Energy conservation in traffic

This paper discusses the energy that is being wasted in the transport section in Amman due to three main factors: namely, the time delay at the major traffic light intersections, the warming up periods of vehicles, and the drag force acting on heavy vehicles. It was found that the fuel which is being used due to the first and second factors contribute 2.2 and 3.0% to the total annual fuel cost in Jordan. Finally, recommendations and suggestions are given to cut down the fuel consumption in Amman due to the above mentioned factors.     

The Advanced Energy Initiative

The President's Advanced Energy Initiative (AEI), launched in 2006, addresses the challenges of energy supply and demand facing our Nation by supporting research and development of advanced technologies for transportation and stationary power generation. The AEI portfolio includes clean coal, nuclear and renewable energy technologies (solar and wind) for stationary power generation and advanced battery technologies, cellulosic ethanol as a fuel and hydrogen fuel cells for transportation. These research and development programs are underpinned by comprehensive life-cycle analysis efforts using models such as Hydrogen Analysis (H2A) and Greenhouse Gases, Regulated Emissions and Energy Use in Transportation (GREET) to enable a better understanding of the characteristics and trade-offs associated with advanced energy options and to help decision makers choose viable pathways for clean, reliable and affordable energy.     

Energy efficiency technologies for road vehicles

A key message of the Fourth Assessment Report (AR4) of the Intergovernmental Panel on Climate Change is that improved energy efficiency is one of society’s most important instruments for combating climate change. This article reviews a range of energy efficiency measures in the transportation sector as discussed in AR4 and assess their potentials for improving fuel efficiency. The primary focus is on light-duty vehicles because they represent the largest portion of world transport energy use and carbon dioxide emissions; freight trucks, a rapidly expanding source of greenhouse emissions, are also discussed. Increasing energy efficiency can be achieved by improving the design and technology used in new vehicles, but vehicle technology is only one component of fleet fuel economy. Measures that create strong incentives for customers to take energy efficiency into consideration when buying and operating their vehicles will be crucial to policy success.

Meeting the challenges in the transport sector

This paper provides an industry leader's perspectives on the potential for transportation fuel cells, reviewing their development progress, describing their advantages and barriers, and identifying paths to successful commercial deployment. UTC Power has developed proton exchange membrane (PEM) fuel cell technology for transportation since 1998, building upon applicable innovations from the company's space fuel cell and stationary fuel cell programs. PEM fuel cell durability improvements are discussed, highlighting achievements in the understanding of decay mechanisms and the design of effective mitigations. The potential for high-volume production to make automotive fuel cells cost competitive with internal combustion engines is explained. The paper underscores the important role that initial deployment of PEM technology for transit buses can play, although development of automotive fuel cells must continue in parallel as the hydrogen infrastructure develops. Suggestions are offered on how policies and regulations, communication and education, and improved codes and standards can all help to promote the widespread use of fuel cells in transportation.     

Energy and exergy analysis of microfluidic fuel cell

Microfluidic fuel cell (MFC) is a promising fuel cell type because its membraneless feature implies great potential for low-cost commercialization. In this study, an energy and exergy analysis of MFC is performed by numerical simulation coupling computational fluid dynamics (CFD) with electrochemical kinetics. MFC system designs with and without fuel recirculation are investigated. The effects of micropump efficiency, fuel flow rate and fuel concentration on the MFC system performance are evaluated. The results indicate that fuel recirculation is preferred for MFC to gain higher exergy efficiency only if the efficiency of the micropump is sufficiently high. Optimal cell operating voltage for achieving the highest exergy efficiency can be obtained. Parasitic effect will cause a significant reduction in the exergy efficiency. An increase in the fuel concentration will also lead to a reduction in the exergy efficiency. Increasing the fuel flow rate in a MFC with fuel recirculation will cause a fluctuating variation in the exergy efficiency. On the other hand, in a one-off MFC system, the exergy efficiency decreases with increasing fuel flow rate. The present work enables better understanding of the energy conversion in MFC and facilitates design optimization of MFC.     

Gaseous products evolution during microwave pyrolysis of tire powders

Microwave pyrolysis of tire powders were run in a laboratory scale microwave oven (2.45 GHz). A special attention was dedicated to the yields of gaseous products during the microwave pyrolysis at different powers (300, 500, and 700 W). Triple-channel refinery gas chromatograph was used to quickly detect the gas composition of tire pyrolysis and its evolution during the process. H₂, CO, and CH₄, up to 90% of the total volume of pyrolytic gases, were the most predominant gaseous products. As the pyrolysis proceeded, the composition exhibited a significantly changes, e.g., more H₂ was produced and less CH₄ was generated. As the power increased, the content of CH₄ + CO₂ decreased, while the fractions of H₂ + CO rapidly increased at the intense stage of the microwave pyrolysis. The maximum yields of gaseous and liquid products and the maximum conversion of tires were obtained at 500 W.     

Energy efficiency improvements in longan drying practice

This paper presents and evaluates methods of improvement of energy utilization and reduction of energy cost in conventional unpeeled longan drying. Existing dryers were modified into a new dryer arrangement. Performance in terms of specific energy utilization, thermal efficiency and operating cost indices for both traditional and new designs was evaluated. Results showed that the modified dryer yielded an average thermal efficiency of 0.35, compared to 0.29 for the existing dryer. For the same mass of dried longan produced, specific energy utilization and fuel cost were reduced by more than 16% and 80%, respectively. The improvement was attributed to fuel switching from liquefied petroleum gas to wood, heat recovery via hot air recirculation, better temperature and humidity control, and thermal insulation. The new dryer with improved design and better energy efficiency was estimated to have payback period less than 3 years.     

Energy management of a fuel cell hybrid ultra-energy efficient vehicle

This paper focuses on energy management in an ultra-energy efficient vehicle powered by a hydrogen fuel cell with rated power of 1 kW. The vehicle is especially developed for the student competition Shell Eco-marathon in the Urban Concept category. In order to minimize the driving energy consumption a simulation model of the vehicle and the electric propulsion is developed. The model is based on vehicle dynamics and real motor efficiency as constant DC/DC, motor controllers and transmission efficiency were considered. Based on that model five propulsion schemes and driving strategies were evaluated. The fuel cell output parameters were experimentally determined. Then, the driving energy demand and hydrogen consumption was estimated for each of the propulsion schemes. Finally, an experimental study on fuel cell output power and hydrogen consumption was conducted for two propulsion schemes in case of hybrid and non-hybrid power source. In the hybrid propulsion scheme, supercapacitors were used as energy storage as they were charged from the fuel cell with constant current of 10 A.     

Energy conservation with tumbler drying in laundries

While the energy consuming process of drying paper, textiles and construction materials during manufacturing has warranted a large number of studies, the more dispersed everyday activity of laundry drying seems not to have awakened as much interest. This is perhaps because laundry drying installations are usually either domestic or comparatively small. Nevertheless, the energy used for laundry drying represents 0.5% of the total electrical energy use in Switzerland for example, and that figure is bound to be still higher in other countries. In this article it is demonstrated that conventional tumbler dryer technology is susceptible to improvement by the use of heat recovery heat exchangers. The energy recovery potential may be as high as 20% of that required for heating the drying air. The additional investment required for the heat recovery heat exchanger is paid back in less than two years of normal use.     

Recycled tire crumb rubber anodes for sustainable power production in microbial fuel cells

One of the greatest challenges facing microbial fuel cells (MFCs) in large scale applications is the high cost of electrode material. We demonstrate here that recycled tire crumb rubber coated with graphite paint can be used instead of fine carbon materials as the MFC anode. The tire particles showed satisfactory conductivity after 2-4 layers of coating. The specific surface area of the coated rubber was over an order of magnitude greater than similar sized graphite granules. Power production in single chamber tire-anode air-cathode MFCs reached a maximum power density of 421 mW m⁻², with a coulombic efficiency (CE) of 25.1%. The control graphite granule MFC achieved higher power density (528 mW m⁻²) but lower CE (15.6%). The light weight of tire particle could reduce clogging and maintenance cost but posts challenges in conductive connection. The use of recycled material as the MFC anodes brings a new perspective to MFC design and application and carries significant economic and environmental benefit potentials.     

A global survey of hydrogen energy research,development and policy

Several factors have led to growing interest in a hydrogen energy economy, especially for transportation. A successful transition to a major role for hydrogen will require much greater cost-effectiveness, fueling infrastructure, consumer acceptance, and a strategy for its basis in renewable energy feedstocks. Despite modest attention to the need for a sustainable hydrogen energy system in several countries, in most cases in the short to mid term hydrogen will be produced from fossil fuels. This paper surveys the global status of hydrogen energy research and development (R&D) and public policy, along with the likely energy mix for making it. The current state of hydrogen energy R&D among auto, energy and fuel-cell companies is also briefly reviewed. Just two major auto companies and two nations have specific targets and timetables for hydrogen fuel cells or vehicle production, although the EU also has an aggressive, less specific strategy. Iceland and Brazil are the only nations where renewable energy feedstocks are envisioned as the major or sole future source of hydrogen. None of these plans, however, are very certain. Thus, serious questions about the sustainability of a hydrogen economy can be raised.     

Dehydrogenation of perhydro-N-ethylcarbazole under reduced total pressure

Liquid organic hydrogen carrier (LOHC) systems represent a promising storage option for hydrogen produced from renewable electricity by water electrolysis. Regarding the efficiency of the endothermal hydrogen release reaction, this technology greatly benefits from a direct heat integration with the waste heat of the energetic use of the released hydrogen, e. g. in a fuel cell. To enable such beneficial set-up, the reaction temperature of hydrogen release must be below the operation temperature of the applied fuel cell which calls for both low temperature dehydrogenation catalysis and high temperature fuel cell operation. This paper demonstrates that such combination may be suitable if reduced pressure dehydrogenation of perhydro-N-ethylcarbazole (H12-NEC) is combined with hydrogen electrification in a high temperature polymer electrolyte membrane fuel cell (HT-PEMFC). Dehydrogenation reactions of H12-NEC were carried out between 160 °C and 200 °C applying different hydrogen partial pressures in the dehydrogenation unit to mimic the effect of a sucking fuel cell operation mode, i.e. the reduction of hydrogen partial pressure in the dehydrogenation unit caused by the fuel cell operation. Our kinetic analysis reveals that a dehydrogenation temperature of 180 °C combined with 500 mbar hydrogen partial pressure represent, for example, a suitable parameter set for efficient hydrogen release.     

Well-to-wheel study of passenger vehicles in the Norwegian energy system

For the evaluation of potential routes for production and application of hydrogen in a future energy system, well-to-wheel (WtW) methodologies provide a means of comparing overall impacts of technologies and fuels in a consistent and transparent manner. Such analysis provides important background information for decision makers when implementing political incentives for the conversion to more environmentally friendly energy production and consumption. In this study, a WtW approach was applied in order to evaluate the energetic and environmental impacts of introducing hydrogen in the transportation sector, in terms of energy efficiency and emissions of CO₂ and NO_x, under conditions relevant for the Norwegian energy system. The hydrogen chains were compared to reference chains with conventional fuels.     

Experimental study on clamping pressure distribution in PEM fuel cells

To study the effect of internal pressure distribution on the performance of a PEM fuel cell, a pressurized endplate was designed and fabricated. The endplate had a built-in hydraulically pressurized pocket with a thin wall facing the fuel cell assembly. Pressure sensitive films were used to measure the pressure distribution for both conventional and newly designed end plates. Fuel cell performance tests were conducted under selected conditions. It was found that the pressure distribution for the newly designed endplates was more uniform than for the conventional end plates, and an improved fuel cell performance was obtained with the newly designed end plates as well.     

Hydrogen pressure drop characteristics in a fuel cell stack

Research on hydrogen pressure characteristics was performed for a fuel cell stack to supply a rule of hydrogen pressure drop for flooding diagnostic systems. Some experiments on the hydrogen pressure drop in various operating pressure, temperature, flowrate and stack current conditions were carried out, and hydrodynamic calculation was managed to compare with the experiment results. Results show that the hydrogen pressure drop is strongly affected by liquid water content in the flow channel of fuel cells, and it is not in normal relation with flowrate when the stoichiometric ratio is inconstant. The total pressure drop can be calculated by a frictional pressure loss formula accurately, relating with mixture viscosity, stack temperature, operating pressure, stoichiometric ratio and stack current. The pressure drop characteristics will be useful for predicting liquid water flooding in fuel cell stacks before flow channels have been jammed as a diagnostic tool in electric control systems.     

Energy conservation on Nova Scotia farms: Baseline energy data

Direct energy use is a small but essential component of the farm greenhouse gas (GHG) budget. Improvements in energy efficiency and renewable energy can help reduce farm operating costs, improve air quality and reduce GHG emission levels. Energy conservation is especially important in Nova Scotia (NS), Canada, where fossil fuels, particularly coal, remain the primary source of electrical generation. Responses from mail surveys were used to establish baseline data on a cross-section of NS farms with respect to direct energy costs and usage to demonstrate differences in farm type and size. A 32% (N=224) response rate was achieved. Based on this survey, the average energy bill for a NS farm in 2004 was $11,228, with most (61.7%) of their energy cost attributable to the purchase of petroleum products. Almost all farmers (96.4%) indicated that their energy cost was a primary concern. Farmers identified the operation of vehicles and mobile equipment, as well as lighting and heating as having the greatest energy requirements in their operations. Energy usage varied with farm type and size. NS farms consumed 1.2 petajoules of energy equivalent to 127 kilotonnes of CO₂ with 52.7% of emissions from electricity use in 2004.     

Effect of nonuniformity of the contact pressure distribution on the electrical contact resistance in proton exchange membrane fuel cells

Electrical contact resistance (ECR) is one of the most important factors affecting the ohmic loss in proton exchange membrane (PEM) fuel cells. Dominated by the contact pressure at the interface of two neighboring components, the ECR can be reduced by increasing the clamping force applied on fuel cell stack. However, too large a clamping force will result in excessive resistance to the transport of reactants in the gas diffusion layer (GDL) and even damage to the fuel cell components. Therefore, for a given clamping force, the minimum ECR is expected by making the pressure distribution as uniform as possible. This paper investigates two questions: (a) how to evaluate the distribution of non-uniform pressure based on the ECR, and (b) in what situation will a uniform pressure distribution reduce the ECR obviously, i.e., the sensitivity of the contact resistance to the pressure distribution.     

电厂锅炉风机的节能分析

从风机在电厂中的应用现状着手,分析了电厂风机的节能途径。通过对风机的几种变速装置的经济性分析,得出选用变频调速装置节能是非常有效的,同时也为其它风机行业高效率利用能源提供了相关依据。     

Reactant recirculation system utilizing pressure swing for proton exchange membrane fuel cell

To minimize the wastage of supplied reactant, fuel cells need to be operated in either dead-end or recirculation modes. A fuel cell operating in a dead-end mode is not durable without periodic purging because of flooding; therefore, a little reactant is unavoidably wasted. Conventional recirculation systems employ mechanical pumps or ejectors as their recirculation devices, but they have drawbacks originating from the inherent properties of pumps and ejectors. This paper proposes a pumpless reactant recirculation system, the pressure swing recirculation system, which utilizes pressure swings produced by the reactant supply and consumption. This system requires only two check valves and a fluid control device, and operates by alternating between the equivalent flow-through and dead-end modes. The proposed system was applied for both anode and cathode of a PEMFC. A single cell was operated in dead-end and pressure swing recirculation modes for comparative analyses. The resultant cell performances in the dead-end mode deteriorated rapidly because of flooding, while those in the pressure swing recirculation using high-purity reactants were stable and durable over 10 h. The experimental results demonstrated that the pressure swing operation could expel the product water from the cell, and operations over 10 h were achievable as long as the purity of the supplied reactants was high enough.     

Energy conservation through recycling

A critical review of the literature is used to suggest best estimates of the energy savings due to recycling one tonne of a number of materials. the use of these estimates is demonstrated by a number of illustrative applications. Substantial energy savings may be made by recycling most metals or paper. the savings from reclaiming glass cullet are marginal, although there is considerable potential for energy conservation through the substitution of returnable for non-returnable bottles. the recycling of materials already saves some 5 per cent of the U.K. total energy requirement, and this contribution could potentially be doubled. the recovery of fuel products and/or materials from solid waste is also shown to be an attractive and efficient energy source.