Strategies for Improving Anion Exchange Membrane Fuel Cell Performance by Optimizing Electrode Conditions

We systematically study anion exchange membrane fuel cells (AEMFCs) based on poly(aryl-co-aryl piperidinium) (c-PAP) copolymers and provide a scalable scenario for high-performance AEMFCs, covering the optimization of the relative humidity (RH), catalyst species, catalyst interfaces, and hydrophobic treatment. Specifically, high-water-permeable c-PAP ionomers in the presence of moderate relative humidity (RH) (75%/100%) can be used to address anode flooding and cathode dry-out issues. The composition of the catalyst layer and the anode hydrophobic treatment significantly impact the power density of AEMFCs. c-PAP-based AEMFCs with optimum catalyst composition achieve a peak power density (PPD) of 2.70 W cm-2 at 80 oC in H2-O2 after hydrophobic treatment. Pt1Co1/C cathode-based AEMFCs reach a PPD of 1.80 W cm-2 along with an outstanding specific power of 13.87 W mg-1. Moreover, these AEMFCs can be operated under a 0.2 A cm-2 current density at 60 oC for over 300 h with a voltage decay rate of ~300 μv h-1.

CO2 Capture from IGCC by Low-Temperature Synthesis Gas Separation

Capture conditions for CO2 vary substantially between industrial point sources. Depending on CO2 fraction and pressure level, different capture technologies will be required for cost- and energy-efficient decarbonisation. For decarbonisation of shifted synthesis gas from coal gasification, several studies have identified low-temperature CO2 capture by condensation and phase separation as an energy- and cost-efficient option. In the present work, a process design is proposed for low-temperature CO2 capture from an Integrated Gasification Combined Cycle (IGCC) power plant. Steady-state simulations were carried out and the performance of the overall process, as well as major process components, were investigated. For the baseline capture unit layout, delivering high-pressure CO2 at 150 bar, the net specific power requirement was estimated to 273 kJe/kgCO2, and an 85% CO2 capture ratio was obtained. The impact of 12 different process parameters was studied in a sensitivity analysis, the results of which show that compressor and expander efficiencies, as well as synthesis gas separation temperature, have the highest impact on power requirements. Modifying the process to producing cold liquid CO2 for ship transport resulted in 16% increase in net power requirements and is well suited for capturing CO2 for ship transport.

The metabolic cost of turning right side up in the Mediterranean spur-thighed tortoise (Testudo graeca)

Armoured, rigid bodied animals, such as Testudines, must self-right should they find themselves in an inverted position. The ability to self-right is an essential biomechanical and physiological process that influences survival and ultimately fitness. Traits that enhance righting ability may consequently offer an evolutionary advantage. However, the energetic requirements of self-righting are unknown. Using respirometry and kinematic video analysis, we examined the metabolic cost of self-righting in the terrestrial Mediterranean spur-thighed tortoise and compared this to the metabolic cost of locomotion at a moderate, easily sustainable speed. We found that self-righting is, relatively, metabolically expensive and costs around two times the mass-specific power required to walk. Rapid movements of the limbs and head facilitate successful righting however, combined with the constraints of breathing whilst upside down, contribute a significant metabolic cost. Consequently, in the wild, these animals should favour environments or behaviours where the risk of becoming inverted is reduced.

Coupling aqueous zinc batteries and perovskite solar cells for simultaneous energy harvest, conversion and storage

Simultaneously harvesting, converting and storing solar energy in a single device represents an ideal technological approach for the next generation of power sources. Herein, we propose a device consisting of an integrated carbon-based perovskite solar cell module capable of harvesting solar energy (and converting it into electricity) and a rechargeable aqueous zinc metal cell. The electrochemical energy storage cell utilizes heterostructural Co2P-CoP-NiCoO2 nanometric arrays and zinc metal as the cathode and anode, respectively, and shows a capacity retention of approximately 78% after 25000 cycles at 32 A/g. In particular, the battery cathode and perovskite material of the solar cell are combined in a sandwich joint electrode unit. As a result, the device delivers a specific power of 54 kW/kg and specific energy of 366 Wh/kg at 32 A/g and 2 A/g, respectively. Moreover, benefiting from its narrow voltage range (1.40–1.90 V), the device demonstrates an efficiency of approximately 6%, which is stable for 200 photocharge and discharge cycles.

Evaluating multifunctional efficiency of a structural battery composite via thermo-electro-chemical modelling

The emerging research field of structural batteries aims to combine the functions of load bearing and energy storage to improve system-level energy storage in battery-powered vehicles and consumer products. Structural batteries, when implemented in electric vehicles, will be exposed to greater temperature fluctuations than conventional batteries in EVs. However, there is a lack of published data regarding how these thermal boundary conditions impact power capabilities of the structural batteries. To fill this gap, the present work simulates transient temperature-dependent specific power capabilities of high aspect ratio structural battery composite by solving one-dimensional heat transfer equation with heat source and convective boundary conditions. Equivalent circuit modeling of resistivity-induced losses is used with a second-order finite difference method to examine battery performance. More than 60 different run configurations are evaluated, examining how thermal boundary conditions and internal heat influence power capabilities and multifunctional efficiency of the structural battery. The simulated structural battery composite is shown to have good specific Young’s modulus (79.5 to 80.3% of aluminum), a specific energy of 158 Wh/kg, and specific power of 41.2 to 55.2 W/kg, providing a multifunctional efficiency of 1.15 to 1.17 depending on configuration and thermal loading conditions and demonstrating the potential of load-bearing structural batteries to achieve mass savings. This work emphasizes the dependency of power efficiency on cell design and external environmental conditions. Insulating material is shown to improve multifunctional efficiency, particularly for low ambient temperatures. It is demonstrated that as cell temperature increases due to high ambient temperature or heat generation in the battery, the specific power efficiency increases exponentially due to a favorable nonlinear relation between ionic conductivity and cell temperature. The simulations also demonstrate a thermal feedback loop where resistivity-induced power losses can lead to self-regulation of cell temperature. This effect reduces run-averaged losses, particularly at low ambient temperature.

The effect of power use on specific investments: the moderating role of interdependence structure

PurposePower use widely exists in buyer–supplier relationships (BSRs). Different directions of power use (i.e. buyer's power use and supplier's power use) intertwining with different types of power (i.e. coercive and noncoercive power) make it insufficient to regard power use as a single construct when examining its effect on a firm's following response. Besides, interdependence structure characterized by joint dependence and dependence asymmetry may influence the effect of a specific power use by shaping the firm's interpretation and cognition toward the relationship. Specifically, this study examines how four types of power use a buyer facing and an interdependence structure with its supplier affect its specific investments to the supplier.Design/methodology/approachThis study tests the proposed relationships using regression analysis, based on data from 240 manufacturing firms in China on their perceived relationships with their major suppliers.FindingsResults show that buyer's coercive power use (BCP) negatively affects buyer's specific investments while noncoercive power use (BNP) does not play a significant role. Both supplier's coercive power use (SCP) and noncoercive power use (SNP) are positively related to buyer's specific investments. Joint dependence positively moderates the effect of BNP and dependence asymmetry negatively moderates the effects of BCP and SNP on buyer's specific investments.Originality/valueThis study contributes to the literature on power use by identifying different types of power use and their different roles in influencing buyer's specific investments. The study also contributes to the literature on interdependence structure by demonstrating the different roles of joint dependence and dependence asymmetry.

Self-Balancing Supercapacitor Energy Storage System Based on a Modular Multilevel Converter

Energy Storage Systems (ESS) are an attractive solution in environments with a high amount of renewable energy sources, as they can improve the power quality in such places and if required, can extend the integration of more renewable sources of energy. If a large amount of power is needed, then supercapacitors are viable energy storage devices due to their specific power, allowing response times that are in the range of milliseconds to seconds. This paper details the design of an ESS that is based on a modular multilevel converter (MMC) with bidirectional power flow, which reduces the number of cascaded stages and allows the supercapacitors SCs to be connected to the grid to perform high-power transfers. A traditional ESS has four main stages or subsystems: the energy storage device, the balancing system, and the DC/DC and DC/AC converters. The proposed ESS can perform all of those functions in a single circuit by adopting an MMC topology, as each submodule (SM) can self-balance during energy injection or grid absorption. This article analyses the structure in both power flow directions and in the control loops and presents a prototype that is used to validate the design.

Global Growth in Offshore Wind Turbine Technology

Due to the commissioning of floating wind units, the latest technological developments, significant growth, and improvements in turbines, developments in offshore wind power capacity are estimated to increase faster than in the last two decades. The total installed offshore wind power capacity, which is currently 35 GW, is predicted to be approximately 382 GW by 2030 and approximately 2,002 GW by 2050. For this reason, attempts are proposed to lower levelised cost of electricity (LCOE) for offshore wind power generation more than for other energy sources. In this study firstly, the global growth in the nominal capacity and size of offshore wind turbines over the last twenty years is examined. Then, the effects of this increase in nominal capacity and size on the LOCE, total installation cost (TIC), and turbine capacity factor are investigated. In parallel with this development, the changes in distance to shore and water depth for installation offshore wind power plants are reviewed according to the years. In addition, the effects of this global growth on wind farm capacity, turbine-specific power capacity, number of turbines per GW, and area needed per GW are investigated and discussed in detail.

Uncovering Contributing Factors to Interruptions in the Power Grid: An Arctic Case

Electric failures are a problem for customers and grid operators. Identifying causes and localizing the source of failures in the grid is critical. Here, we focus on a specific power grid in the Arctic region of Northern Norway. First, we collected data pertaining to the grid topology, the topography of the area, the historical meteorological data, and the historical energy consumption/production data. Then, we exploited statistical and machine-learning techniques to predict the occurrence of failures. The classification models achieve good performance, meaning that there is a significant relationship between the collected variables and fault occurrence. Thus, we interpreted the variables that mostly explain the classification results to be the main driving factors of power interruption. Wind speed of gust and local industry activity are found to be the main controlling parameters in explaining the power failure occurrences. The result could provide important information to the distribution system operator for implementing strategies to prevent and mitigate incoming failures.

Layout analysis of compressed air and hydraulic energy storage systems for vehicles

The compressed air energy storage system has a better energy density, while the widely used hydraulic one is superior in power performance. Therefore, they are suitable for different hybrid vehicles, which require a comparative study on the performances and vehicle applicability of the broad pressure energy storage system layouts. In this paper, an integrated mathematical model of four basic pressure layouts is presented for characteristic analysis and applicability discussion. Results show that the open volume layout achieves the best power performance with the flow specific power of 13.92 MJ/m3, thus it is suitable for heavy hybrid trucks and mobile machinery. The open mass layout achieves the best energy performance with the energy density of 124.35 MJ/m3, which can be used in light new energy passenger vehicles. And the performance of the closed volume layout is close to the open volume layout with the flow specific power of 9.78 MJ/m3, so it could be applied to middle and light hybrid trucks. This research provides a basis for the hybrid method of pressure energy storage system layouts for vehicles, and could be applied in the design and research of non-electric hybrid vehicles in the near future.