-SCT bilayer design will be compared against the baseline and its degradation mechanism will be investigated. The model will also be validated by long-term overpotential testing data as a function of time under 1A/cm2. It will be used as an optimization tool to mitigate delamination and extend the cell lifetime under higher current densities. Key Words: Electrolysis, Oxygen Electrode (OE), Delamination, Chemical Expansion, J integral, Crack Growth Rate Figure 1

(Invited) Electrochemical Pumping for Hydrogen Storage and Distribution in the Natural Gas Pipeline

Over the next decade, the production and use of hydrogen in various sectors of the global economy is anticipated to grow significantly. It is an already important feedstock in the production of ammonia and desulfurization of fuels in addition to being used in metals refining and as a coolant in thermal electric power plants. More recently, hydrogen is being considered for long-term seasonal energy storage for energy derived from renewables like solar and wind. To alleviate the severe costs of building out completely new infrastructure, the U.S. natural gas pipeline represents an enticing proposition for hydrogen storage and a potential distribution network from centralized production facilities. Embrittlement concerns of the pipeline with hydrogen limit the hydrogen partial pressure/concentration of hydrogen to be stored. Because many end use applications often require high purity hydrogen, it is necessary to separate/de-blend hydrogen from natural gas and compress it at the point-of-use. This talk presents high-temperature polymer electrolyte membrane (HT-PEM) electrochemical hydrogen pumps for separating hydrogen from gas mixtures. Hydrogen purification to +99% from syngas (25mol% hydrogen and 40mol% carbon monoxide (CO)) at 1 A cm-2 and cell voltage of 0.4 V with an electrochemical hydrogen pump was demonstrated. About 90% of hydrogen used in the United States today derives from steam-reformed natural gas that contains large concentrations of CO – which is a potent platinum electrocatalyst poison at temperatures below 100 °C. The hydrogen purification from syngas was possible with an electrochemical hydrogen pump operated at 220 °C and by using: i.) an ion pair HT-PEM that exploits electrostatic interactions to prevent phosphoric acid leaching at elevated temperatures from the membrane matrix and in the presence of water and ii.) a phosphonic acid ionomer electrode binder. The membrane electrode assembly (MEA) with the said materials and platinum on carbon (Pt/C) electrocatalyst was also effective for purifying hydrogen from other types of reformed hydrocarbons with different CO and hydrogen concentrations. Unexpectedly, operating the HT-PEM hydrogen pump at 220 °C minimized CO impact on cell polarization. At this temperature, cell polarization was governed by the hydrogen concentration in the gas feed. These observations motivate future work to develop new electrodes and electrode binders that can extract, purify, and compress hydrogen with feed streams that have low hydrogen content and contain other constituents in natural gas (methane, ethane, t-butyl mercaptan, etc).

Lead-acid battolyser concept

To achieve net-zero carbon emissions, intermittent renewable energy generators will need to replace dispatchable greenhouse gas emitting generators and alternative fuels will be required for industries dependent on fossil fuels. Energy storage such as batteries will be required to compensate for any mismatch between generation and consumption. Hydrogen can also be created during periods of high generation for seasonal energy storage and fossil fuel replacement. Integrated battery-electrolysers, known as battolysers offer a solution to both battery storage and hydrogen generation. A nickel-iron battolyser has been developed by Delft University, however, alternative chemistries should be investigated due to the strain on resources caused by scaling up of production. This paper examines an alternative battolyser chemistry based on a lead acid battery. The paper includes details on the construction of a lead-acid battolyser prototype and measured performance characteristics for a proof-of-concept. The paper shows that energy storage and hydrogen production are both possible using a lead-acid battolyser, although initial data shows performance does not match theory.

Model predictive approaches for cost-efficient building climate control with seasonal energy storage

Due to the increasing share of fluctuating renewable energy, a seasonal energy storage with a high capacity is needed, which stores the summer surplus electricity to satisfy the winter heating demand.It is assumed that the control integration of a novel thermochemical seasonal energy storage concept into a building energy system can meet this requirement and save operating costs. For this purpose, a model-predictive control concept with a prediction horizon beyond that of public weather forecasts is crucial.A state-based model is developed consisting of a building, a water buffer and a heat supply. To assess the effects of seasonal storage, different heat supply configurations are considered. On this basis, two Model Predictive Control (MPC) concepts are designed to efficiently operate the system over one year. Since public weather forecasts are reliable in the time range of several days, test reference year data are used to approximate the weather forecast beyond the public forecast period. Additionally, the control hierarchy is comprised of a superordinate optimal generation scheduling (OGS) and a subordinate MPC. The concepts follow the scheduled long-term lime storage trajectory and realise possible short-term yields based on the current public forecast. The trajectory tracking is formulated either in the objective function or the constraints.The integration of the novel lime storage module into the heat supply of a building allows a reduction of operating costs of 18% in the realistic scenario and up to 80% in case of highly fluctuating electricity prices. This reduction potential is fully exploited by the developed control approaches, but it is very sensitive to the change of the controller parameters, the fluctuation of the electricity price and the weather data. Moreover, by applying the objective-based reference tracking approach, the higher-level scheduling hierarchy could be avoided.Through the results of this work, it is confirmed that the integration of a seasonal energy storage system can greatly reduce annual operating costs and that it is not crucial to apply a prediction horizon beyond that of public forecasts.

Decarbonising the residential heating sector: A techno-economic assessment of selected technologies

Decarbonising the residential heating sector through electrification can add to the existing flexibility demands in the electricity sector arising from spatio-temporal mismatches in supply in demand. Heat demand peaks during winter require seasonal flexibility, since solar availability is at its minimum, while uncontrolled scheduling of heating appliances requires short term flexibility. However, scheduling appliances optimally and seasonal energy storages can deliver short and long term flexibility by temporarily increasing indoor room temperatures in the short term, and hydrogen generation through electrolysis in the long term. Furthermore, waste heat of fuel cells for power supply coincides with heat demand during winter. Therefore, a techno-economic assessment of different heat provision technologies and refurbishments is performed with a building model implementing flexible heat demand. The model can invest in and schedule different appliances and thereby control the indoor temperature within given boundaries. Emission reductions are then applied and sensitivity analyses for indoor temperatures and H2 prices are performed. The results show that using a combination of solar PV, heat pumps, electrolysers and fuel cells is more cost-efficient than refurbishments. Hydrogen combustion is only used when hydrogen prices fall below gas prices, or when the lower indoor boundary temperature is above 23 °C.

Natural iron ores for large-scale thermochemical hydrogen and energy storage

A stable energy supply will require balancing the fluctuations of renewable energy generation due to the transition to renewable energy sources. Intraday and seasonal storage systems are often limited to local geographical or infrastructural circumstances.This study experimentally verifies the application of inexpensive and abundant natural iron ores for energy storage with combined hydrogen and heat release. The incorporated iron oxides are reduced with hydrogen from electrolysis to store energy in chemically bonded form. The on–demand reoxidation releases either pure hydrogen or high-temperature heat as valuable products. Natural iron ores as storage material are beneficial as the specific costs are lower by an order of magnitude compared to synthetic iron oxide-based materials.Suitable iron ores were tested in TG analysis and in a 1 kW fixed-bed reactor. Siderite, a carbonate iron ore, was verified as promising candidate, as it shows significantly lower reaction temperatures and twice the storage capacity over other commercial iron ores such as ilmenite. The specific storage costs are as low as 80–150 $ per MWh hydrogen stored, based on the experimental in-situ tests. The experimentally determined volumetric energy storage capacity for the bulk material was 1.7 and 1.8MWhm−3 for hydrogen and heat release, respectively. The raw siderite ore was stable for over 50 consecutive cycles at operating temperatures of 500–600 °C in in-situ lifetime tests.The combination of high abundance, low price and reasonable capacity can thus result in very low specific energy storage costs. The study proofs that suitable natural iron ores are an interesting economic solution for large-scale and seasonal energy storage systems.

Full-Scale Demonstration of Combined Ground Source Heating and Sustainable Urban Drainage in Roadbeds

This paper proposes and demonstrates, in full scale, a novel type of energy geostructure (“the Climate Road”) that combines a ground-source heat pump (GSHP) with a sustainable urban drainage system (SUDS) by utilizing the gravel roadbed simultaneously as an energy source and a rainwater retarding basin. The Climate Road measures 50 m × 8 m × 1 m (length, width, depth, respectively) and has 800 m of geothermal piping embedded in the roadbed, serving as the heat collector for a GSHP that supplies a nearby kindergarten with domestic hot water and space heating. Model analysis of operational data from 2018–2021 indicates sustainable annual heat production levels of around 0.6 MWh per meter road, with a COP of 2.9–3.1. The continued infiltration of rainwater into the roadbed increases the amount of extractable heat by an estimated 17% compared to the case of zero infiltration. Using the developed model for scenario analysis, we find that draining rainwater from three single-family houses and storing 30% of the annual heating consumption in the roadbed increases the predicted extractable energy by 56% compared to zero infiltration with no seasonal energy storage. The Climate Road is capable of supplying three new single-family houses with heating, cooling, and rainwater management year-round.

Accelerated and long-time creep testing of extruded polystyrene using isothermal and stepped isothermal method

Seasonal Sensible Thermal Energy Storages based on existing inside structures are cost effective and require insulation materials with high performance. The insulation must endure high temperatures and high pressure for a long period. In this study, the creep effects of the insulation material XPS (extruded polystyrene foam) at high temperatures and pressure are investigated to determine whether XPS is a suitable insulation material to be applied on the inside of STES. Two studies were conducted: an isothermal long-term creep experiment and a SIM (Stepped Isothermal Method) experiment. The results of the first study were fitted using the Findley approach and extrapolated to 50 years. The SIM study is a method to accelerate creep effects using thermal effects and the Boltzmann superposition principle. Creep strain after 50 years is directly calculated by extrapolation. Both studies indicate that creep strain in XPS remains well below 6% with an applied load of 61.1 kPa at 60 °C after 50 years. Additionally, a material model that predicts creep strain at different or varying temperatures and stress was developed using the SIM data. • Creep behavior of XPS at elevated temperatures of 60 °C for 50 years. • Stepped Isothermal Method (SIM) and Findley Fit with thermal insulation material. • SIM with samples whose ratio of thickness to cross-sectional area is lower than one. • SIM with the duration and extent of the temperature steps individual for each step.

Fabrication of LiOH-metal organic framework derived hierarchical porous host carbon matrix composites for seasonal thermochemical energy storage

Fabrication of LiOH-metal organic framework derived hierarchical porous host carbon matrix composites for seasonal thermochemical energy storage

Scenarios to Decarbonize Austria’s Energy Consumption and the Role of Underground Hydrogen Storage

The European Union is aiming at reaching greenhouse gas (GHG) emission neutrality in 2050. Austria’s current greenhouse gas emissions are 80 million t/year. Renewable Energy (REN) contributes 32% to Austria’s total energy consumption. To decarbonize energy consumption, a substantial increase in energy generation from renewable energy is required. This increase will add to the seasonality of energy supply and amplifies the seasonality in energy demand. In this paper, the seasonality of energy supply and demand in a Net-Zero Scenario are analyzed for Austria and requirements for hydrogen storage derived. We looked into the potential usage of hydrogen in Austria and the economics of hydrogen generation and technology and market developments to assess the Levelized Cost of Hydrogen (LCOH). Then, we cover the energy consumption in Austria followed by the REN potential. The results show that incremental potential of up to 140 TWh for hydropower, photovoltaic (PV), and wind exists in Austria. Hydropower generation and PV is higher in summer- than in wintertime, while wind energy leads to higher energy generation in wintertime. The largest incremental potential is PV, with agrivoltaic systems significantly increasing the area amenable for PV compared with PV usage only. Battery Electric Vehicles (BEV) and Fuel Cell Vehicles (FCV) use energy more efficiently than Internal Combustion Engine (ICE) cars; however, the use of hydrogen for electricity generation significantly decreases the efficiency due to electricity–hydrogen–electricity conversion. The increase in REN use and the higher demand for energy in Austria in wintertime require seasonal storage of energy. We developed three scenarios, Externally Dependent Scenario (EDS), Balanced Energy Scenario (BES) or Self-Sustained Scenario (SSS), for Austria. The EDS scenario assumes significant REN import to Austria, whereas the SSS scenario relies on REN generation within Austria. The required hydrogen storage would be 10.82 bn m3 for EDS, 13.34 bn m3 for BES, and 18.69 bn m3 for SSS. Gas and oil production in Austria and the presence of aquifers indicates that sufficient storage capacity might be available. Significant technology development is required to be able to implement hydrogen as an energy carrier and to balance seasonal energy demand and supply.

Competitiveness of syngas biomethanation integrated with carbon capture and storage, power-to-gas and biomethane liquefaction services: Techno-economic modeling of process scenarios and evaluation of subsidization requirements

Biomethanation of biomass-derived syngas represents a promising bioenergy conversion technology that can be operated within integrated plants to deliver ancillary services such as carbon capture and storage (CCS), seasonal energy storage and fuel densification. In the present study, we developed a set of techno-economic process models considering syngas biomethanation as a core unit complemented by Power-to-Gas (PtG), pure oxygen compression, CCS, and biomethane liquefaction. Four different plant configurations and five operating modes with biomass inputs ranging between 8.4 and 60.2 MW were investigated overall, indicating biomethane yields between 0.16 and 0.48 m3 kg−1 (dry basis). An energy analysis demonstrated how intensive PtG operation delivers substantially higher biomethane cold gas efficiencies (44.4%) compared to operating modes without electrolysis (30%–34.8%). In fact, a small-scale PtG-biomethanation configuration (S-EL) delivers the lowest biomethane minimum selling price (MSP) of 1.63 € m−3. Under existing biomethane subsidies in Denmark and Italy, S-EL would achieve profitability only under stored electricity costs equivalent to approximately 50% of the current levelized cost of renewable electricity generation in the two countries, combined with maximum biomass costs of 50 and 30 € t−1, respectively. All other configurations suffer from high costs and efficiency limitations and would require subsidies equivalent to 126%–348% of the current natural gas consumer price to reach profitability. The study provides evidence to support an intensification of targeted policies that support multi-service plants, and it highlights the need for access to low electricity prices as well as the urgency for low-cost gasification technologies.

The energy, exergy, and techno-economic analysis of a solar seasonal residual energy utilization system

Building heating projects lead to massive energy consumption and carbon emissions. Despite solar energy being clean and abundant for building heating, it has a temporal mismatch issue in which the energy demand and provision are opposite in magnitude between the heating and non-heating seasons. This paper propounds an energy management strategy, which aims to use year-round solar energy efficiently by producing heat in the heating season and generating electricity from the non-heating season's solar residual energy. The results prove that it can meet most of the space heating demand of the target district and provide extra electricity in the non-heating season. The year-round solar effective utilization duration is elevated to 2.48-fold of the conventional solar heating project and the annual thermal energy storage efficiency of 91.22% manifests that solar energy can be utilized more efficiently than the seasonal storage system (< 60%) throughout the whole year. Furthermore, the life cycle cost analysis indicates that the unit energy cost of this system (0.102 €/kWh) is lower than the solar seasonal energy storage system. Therefore, the solar energy supply-demand mismatch problem is settled via this energy management strategy and it is prospective to be promoted worldwide in the future.

Modeling of a Grid-Independent Set-Up of a PV/SOFC Micro-CHP System Combined with a Seasonal Energy Storage for Residential Applications

Renewable energy sources based on solar and wind energy provide clean and efficient energy. The intermittent behaviour of these sources is challenging. At the same time, the needs for efficient, continuous and clean energy sources are increased for serving both electricity and thermal demands for residential buildings. Consequently, complimentary systems are essential in order to ensure a continuous power generation. One of the promising energy sources that helps in reducing CO2 emissions, in addition to providing electrical and thermal energy efficiently, is a Solid Oxide Fuel Cell (SOFC) system operated in a combined heat and power (CHP) mode, due to high electrical efficiencies (in full and part load) and the fuel flexibility. Currently, most studies tend to focus on fuel cell model details with basic information about the building’s energy requirements. Nevertheless, a deep understanding of integrating fuel cell micro-CHP systems with renewable energy systems for the residential sector is required. Moreover, it is important to define an operating strategy for the system with a specific controlling method. This helps in evaluating the performance and the efficiency of the building energy system. In this study, an investigation of different configurations of a hybrid power system (HPS) was carried out. The intended aim of this investigation was to optimize a HPS with minimal CO2 emissions, serving the energy demands for a single-family house efficiently and continuously. As a result of this study, a photovoltaic (PV)/SOFC micro-CHP system has satisfied the intended goal, where the CO2 emissions are significantly reduced by 88.6% compared to conventional systems. The SOFC micro-CHP plant operated as a complimentary back-up generator that serves the energy demands during the absence of the solar energy. Integrating the Power to Gas (PtG) technology leads to a similar emission reduction, while the PtG plant provided a seasonal energy storage. The excess energy produced during summer by the PV system is stored in the fuel storage for a later use (during winter). This SOFC micro-CHP configuration is recommended from an energy and environmental perspective. In terms of feasibility, the costs of SOFC based micro-CHP systems are significantly higher than traditional technologies. However, further technology developments and the effect of economy of scale may cause a substantial drop in costs and the micro-CHP shall become economically competitive and available for residential users; thus, enabling a self-sufficient and efficient energy production on site.

Scalable Gas Diffusion Electrode Fabrication for Electrochemical CO2 Reduction Using Physical Vapor Deposition Methods.

Electrochemical CO2 reduction (ECR) promises the replacement of fossil fuels as the source of feedstock chemicals and seasonal storage of renewable energy. While much progress has been made in catalyst development and electrochemical reactor design, few studies have addressed the effect of catalyst integration on device performance. Using a microfluidic gas diffusion electrolyzer, we systematically studied the effect of thickness and the morphology of electron beam (EB) and magnetron-sputtered (MS) Cu catalyst coatings on ECR performance. We observed that EB-Cu outperforms MS-Cu in current density, selectivity, and energy efficiency, with 400 nm thick catalyst coatings performing the best. The superior performance of EB-Cu catalysts is assigned to their faceted surface morphology and sharper Cu/gas diffusion layer interface, which increases their hydrophobicity. Tests in a large-scale zero-gap electrolyzer yielded similar product selectivity distributions with an ethylene Faradaic efficiency of 39% at 200 mA/cm2, demonstrating the scalability for industrial ECR applications.

A particle receiver-driven thermochemical cycle employing elemental sulphur for solar thermochemical energy storage: Investigation of particles as concentrated sunlight harvesting media and sulphur trioxide splitting catalysts

The present work is part of an approach targeted on demonstrating a concentrated solar energy-driven thermochemical cycle employing solid elemental sulphur as a chemical energy vector and a seasonal solar energy storage medium. In exploring the concept of coupling this cycle to a centrifugal particle solar receiver, bauxite-based particles, commercial and composition-modified, were tested and validated with respect to their suitability for simultaneous operation as solar energy harvesting media and sulphur trioxide splitting catalysts.Long-term catalytic activity tests exceeding 1000 h of operation at 850 °C, demonstrated that properly composition-modified bauxite particles were capable of achieving stable SO3 conversion exceeding 70% (about 80% of equilibrium value under conditions studied) and exhibiting no or negligible loss of catalytic performance after this extended operation. In addition, such composition modification enhanced the particles’ solar irradiation absorptance, which resulted in substantially higher than that of their commercial, non-modified bauxite counterparts. Commercial bauxite particles on the other hand, demonstrated much better mechanical strength, flowability, and attrition- and thermal shock resistance together with measurable, yet lower catalytic activity, which deteriorated with prolonged on-stream exposure. The combined results obtained advocate for the eventual selection of an “allothermal” cascaded sulphur trioxide splitting/sulphuric acid decomposition reactor, containing a non-moving catalytic bed that is heated indirectly by a moving bed of high-temperature (≥900 °C) non-modified commercial bauxite particles irradiated in the centrifugal solar particle receiver.

Research priorities for seasonal energy storage using electrolyzers and fuel cells

Paul A. Kempler is a research assistant professor at the University of Oregon and the Associate Director for the Oregon Center for Electrochemistry (OCE). At the OCE, he has developed three graduate laboratory courses in electrochemistry and electrochemical engineering and serves as the liaison to industry partners. His current research interests include interfacial ion transfer in energy conversion and the technoeconomic analysis of decarbonized energy systems. Paul received his PhD in chemical engineering from the California Institute of Technology for research on catalyst integration and gas evolution in photoelectrochemical cells for water splitting. John James Slack is a senior scientist at Nikola Corporation. John specializes in developing novel materials, studying their interactions, and designing nanostructured architectures within fuel cell cores. In the first two years of his career, he authored two successful proposals worth $2.7 million and has co-authored several patents related to advancing the field of fuel cell membrane electrode assemblies. He is active in the fuel cell community, regularly presenting to the Department of Energy and to the Million Mile Fuel Cell Truck Consortium. John's background is in chemical engineering, and he obtained his PhD at Vanderbilt University in 2019. Andrew M. Baker is a senior scientist at Nikola Corporation. His current research is focused on improving the performance and durability of membrane-electrode-assembly materials and accelerated stress test development for heavy-duty PEM fuel cell applications. Prior to working at Nikola, he was a scientist at Los Alamos National Laboratory. He received his PhD in mechanical engineering from the University of Delaware in 2017.