The energy situation in OIC countries The possible contribution of renewable energy resources

The paper reviews the socioeconomic situation and energy utilization in Organization of Islamic Conference (OIC) countries which vary considerably. The review indicates that growing energy requirements are associated with economic development and population increase. Renewable energy utilization is indicated as an appropriate alternative for providing a considerable portion of future energy demand in certain energy-consuming sectors. When reviewing the present state of the art of major renewable energy technologies, particular attention is paid to both direct and indirect solar technologies. Possible adaption of renewables into the socioeconomic structures of OIC countries is discussed. The programme of action for renewables in the OIC is stressed, pointing to the priority attached to enhancing the renewable energy contribution.     

The use of natural gas and geothermal energy in school units. Greece: A case study

The ever-increasing degradation of the environment along with high demands for energy consumption in buildings has prompted many countries to use other energy sources such as natural gas and geothermal energy instead of oil.This study refers to the use of natural gas in school units in Greece. More specifically, it focuses on school units that are connected to the natural gas network and on the economic and environmental benefits arising from this.In this context, the advantages and disadvantages in using natural gas are compared with those resulting from the use of geothermal energy. In areas which have a significant geothermal potential, the choice of geothermal heating and cooling of large school units is the best solution, but this however does not apply to all areas. Clearly, the development of geothermal energy in school units is still in pilot stage.However, the use of natural gas in school units has been rising over the last decade and it has already contributed to some extent towards the reduction of carbon dioxide and towards saving natural resources. Thus, the survey shows clear advantages in using natural gas and in plans to extend its use to other school units.     

Renewable energy sources in the Egyptian electricity market: A review

This review paper presents an appraisal of renewable energy RE options in Egypt. An appraisal review of different REs is presented. The study shows that electric energy produced from REs in Egypt are very poor compared with other energy sources. The utilization of the renewable energies can also be a good opportunity to fight the desertification and dryness in Egypt which is about 60% of Egypt territory. The rapid growth of energy production and consumption is strongly affecting and being affected by the Egyptian economy in many aspects. It is evident that energy will continue to play an important role in the development of Egypt's economy in coming years. The total installed electricity generating capacity had reached around 22025 MW with a generating capacity reached 22605 MW at the end of 2007. Hydropower and coal has no significant potential increase. During the period 1981/82-2004/05 electricity generation has increased by 500% from nearly 22 TWh for the year 1981/1982 to 108.4 TWh in the year 2004/2005 at an average annual growth rate of 6.9%. Consequently, oil and gas consumed by the electricity sector has jumped during the same period from around 3.7 MTOE to nearly 21 MTOE. The planned installed capacity for the year 2011/2012 is 28813 MW and the required fuel (oil and gas) for the electricity sector is estimated to reach about 29 MTOE by the same year. The renewable energy strategy targets to supply 3% of the electricity production from renewable resources by the year 2010. Electrical Coverage Electrical energy has been provided for around 99.3% of Egypt's population, representing a positive sign for the welfare of the Egyptian citizen due to electricity relation to all development components in all walks of life. The article discusses perspectives of wind energy in Egypt with projections to generate ∼ 3.5 GWe by 2022, representing ∼9% of the total installed power at that time (40.2 GW). Total renewables (hydro + wind + solar) are expected to provide ∼7.4 GWe by 2022 representing ∼ 19% of the total installed power. Such a share would reduce dependence on depleting oil and gas resources, and hence improve country's sustainable development.     

The use of multiple criteria decision making methodologies for the promotion of RES through funding schemes in Cyprus,A review

In isolated energy systems with no indigenous sources of energy such as the one of the Republic of Cyprus, the renewable energy option is the only alternative to achieve energy independence. Though, the relative technological maturity of renewable energy sources and their satisfactory efficiencies, their implementation has not reached the expected levels in many regions. This situation is mainly due to the fact that the up-to-date efforts for their development have been underestimated and the parameters involved in drafting subsidy schemes are in some cases misinterpreted and not given the appropriate attention. Decision makers are faced with ongoing major energy challenges such as fossil fuel depletion, increasing demand, energy prices and thus the move towards a sustainable energy development is crucial and highly complicated. This paper investigates the use of MCDM methods and then implements the methods for three subsidy schemes available in Cyprus.     

Application of geographical information systems to rural electrification with renewable energy sources

This paper approaches one of the main problems of rural electrification: the choice of the most appropriate technology for each case. The main objective of this project is to apply Geographical Information Systems (GIS) to divide the research zone into areas in that are more appropriate for either conventional or renewable technologies. The approaches for choosing among the different technologies are usually technical and economic; these may be jointly considered by the leveling electric cost (LEC). Determination of the LEC is a complex task that requires knowledge of the capacity factor. This paper shows the conclusions of the technical and economic parameter analysis involved in the determination of the LEC for each technology. This analysis has allowed us to carry out proposals of improvement in the methodology of the GIS of rural electrification. The resulting GIS has been verified in the municipality of Lorca (Murcia, Spain).     

A comprehensive energy solution for households employing a micro combined cooling,heating and power generation system

In recent years, micro combined cooling, heating and power generation (mCCHP) systems have attracted much attention in the energy demand side sector. The input energy of a mCCHP system is natural gas, while the outputs include heating, cooling and electricity energy. The mCCHP system is deemed as a possible solution for households with multiple energy demands. Given this background, a mCCHP based comprehensive energy solution for households is proposed in this paper. First, the mathematical model of a home energy hub (HEH) is presented to describe the inputs, outputs, conversion and consumption process of multiple energies in households. Then, electrical loads and thermal demands are classified and modeled in detail, and the coordination and complementation between electricity and natural gas are studied. Afterwards, the concept of thermal comfort is introduced and a robust optimization model for HEH is developed considering electricity price uncertainties. Finally, a household using a mCCHP as the energy conversion device is studied. The simulation results show that the comprehensive energy solution proposed in this work can realize multiple kinds of energy supplies for households with the minimized total energy cost.     

The use of floor panel energy storage in a heat pump heated dwelling

A method of improving the performance of heat pumps for domestic space heating has been investigated. The study focuses on the short-term storage of heat pump output energy in concrete floor panels. This paper describes the dynamic computer simulation of an air to water heat pump, a floor panel energy store and energy flowpaths in a dwelling. The heating plant, controls and building thermal behaviour, were simulated as a complete energy system to enable the study of interactions between the subsystems. The model heating system comprised a number of under floor water heated panels installed in ground floor rooms of a two storey dwelling. Supplementary energy was supplied by direct electric heaters situated in most rooms. Heat pump operating periods were controlled as a function of the external air temperature within two prescribed occupancy intervals per day. Results of the investigation indicate that a heat pump system using floor panel storage and emission may be efficiently managed to provide nearly continuous heating with little supplementary energy input. The short-term storage of energy in thick floor panels allowed the heat pump to be operated for extended periods without cycling. Because of this, the seasonal loss in heat pump performance resulting from intermittent operation was less than 1 per cent. Attempting to supply the total space heating load with the heat pump and floor panel system resulted in severe overheating during periods of high solar or casual gain. Under these conditions the simple control strategy based on the measurement of external air temperature was ineffective. This problem was eliminated by reducing the heat pump energy input to the dwelling and supplying about 10 per cent of the seasonal energy demand by direct electric heaters. The influence of floor panel energy storage capacity on the performance of the heating system was investigated. Concrete panel depths of between 25 and 150 mm were considered. The seasonal system efficiency was found to increase with floor panel thickness, although not significantly with panel depths beyond 100 mm. The extensive use of floor slabs to store energy caused mean floor temperatures to be higher than when using direct electric air heaters only. However, with the depth of under floor insulation considered in the study (75 mm), heating the floor slab increased the seasonal energy loss of the building by only 4 per cent.     

天然气热电冷总能系统应用模式的探讨

我国的天然气储量相对有限，并且远离需求中心；与国际水平相比，中国的天然气价格较高。为了使天然气得到合理有效的利用，应该提高能源的利用率。针对这种情况，提出了天然气热电冷总能系统的应用模式，并对不同模式所用的几种主要动力设备进行了比较，以燃气内燃机加余热型直燃机和燃气机热泵系统为例对联结方式进行了论述。最后对系统的特点以及在国内的发展和应用情况进行了介绍，并指出了在我国的发展前景。     

Frequency control by the PV station in electric power systems with hydrogen energy storage

The rapid growth of renewable energy capacity, in particular photovoltaic systems, is creating challenges associated with changing the rate of transient processes in the power system. This is due to the approach PV systems are connected to the grid using power converters and the absence of a rotating mass in the PV power plant. One of the most pressing challenge is the participation of PV stations in the process of frequency control in power systems, including in emergency modes. Simultaneously with PV power plants, it is efficient to use energy storage systems, including hydrogen ones. This is due to the fact that it is possible to obtain hydrogen for such energy storage systems using excess energy from PV power plants. The article proposes to solve the problem of frequency regulation in the power system by using an algorithm that allows to control the frequency in the power system using a synthetic inertia block of PV station, including at different levels of insolation and temperature of PV panels. The robustness of the proposed algorithm allows it to be used at different levels of power generated by the PV station, as well as in emergency modes.     

供应不同品位工业蒸汽的1 000 MW机组能耗特性分析

为分析工业供汽机组供不同品位蒸汽的能耗特性,考虑到工业供汽机组多热用户参数及多供热汽源点的特点,建立了供热机组变工况计算及能耗特性分析模型。以某1 000 MW工业供汽机组为例,分别采用好处归电法、好处归热法、做功能力法和等效热降法研究了电负荷、中压工业热负荷、低压工业热负荷、供汽汽源点等因素对机组能耗特性的影响规律。结果表明：不同供热方式下采用同一方法计算的供热煤耗率随电负荷变化的趋势一致,随热负荷变化不大;不同供热方式下采用同一方法计算的发电煤耗率随热负荷变化的趋势一致,随电负荷变化的趋势有差异;当电负荷为620 MW、热负荷为220 t/h时,在再热热段蒸汽供中压蒸汽方式下按照好处归电法、做功能力法、等效热降法、好处归热法分配的供热煤耗率分别为37.46,26.43,25.83和22.52 kg/GJ,发电煤耗率分别为280.39,291.80,292.42和295.84 g/(kW•h)。     

Renewable sources of energy and technologies in Austria: Present situation, goals and prospects

The main goal of the energy policy of the Austrian government is, beside of a more efficient use of energy, the increase of renewable sources of energy. The technical, economical and ecological aspects of renewable sources of energy and their technologies are analysed and the present situation of renewable sources of energy in Austria and its prospects are described. Of the renewable energy carriers the following resources are of importance in Austria: hydropower, firewood, biogenic energy carriers, including fuels, solar energy and ambient heat and geothermic energy.     

Analysis of trigeneration plants: engine with liquid desiccant cooling and micro gas turbine with absorption chiller

The performances of two natural gas small‐scale trigeneration plants are dealt with in the paper. The two plants are part of a new cogeneration and trigeneration system laboratory at the Politecnico di Torino (Turin, Italy), which will be set up and exploited for scientific and technical purposes. The first plant has 126/220/210 kW electrical, heating and cooling capacities, respectively, and it is characterized by an innovative internal combustion engine (ICE) that has been coupled to a liquid LiCl–water desiccant cooling system. The other plant has 100/145/98 kW electrical, heating and cooling capacities and is composed of a micro gas turbine, coupled to a LiBr–Water absorption chiller. The aim of the paper was comparing the performances of the two plants from an energetic and economic point of view; the Primary Energy Savings are calculated for both installations through a commonly accepted methodology proposed by the European Union, and through another methodology, reported in literature, which seems more suitable to describe the energetic performances of trigeneration plants. The savings calculated with this second procedure result to be lower than those of the European Union methodology; moreover, the ICE installation always denotes higher performances with respect to the microturbine. From the economic point of view, it is evident that a fuel tax reduction for high‐efficiency cogeneration plants is an essential contribution for the support and development of these systems. Copyright © 2011 John Wiley & Sons, Ltd.     

Fast market penetration of energy technologies in retrospect with application to clean energy futures

The fast penetration of energy technologies in the past was analyzed and applied to investigate the prospects of new energy technologies. The results show that single energy sources have obtained quite a dominant position in the past. In the USA, at one time both oil and coal each represented over half of all the yearly additions to energy capacity for more than half a century and reached a dominant position in overall energy production. Oil showed a similar dominance on a global scale. For two decades nuclear power represented one third of all the new electricity added worldwide and over 60% in the countries possessing nuclear power. In some countries nuclear grew to around half of all electricity in less than just 10 years. Applying these empirical observations to new renewables and assuming similar growth conditions as for the old technologies, the share of renewable electricity could grow from its present 19% to 60% by 2050, which would drop the baseline CO₂ emissions by 27%. The share of new renewables of all electricity would come up to 42%. The rate of adoption of these new technologies would not exceed that of oil or nuclear in the past, but they would need to dominate new electricity investments from 2030 onwards. A hypothetical fast-track case for solar photovoltaics, assuming an expansion similar to that seen in the case of nuclear and oil, would lead to a 20–25% share of all electricity in 2050. An important observation is that the fast and high penetration of energy technologies implies, in most cases, a full lock-in into these, requiring a preferential position regarding investments and a favorable long-term policy framework.     

Energetic and exergetic performance evaluation of a combined heat and power system with the micro gas turbine (MGTCHP)

This study deals with the energetic and exergetic performance assessment of a combined heat and power system with micro gas turbine (MGTCHP). Quantitative energy and exergy balance for each component and the whole MGTCHP system was considered, while energy and exergy consumption within the system were determined. The performance characteristics of this MGTCHP system were evaluated using energy and exergy analyses methods. The energetic and exergetic efficiencies of the MGTCHP system are calculated as 75.99% with 254.55 kW (as 99.15 kW—electrical and 155.40 kW—hot water_{@363.15 K}) and 35.80% with 123.61 kW (as 99.15 kW—electrical and 24.46 kW—hot water_{@363.15 K}), respectively. The maximum energy loss and exergy consumption occur at 44.03 kW in the stack gas and 129.61 kW in the combustion chamber, respectively. Copyright © 2007 John Wiley & Sons, Ltd.     

我国热电冷三联产存在问题分析

热、电、冷三联产实现了能源的梯级利用,不但可以达到节约能源的目的,而且可以减少温室气体的排放,实现环保效益。该技术在国内外得到了广泛的发展和应用。从技术、节能、经济性等角度剖析了阻碍我国热、电、冷发展的主要问题,并提出了相应的解决措施。     

Theoretical research of a silica gel–water adsorption chiller in a micro combined cooling,heating and power (CCHP) system

A novel micro CCHP system, which is based on a two bed silica gel–water adsorption chiller, is constructed in this work. To reveal the chiller characteristic in this system, a transient model of the adsorption chiller is developed. According to the comparison of the simulated results and experimental data, the presented model shows a good performance in predicting the chiller performance, with both stable and variable heat source temperature. With the analysis of simulated results, it is found that the cooling capacity and the coefficient of performance (COP) of the chiller are influenced significantly by the average value and variation rate of electric load, as well as the average value of cooling load. The water tank also shows a great effect on the chiller performance. To get better performance of the chiller, the water tank should be adopted when the electric load is low or its variation rate is positive, and should not be utilized when the electric load is high or its variation rate is negative. A 500 L water tank is recommended in order to get better performance and acceptable start-up time. Furthermore, to get better performance as well as higher security, a cold accumulator should be adopted.     

Resource potential and scope of utilization of renewable energy in Jammu and Kashmir, India

Jammu and Kashmir the northern most state of India is blessed with immense potential for utilization of renewable energy. The state at present is fairly untapped in terms of energy utilization and thus venturing into this region would definitely prove to be profitable. The natural energy sources like sunshine, wind, vegetation, water flow, biomass and other biological wastes though abundantly available in the state yet are not being potentially harnessed resulting in very low per capita energy availability, deforestation and poor health. Renewable energy acquires a promising option not only for energy availability next view and of environment protection but also the socio-economic conditions of the people residing in these areas can be improved to a great extent. The hydroelectric power has tremendous potential for generation of electricity in the state because the topography of the state provides extensive network of canals and streams. This paper describes the resource potential and opportunity to enter the market and bring more renewable energy projects in the form of solar, biomass derived fuels, biogas and hydroelectric in the state.     

Development of a thermally enhanced frame wall with phase‐change materials for on‐peak air conditioning demand reduction and energy savings in residential buildings

This paper presents the development of a thermally enhanced frame wall that reduces peak air conditioning demand in residential buildings. A frame wall that integrates a highly crystalline paraffin phase‐change material (PCM), via macro‐encapsulation, was developed, constructed, and evaluated. This prototype wall is referred to as phase‐change frame wall (PCFW). Results from field testing show that the PCFW reduced wall peak heat fluxes by as much as 38%. For a period of several days that included walls facing different directions, the average wall peak heat flux reduction was approximately 15% when PCFWs with a 10% concentration of PCM (based on indoor sheathing weight) were used and approximately 9% when a 20% PCM concentration was used. The average space‐cooling load was reduced by approximately 8.6% when 10% PCM was applied and 10.8% when 20% PCM was used. The level of insulation in the PCFWs that were tested was 1.94m²K/W (R‐11). Copyright © 2005 John Wiley & Sons, Ltd.     

A comprehensive thermodynamic analysis of load‐flexible CHP plants using district heating network

Because of the rapid expansion of intermittent renewable energy, conventional coal‐fired power plants, including combined heat and power (CHP) plants, are required to improve the quick‐response ability to respond the changing demand of the grid. However, the flexibility of CHP plants is not easy to be improved because of the restriction of traditional load variation mechanism. This work presents a comprehensive thermodynamic analysis on the flexibility‐improving scheme using the thermal energy storage (TES) capacity of district heating (DH) network. A typical CHP plant and related DH network were selected as a case study. The flexibility demand under the context of renewables accommodation in the short timescale (counted by minutes) and the operational characteristics of CHP plants were analyzed on the basis of experimental data and thermodynamics. Besides, the influence of heat supply adjustment on heat users' indoor temperature was quantified with a dynamic model, and the thermal inertia of the DH network is discussed. Moreover, a thermodynamic model for the load variation processes simplified with operational characteristics was established to analyze the response ability improvement of CHP plants. Results of the case study show, the scheme can shorten approximately 34% of the response time while almost have no influence on the indoor temperature of heat users.     

空冷平台外部流场的数值模拟

采用SIMPLE算法和k-ε模型,以我国某600MW直接空冷电厂为例,对其空冷平台外部流场进行了数值模拟.分析了不同风速对直接空冷凝汽器换热效率的影响,阐述了热风回流现象产生的原因.结果表明:随着环境风速的提高,空冷凝汽器的换热效率先升后降,理论上存在换热效率最佳的风速值;热风回流使冷空气吸入量减少,并降低了换热偏差,因而影响了换热效率.