Overview on nanostructured membrane in fuel cell applications

Fuel cells are expected to soon become a source of low- to zero-emission power generation for applications in portable technologies and electric vehicles. Allowing development of high quality solid electrolytes and production of smaller fuel cells, significant progress has been made in the development of fuel cell membranes using nanotechnology. Nanostructures have been recognized as critical elements to improve the performance of fuel cell membranes. This paper provides an overview of research and development of nanostructured membranes for different fuel cell applications and focuses on improvement of fuel cell membranes by these nanostructures. Theoretical studies using molecular-scale modeling and simulation of fuel cell membranes have also been included in this review. Other issues regarding the technology limitations, research challenges and future trends are also reviewed.     

SOFC-APU systems for aircraft: A review

This review brings together publications in the form of articles, reports, theses and patents related to the use of solid oxide fuel cells in aircraft with a focus on replacing the current auxiliary units with a hybrid system. The potential advantages and main challenges of the new technology are reported, indicating some possible trends in this technology. However, even after many studies, some initial challenges remain. For example, the hybrid system did not achieve the necessary weight-efficiency-ratio, and there seems to be no consensus on the choice of the best fuel. We conclude that the most viable short-term applications appear to be unmanned units, particularly because of security issues and low technology maturity. Smaller power applications, in which the new system is responsible for peripheral services such as a power supply for air conditioning, toilets, and heating up food, are candidates to enter the market in the short or medium term. In the long term, applications for fully electric aircraft and clean fuels will certainly be the focus of larger aircraft manufacturers.     

A review of polymer electrolyte membrane fuel cells: Technology,applications, and needs on fundamental research

Polymer electrolyte membrane (PEM) fuel cells, which convert the chemical energy stored in hydrogen fuel directly and efficiently to electrical energy with water as the only byproduct, have the potential to reduce our energy use, pollutant emissions, and dependence on fossil fuels. Great deal of efforts has been made in the past, particularly during the last couple of decades or so, to advance the PEM fuel cell technology and fundamental research. Factors such as durability and cost still remain as the major barriers to fuel cell commercialization. In the past two years, more than 35% cost reduction has been achieved in fuel cell fabrication, the current status of $61/kW (2009) for transportation fuel cell is still over 50% higher than the target of the US Department of Energy (DOE), i.e. $30/kW by 2015, in order to compete with the conventional technology of internal-combustion engines. In addition, a lifetime of ∼2500 h (for transportation PEM fuel cells) was achieved in 2009, yet still needs to be doubled to meet the DOE’s target, i.e. 5000 h. Breakthroughs are urgently needed to overcome these barriers. In this regard, fundamental studies play an important and indeed critical role. Issues such as water and heat management, and new material development remain the focus of fuel-cell performance improvement and cost reduction. Previous reviews mostly focus on one aspect, either a specific fuel cell application or a particular area of fuel cell research. The objective of this review is three folds: (1) to present the latest status of PEM fuel cell technology development and applications in the transportation, stationary, and portable/micro power generation sectors through an overview of the state-of-the-art and most recent technical progress; (2) to describe the need for fundamental research in this field and fill the gap of addressing the role of fundamental research in fuel cell technology; and (3) to outline major challenges in fuel cell technology development and the needs for fundamental research for the near future and prior to fuel cell commercialization.     

Solar-powered hydrogen refuelling station for unmanned aerial vehicles: Design and initial AC test results

Fuel cell technology can offer environmental benefits (low noise and emissions) and also a competitive advantage over conventional power sources (better performance, low thermal signature, less vibration issues, etc) in small manned and unmanned electric air vehicles (UAVs). To develop an environmentally acceptable solution, the hydrogen fuel source must be produced on-site from renewable energy sources. This paper describes the development and testing of a fully operational small-scale demonstrator to generate and supply hydrogen for 2 to 3 daily fuel cell-powered UAV operations. The purity of the hydrogen delivered to the air platforms is ≥99.99%.     

Advancements and current technologies on hydrogen fuel cell applications for marine vehicles

Maritime industry has led renewable energy sources for the greener environment and efficient vehicles that effect by increasing population and energy demands. Hydrogen is one of the most popular of these renewable energy sources and one of the most favourable research area, worldwide. In this study, authors reported the usage of hydrogen fuel cells in marine transport as main power forwarder, their advantages and challenges under the lights on state of art and furthermore new technologies perspective. The latest research activities, hydrogen production and storage methods with challenges are analyzed and the developments of fuel cell based marine vehicles are discussed. In detailed, newly approachment of electrolyses from seawater for sustainable fuel necessity is discussed. As a result, this forseen study is important in terms of handling energy from seawater and compiling the latest technology for marine transport.     

Research progress on biomass-derived carbon electrode materials for electrochemical energy storage and conversion technologies

Electrochemical energy technologies such as fuel cells, supercapacitors, and batteries are some of the most suitable energy storage and conversion devices to meet our needs proving the future generation’s equitable opportunity to meet their own needs. For this purpose, an earth-abundant precursor such as biomass is the best candidate for the synthesis of the next generation of low-cost and green electrode materials. This review summarizes the most recent progress in biomass-derived carbons for use in fuel cells, supercapacitors and lithium-ion batteries, the physical-chemical properties, desired features, performances, and limitations for electrochemical energy technologies. Several thermochemical treatments such as chemical activation, template methods, doping and hydrothermal treatments have been reviewed. Finally, we provide the reader with comprehensive information of the challenges, future research efforts, advantages, limitations and opportunities which will be a fundamental insight for the future design of biomass-derived carbon electrode materials for electrochemical storage and conversion systems.     

Fuel cell systems for long-endurance autonomous underwater vehicles – challenges and benefits

Autonomous underwater vehicles (AUVs) are programmable, robotic vehicles that can drift, drive, or glide through the ocean without real-time control by human operators. AUVs that also can follow a planned trajectory with a chosen depth profile are used for geophysical surveys, subsea pipeline inspection, marine archaeology, and more. Most AUVs are followed by a mother ship that adds significantly to the cost of an AUV mission. One pathway to reduce this need is to develop long-endurance AUVs by improving navigation, autonomy and energy storage. Long-endurance AUVs can open up for more challenging mission types than what is possible today. Fuel cell systems are a key technology for increasing the endurance of AUVs beyond the capability of batteries. However, several challenges exist for underwater operation of fuel cell systems. These are related to storage or generation of hydrogen and oxygen, buoyancy and trim, and the demanding environment of the ambient seawater. Protecting the fuel cell inside a sealed container brings along more challenges related to condensation, cooling and accumulation of inert gases or reactants. This paper elaborates on these technical challenges and describes the solutions that the Norwegian Defence Research Establishment (FFI) has chosen in its development of a fuel cell system for long-endurance AUVs. The reported solutions enabled a 24 h demonstration of FFI's fuel cell system under water. The remaining work towards a prototype sea trial is outlined.     

Hydrogen energy systems for underwater applications

The most critical development in conventional underwater applications in recent years is to use hydrogen energy systems, including Air Independent Propulsion (AIP) systems. Proton Exchange Membrane (PEM) fuel cell-powered AIP systems increase interest worldwide. They offer many advantages such as longer endurance time without going to the surface for 2–3 weeks or without snorkeling with an average speed, perfectly silent operation, environmentally friendly process, high efficiency, and low thermal dissipation underwater. PEM fuel cells require a continuous source of hydrogen and oxygen as reactants to sustain a chemical reaction to produce electrical energy. Hydrogen storage is the critical challenge regarding the quality of supplied hydrogen, system weight, and volume. This paper reviewed hydrogen/oxygen storage preferences coupled with PEM Fuel Cell applications in the literature for unmanned underwater vehicles. Since underwater vehicles have different volume and weight requirements, no single hydrogen storage technique is the best for all underwater applications.     

Large-vscale hydrogen production and storage technologies: Current status and future directions

Over the past years, hydrogen has been identified as the most promising carrier of clean energy. In a world that aims to replace fossil fuels to mitigate greenhouse emissions and address other environmental concerns, hydrogen generation technologies have become a main player in the energy mix. Since hydrogen is the main working medium in fuel cells and hydrogen-based energy storage systems, integrating these systems with other renewable energy systems is becoming very feasible. For example, the coupling of wind or solar systems hydrogen fuel cells as secondary energy sources is proven to enhance grid stability and secure the reliable energy supply for all times. The current demand for clean energy is unprecedented, and it seems that hydrogen can meet such demand only when produced and stored in large quantities. This paper presents an overview of the main hydrogen production and storage technologies, along with their challenges. They are presented to help identify technologies that have sufficient potential for large-scale energy applications that rely on hydrogen. Producing hydrogen from water and fossil fuels and storing it in underground formations are the best large-scale production and storage technologies. However, the local conditions of a specific region play a key role in determining the most suited production and storage methods, and there might be a need to combine multiple strategies together to allow a significant large-scale production and storage of hydrogen.     

The possible failure mode and effect analysis of membrane electrode assemblies and their potential solutions in direct methanol fuel cell systems for portable applications

One of the major challenges in direct methanol fuel cells (DMFCs) is to design reliable and stable FC systems that satisfy the very high dynamic demand in various environmental conditions for portable devices. This paper provides an overview of several failure modes and effect analyses (FMEAs) which can have significant consequences on the durability and stability of DMFCs, including high and sub-zero temperature storage, dry and high humidification atmospheres, and fuel/oxidation starvation by breakdown of fuel/air supply components. Firstly, some characterization methods are discussed to investigate changes of membrane electrode assemblies (MEAs) in terms of their physiochemical and electrochemical properties after testing in various simulated failure modes. Secondly, possible mitigating solutions to minimize the hazards associated with them are suggested through a fundamental understanding and scientific approach. The relationship between the causes and symptoms in DMFC systems is determined by examining a variety of failure sources.