Trends in home computing and energy demand

Household energy demand due to domestic computer usage has changed beyond recognition over the past thirty years. Computers are now used in most homes, almost every day and laptop ownership has overtaken traditional desktop computers. Mobile devices give access to services that in the past required desktops, and they are usually more energy efficient. Today's computers usually rely on wireless routers that are often run all day. The effect of these changes on electricity use in the home has been profound. At least 60% more electricity was used for UK home computing in 2012 than in 1990. The implications of recent changes in information technology use are assessed for domestic electricity use and carbon emissions, using data from the Household Electricity Survey (HES) – the most detailed survey of electricity consumption in UK homes. On average, routers use twice as much energy per day as the laptops they serve. Laptops also draw power at a different time of day compared with desktop computers – which has implications for generation. Policy and practical recommendations are made for reducing energy use for information technology, including the estimated energy savings that could be achieved if UK routers met the US Energy Star standard for energy efficiency.     

The wind power potential of the eastern Mediterranean region of Turkey

The wind energy potential in the eastern Mediterranean region has been investigated using hourly wind data taken from seven stations during 1992-2001 periods by the Turkish Meteorological Service. The present work suggests that in the east Mediterranean Sea coast of Turkey, wind energy sources are convenient for electricity generation. The mean power density was determined as 500 W/m² in many areas of this region at 25 m from the ground level. The most promising locations in terms of wind power generation are identified. The contours of constant wind speed and power potential could lead the private power developers to decide the locations of appropriate wind farms.     

Uncertainty in estimating renewable energy utilisation potential: a case of solar thermal power generation in India

Estimation of renewable energy utilisation potential is important for identification of niche areas and prioritisation amongst different options. However, large variation in the potential estimates has been observed in different studies for the same renewable energy technology. This study is an attempt to analyse such a variation in the estimated potential for solar thermal power generation in India. From the analysis of three studies, it is found that the values of input parameters and the assumptions made substantially affect the estimated potential. The estimates of the utilisation potential depend upon the categories of wastelands selected, the chosen values of threshold DNI and wind speed as well as the criteria used for allocating suitable wastelands between solar photo-voltaic (PV) and thermal power generation. It is therefore critically important that reported values of renewable energy utilisation potential be interpreted and used with full cognisance of assumptions made and input parameters used in estimation.     

Power grid balancing of energy systems with high renewable energy penetration by demand response

It is generally accepted that the integration of intermittent energy resources like wind energy and photovoltaics into an electricity system cannot exceed a limit of around 20% or 25%, see, e.g. [EWEA, 2005. Large-scale integration of wind energy in the European power supply: analysis, issues and recommendations. The European Wind Energy Association]. However, the decoupling of electricity generation and consumption cannot be implemented only by use of electricity storage. In the end, electricity is converted into many different energy services – quite often into thermal energy – which is better suited for storage. This article presents the results of investigations which studied the potential of those demand response activities for Germany. The investigations are based on both modelling of thermal storage devices and laboratory tests.     

The impact of building-integrated photovoltaics on the energy demand of multi-family dwellings in Brazil

Brazil faces a continuous increase of energy demand and a decrease of available resources to expand the generation system. Residential buildings are responsible for 23% of the national electricity demand. Thus, it is necessary to search for new energy sources to both diversify and complement the energy mix. Building-integrated photovoltaic (BIPV) is building momentum worldwide and can be an interesting alternative for Brazil due its solar radiation characteristics. This work analyses the potential of seven BIPV technologies implemented in a residential prototype simulated in three different cities in Brazil (Natal, Brasília and Florianópolis). Simulations were performed using the software tool EnergyPlus to integrate PV power supply with building energy demand (domestic equipment and HVAC systems). The building model is a typical low-cost residential building for middle-class families, as massively constructed all over the country. Architectural input and heat gain schedules are defined from statistical data (Instituto Brasileiro de Geografia e Estatística—Brazilian Institute for Geography and Statistics (IBGE) and Sistema de Informações de Posses de Eletrodomésticos e Hábitos de Consumo—Consumer Habits and Appliance Ownership Information System (SIMPHA)). BIPV is considered in all opaque surfaces of the envelope. Results present an interesting potential for decentralized PV power supply even for vertical surfaces at low-latitude sites. In each façade, BIPV power supply can be directly linked to local climatic conditions. In general, for 30% of the year photovoltaic systems generate more energy than building demand, i.e., during this period it could be supplying the energy excess to the public electricity grid. Contrary to the common belief that vertical integration of PV is only suitable for high latitude countries, we show that there is a considerable amount of energy to be harvested from vertical façades at the sites investigated.     

基于低碳厦门规划的节能建筑分析

低能耗建筑正日益成为人们关注的焦点,这种建筑基本不消耗或极少消耗煤炭、石油、电力等能源,就能维持建筑的正常运转需要。低能耗建筑的主要特点是除了强调建筑围护结构被动式节能设计外,将建筑能源需求转向太阳能、风能、浅层地热能、生物质能等可再生能源,为人们的建筑行为,为人类、建筑与环境和谐共生寻找到最佳的解决方案。     

Urban energy generation: Influence of micro-wind turbine output on electricity consumption in buildings

Small scale wind turbines installed within the built environment is classified as microgeneration technology. Such turbines may soon become a commercial reality in the UK as a result of both advancements in technology and new financial incentives provided by the government. In addition, microgeneration technologies, especially those with appreciable resource, have the potential to reduce built environment related CO₂ emissions coupled with reductions in consumers’ electricity costs. In many cases payback on capital investment is within the lifetime of the device. Micro-wind turbines installed in certain areas in the UK will fit within such criteria. The work presented here addresses modelling of such installations around the UK and presents a methodology to assess the suitability and the economic viability of micro-wind turbines for domestic dwellings. A modelling tool “μ-Wind” has been developed specifically for studying both energy yields and the payback periods for micro-wind turbines. μ-Wind predicts wind turbine performance prior to installation according to specific power curves either defined by turbine manufacturers or the user. Numerical consideration of wind speed data at specific UK sites was used to estimate energy yields and the results are projected to real electricity demand data from monitored dwellings in the UK. The results show that it is possible to predict with a good degree of accuracy the expected financial payback period for a typical domestic dwelling. Furthermore, the paper postulates that micro-wind technology could have the potential to make a significant impact upon domestic electricity generation when located at the windiest sites in the UK. The likelihood of a proliferation of these turbines in the urban or suburban environment is low but at coastal or inland high elevation sites the technology appears to have a promising future.     

Renewable energy scenario in Telangana

ABSTRACT

This article presents an analysis of the current situation of renewable energy in Telangana, India, and predicts the future of renewable energy resources in the state. In India, maximum power is generated using conventional energy sources such as coal and mineral oil. They highly pollute the atmosphere. If new power plants are to be set up, then the import of highly volatile fossil fuels is inevitable. Though nuclear energy is a good alternative to reduce fossil fuel consumption, it is equally hazardous to human life. Hence, the energy world should think of judicious use of renewable energy resources such as solar, wind, ocean, biomass, and geothermal energy. The R&D activities carried out in India in the past three decades have shown good progress in finding a feasible solution to the problem of searching new renewable energy resources. Telangana is the state committed to use the renewable resources in a better way to fulfil its electrical energy needs. This article also analyses the current energy needs of the state and forecasts energy consumption and production in the future with the aim of finding whether the state can continue on the path of development and augment its renewable energy resources.     

风光互补发电系统在工程中应用的可行性分析

根据烟台市的风能太阳能资源条件,考虑到风能太阳能发电的互补特性,将风力发电装置和光伏发电装置组合成风光复合发电系统,分析了该复合系统的结构组成及原理,研究结果表明：该系统能够满足负载对用电量的要求,经济性较好,在解决偏远的高速公路路灯以及孤岛等的供电问题上提供了新的解决方式。     

Assessment of electricity generation by wind power in nine costal sites in Malaysia

In this article, the wind power potential in Malaysia is examined. Hourly wind speed data for nine sites in Malaysia are used to optimally design wind power systems for remote housing electrification. These nine sites are Bintulu, Kota Kinabalu, Kuala Terengganu, Kuching, Kudat, Mersing, Sandakan, Tawau and Pulau Langkawi. The designed wind power systems are supposed to supply hourly load demand 6.13?kWh/day, 0.52?kW peak with 1% loss of load probability. The unit cost of the energy produced by each system is calculated and compared to the unit cost of the energy produced by a standalone photovoltaic (PV) power systems and a diesel generator power systems. The results show that the average unit cost of the energy produced by a wind power system in Malaysia is 1.6–7.29?USD/kWh while it is 0.35–0.5?USD/kWh and 0.27–0.30?USD/kWh for PV power system and diesel generator power system, respectively. Based on this, the use of wind power systems as standalone systems is not recommended for the selected sites.     

建筑一体化电热冷联产光伏组件能量特性研究

传统太阳能光伏或光热建筑一体化只能为建筑提供单一电能或热能。通过研究一种集成发电、集热、制冷3种功能的建筑一体化电热冷联产光伏组件,对其夏季工况下能量特性进行了实际检测。结果表明:白天,组件集热同时能有效降低光伏电池温度,组件工作温度高于环境温度约8~16℃,发电和集热效率分别为14.1%~13.7%和40.1%~15.7%;晴朗夜间,组件通过对流和辐射两种传热方式进行散热制冷,总制冷功率为26.0~268.5 W/m~2。电热冷联产光伏组件适合与热泵结合,为建筑提供所需能源。     

Assessing wind energy potential for electricity generation using WECS in eight selected stations of Ethiopia

Wind utilisation for effective electricity generation has dated since last two decades by means of the modern wind turbines and has proved as a mature, reliable and efficient technology. This paper integrates the wind characteristics and performance of selected wind energy conversion systems (WECSs) from eight selected stations within Tigray region in Ethiopia. The wind speed data were collected over a period between 2002 and 2014. Based on the Paci?c Northwest Laboratory (PNL) classification, all the selected stations fall into Class 1. Therefore, these stations may be advised for small-scale power applications. Furthermore, the highest annual energy output achieved was 3902.31?MWh using VESTAS V110 – 2.0 at Mekele.     

Way forward in meeting energy challenges in Pakistan

In this review the energy potential of Pakistan from hydro, coal, wind, solar and nuclear sources has been discussed. The new projects that are being commissioned on coal, wind, solar, hydel and nuclear-based technologies have also been mentioned. The review has also explored the future prospects of the country’s energy requirements. Pakistan has potential to produce 100,000?MW of electricity from Thar coal for 20 years, 56,000?MW of hydroelectricity, 150,000?MW of wind energy and ～50,000?MW from solar sources. The coal-fired power generation is expected to 11,500?MW in period 2017–2019. The country is moving in the right direction to cater its energy needs. However, there is a need to find local and foreign investment in the country to meet high energy demands in the country in future.     

Analysis and optimization of the use of CHP-ORC systems for small commercial buildings

The use of combined heating and power (CHP) systems is increasing rapidly due to their high potential of reducing primary energy consumption (PEC), cost, and carbon dioxide emissions (CDE). These reductions are mainly due to capturing the exhaust heat to satisfy the thermal demand of a building. However, when the CHP system is operated following the electric load, the recovered exhaust heat may or may not be sufficient to satisfy the thermal demand of the facility. When the recovered exhaust heat is more than the heat required, the excess is usually discarded to the atmosphere. An organic rankine cycle (ORC) can be used to recover the surplus exhaust heat to generate extra electricity. Therefore, combining the ORC system with the CHP system (CHP-ORC) reduces the electricity that has to be produced by the CHP system, thereby reducing the total PEC, cost, and CDE. The objective of this paper is to study the energetic, economical, and environmental performance of a combined CHP-ORC system and compare its performance to a standalone CHP system and a reference building for different climate zones. A comparison of a CHP-ORC system operating 24 h with a system operating during typical office hours is also performed.     

Environmental impact of building-related and user-related energy consumption in dwellings

Energy consumption in dwellings contributes significantly to their total negative environmental impact. This paper quantitatively assesses the environmental impact of building-related and user-related gas and electricity consumption in a Dutch apartment dwelling using life cycle assessment (LCA) methodology. Several scenarios for gas and electricity consumption are compared to assess what effect changes in building characteristics and user behaviour have on the environmental impacts of energy consumption. This study shows that gas consumption significantly contributes to four environmental impact categories, which can be most effectively countered by reducing the heat demand of the dwelling. A 23% reduction in gas consumption leads to up to 13% less overall environmental impacts. Particularly in buildings with low heat demand, electricity consumption dominates all environmental impact categories. These can most effectively be reduced by changing the electricity demand of the user: 47% less electricity consumption leads to a 9–45% reduction in the total environmental impact. However, since electricity consumption continues to rise, the environmental effects of electricity use may be better reduced by changing the environmental impact of the electricity supply. Theoretically, when electricity consumption remains the same, over 90% less environmental impact could be reached by using 100% wind power to generate electricity.     

The impact of the integration of renewable energy sources in the electricity price formation: is the Merit-Order Effect occurring in Portugal?

This study investigates the relationship between wholesale electricity price behaviour and the integration of new renewable energy sources in the electricity system in Portugal. The research analyses two different samples, namely: the significant deployment of wind power versus the abrupt increase in the installed capacity of solar photovoltaic. Daily data from 2011 until 2019 and, a SARMAX/EGARCH approach has been conducted to assess the merit-order effect. The main results suggest that electricity production from wind power is decreasing the price of electricity but increasing its volatility. In addition, there is evidence for the leverage effect in electricity price.     

Zero energy buildings and mismatch compensation factors

This paper takes an overall energy system approach to analysing the mismatch problem of zero energy and zero emission buildings (ZEBs). The mismatch arises from hourly differences in energy production and consumption at the building level and results in the need for exchange of electricity via the public grid even though the building has an annual net-exchange of zero. This paper argues that, when looked upon from the viewpoint of the overall electricity supply system, a mismatch can be both negative and positive. Moreover, there are often both an element of levelling out mismatches between individual buildings and an element of economy of scale. For these three reasons mismatches should be dealt with at the aggregated level and not at the individual level of each building. Instead, this paper suggests to compensate the mismatch of a building by increasing (or decreasing) the capacity of the energy production unit. Based on historical data for the electricity supply area in western Denmark, this paper makes a first attempt to quantify mismatch compensation factors. The results indicate that such compensation factors are a little below one for buildings with photovoltaics (PV) and a little above one for buildings with wind turbines.     

Application of latent heat thermal energy storage in buildings: State-of-the-art and outlook

Latent heat thermal energy storage (LHTES) is becoming more and more attractive for space heating and cooling of buildings. The application of LHTES in buildings has the following advantages: (1) the ability to narrow the gap between the peak and off-peak loads of electricity demand; (2) the ability to save operative fees by shifting the electrical consumption from peak periods to off-peak periods since the cost of electricity at night is 1/3–1/5 of that during the day; (3) the ability to utilize solar energy continuously, storing solar energy during the day, and releasing it at night, particularly for space heating in winter by reducing diurnal temperature fluctuation thus improving the degree of thermal comfort; (4) the ability to store the natural cooling by ventilation at night in summer and to release it to decrease the room temperature during the day, thus reducing the cooling load of air conditioning. This paper investigates previous work on thermal energy storage by incorporating phase change materials (PCMs) in the building envelope. The basic principle, candidate PCMs and their thermophysical properties, incorporation methods, thermal analyses of the use of PCMs in walls, floor, ceiling and window etc. and heat transfer enhancement are discussed. We show that with suitable PCMs and a suitable incorporation method with building material, LHTES can be economically efficient for heating and cooling buildings. However, several problems need to be tackled before LHTES can reliably and practically be applied. We conclude with some suggestions for future work.     

Rooftop photovoltaic (PV) systems for industrial halls: Achieving economic benefit via lowering energy demand

Industrial halls are characterized with their relatively high roof-to-floor ratio, which facilitates ready deployment of renewable energy generation, such as photovoltaic (PV) systems, on the rooftop. To promote deployment of renewable energy generation, feed-in tariff (FIT) higher than the electricity rate is available in many countries to subsidize the capital investment. FIT comes in different forms. For net FIT, in order to maximize the economic benefit, surplus electricity generation at each hour is desirable.One way to achieve surplus electricity generation is by increasing generation capacity, which is synonymous to higher capital investment. In fact, surplus electricity generation can also be achieved by lowering the energy demand of the building. This particularly the case for industrial halls, which are usually subject to high energy demand for space conditioning in order to remove the excess heat gain due to the many power-intensive processes.Building energy performance simulation tools can be used to explore the different building design options that could lower the energy demand. In this paper, single-objective optimization on investment return will be deployed to study the cost effectiveness among different options in lowering energy demand. It will be demonstrated with a case study of a warehouse.     

A fresh breeze after Fukushima? Analysing Japan’s current limitations and future prospects of wind power development

Wind power generation in Japan is underdeveloped. Despite relatively good geographical and meteorological conditions, wind supplies less than 0.2% of the national electricity demand. Germany, in contrast, is able to provide over 6% of its electricity from wind power. This article will outline the main reasons for the marginal position of wind power in Japan by comparing and contrasting it with the political market for wind power in Germany. Using the concept of ‘Technological Innovation Systems’ (TIS), this paper will show how wind power has been impeded in Japan, but has been fostered in Germany, where policy designs and market mechanisms have produced positive feedback loops. Both technical problems and political inertia account for the modest growth of wind power in Japan.