Fuel cells,an alternative to standard sources of energy

Three E’s are the national energy policy drivers of any country of the world, Energy security, Economic growth and Environmental protection. A fuel cell is an energy conversion device that produces electricity by electrochemically combining fuel (hydrogen) and oxidant (oxygen from the air) gases through electrodes and across an ion conducting electrolyte. The principal characteristic of a fuel cell is its ability to convert chemical energy directly into electrical energy giving much higher conversion efficiencies than any conventional thermo-mechanical system thus extracting more electricity from the same amount of fuel, operate without combustion so they are virtually pollution free and have quieter operation since there are no moving parts. The emission of fuel cells running on hydrogen derived from a renewable source will be nothing but water vapour. Fuel cells are presently under development for a variety of power generation applications in response to the critical need for a cleaner energy technology. This paper reviews the existing or emerging fuel cells technologies, their design and operation, their limitations and their benefits in connection with energy, environment and sustainable development relationship. Few potential applications of fuel cell will be discussed.     

Comparison of energy efficiency strategies in the industrial sector of Slovenia

More efficient use of energy is one of the national strategic issues for Slovenia. The new Energy Act of 1999 requires preparation of a national energy programme, to be based in part on an integrated resource planning approach at the national level. An industrial module was developed to form part of the applicable energy system analysis tools, namely a Reference Energy Model for PlaNet (PlaNet: Planning Network) under the MESAP (Modular Energy System Analysis and Planning Environment) system analysis package (Institute for Energy Economics and the Rational Use of Energy, University of Stuttgart). This bottom-up model allows for modelling of energy efficiency measures. The quandary of energy intensity versus energy efficiency was resolved by explicit presentation of a market valuation process for each industrial sector, which relates value added to a physical product indicator. Future structural changes and improvements of product value were developed, based on past trends and taking into consideration the contribution of sectors to the GDP in a “similar” country like Austria. At the process level, two strategies with different speed of introduction of energy efficiency measures were compared (Reference and Intensive) for the period from 1997 to 2020. Expedient activation of savings potentials brings economic benefits and reduction of direct and indirect greenhouse gas emissions. Improvements to internal industrial conversion systems, notably cogeneration of electricity and heat, produce a major part of the overall efficiency gains.     

Transport energy modeling with meta-heuristic harmony search algorithm,an application to Turkey

This study proposes a new method for estimating transport energy demand using a harmony search (HS) approach. HArmony Search Transport Energy Demand Estimation (HASTEDE) models are developedtaking population, gross domestic product and vehicle kilometers as an input. The HASTEDE models are in forms of linear, exponential and quadratic mathematical expressions and they are applied to Turkish Transportation sector energy consumption. Optimum or near-optimum values of the HS parameters are obtained with sensitivity analysis (SA). Performance of all models is compared with the Ministry of Energy and Natural Resources (MENR) projections. Results showed that HS algorithm may be used for energy modeling, but SA is required to obtain best values of the HS parameters. The quadratic form of HASTEDE will overestimate transport sector energy consumption by about 26% and linear and exponential forms underestimate by about 21% when they are compared with the MENR projections. This may happen due to the modeling procedure and selected parameters for models, but determining the upper and lower values of transportation sector energy consumption will provide a framework and flexibility for setting up energy policies.     

Renewable energy resource potential in Pakistan

Pakistan energy situation is seriously troubling today due to lack of careful planning and implementation of its energy policies. To avoid the worse situation in the years ahead, the country will have to exploit its huge natural renewable resource. In this paper a review is being presented about renewable energy resource potential available in the country to be exploited for useful and consistent energy supplies. On average solar global insolation 5–7 kWh/m²/day, wind speed 5–7.5 m/s, Biogas 14 million m³/day, microhydel more than 600 MW (for small units) with persistency factor of more than 80% over a year exist in the country. Solar and wind maps are presented along with identification of hot spring sites as resource of geothermal energy. The research results presented in this paper are not only useful for government policy makers, executing agencies but also for private sector national and international agencies and stake holders who want to invest in Pakistan for renewable energy projects or business.     

Input-output techniques and energy cost of commodities

This article quantifies the desirability of several methods of calculating energy cost of commodities from input-output data, using an a priori technique based on exact treatment of an artificially ‘homogenized’ A-matrix. The use of an average energy price (the same to all consuming sectors) is much inferior to the use of different prices, even if full attention is paid to indirect economic effects through use of the inverted matrix (I - A) ^?1. However, there is relatively little advantage in inserting actual energy use data into the A-matrix instead of merely premultiplying (I - A) ^?1 by an energy use vector. The latter conclusion has one important exception, pertaining to comparison of primary and secondary energy types, which is not predicted by the analysis here.     

An oriented-design simplified model for the efficiency of a flat plate solar air collector

In systems design, suitably adapted physical models are required. Different modelling approaches for a solar air collector were studied in this paper. First, a classical model was produced, based on a linearization of the conservation of energy equations. Its resolution used traditional matrix methods. In order to improve the possibilities for use in design, the behaviour of the collector was next expressed in terms of efficiency. Lastly, simplified models constructed from the results obtained with the classical linearized model, and explicitly including the design variables of the collector, were proposed. These reduced models were then evaluated in terms of Parsimony, Exactness, Precision and Specialisation (PEPS). It was concluded that one of them (D2), using a low number of variables and of equations, is well suited for the design of solar air collector coupled with other sub-systems in more complex devices such as solar kiln with energy storage.     

Large-area photovoltaics based on low band gap copolymers of thiophene and benzothiadiazole or benzo-bis(thiadiazole)

Large-area solar cells (active area=3 and 10 cm²) were prepared with low band gap polymers based on thiophene and benzothiadiazole (1) or thiophene and benzo-bis(thiadiazole) (2). The band gaps of the polymers were 1.65 and 0.67 eV, respectively. The best photovoltaic performance was obtained for the device ITO/PEDOT/1:PCBM (1:2)/Al with an active area of 3 cm². The efficiency of the device was 0.62%. This is a high efficiency for a low band gap polymer in a large-area organic solar cell and thus polymer 1 is a very promising material for organic solar cells. The devices based on 2 were found to give poor devices when employed in bulk heterojunctions with PCBM. This was linked to a poor alignment of the energy levels in 2 with that of the electrodes and PCBM, showing that the requirement for a control of the positions of the energy levels becomes increasingly important as the band gap decreases.     

Electrochemical and chemical enrichment methods of a sodic–saline inoculum for microbial fuel cells

In microbial fuel cells (MFCs) efficient extracellular electron transfer microbes, also known as anode-respiring bacteria, play an important role on cell performance. This type of microbes can be developed by application of enrichment procedures. The objective of this study was to compare a chemical (only C, final terminal electron acceptor Fe(III)), an electrochemical (only E), and a hybrid method (H, i.e., E followed by 3 serial transfers in iron (III) citrate medium) enrichment methods departing from a saline–sodic soil inoculum. In the electrochemical enrichment procedure in an electrolysis cell, the inoculum was subjected to a continuous electrical stress continually by posing the cell at −150 mV/SCE (+94 mV/SHE). The only C enrichment method delivered powers superior to the only E one (higher values of P_An,max = 49 mW m⁻² and P_V,max = 558 mW m⁻³ of C compared to 33 and 379 of only E). Interestingly, overall resistance as determined by EIS was lower for only E (1240 Ω) than for only C (1632 Ω). Yet, the hybrid H method, showed electrochemical characteristics consistently superior to both only C and only E methods (higher P_An,max and P_V,max, lower internal resistance). Further detailed electrochemical studies of only E-method showed that the anodic resistance decreased with the time of operation of the electrolysis cell that would be consistent with the adaptability/enrichment purpose of the method. Also, Cyclic voltammetry peaks with values close to those reported for bacterial cytochromes appeared with time of cell operation.     

Energy for the future: An Environmentally Resilient Strategy

ETE 21 (Energy, Technology and the Environment — a Circle to Promote Rational Action for the 21st Century) proposes technological solutions to meeting the growing needs for energy in an ecologically responsible and economically viable manner. When such technological solutions face barriers to their acceptance policy instruments may need to be considered — as a last resort. This paper considers the policy options available after briefly discussing the environmental objectives and technological solutions.Environmental Objectives need to be defined, before policy issues are addressed. In the field of human needs air rates highest, followed by water, food, shelter, comfort, power and mobility. The last three in this league table are particularly dependent on energy in modern society. Meeting he needs for energy creates repercussions higher in the league table either directly through atmospheric or water pollution or indirectly through possible climate change. ETE 21 believes that rational action would require tackling the pollutants and their direct adverse impacts. In most cases this will help relieve the indirect (and still ill-determined) effects of so-called Green House Gases.Technological solutions provide the most logical and promising option to ameliorate the impact of the use of the energy in an ecologically responsible and economically viable way. Most new technologies will enter the system through the commercial pricing mechanism. In certain cases e.g. where heavy front-end (capital) loading is involved some “greening of the invisible hand” might expedite technological penetration. Established accounting systems do not take the negative externalities (pollutants, CO₂) into account, nor social costs (health, congestion, time loss). Mechanisms are being devised to quantify such environmental costs. As such they may (via “trial and error”) help to steer public policy.Policy Options can in the first instance be confined to education, persuasion and exhortation. If these do not achieve the environmental objectives within the timescale desired, forms of intervention (dirigism) will need to be introduced. These range from Market to Mandatory Instruments, which in turn can be sub-categorised. This will be discussed in the presentation. A Resilient Strategy can be achieved by testing alternative strategies against a spectrum of environmental objectives.     

Tradable white certificate schemes: fundamental concepts

A number of European countries have introduced market-based instruments to encourage investment in energy efficiency improvement and achieve national energy savings targets. Some of these schemes are based on quantified energy savings obligations imposed on energy distributors or suppliers, coupled with a certification of the energy savings (via white certificates), and a possibility to trade certificates. The paper describes the concept and the main elements of a tradable white certificate scheme, where appropriate giving examples from existing schemes in Europe. It discusses design and operational features that are key to achieve the overall savings targets, such as delineation of the scheme in terms of obliged parties, eligible projects and technologies, institutional structure, and processes to support the scheme, such as measurement and verification. Finally, the paper looks at a number of open issues, most importantly the possibility of creating a voluntary market for white certificates via integration into the carbon market.

Breaking down the silos: the integration of energy efficiency, renewable energy, demand response and climate change

This paper explores the feasibility of integrating energy efficiency program evaluation with the emerging need for the evaluation of programs from different “energy cultures” (demand response, renewable energy, and climate change). The paper reviews key features and information needs of the energy cultures and critically reviews the opportunities and challenges associated with integrating these with energy efficiency program evaluation. There is a need to integrate the different policy arenas where energy efficiency, demand response, and climate change programs are developed, and there are positive signs that this integration is starting to occur.

Computational investigation of hydrogen storage on B6Ti3+

The structures and hydrogen storage capacities of B₆Ti₃⁺ have been theoretically investigated using DFT with PBE exchange and correlation functional. It is found that the most stable B₆Ti₃⁺01 cluster can maximally adsorb ten hydrogen molecules, which corresponds to a gravimetric uptake capacity of 8.82 wt%. The uptake capacity exceeds the 2015 target set by US Department of Energy for vehicular application. Moreover, the HOMO-LUMO gap value of B₆Ti₃⁺01 (10H₂) is larger than that of B₆Ti₃⁺01, which manifests the B₆Ti₃⁺01 will be more stable after 10H₂ adsorbed. The hydrogen adsorption energies with Gibbs free energy correction are carried out to reveal whether adsorption of hydrogen on B₆Ti₃⁺ is favorable or not at different temperatures. The results indicate that the adsorption of ten hydrogen molecules on B₆Ti₃⁺01 is energetically favorable in a fairly wide temperature range. Therefore, B₆Ti₃⁺01 is considered to be a promising material for hydrogen storage.     

Electron irradiation and thermal annealing effect on GaAs solar cells

This paper describes the effect of electron irradiation and thermal annealing on LPE AlGaAs/GaAs heterojunction solar cells with various p/n junction depths. The electron irradiation experiments were performed with energy of 3 MeV, fluences ranging from 1×10¹⁴ to 5×10¹⁵ e/cm². The results obtained demonstrate that the irradiation-induced degradation of performances of the cells is mainly in the short circuit current and could be mostly recovered by annealing at 260°C for 30 min. Four electron traps, E_c−0.24 eV, E_c−0.41 eV, E_c−0.51 eV, E_c−0.59 eV, were found by DLTS analysis, only two shallow levels of which could be removed by the annealing.     

The first principle screening and design of the high-performance organic photosensitizers based on EY2− dye in homogeneous non-noble metal photocatalytic hydrogen production system

Photocatalytic hydrogen production, capable of dissociating water to make hydrogen using sunlight as abundant and clean energy, provides a promising solution for energy crisis. However, currently dominated metal complexes photosensitizers are based on precious and rare metal elements, which prohibits large scale applications. Herein, based on the experimental dye Eosin Y (EY²⁻), we report a series of metal-free organic dyes EY^2-1- EY^2-18 and present a systematic study on their ground-state geometry, electrochemistry, energy gap, reduction potential and driving force by using density functional theory (DFT) and time-dependent DFT (TDDFT). The calculated results show that compared to other dyes, the dye EY^2-11 has a large visible light absorption range, a higher reduction potential and greater driving force, which indicates that EY^2-11 is a promising candidate for the visible-light-driven hydrogen production. Our theoretical researches are expected to provide valuable insights for designing efficient metal-free organic photosensitizers.     

Policy implications of generalised distributed lags and the estimated demand for petroleum products

In many recent analyses of energy consumption, the following functional form is assumed: Q_t = BX_t + λQ_t-1 + e_t where Q_t is a vector of consumption data, X_t is a matrix of explanatory economic variables, Q_t?1 is a vector of consumption lagged one observation period, B and λ are regression parameters to be estimated and e_t is a vector of appropriately distributed random disturbances. Although this specification is attractive in the sense that both short- and long-term elasticities can be obtained from it, it does require certain restrictive assumptions to be met in order for it to be theoretically valid. This paper tests those assumptions and finds them not met for certain petroleum products. An alternative specification is suggested and policy differences between the popular but incorrect specification and the suggested one are presented. These differences are shown to be substantial.     

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.

Energy management of an FC/UC hybrid vehicular power system using a combined neural network-wavelet transform based strategy

An energy management strategy (EMS) is one of the most important issues for the efficiency and performance of a hybrid vehicular system. This paper deals with a neural network and wavelet transform based EMS proposed for a fuel cell/ultra-capacitor hybrid vehicular system. The proposed method combines the capability of wavelet transform to treat transient signals with the ability of auto-associative neural network supervisory mode control. The main originality of the paper is related with the application of neural network instead of another intelligent control method, fuzzy logic, which is presented in the recent publication of the authors, and the combination of neural network-wavelet transform approaches. Then, the effectiveness comparison of both methods considering one of the most important points in a vehicular system, fuel consumption (or hydrogen consumption), is realized. The mathematical and electrical models of the hybrid vehicular system are developed in detail and simulated using MATLAB^®, Simulink^® and SimPowerSystems^® environments.     

Introducing technology learning for energy technologies in a national CGE model through soft links to global and national energy models

This paper describes a method to model the influence by global policy scenarios, particularly spillover of technology learning, on the energy service demand of the non-energy sectors of the national economy. It is exemplified by Norway. Spillover is obtained from the technology-rich global Energy Technology Perspective model operated by the International Energy Agency. It is provided to a national hybrid model where a national bottom-up Markal model carries forward spillover into a national top-down CGE¹ model at a disaggregated demand category level. Spillover of technology learning from the global energy technology market will reduce national generation costs of energy carriers. This may in turn increase demand in the non-energy sectors of the economy because of the rebound effect. The influence of spillover on the Norwegian economy is most pronounced for the production level of industrial chemicals and for the demand for electricity for residential energy services. The influence is modest, however, because all existing electricity generating capacity is hydroelectric and thus compatible with the low emission policy scenario. In countries where most of the existing generating capacity must be replaced by nascent energy technologies or carbon captured and storage the influence on demand is expected to be more significant.     

ACROPOLIS: An example of international collaboration in the field of energy modelling to support greenhouse gases mitigation policies

Energy models are considered as valuable tools to assess the impact of various energy and environment policies. The ACROPOLIS initiative, supported by the European Commission and the International Energy Agency, used up to 15 energy models to simulate and evaluate selected policy measures and instruments and then compare their impacts on energy systems essentially in terms of costs of greenhouse gas emissions (GHG) reduction and energy technology choice. Four case studies are formulated considering policies and measures on renewable portfolio schemes and internationally tradable green certificates, emissions trading and global GHG abatement target, energy efficiency standards and internalisation of external costs. The main focus of the project is on the electricity sector. From a large set of quantified results, ACROPOLIS provides an international scientific consensus, on some key issues, which could be useful in assessing and designing energy and environment policies at the world, European and national/regional levels. It concludes that the Kyoto targets (and their continuation beyond 2010 in specific scenarios) could be achieved at a cost around 1% of GDP through global emissions trading, indicating also that this flexibility mechanism is a more cost-effective instrument for GHG mitigation than meeting the goal domestically without trade. It demonstrates that internalising external costs through a price increase reduces local pollutants (SO_x, NO_x, and others) and it produces other benefits such as triggering the penetration of clean technologies in addition to the curbing of CO₂ emissions.     

Enhanced water splitting through different substituted cobalt-salophen electrocatalysts

Synthesis of stable catalysts for water splitting is important for the renewable and clean energy production. Here, water oxidation activities of cobalt (II) complexes CoL¹-CoL³ (1–3) with salophen type ligands (N,N′-bis(salicylidene)-4-chloro-1,2-phenylendiamine (H₂L¹), N,N′-bis(salicylidene)-4-bromo-1,2-phenylendiamine (H₂L²) and N,N′-bis(salicylidene)-4-nitro-1,2-phenylendiamine (H₂L³)) are studied by electrochemical techniques, FE-SEM images and XRD patterns. Linear sweep voltammetry studies indicate that 2 and 3 have superior activities and only require the overpotential of 316 and 247 mV vs. RHE at current density of 10 mA/cm² with Tafel slopes of 75 and 50 mVdec^?1 at pH = 11. Experiments show relationships between the stability of the complexes and their catalytic activity. It is revealed that substituents on ligands affect the catalytic behaviors. Experiments show that in the presence of 2 and 3, the complexed cobalt ions are likely candidates as molecular catalysts for water oxidation. It is speculated that the O–O bond formation occurs by oxidizing the active center of cobalt complexes.