Thermal management issues in a PEMFC stack – A brief review of current status

Understanding the thermal effects is critical in optimizing the performance and durability of proton exchange membrane fuel cells (PEMFCs). A PEMFC produces a similar amount of waste heat to its electric power output and tolerates only a small deviation in temperature from its design point. The balance between the heat production and its removal determines the operating temperature of a PEMFC. These stringent thermal requirements present a significant heat transfer challenge. In this work, the fundamental heat transfer mechanisms at PEMFC component level (including polymer electrolyte, catalyst layers, gas diffusion media and bipolar plates) are briefly reviewed. The current status of PEMFC cooling technology is also reviewed and research needs are identified.     

Performance evaluation of radiant baseboards (skirtings) for room heating – An analytical and experimental approach

The aim of this study was to investigate the thermal performance of the hydronic radiant baseboards currently used for space heating in built environments. The presently available equations for determination of heat outputs from these room heaters are valid for a certain height at a specific temperature range. This limitation needed to be addressed as radiant baseboards may be both energy and cost efficient option for space heating in the future. The main goal of this study was therefore to design an equation valid for all baseboard heights (100–200 mm) and excess temperatures (9–60 °C) usually used in built environments.The proposed equation was created by curve fitting using the standard method of least squares together with data from previous laboratory measurements. It was shown that the predictions by the proposed equation were in close agreement with reported experimental data. Besides, it was also revealed that the mean heat transfer coefficient of the investigated radiant baseboards was about 50% higher than the mean heat transfer coefficient of five conventional panel radiators of different types.The proposed equation can easily be used or programed in energy simulation codes. Hopefully this will help engineers to quantify more accurately the energy consumption for space heating in buildings served by radiant baseboards.     

Thermal performance and energy saving investigation in a modified baseboard radiator and compare it with conventional heating systems—Experimental and CFD approach

In the present work, thermal performance of a new modified baseboard radiator is investigated experimentally based on the European Standard EN-442. Temperature distribution and thermal comfort conditions of the floor heating system and panel radiator is compared with the present system numerically. To validation of the simulation results, a comparison has been made between the simulation and the experimental obtained results. Comparison shows that there is a good agreement between them. The heat output rate of the new system increased about 46.06% compared with conventional baseboard radiant model and also the baseboard heating system is capable of providing better thermal comfort conditions than two other systems. Energy consumption in three systems is investigated experimentally by smart temperature control mechanism. Results show that energy consumption in the baseboard radiant is 83.03% and 55.96% lower than floor heating system and panel radiator, respectively.     

Thermal performance and embodied energy analysis of a passive house – Case study of vault roof mud-house in India

This paper investigates thermal performance of an existing eco-friendly and low embodied energy vault roof passive house (or mud-house) located at Solar Energy Park of IIT Delhi, New Delhi (India). Based on embodied energy analysis, the energy payback time for the mud-house was determined as 18 years. The embodied energy per unit floor area of R.C.C. building (3702.3 MJ/m²) is quiet high as compared to the mud-house (2298.8 MJ/m²). The mud-house has three rooms with inverted U-shape roof and remaining three rooms with dome shape roof. A thermal model of the house consisting of six interconnected rooms was developed based on energy balance equations which were solved by using fourth order Runge Kutta numerical method. The predicted six room air temperatures were found in good agreement with the experimental observed data on hourly basis in each month for one year. The annual heating and cooling energy saving potential of the mud-house was determined as 1481 kW h/year and 1813 kW h/year respectively for New Delhi composite climate. The total mitigation of CO₂ emissions due to both heating and cooling energy saving potential was determined as 5.2 metric tons/year. The annual carbon credit potential of mud-house was determined as € 52/year. Similar results were obtained for the different climatic locations in India.     

Energy use in Indian household sector – An actor-oriented approach

Over the years, significant changes have taken place with regard to the type as well the quantity of energy used in Indian households. Many factors have contributed in bringing these changes. These include availability of energy, security of supplies, efficiency of use, cost of device, price of energy carriers, ease of use, and external factors like technological development, introduction of subsidies, and environmental considerations. The present paper presents the pattern of energy consumption in the household sector and analyses the causalities underlying the present usage patterns. It identifies specific (groups of) actors, study their specific situations, analyse the constraints and discusses opportunities for improvement. This can be referred to “actor-oriented” analysis in which we understand how various actors of the energy system are making the system work, and what incentives and constraints each of these actors is experiencing. It analyses actor linkages and their impact on the fuel choice mechanism. The study shows that the role of actors in household fuel choice is significant and depends on the level of factors – micro, meso and macro. It is recommended that the development interventions should include actor-oriented tools in energy planning, implementation, monitoring and evaluation. The analysis is based on the data from the national sample survey (NSS), India. This approach provides a spatial viewpoint which permits a clear assessment of the energy carrier choice by the households and the influence of various actors. The scope of the paper is motivated and limited by suggesting and formulating a powerful analytical technique to analyse the problem involving the role of actors in the Indian household sector.     

SusDesign – An approach for a sustainable process system design and its application to a thermal power plant

This paper presents a structured process design approach, SusDesign, for the sustainable development of process systems. At each level of process design, design alternatives are generated using a number of thermodynamic tools and applying pollution prevention strategies followed by analysis, evaluation and screening processes for the selection of potential design options. The evaluation and optimization are carried out based on an integrated environmental and cost potential (IECP) index, which has been estimated with the IECP tool. The present paper also describes a flowsheet optimization technique developed using different thermodynamic tools such as exergy/energy analysis, heat and mass integration, and cogeneration/trigeneration in a systematic manner.The proposed SusDesign approach has been successfully implemented in designing a 30 MW thermal power plant. In the case study, the IECP tool has been set up in Aspen HYSYS process simulator to carry out the analysis, evaluation and screening of design alternatives.The application of this approach has developed an efficient, cost effective and environmentally friendly thermal system design with an overall thermal efficiency of 70% and CO₂ and NO emissions of 0.28 kg/kW h and 0.2 g/kW h respectively. The cost of power generation is estimated as 4 ¢/kW h. These achievements are significant compared to the conventional thermal power plant, which demonstrates the potential of the SusDesign approach for the sustainable development of process systems.     

Towards a low carbon energy future – Renewable energy cooperation between Germany and Norway

Renewable energy is a cornerstone of German climate change policies. Germany has adopted particularly ambitious renewable energy targets, and is now implementing an Energiewende – a transition to a nuclear-free and low-carbon energy system. The transition could be eased through European cooperation. This article investigates the economic, political, environmental and technological factors that act as drivers and barriers to renewable energy cooperation between Germany and Norway. The article finds that German actors see Norwegian electricity as a means for enhancing the stability of their electricity system as Germany shifts to a greater reliance on renewables. In Norway the picture is more mixed. Norwegian state-owned electricity producers and grid operators are interested in cooperation largely out of profit motives, but expect Germany to create a favorable environment for investors. Energy-intensive industries and consumers on the other hand, are afraid that more electricity cooperation with Germany will raise electricity prices. The Norwegian environmental movement is split on the issue. Parts of the movement see renewable energy cooperation as an important step towards a European low-carbon energy future. Nature and outdoor organizations, however, argue that new renewable energy infrastructure, including pumped-storage hydropower, will result in major environmental impacts. If cooperation is to be achieved, these economic and environmental concerns will have to be taken seriously.     

Advanced control systems engineering for energy and comfort management in a building environment—A review

Given restrictions that comfort conditions in the interior of a building are satisfied, it becomes obvious that the problem of energy conservation is a multidimensional one. Scientists from a variety of fields have been working on this problem for a few decades now; however, essentially it remains an open issue. In the beginning of this article, we define the whole problem in which the topics are: energy, comfort and control. Next, we briefly present the conventional control systems in buildings and their advantages and disadvantage. We will also see how the development of intelligent control systems has improved the efficiency of control systems for the management of indoor environment including user preferences. This paper presents a survey exploring state of the art control systems in buildings. Attention will be focused on the design of agent-based intelligent control systems in building environments. In particular, this paper presents a multi-agent control system (MACS). This advanced control system is simulated using TRNSYS/MATLAB. The simulation results show that the MACS successfully manage the user’s preferences for thermal and illuminance comfort, indoor air quality and energy conservation.     

Parametric studies of a double-cell stack of PEMFC using Grafoil™ flow-field plates

A parametric study of a double-cell stack of a proton exchange membrane fuel cell (PEMFC) using Grafoil™ flow-field plates is performed. A self-made membrane–electrode assembly (MEA) is used to integrate the PEMFC. Emphasis is placed on the effect of the transport parameters such as cell temperature, pressure and humidity of the reaction side, and flow-field geometry on the performance of the stack. Potential–current and power–current curves are presented. At a fixed dew point of the incoming reactants, say T_dp=30 °C, increasing the cell operating temperature past a threshold value of about 50 °C reduces the cell performance due to membrane dehydration. At a fixed cell operating temperature, a high flow back-pressure increases the cell performance through enhancing the reaction on both electrodes of the fuel cell. Moreover, the cell performance for the pressurised cathode side is better than that for the pressurised anode side due to the favourable back-diffusion of water in the membrane. Finally, empirical correlations are developed to describe the electrode process of the PEMFC stack under various operating conditions.     

An energy efficient Swedish pulp and paper industry – exploring barriers to and driving forces for cost-effective energy efficiency investments

Despite the need for increased industrial energy efficiency, studies indicate that cost-effective energy efficiency measures are not always implemented, which is explained by the existence of barriers to energy efficiency. This paper investigates whether this holds for the Swedish pulp and paper industry, and if so, investigates the barriers inhibiting and the driving forces stressing cost-effective energy efficiency investments. By so, this case study covers about 2% of the EU-25 industrial end-use of energy. The overall results from a questionnaire show that there is an energy efficiency gap in the sector and that the largest barriers were technical risks such as risk of production disruptions, cost of production disruption/hassle/inconvenience, technology inappropriate at the mill, lack of time and other priorities, lack of access to capital, and slim organization. As regards the driving forces for energy efficiency, the highest ranked driving forces were cost reductions resulting from lower energy use, people with real ambition, long-term energy strategy, the threat of rising energy prices, the electricity certificate system, the PFE. The results show that many of the barriers and driving forces were not solely market-related, e.g., lack of time or other priorities, slim organization, other priorities for capital investments, lack of staff awareness, and long decision chains indicate that firm-specific barriers plays an important role. These barriers may not be overcome by market-related public policy instruments but is rather a consequence of how the energy issue is organized within the firms. The second and the third largest driving forces, people with real ambition and a long-term energy strategy further support this.

Investment in oil and gas field materials technology – the key to a secure energy supply

Abstract

Many national and international programmes have renewable energies as a prime focus for long term R&D investment. This focus arises from an environmental perspective and the objective of a carbon abatement energy society, and may also be fuelled by often over-dramatised reports of declining oil and gas reserves. It is argued that investment in oil and gas must be a vital component of R&D planning and energy policy if energy supplies are to be assured, and that advances in materials and materials technologies will be key to these efforts.     

Toward greener supply chains: is there a role for the new ISO 50001 approach to energy and carbon management?

Considering the increased interest of stakeholders in climate change and a low-carbon economy, this article has investigated and identified several contributions of the ISO 50001 in support of the adoption of green supply chain management (GSCM). In this context, energy efficiency and reduced CO₂ emissions are critical. Therefore, the proposal for and the requirements of ISO 50001 can generate useful insights on how to structure green and low-carbon supply chains, hence helping to address the challenges posed by climate change.     

In-stream energy converters in a river – Effects on upstream hydropower station

The use of in-stream energy converters in rivers is an area of research that is still in its preliminary stages. The driving force of river flows is the potential energy the water gains when it precipitates on mountainsides, and this energy is traditionally converted by hydropower stations, where dams are used to create a larger head. Using an in-stream energy converter would be advantageous in areas restricted by regulation. In this paper the effects of using these converters on the upstream water level in a river are studied. This has been done both with an analytical model and with a numerical model. The analytical model described the water level increase due to energy capture to depend on how large fraction of the channel that is blocked by the turbine. It was also shown that as the converter induces drag on the flow, and as energy is lost in wake mixing, the total head loss will be a sum of energy capture and energy losses. The losses correspond to a considerable fraction of the total head drop. The numerical model was used to evaluate these results. The model used was the 3D numerical model MIKE from the DHI Group in Sweden. Turbines were modelled with an inbuilt function in the program. The results from the model did not correspond to the analytical results, as the energy capture was equal to the head drop in the program.     

Austria's wind energy potential – A participatory modeling approach to assess socio-political and market acceptance

Techno-economic assessments confirm the potential of wind energy to contribute to a low carbon bioeconomy. The increasing diffusion of wind energy, however, has turned wind energy acceptance into a significant barrier with respect to the deployment of wind turbines. This article assesses whether, and at what cost, Austrian renewable energy targets can be met under different expansion scenarios considering the socio-political and market acceptance of wind energy. Land-use scenarios have been defined in a participatory modeling approach with stakeholders from various interest groups. We calculated the levelized cost of electricity (LCOE) for all of the potential wind turbine sites, which we used to generate wind energy supply curves. The results show that wind energy production could be expanded to 20% of the final end energy demand in three out of four scenarios. However, more restrictive criteria increase LCOE by up to 20%. In contrast to common views that see local opposition against wind projects as the main barrier for wind power expansion, our participatory modeling approach indicates that even on the level of key stakeholders, the future possible contribution of wind energy to Austrian renewable energy targets reaches from almost no further expansion to very high shares of wind energy.     

Electric system management through hydrogen production – A market driven approach in the French context

Hydrogen is usually presented as a promising energy carrier that has a major role to play in low carbon transportation, through the use of fuel cells. However, such a development is not expected in the short term. In the meantime, hydrogen may also contribute to reduce carbon emissions in diverse sectors among which methanol production. Methanol can be produced by combining carbon dioxide and hydrogen, hence facilitating carbon dioxide emission mitigation while providing a beneficial tool to manage the electric system, if hydrogen is produced by alkaline electrolysis operated in a variable way driven by the spot and balancing electricity markets. Such a concept is promoted by the VItESSE² project (Industrial and Energy value of CO₂ through Efficient use of CO₂-free electricity - Electricity Network System Control & Electricity Storage). Through the proposed market driven approach, hydrogen production offers a possibility to help managing the electric system, together with an opportunity to reduce hydrogen production costs.     

Cost-effective energy carriers for transport – The role of the energy supply system in a carbon-constrained world

The aim of this study is to examine how the options for producing electricity, fuels, and heat in a carbon-constrained world affect the cost-effectiveness of a range of fuels and propulsion technologies in the transportation sector. GET 7.0, a global energy system model with five end-use sectors, is used for the analysis. We find that an energy system dominated either by solar or by nuclear tends to make biofuels in plug-in hybrids cost-effective. If coal with carbon capture and storage (CCS) dominates the energy system, hydrogen cars, rather than plug-in hybrids tend to become cost-effective. Performing a Monte Carlo simulation, we then show that the general features of our results hold for a wide range of assumptions for the costs of vehicle propulsion technologies (e.g., batteries and fuel cells). However, sufficiently large changes in say the battery costs may overturn the impact of changes in the energy supply system, so that plug-in hybrid vehicles become cost-effective even if coal with CCS dominate the energy supply. We conclude that analyses of future energy carriers and propulsion technologies need to consider developments in the energy supply system.