我国高效节能配电变压器的生命周期成本分析

本文基于生命周期成本法,分析高效节能配电变压器的投资经济效果。本文首先分析了我国配电变压器能效等级的变化趋势并与欧盟标准进行对比;其次应用生命周期成本法计算各能效等级配电变压器的生命周期成本及动态投资回收期;最后,以S系列630／10型配电变压器为例,进行生命周期成本分析及负载率灵敏度分析。结果显示,在有政府补贴情景下,能效1级、能效2级配电变压器与能效3级配电变压器相比具有明显的投资优势,为推广高效节能配电变压器创造了有利条件。     

Performance of residential fuel-cell-combined heat and power systems for various household types in Japan

A residential fuel-cell-combined heat and power (FC-CHP) system is considered a promising low-carbon technology that can reduce residential energy consumption and thus, achieve Japan's greenhouse gas (GHG) emissions reduction targets. However, to consider future directions for the systems' research and development, it is critical to understand the relationships between the performances of FC-CHP systems and residential energy demand profiles, which vary by household characteristic. This study evaluates the effects of applying city gas-fueled FC-CHP systems to Japanese households with different attributes. We compare total costs and GHG emissions for residential energy use between the FC-CHP systems and a conventional system. The economic performance results suggest that the basic PEMFC-CHP systems have an economic advantage only for four-person families with teenage children and further development efforts for low-output FC-CHP systems are required to enable various households save energy costs. The environmental evaluation results show that SOFC-CHP systems can drastically reduce GHG emissions from particularly small-sized households.     

Improving distribution efficiency of electrical network using geo-electrical options: a case study in a rural area of Assam (India)

Reduction of electricity distribution loss is a major area of focus in India. This paper aims to investigate geo-electrical options to improve distribution efficiency of electrical network. Distribution efficiencies corresponding to several possible electrical network options are assessed using Geographical Information System (GIS) integrated electrical theory. An existing electrical distribution network of a rural area in Assam (India) is considered for the present investigation. Information related to characteristics of loads, features of conductors, and transformers of the existing network are used for this investigation. The line losses of the three existing transformers are estimated at about 36, 20, and 3?% of their respective connected loads. Longer distribution lines associated with higher loads are the causes of higher line losses. Using basic electrical theory and GIS tools, it is found that line losses can be reduced in the existing distribution system through management of distribution transformer and reconductoring. Two alternative locations for each of the three transformers are identified for optimal management of distribution transformers. Similarly, five different types of commercially available conductors are identified for possible reconductoring to reduce line loss. The economic viability of reconductoring of distribution lines are also assessed through an economic analysis. Net present values of total expenditure comprising purchase prices of conductor and cost attributed to line losses are estimated considering 30?years of useful life. The existing conductor has the worst economic merit, though it is the cheapest amongst all. A net saving of about US $24,084 is possible through the best choice of distribution conductor for the village.     

10 kV配电变压器经济运行方式的可行性及经济性分析

针对农村和城市小区的变压器长时间处于空载和轻载状态导致损耗增大的问题,提出了一种变压器组优化经济运行方案。以变压器实时负荷为主要控制参量优化组合变压器组的投切运行,采用电压互感器取能方案解决配电线路停运后变压器高低压侧断路器操作机构的取能问题(冷启动),保证了供电的及时性和变压器的自动投切。并以某小区变电箱内两台变压器组为例,定量分析了优化运行的经济效益,最后通过数字仿真验证了所提方案的可行性。     

Update of indicators for climate change mitigation in Greece

This paper analyses the factors affecting greenhouse gas (GHG) emissions in Greece, (i.e. the drivers of pressures on climate change), using environmental indicators related to energy, demographics and economic growth. The analysis is based on the data of 2008 and considers types of fuel and sectors. The Kaya identity is used to identify the relationship between drivers and pressures, using annual time series data of National GHG emissions, population, energy consumption and gross domestic product. The analysis shows that over the period 2000–2008, GHG emissions show a slight variation, but they are almost stabilised, with a total increase of 1.6%. Despite the economic growth over that period, this stabilisation may be considered as a combination of reductions in the energy intensity of GDP and the carbon intensity of energy, which are affected by improvements in energy efficiency and introduction of “cleaner” fuels, such as natural gas and renewables in the energy mixture of the country.     

The status and prospects of renewable energy for combating global warming

Reducing anthropogenic greenhouse gas (GHG) emissions in material quantities, globally, is a critical element in limiting the impacts of global warming. GHG emissions associated with energy extraction and use are a major component of any strategy addressing climate change mitigation. Non-emitting options for electrical power and liquid transportation fuels are increasingly considered key components of an energy system with lower overall environmental impacts. Renewable energy technologies (RETs) as well as biofuels technologies have been accelerating rapidly during the past decades, both in technology performance and cost-competitiveness — and they are increasingly gaining market share. These technology options offer many positive attributes, but also have unique cost/benefit trade-offs, such as land-use competition for bioresources and variability for wind and solar electric generation technologies. This paper presents a brief summary of status, recent progress, some technological highlights for RETs and biofuels, and an analysis of critical issues that must be addressed for RETs to meet a greater share of the global energy requirements and lower GHG emissions.     

Energy efficiency optimization in distribution transformers considering Spanish distribution regulation policy

In transmission and distribution systems, the high number of installed transformers, a loss source in networks, suggests a good potential for energy savings. This paper presents how the Spanish Distribution regulation policy, Royal Decree 222/2008, affects the overall energy efficiency in distribution transformers. The objective of a utility is the maximization of the benefit, and in case of failures, to install a chosen transformer in order to maximize the profit. Here, a novel method to optimize energy efficiency, considering the constraints set by the Spanish Distribution regulation policy, is presented; its aim is to achieve the objectives of the utility when installing new transformers. The overall energy efficiency increase is a clear result that can help in meeting the requirements of European environmental plans, such as the ‘20–20–20’ action plan.     

Profiting from negawatts: Reducing absolute consumption and emissions through a performance-based energy economy

Current energy and GHG emissions policies either focus directly on emissions or promote renewable production and the implementation of specific efficiency measures. Meanwhile, the fundamental structure of the energy market based on profits through energy throughput remains largely unchallenged. This policy oversight prevents the transition to an energy economy in which profits are based on energy services delivered at the lowest energy cost: a performance-based energy economy (PBEE). The PBEE applies the combined concepts of the performance economy and energy services to the energy sector. Energy Service Companies (ESCOs) are discussed as an example of PBEE practices. The implications for energy suppliers and consumers as well as the conditions for PBEE diffusion and consequences for technological change are also explored. The expected environmental, social and economic benefits are described. However, absolute consumption and emissions reductions may prove elusive due to the rebound effect. In order to forestall rebound-led increases, complementary policy measures likely to lead to absolute reductions are required.     

Sustainable energy system design with distributed renewable resources considering economic,environmental and uncertainty aspects

Electricity generation using renewable energy generation technologies is one of the most practical alternatives for network planners in order to achieve national and international Greenhouse Gas (GHG) emission reduction targets. Renewable Distributed Generation (DG) based Hybrid Energy System (HES) is a sustainable solution for serving electricity demand with reduced GHG emissions. A multi-objective optimisation technique for minimising cost, GHG emissions and generation uncertainty has been proposed in this paper to design HES for sustainable power generation and distribution system planning while considering economic and environmental issues and uncertainty in power availability of renewable resources. Life cycle assessment has been carried out to estimate the global warming potential of the embodied GHG emissions from the electricity generation technologies. The uncertainty in the availability of renewable resources is modelled using the method of moments. A design procedure for building sustainable HES has been presented and the sensitivity analysis is conducted for determining the optimal solution set.     

MW cogenerated proton exchange membrane fuel cell combined heat and power system design for eco-neighborhoods in North China

Buildings account for most of the greenhouse gas (GHG) emissions causing global warming. The development of eco-neighborhood can improve the energy efficiency of buildings and reduce GHG emissions. A combined heat and power (CHP) system based on proton exchange membrane fuel cells (PEMFCs) is designed to supply electricity and thermal for eco-neighborhood in North China with low GHG emissions. Effects of different inlet parameters, such as PEMFC inlet pressure and current density, on multi-stack CHP system performance are discussed. Coupled with a dynamic load scenario, the adaptability of the designed PEMFC-CHP system is studied through PI control with an electricity-led strategy and a thermal-led strategy. Both strategies can effectively reduce GHG emissions and the eco-neighborhood with PEMFC-CHP system is more environmental friendly compared to conventional energy supply. The electricity-led strategy can satisfy the energy consumption of the eco-neighborhood but with thermal waste. The energy consumption for most of the time during a year can be satisfied by the PEMFC-CHP system under the thermal-led strategy, but the electricity gap exists as the thermal demand is lower. Under the electricity-led strategy, the GHG emission reduction of the eco-neighborhood under electricity-led strategy and thermal-led strategy are around 7000 ton and 5000 ton per year, respectively.     

Kyoto Protocol implementation in Serbia as precognition of sustainable energetic and economic development

The paper gives reasons for low energy efficiency typical of the Serbian economy, which is based on outdated and dirty technologies. The comparison of selected economic indicators and indicators of energy efficiency in both Serbia and the European Union points out the benefits of the Kyoto Protocol implementation due to the growth of competitiveness in the global market. Serbia has no obligation to reduce GHG emissions, the authors point to the proposals whose implementation along with the mechanisms of the Protocol can enable Serbia the access to markets that trade GHG emissions and the access to dedicated funds, self-financing or attracting foreign investments to raise energy efficiency, which will be accompanied by adequate economic benefits. A similar principle can be applied in all countries that are not obliged to reduce GHG emissions. The application of different mechanisms aiming to increase energy efficiency in Serbia, could contribute to the increase of GDP annual growth rate from 5% to 7%, which cannot be achieved by any other economic instrument. Energy efficiency, which is actually a question of competitiveness of each economy, can finance itself through the mechanisms of the Kyoto Protocol by selling excess emissions resulting from improved energy efficiency.     

Energy efficiency,sustainability and economic growth

This paper explores two linked theses related to the role energy in economic development, and potential sources of increased energy efficiency for continued growth with reduced greenhouse gas (GHG) emissions. The first thesis is that, while reduced GHG emissions are essential for long-term global sustainability, the usual policy recommendation of increasing energy costs by introducing a carbon tax may be relatively ineffective under current market structures and have an unnecessarily adverse impact on economic growth. Our second thesis is that there exists a practical near-term strategy for reducing GHG emissions while simultaneously encouraging continued technology-driven economic growth. Moreover, this strategy does not require radical new technologies, but rather improved regulation or—more precisely—better deregulation of the electric power sector.     

Greenhouse gas and energyassessment of the biogas from co-digestion injected into the natural gas grid: A Swedish case-study including effects on soil properties

In this study, a large, farm-based, co-digestion plant in southern Sweden, using manure and various food industry wastes is investigated concerning its use of energy and its emissions of greenhouse gases from a life cycle perspective based on measured, site-specific data. The biogas is upgraded and utilized as a vehicle fuel, distributed via the natural gas grid. The case-study also includes a novel approach in which potential changes in soil compaction and soil carbon levels are assessed, based on farm-specific conditions, when digestate replaces mineral fertilizer. An additional objective is to identify potential technical improvements leading to further GHG reductions, and the cost of such measures. According to this case-study, biogas produced from food industry waste and manure in a modern co-digestion plant could reduce GHG emissions by approximately 90% compared to conventional fossil fuels. The corresponding energy input:output ratio is calculated to be about 25%, where the use of electricity in the biogas process, upgrading and pressurisation is the dominating energy input. Finally, several possible technical improvements to further reduce GHG emissions were identified. The economic prerequisites of the specific improvements varied, from profitable from a business perspective to unprofitable from a socio-economic point-of-view.     

Electricity and heating system in Kazakhstan: Exploring energy efficiency improvement paths

The Kazakh energy system is less efficient than most other national energy systems. The electricity and heat sub-systems account for about one half of the difference between the primary energy supply and the final consumption. After reviewing the technology chains of electricity and heat generation, transmission and distribution and their organisation, this paper presents scenario studies on the possible evolutions of these sub-systems to 2030. It describes the representation of the heat and electricity chains in the MARKAL–TIMES-Kazakhstan model, with focus on the residential and commercial sectors, and some key input data assumptions. The main scenario drivers are the need to improve the efficiency of electricity and heat in the residential and commercial sectors and to reduce GHG emissions from the energy system as a whole. The model results point to the possibility of achieving cost effective energy efficiency improvement of more than 2% per annum and it would entail a net economic advantage to the country.     

Energy consumption, costs and environmental impacts for urban water cycle services: Case study of Oslo (Norway)

Energy consumption in the operation and maintenance phase of the urban water and wastewater network is directly related to both the quantity and the desired quality of the supplied water/treated wastewater - in other words, to the level of service provided to consumers. The level of service is dependent on not just the quantity and quality of the water but also the state of the infrastructure. Maintaining the infrastructure so as to be able to provide the required high level of service also demands energy. Apart from being a significant operational cost component, energy use also contributes to life-cycle environmental impacts. This paper studies the direct energy consumption in the operation and maintenance phase of the water and wastewater system in Oslo; and presents a break-up among the different components of the network, of quantities, costs and environmental impacts. Owing to the diversity in the periods of time for which comprehensive data for the whole system are available, the study period is restricted to years 2000-2006. The per-capita annual consumption of energy in the operational phase of the system varied between 220 and 260 kWh; and per-capita annual expenses on energy in inflation-adjusted year-2006-Euros ranged between 6.5 and 11 Euros. The energy consumed on the upstream, per unit volume water supplied was around 0.4 kWh on average, while the corresponding value for the downstream was 0.8 kWh per cubic metre wastewater treated. The upstream Greenhouse gas (GHG) emissions ranged between 70 and 80 g per cubic metre of water supplied, about 22% greater on average than the corresponding specific GHG emissions on the downstream.     

Energy-efficient distribution transformers in Europe: impact of Ecodesign regulation

This paper assesses the impact of energy-efficient distribution transformers through the implementation of energy efficiency classes, as well as through mandatory standards that remove the worst transformers from the market. Energy-efficient distribution transformers can not only save about 1 % of all the electricity generated but can also save very large investments in power generation and transmission power systems. Technical solutions to reduce energy consumption of transformers are available, but the market penetration of high-efficient transformers is significantly lower than it could be. The paper analyses the main market and regulatory failures and identifies that the introduction of efficiency classes and minimum energy performance standards (MEPS) is the best way to foster energy performance in distribution transformers. Policies and measures supporting energy-efficient distribution transformers around the world are reviewed. The use of Ecodesign methodology do define possible transformer MEPS regulation is discussed for different types of distribution transformers, as well as the associated impacts. Sensitivity analysis in relation to key parameters (load factor and electricity prices) is analyzed. The energy saving potential and the environmental impacts are calculated until the year 2050 in the European Union, as well as at world level. The potential savings in the year 2050 represent about 35 TWh of electricity in Europe, equivalent to about four million tons of reduced CO₂ emissions. For the world, the estimated impact in 2050 is about 450 TWh equivalent to about 180 million tons of reduced CO₂ emissions.     

Assessment of externalities related to global and local air pollutants with the NEEDS-TIMES Italy model

This work is aimed to illustrate the potentiality of the multi-region NEEDS-TIMES modelling platform, in the economic evaluation of the environmental damages due to air pollution. In particular the effects of external costs on the least-cost optimised energy system configuration were analysed in a national case study with the NEEDS-TIMES Italy model, considering the externalities related to local and global air pollutants (NO_x, SO₂, VOC, particulates and GHGs). Different scenarios were compared to emphasise the role of external costs in the achievement of strategic environmental targets. The main results obtained are discussed, focusing on the changes in energy fuel mix as well as in local air pollutants and GHG emissions, highlighting the main conclusions in terms of policy strategies.     

基于禁忌搜索算法的配电变压器经济运行

针对变电站配电变压器电能损耗严重的问题,提出一种利用禁忌搜索算法对配电变压器运行方式进行优化的方法,即利用禁忌搜索原理,以经济效益为目标函数,对变电站两台及以上配电变压器的备选投切点进行优选,从而获得配电变压器运行方式的最优控制策略,并通过MATLAB编程对算例进行验证。结果表明,该方法可减少配电变压器的电能损耗,具有良好的经济效益;此外,该方法还约束了投切次数,可避免设备频繁投切造成的电力系统安全隐患。     

Energy demand and greenhouse gas emissions during the production of a passenger car in China

Rapidly-rising oil demand and associated greenhouse gas (GHG) emissions from road vehicles in China, passenger cars in particular, have attracted worldwide attention. As most studies to date were focused on the vehicle operation stage, the present study attempts to evaluate the energy demand and GHG emissions during the vehicle production process, which usually consists of two major stages—material production and vehicle assembly. Energy demand and GHG emissions in the material production stage are estimated using the following data: the mass of the vehicle, the distribution of material used by mass, and energy demand and GHG emissions associated with the production of each material. Energy demand in the vehicle assembly stage is estimated as a linear function of the vehicle mass, while the associated GHG emission is estimated according to the primary energy sources. It is concluded that the primary energy demand, petroleum demand and GHG emissions during the production of a medium-sized passenger car in China are 69,108 MJ, 14,545 MJ and 6575 kg carbon dioxide equivalent (CO₂-eq). Primary energy demand, petroleum demand and GHG emissions in China’s passenger car fleets in 2005 would be increased by 22%, 5% and 30%, respectively, if the vehicle production stage were included.     

An estimation of energy and GHG emission intensity caused by energy consumption in Korea: An energy IO approach

In Korea, 97% of the energy resources are imported. The growth rate of greenhouse gas (GHG) emission per capita in the country was the highest in the world during 1990 and 2004. Moreover, 83% of the domestic GHG emissions stemmed from energy use in the year 2004. Therefore, there is an urgent need to develop an econometric model for energy intensity and GHG emission intensity in view of the poor energy endowment and environmental situation in Korea.