Balance Of Plant Research Articles

Technical and Economic Analysis of Pemfcs and DMFCs for Material Handling Applications

There has been tremendous growth in the material handling industry partially driven by the fast-growing logistics industry. As the major transport equipment, forklift trucks powered by internal combustion engine and petroleum-driven fuels such as gasoline, diesel, or liquefied petroleum gas (propane) historically dominate the forklift industry. Within the 850,000 total forklifts in use across the United States, there are only more than 20,000 forklifts driven by fuel cells. Based on available forklift deployment data between 2004 and 2014, it is estimated that only about 6% of fuel-cell forklifts are driven by DMFC. DMFC-driven forklifts have huge growth potentials due to its low infrastructure cost, low fuel cost, and easy handling of liquid methanol. As a result, the research team will analyze the technical and economic feasibility of DMFCs as the next generation power source for the material handling industry.Preliminary analyses have compared the life cycle cost (LCC) of PEMFC forklifts and DMFC forklifts. The analyses include the cost of fuel cell components, balance of plant (BOP), system assembly, fuel cost, performance of the fuel cell, as well as the average operating conditions of Class I, II, and III forklifts. If the hydrogen price is assumed to be $8/kg, the min LCC ($36,682) of the PEM fuel cell is reached at a moderate current density (533 mA/cm2). Due to the high price of hydrogen, the fuel cost over the lifetime ($26,415 or 72%) is counted for the majority of LCC while the cost of infrastructure and fuel cell installation ($10,267 or 28%) makes up the rest of LCC. The LCC of PEM fuel cell is very sensitive to the hydrogen price. When the hydrogen price varies between $4/kg and $12/kg, the LCC changes between $23,079 and $49,691.The min LCC ($43,308) of the DMFC is reached at a similar current density (591 mA/cm2). Even though DMFC has much lower efficiency (27%) at the min LCC than PEM fuel cell (60%), the fuel cost of DMFC over lifetime ($17,273) is lower than that of the PEM fuel cell because hydrogen price is at least an order of magnitude higher than methanol price per heating value. Since DMFC uses much more PGM catalyst than PEM fuel cell to generate the same amount of power, DMFC’s installation cost accounts for the majority (60%) of DMFC’s LCC. Comparisons between the LCCs of DMFC and PEMFC indicate that DMFC could be a more economic feasible technology than PEMFC for Class I and II forklifts in relatively small warehouses with less than a dozen forklifts and/or if the hydrogen price is high (>$10/kg).

High-Efficiency Reversible Hydroxide Exchange Membrane Fuel Cells

Reversible fuel cells have advantages over rechargeable batteries due to their high energy density, minimal self-discharge, and low cost. Reversible hydroxide exchange membrane fuel cells (HEMFCs) are attractive due to their ability to work with platinum-group-metal (PGM)-free catalysts. HEMFCs and hydroxide exchange membrane electrolyzers (HEMELs) have been separately studied. However, it remains a challenge to integrate the two into a single reversible cell. The major factors that limit the development of unitized reversible HEMFCs are low performance of bifunctional oxygen catalysts, hydroxide membrane stability, hydroxide ion conductivity and water management. Previous research has been focusing on electrolyte-fed HEMELs 1. However, the corrosive alkaline solution presents material compatibility problems and increases the system and balance of plant (BOP) complexity. For example, the presence of alkaline solutions can increase the complexity of the unitized reversible fuel cell system due to adding extra water purging steps during the transition between electrolyzer mode and fuel cell mode.In this study, we have developed a pure water-fed reversible HEMFC which makes it possible to use stainless steel to replace the titanium current collectors commonly used in proton exchange membrane electrolyzers (PEMELs) to reduce the manufacturing cost. We have made tremendously progress to make the HEMFC reversible without the addition of alkaline or bicarbonate electrolyte. This is the first reported reversible HEMFC with the highest round trip efficiency (RTE) at an appreciable current density (48% @ 0.5 A/cm2). The reversible test result is shown in Figure 1. In addition to the initial RTE evaluation, we also achieved promising MEA stability. However, a voltage increase was also observed in the initial stage of the durability test which is presumptively attributed to the ionomer wash-out and catalyst layer restructuring. These challenges have been addressed by innovative electrode design. Acknowledgement: The project is finacially supported by the Department of Energy's HFTO under the Grant DE-EE0008438. Reference: Abbasi, R., Setzler, B. P., Lin, S., Wang, J., Zhao, Y., Xu, H., Pivovar, B., Tian, B., Chen, X., Wu, G., Yan, Y., A Roadmap to Low‐Cost Hydrogen with Hydroxide Exchange Membrane Electrolyzers. Mater.2019, 31, 1805876 Figure 1

Microporous Layer Design for High Performing Open-Cathode Polymer Electrolyte Membrane Fuel Cells

Polymer electrolyte membrane fuel cells (PEMFCs) are a key sustainable energy source which can cater for energy demands ranging from miniature power requirements to portable, automotive and various stationary power applications. PEMFCs deliver electricity by means of undergoing electrochemical reactions and produce water and heat as by-products. At high current densities, flooding and overheating can cause local hot spots leading to degradation and failure of the membrane electrode assembly (MEA) during long term operations [1]. Hence, hygrothermal management is normally ensured by means of liquid cooling of the bipolar plates. However, this traditional design incurs extra cost of balance-of-plant (BOP) components and enhances the overall size of the system. Using ambient air as oxidant as well as coolant with an ‘open-cathode’ design can drastically reduce the system size and weight, however the performance of such a system is limited by overheating and drying of the MEA.The objective of the present work is to develop a suitable microporous layer (MPL) design for efficient cell performance of an open-cathode PEMFC system operating at hot ambient air conditions. A pre-validated comprehensive, 3D computational fuel cell model [2] is used to study the mass, momentum and heat balance inside the system along with water transport and current distribution in various components of the system. The gas diffusion layer (GDL) comprised of a bi-layer macroporous substrate and MPL structure is one of the key components of the overall system design and plays a significant role in water transport inside the cells [3]. Whereas in conventional liquid-cooled systems, the presence of a hydrophobic MPL can facilitate wicking of liquid water out of the MEA to prevent oversaturation and flooding [4], ‘open-cathode’ fuel cells are more likely to experience drying than flooding and may therefore benefit from alternate MPL designs. As shown in Figure 1, thinner MPLs (30 μm) with higher porosity (60%) are found to result in elevated open-cathode cell performance as a result of optimum water retention and O2 diffusion across the MPL. The increment in performance is found to be broadly visible at higher current densities, where mass transport effects are more dominant. The MPL effective diffusivity which is a function of its porosity along with the MPL thickness are also found to be important for the overall thermal and water balance of the MEA. The optimum RH and temperature levels achieved in the MEA are further found to negate the overheating and drying effects obtained in earlier system designs.AcknowledgmentsThis work was supported by the funding provided by Simon Fraser University and Indian Oil R&D Centre under the SFU-IOCL joint PhD program in clean energy.

Dynamic modelling of the helium-cooled DEMO fusion power plant with an auxiliary boiler in Apros

The Demonstration Fusion Power Plant (DEMO) project aims to construct and successfully operate an industrial size tokamak fusion power plant generating electricity and supplying it to the grid. In order to succeed in this task, several challenges in the current fusion technologies have to be overcome. One key challenge is related to the pulsed operation of the machine and adoption of conventional power conversion systems, which are usually designed for their continuous operation. The DEMO balance-of-plant systems have to be designed to manage a periodical drop in fusion heat production during the dwell period. A configuration utilizing an Auxiliary Boiler (AUXB) between the helium-cooled Primary Heat Transfer System (PHTS) and the Power Conversion System (PCS) have been studied over the course of several years within the EUROfusion Balance of Plant (BoP) work package. In such arrangement the AUXB provides necessary power to maintain ∼50 % power generation conditions in the PCS during dwell time. KIT developed a realistic PCS scheme and performed steady-state balance analysis for pulse and dwell operation of DEMO with the simulation tool Ebsilon®. To complement the static analyses VTT has made a model of the same configuration with the Apros® system code. Dynamic analyses have been performed to assess plant performance during power cycles consisting of transitions from pulse to dwell and back to pulse operation. The goal of present study was to verify that the developed balance-of-plant concept is feasible, to establish and optimize a plausible control strategy minimizing various stresses on the components, i.e. enhancing reliability of DEMO operation, moreover, providing input for further improvements. It was concluded that although in certain aspects (e.g. steam qualities and deaerator pressure) the model showed acceptable behavior, on the other hand considering turbine pressures and feedwater temperatures the AUXB power was not sufficient to maintain the desirable conditions during dwell as postulated by Ebsilon Heat Balance.

ESTIMATION OF THERMAL POWER PLANT WORKERS EXPOSURE TO MAGNETIC FIELDS AND SIMULATION OF HAZARD ZONES.

Extremely low-frequency magnetic fields (ELF-MFs) have raised some concerns due to their possible effects on workers' health. In this study ELF-MFs were measured in different units of the thermal power plant based on gridding the indoor space. The exposure level was measured by spot measurement based on the IEEE Std C95.3.1 and then simulated in units with the highest magnetic field intensity by using ArcGIS software. The operators and balance of plant (BOP) technicians (12.64±9.74μT) and office workers (2.41±1.22μT) had the highest and lowest levels of both measured and estimated ELF-MFs exposure. The highest measured ELF-MFs were in the vicinity of the power transmission lines in the transformers' building (48.2 μT). Our simulation showed the high and low exposure areas and ranked exposure well; but, the actual measurements of ELF-MFs exposure were in all cases higher than the estimated values, which means we still need to improve our estimations.

A Portable Direct Methanol Fuel Cell Power Station for Long-Term Internet of Things Applications

With regard to the best electro-chemical efficiency of an active direct methanol fuel cell (DMFC), the stacks and their balance of plant (BOP) are complex to build and operate. The yield of making the large-scale stacks is difficult to improve. Therefore, a portable power station made of multiple simpler planar type stack modules with only appropriate semi-active BOPs was developed. A planar stack and its miniature BOP components are integrated into a semi-active DMFC stack module for easy production, assembly, and operation. An improved energy management system is designed to control multiple DMFC stack modules in parallel to enhance its power-generation capacity and stability so that the portability, environmental tolerance, and long-term durability become comparable to that of the active systems. A prototype of the power station was tested for 3600 h in an actual outdoor environment through winter and summer. Its performance and maintenance events are analyzed to validate its stability and durability. Throughout the test, it maintained the daily average of 3.3 W power generation with peak output driving capability of 12 W suitable for Internet of Things (IoT) applications.

An Optimized Balance of Plant for a Medium-Size PEM Electrolyzer: Design, Control and Physical Implementation

The progressive increase in hydrogen technologies’ role in transport, mobility, electrical microgrids, and even in residential applications, as well as in other sectors is expected. However, to achieve it, it is necessary to focus efforts on improving features of hydrogen-based systems, such as efficiency, start-up time, lifespan, and operating power range, among others. A key sector in the development of hydrogen technology is its production, renewable if possible, with the objective to obtain increasingly efficient, lightweight, and durable electrolyzers. For this, scientific works are currently being produced on stacks technology improvement (mainly based on two technologies: polymer electrolyte membrane (PEM) and alkaline) and on the balance of plant (BoP) or the industrial plant (its size depends on the power of the electrolyzer) that runs the stack for its best performance. PEM technology offers distinct advantages, apart from the high cost of its components, its durability that is not yet guaranteed and the availability in the MW range. Therefore, there is an open field of research for achievements in this technology. The two elements to improve are the stacks and BoP, also bearing in mind that improving BoP will positively affect the stack operation. This paper develops the design, implementation, and practical experimentation of a BoP for a medium-size PEM electrolyzer. It is based on the realization of the optimal design of the BoP, paying special attention to the subsystems that comprise it: the power supply subsystem, water management subsystem, hydrogen production subsystem, cooling subsystem, and control subsystem. Based on this, a control logic has been developed that guarantees efficient and safe operation. Experimental results validate the designed control logic in various operating cases, including warning and failure cases. Additionally, the experimental results show the correct operation in the different states of the plant, analyzing the evolution of the hydrogen flow pressure and temperature. The capacity of the developed PEM electrolysis plant is probed regarding its production rate, wide operating power range, reduced pressurization time, and high efficiency.

Diagnosis of a hydrogen-fueled 1-kW PEMFC system based on exergy analysis

In this study, a model based diagnosis of a hydrogen-fueled 1-kW proton exchange membrane fuel cell (PEMFC) system was conducted based on exergy analysis to identify faulty components. Faulty components of balance of plant (BOP) were experimentally simulated by reducing the rpm signals of the pump, fan, and air and fuel blowers; reducing the output signals of the air and fuel flow meters; increasing the output signal of the temperature sensor; opening the valve between the air blower and the air flow meter; and blocking the heat exchange area during the operation of the PEMFC system. The irreversibility rate, malfunction (MF) and dysfunction (DYS) of each component were calculated for the case under normal condition and simulated failure conditions using the observed data. The residuals of the MF and relative malfunction (RMF) between the normal and failure conditions were the fault indicators used to identify the faulty components in the system. The proposed diagnosis method employing both the MF and the RMF was found to be not only simple but also effective.

Study on Polymer Electrolyte Fuel Cells with Nonhumidification Using Metal Foam in Dead-Ended Operation

Portable power sources have attracted increasing interest and attention, with a focus on the reduction of the system volume. Thus, portable power sources often use polymer electrolyte fuel cell (PEFC) systems with dead-ended operation—which are simpler and more fuel-efficient than conventional PEFC systems. In these systems, the fuel may be supplied under nonhumidified conditions to minimize the balance of plant (BOP). In recent studies, metal foams have been used as flow fields to improve fuel diffusion and water management in the PEFC; the performance can be compared to that of a conventional channel. This study compared the performance and water management ability of channel and metal foam flow fields under nonhumidified conditions with dead-ended operation. The results demonstrate that the average output was similar for both flow fields. In terms of fuel efficiency, the PEFC with the metal foam could be operated for a significantly longer time without purging than that with the channel.

A Computational Analysis on the Operational Behaviour of Open-Cathode Polymer Electrolyte Fuel Cells

Polymer electrolyte membrane fuel cell (PEMFC) is a promising sustainable energy conversion technology to replace conventional fossil fuel based applications. The products of the fuel cell operation are electricity, water, and heat. A common strategy to achieve high power density is to operate at high current densities. However, the rate of heat generation is approximately proportional to the current density and waste heat removal is therefore a challenge for high power density systems. Overheating can cause drying of the conductive polymeric membrane inside the cell causing significant ohmic loss. It can also create local hot spots in the membrane electrode assembly (MEA) that are susceptible to degradation [1]. Hence, liquid coolant such as water or other thermal fluids is used in conventional PEMFCs by embedding separate cooling channels in the flow field plates. However, this type of cooling adds extra balance-of-plant (BOP) components into the system. This can be eliminated by using air as both oxidant and coolant, which is denoted as ‘open-cathode’ design. Even though open-cathode systems considerably reduce BOP cost [2], the open-cathode cell performance is limited by ambient air quality and temperature. The objective of the present work is to simulate the operational behaviour of open-cathode PEMFCs in order to better understand their performance limitations compared to conventional, liquid cooled cells. A comprehensive, 3D computational fuel cell model was developed for this purpose and utilized to study the operational and hygrothermal behaviour of an open-cathode PEMFC at various ambient conditions. Furthermore, the distribution of different cell parameters was analysed across the cell and a relationship was established that the temperature gradient across the cell guides the humidity distribution and hence the overall water management in the cell. These parameters contribute to the net membrane conductivity of the cell which dictates the actual cell performance. Overheating in such kind of a system was found to be key factor limiting the net cell performance while in operation at moderate and higher current densities. The results obtained were also compared with an equivalent liquid cooled cell and a cell operating in hypothetical isothermal condition at similar operating conditions as described in Figure 1. These three sets of modelling results clearly distinguish the operational behaviour of an open-cathode cell against that of a liquid cooled cell and also draws conclusion on factors affecting the low cell performance for an open-cathode system. The results from the study also suggests the inlet air flow rate to be crucial in terms of heat extraction. The net cell performance shifts upwards cushioning the gap between an open-cathode system and a liquid cooled system operating at similar conditions when the inlet air flow rate is increased optimally. AcknowledgementsThis work is supported by the funding provided by Indian Oil R&D and Simon Fraser University under the SFU-IOCL joint PhD program in clean energy. Funding from Natural Sciences and Engineering Research Council of Canada, Canada Foundation for Innovation and British Columbia Knowledge Development Fund is appreciated. This research was undertaken, in part, thanks to funding from the Canada Research Chairs program.

Solid Oxide Electrolyzer System Operational at the H2 Refueling Station of Karlsruhe

AbstractThe tenth H2 refueling station of the German federal state of Baden‐Württemberg was commissioned on September 6, 2017. The Karlsruhe H2 refueling station, located at the multi‐fuels station of Total, is the first one equipped with an onsite hydrogen production using a solid oxide electrolyzer (SOE) system. In the present work, details about the SOE system equipment are reported. Electrical consumption of the integrated stacks module (ISM) and the hot balance of plant (BoP) for steam generation and inlet gas pre‐heating, was monitored during 240 h of steady‐state operation under 100% steam. The average cell voltage of the 90 cells composing the ISM was 1.35 V at 0.4 A cm−2 current density. ISM efficiency was around 91.5% HHVAC considering 100% faradaic efficiency and including the conversion of the AC/DC power supply. Due to the consumption of the hot BoP and system auxiliaries for safety and control, achieved overall system efficiency was 61.4% HHVAC. Independently from electric steam production, around 10% reduction of the ISM electricity consumption could be feasible with the optimization of the inlet air flowrate. Indeed, adapting the inlet air flowrate as function of the outlet hydrogen flowrate would allow reducing the electricity need for inlet air pre‐heating.

Development of a Novel High Efficiency, Low Cost Hybrid SOFC/Internal Combustion Engine Power Generator

The unique and beneficial characteristics of solid oxide fuel cell (SOFC) technology hold much promise for their eventual widespread adoption in numerous residential and commercial building applications. Nevertheless, cost and durability challenges remain that currently limit SOFC technology penetration in stationary energy applications. Under the U.S. DOE ARPA-E INTEGRATE program, the Colorado School of Mines and it partners are developing a novel hybrid stationary power system comprised of an intermediate temperature (600°C), solid oxide fuel cell stack integrated with a high efficiency stationary engine and novel balance-of-plant (BOP) equipment. In collaboration with Colorado State University, Kohler Power Systems, and Air-Squared, Inc., the project aims to demonstrate a system that can generate power (125 kW) from natural gas at high electric efficiency (>70%-LHV), and low cost (<900 $/kW). Project activities on the hybrid SOFC/IC engine system development and system requirements are discussed.

Experimental Analysis for Thermal Performance of Heat Distribution System in hot BoP of 2 kW‐class SOFC

AbstractThis study designed and tested the components of hot balance of plant (BoP) included in a 2 kW‐class solid oxide fuel cell (SOFC) system and evaluated their thermal performance. A Pd/Pt catalytic combustor was fabricated as a component of hot BoP, and integrated hot BoP with an efficient structure was fabricated by calculating the heat transfer rates of the air preheater and steam generator through a theoretical design method. It was found that placement of the air preheater in front of the steam generator exhibited the most excellent heat transfer rate. Moreover, the heat transfer rates of the designed air preheater and steam generator exceeded the upper limit of the maximum possible heat transfer of the preheated air and the water. In experimental results, the thermal efficiency of the integrated system was 60% at the reference heat input and 70% at low heat input. The oxidizing flame of the catalyst was visualized, and the oxidation characteristics of the catalytic combustor were analyzed by measuring the concentration of the final discharged gas, that is, carbon monoxide (CO). This study helps to fabricate the integrated hot BoP system, as it provides design techniques and efficient system configuration.

Modeling and load follow simulation of CPR1000 Nuclear Power Plant implementing Mechanical Shim control strategy

Load follow operation without changing soluble boron concentration is desirable for reasons of economic efficiency, automatic control capability and effluent reduction. Many researchers have investigated the implementations of Mechanical Shim (MSHIM) strategy to different types of Pressurized Water Reactors (PWRs) to achieve this goal. However, their studies mainly focused on reactor core calculations. This paper presents the modeling and load follow simulation of the CPR1000 Nuclear Power Plant (NPP) implementing MSHIM operation and control strategy in MATLAB/Simulink environment. The whole plant model consists of the Nuclear Steam Supply System (NSSS) and the Balance of Plant (BOP) system. The NSSS model consisting of the one-dimensional nodal reactor core model, nonequilibrium three-region pressurizer model and nonlinear, time-dependent lumped parameters U-Tube Steam Generator (UTSG) model was first developed. The BOP system model including dynamic models of key components, piping lines and valves was also developed. These models were then integrated in MATLAB/Simulink according to their coupled relationships with relevant control systems built to obtain the whole plant simulation model. Based on this model, the typical 12-3-6-3/100-50-100 daily load follow maneuvers with constant soluble boron concentrations at the Beginning of Cycle (BOC) and End of Cycle (EOC) were simulated under the MSHIM control strategy. The simulation results have demonstrated the feasibility and safety of the CPR1000 NPP implementing MSHIM control strategy to achieve daily load follow operations at both BOC and EOC. This study could offer a reference to the engineering application of MSHIM control strategy as well as whole plant simulations of PWRs.

Advancements in the Helium-Cooled Pebble Bed Breeding Blanket for the EU DEMO: Holistic Design Approach and Lessons Learned

The helium-cooled pebble bed (HCPB) blanket is one of the two concepts proposed as a driver blanket for the European Union Demonstration Fusion Power Reactor (EU DEMO). In contrast to past conceptual design studies, in the frame of the current Power Plant Physics and Technology of the EUROfusion Consortium, the ongoing EU DEMO preconceptual design activities have adopted a holistic and integrated (i.e., systems engineering) design approach. As a consequence of this new approach, many interfaces and requirements have been identified, some of them driving the design of the blankets. This paper shows the advancements in the HCPB breeding blanket and describes the lessons learned after implementing the new approach. This new set of requirements has led us to reconsider fundamental aspects of the HCPB blanket design, especially in the way of how the heat is extracted from the blanket. Among others, the requirement to achieve a mature balance of plant (BOP) system plays a central role as a key design driver and has forced us to reduce pressure drops in the breeding blanket. In this regard, the blanket has been redesigned, leading to an enhanced concept based on single-module segments with a hexagonal matrix of fuel-breeder pins. Both the fuel-breeder pins and the first wall (FW) are equipped with turbulence promoters (augmented wall roughness in the fuel-breeder pins and V-ribs in the FW), following a similar idea as in the past MAGNOX, Advanced Gas Reactor (AGR), and Gas Cooled Reactor (GCR) programs in fission. This has led to minimizing the pressure drops while maximizing the heat transfer. Also, the blanket outlet temperature has been extended to 520°C, following the same principle as in Generation IV’s GCRs of maximizing the temperature difference across the core to minimize the reactor mass flow rate and thus the circulating power. All these features have led to a remarkably low plant circulating power (80 to 90 MW) and the required power per helium blower (5 to 6 MW), which potentially solves the key long-standing problem of the BOP technology readiness level for an ≈2.4-GW(thermal) helium-cooled DEMO reactor.

On the thermal dynamic behaviour of the helium-cooled DEMO fusion reactor

The EU-DEMO conceptual design is being conducted among research institutions and universities from 26 countries of European Union, Switzerland and Ukraine. Its mission is to realise electricity from nuclear fusion reaction by 2050. As DEMO has been conceived to deliver net electricity to the grid, the choice of the Breeding Blanket (BB) coolant plays a pivotal role in the reactor design having a strong influence on plant operation, safety and maintenance. In particular, due to the pulsed nature of the heat source, the Primary Heat Transfer System (PHTS) becomes a very important actor of the Balance of Plant (BoP) together with the Power Conversion System (PCS). Moreover, aiming to mitigate the potential negative impact of plasma pulsing on BoP equipment, for the DEMO plant is also being investigated a “heat transfer chain” option which envisages an Intermediate Heat Transfer System (IHTS) equipped with an Energy Storage System (ESS) between PHTS and PCS. Within this framework, a preliminary study has been carried out to analyse the thermal dynamic behaviour of the IHTS system for the Helium-Cooled Pebble Bed (HCPB) BB concept during pulse/dwell transition which should be still considered as the normal operating mode of a fusion power plant. Starting from preliminary thermal-hydraulic calculations made in order to size the main BoP components, the global performances of DEMO BoP have been quantitatively assessed focusing the attention on the attitude of the whole IHTS to smooth the sudden power variations which come from the plasma. The paper describes criteria and rationale followed to develop a numerical model which manages to simulate simple transient scenarios of DEMO BoP. Results of numerical simulations are presented and critically discussed in order to point out the main issues that DEMO BoP has to overcome to achieve a viable electricity power output.

Thermal Management of Dynamic Operation of Solid Oxide Cell-Based Energy Storage System for 2 Renewable Electricity Scenarios

The increasing contribution of renewable energy sources (RES) to the power generation sector has motivated researchers to devise new methods for reliable energy storage systems. The significance of mechanisms for storing large amounts of electricity for longer time-scales is accentuated by the dynamics of renewable electricity generation that depend upon the season of the year, time of day, and the location. Conventional large-scale electricity storage technologies such as pumped-hydro and compressed-air storage systems are limited by geographical features (e.g., access to a cavern or high elevations). Traditional rechargeable batteries are limited by the fact that energy and power capacities do not scale independently. One of the promising and multipurpose techniques for storing electricity from these fluctuating renewable sources such as wind and solar, is conversion of the electric power to sustainable and carbon free gaseous fuel like hydrogen (power-to-gas (P2G)). In fact, owing to its diverse applications and worthwhile features such as high gravimetric energy density, hydrogen has become an attractive means of delivering renewable energy to many heavy-duty transport and industrial processes that are difficult to electrify. The renewable hydrogen produced from these zero emission electricity sources could be stored in caverns or injected into existing natural gas grids, initially at low concentrations as mixed with natural gas and ultimately piecewise replacing natural gas in the system. The stored hydrogen could be utilized in transportation for fuel cell electric vehicles (FCEV), in power generation for stationary fuel cells or in chemical industries as a feedstock for chemical synthesis of low-carbon fuels or other products, enabling the eventual decarbonization of all energy conversion. One of the efficient and cost-effective techniques for electrochemical conversion of electricity to hydrogen is steam electrolysis using solid oxide electrolysis cells (SOEC). The steam electrolysis reaction is intrinsically an endothermic reaction for which the required energy is to be supplied as electricity or heat or a combination of both. High temperature electrolyzers, such as SOEC, benefit from both lower energy required for the electrochemical reactions and an ability to provide part of the endothermic energy demand with the heat content of the inlet streams. At high current densities, SOEC can operate exothermically, meaning that the heat generation due to the losses and electricity supply are greater than the endothermic energy demand. When the SOEC systems are connected to intermittent renewable sources like solar or wind, the varying electricity profile will cause the SOEC operation to dynamically switch between endothermic to exothermic modes and all levels of endothermicity and exothermicity in between. This transient behavior of the electrolyzer could lead to highly dynamic thermal response that could have detrimental effects on thermal stress and degradation. In this work, an energy storage system (ESS) is designed in Matlab/Simulink which simulates the dynamic operation of an integrated SOEC system applied to an intermittent RES. The main focus of the research is the thermal management of the SOEC stack during highly dynamic operation throughout the entire operating regime from highly endothermic to thermo-neutral and to highly exothermic operation. An additional thermal management challenge is to keep the SOEC system hot during periods of non-operation (hot standby). These challenges are addressed in the current work by a novel system design that integrates a solid oxide fuel cell (SOFC) with the SOEC and combines several control strategies within the balance of plant (BoP). For thermal balance of the system the SOFC exothermicity is used to reduce the dependence of the system on electric heaters. The SOFC system oxidizes a fraction of the renewable hydrogen produced by SOEC and generates heat and electricity. A heat exchanger network is designed to convey the SOFC heat to the SOEC for a wide range of endothermic conditions. The main function of SOFC is to keep the SOEC warm when it is not operating or when it is operating in highly endothermic regions. The proposed configuration is integrated with 2 different patterns of electricity production from RES: one representing measured wind dominant RES such as that in Germany, and one representing solar dominant RES such as that in California. Dynamic analysis of the system in terms of the electric power generated by RES for these 2 conditions is presented. The response of different parameters in the system to keep the integrated system warm, self-sustaining, and within desired limits for lower thermal stress and degradation are presented. These parameters include required SOFC power, voltage and temperature profiles of both SOEC and SOFC, BoP parasitic consumption, system efficiencies, hydrogen production amounts, consumption, and storage levels during transient operation.

Progress in the design development of EU DEMO helium-cooled pebble bed primary heat transfer system

In the frame of the activities promoted and encouraged by the EURO-fusion Power Plant Physics and Technology (PPPT) department aimed at developing the EU-DEMO fusion reactor, strong emphasis has been recently posed to the whole Balance of Plant (BoP) which represents the set of systems devoted to convert the plasma generated thermal power into electricity and to deliver it to the grid. Among these systems, a very important role is played by the Breeding Blanket (BB) Primary Heat Transfer System (PHTS) as it is responsible to extract more than 80% of the fusion plasma power.In this framework, University of Palermo, Ansaldo Nucleare and CREATE have focused their work to improve thermal-hydraulic, safety and integration features of the Ex-Vessel PHTS for the Helium-Cooled Pebble Bed (HCPB) BB concept of DEMO.Starting from the outcomes obtained in 2016 that have allowed to highlight some criticalities which needed design changes, the paper describes progress and developments of the 2017 HCPB PHTS as well as the goals which have been achieved. The results of the research activity carried out show, in fact, i) an increase of the thermal-hydraulic performances, since a reduction in both total coolant inventory and total pressure drop has been respectively reached, ii) a potential improvement of the overall safety characteristics of the system. Nevertheless a critical assessment of these key parameters reveals that some issues are still open in terms of design integration and feasibility of the whole DEMO BoP for the helium-cooled blanket option, indicating that additional efforts are required to make this technology more attractive.

Calculation of Domestic Raw Materials Using Domestic Resource Cost Method

BATAN, as one of the research institutes, development and utilization of nuclear power, considers establishing and operating non-commercial or experimental power reactors (RDEs). RDE is a nuclear reactor for electricity generation, heat for various industrial processes and producing hydrogen on an experimental scale. One option of RDE type used is High Temperature Gas Cooled Reactor (HTGR). HTGR has distinctive characteristics that are different from other types of power plants but on the other hand has the same general components as other conventional power plants, especially civil structures such as the use of portland cement for the manufacture of concrete in the nuclear island (NI) and the balance of plant (BOP). The purpose of this research is to obtain the readiness of Indonesian industry in its contribution in the development of RDE, especially the saving of foreign exchange so that it can be used as one of the basic considerations in decision making and the policy of NPP development. The methodology used is the method of calculating Domestic Resource Cost (DRC) and literature study. The results obtained are the Indonesian cement production in the period 2010-2016 can generate or save foreign exchange because the value of DRC coefficient less than 1 so it has a comparative advantage, contribute to economic development, and improve the standard of living of the people.

Industry supported improved design of DEMO BoP for HCPB BB concept with energy storage system

The EU Demonstration Fusion Reactor (DEMO) Balance of Plant (BoP) configuration studied consists of the Primary Heat Transfer System (PHTS), the Intermediate Heat Transfer System (IHTS), using HITEC salt as coolant, equipped with a thermal Energy Storage System (ESS), and the Power Conversion System (PCS). This configuration is capable of producing electricity continuously through the pulse time (2 h), as well as dwell time (10 min) of the plant operation. The DEMO BoP development process was supported by industrial partners: Siemens Power and Gas Division and Kraftanlagen Heidelberg (KAH). The efficiency of the proposed Rankine cycle of the PCS is obtained to be not less than 39%. While elaborating the improved DEMO BoP design, KIT developed a plant model using the industrial code EBSILON®.