Power quality assessment of wind turbines and comparison with conventional legal regulations: A case study in Turkey

Renewable energy sources have been investigated for use instead of conventional fossil fuels in many areas. Among these renewable energy sources, wind energy has come into prominence owing to the fact that it is a clean, sustainable and cost-effective type of energy. However, the connection of large wind farms to the grid may cause problems in terms of power quality due to the variability of the energy extracted from the wind. The mentioned power quality problems are generally taken into consideration after the grid integration of wind farms. However, the precautions that can be taken by means of the assessments before the installation of the turbines represent an easier and more economic way. In this study, the possible effects of the grid connected wind turbines on the power quality characteristics have been defined and the MATLAB based models have been constructed so as to calculate these effects. Particularly, fast voltage variations that are difficult to model due to their relations with the human factor have been analyzed in detail. It has been aimed that the models are suitable for use in practice while utilizing various standards such as IEC 61400-21 and IEC 61000-4-15 in order to setup the models. The analyses of the implementations that represent constraints for exploiting the wind resources in Turkey have been realized in terms of production and consumption with a case study. The realized calculations present the applicability of the model to grid conditions with different characteristics. It is also presented that the wind energy penetration can be increased without deteriorating the power quality of the grid with the use of the proposed model.     

Co-benefits analysis on climate change and environmental effects of wind-power: A case study from Xinjiang,China

The combustion of fossil fuel contributes to not only global warming but also the emissions of air pollutants. In China, the rapid growth of energy consumption leads to a large quantity of greenhouse gas (GHG) and air pollutant emissions. Although many measures have been proposed by the local governments to mitigate the GHG emissions and improve air quality, limited economic resources slow the efforts of the local government to implement measures to control both types of emissions. The co-benefits approach can use resources efficiently to solve multiple environmental problems. In this study, we first calculated the CO₂ and air pollutants (SO₂, NO_x and PM_2.5) emissions in Xinjiang Uygur Autonomous Region. Then, the co-benefits of wind power, including mitigation of CO₂ and air pollutants (SO₂, NO_x and PM_2.5) emissions and water savings, were assessed and quantified in the Xinjiang Uygur Autonomous Region. The results demonstrate that, during the 11th five-year period (2006–2010), emissions mitigation by wind power accounted for 4.88% (1065 × 10⁴ t) of CO₂, 4.31% (4.38 × 10⁴ t) of SO₂, 8.23% (3.41 × 10⁴ t) of NO_x and 4.23% (0.32 × 10⁴ t) of PM_2.5 emission by the thermal power sector. The total economic co-benefits of wind power accounted for 0.46% (1.38 billion 2009US$) of the GDP of Xinjiang during 2006–2010.     

Characteristics of co-combustion and kinetic study on hydrothermally treated municipal solid waste with different rank coals: A thermogravimetric analysis

This study presents an investigation on the influence of hydrothermally treated municipal solid waste (MSW) on the co-combustion characteristics with different rank coals, i.e. Indian, Indonesian and Australian coals. MSW blends of 10%, 20%, 30% and 50% (wt.%) with different rank coals were tested in a thermogravimetric analyser (TGA) in the temperature range from ambient to 700 °C under the heating rate of 10 °C/min. Combustion characteristics such as volatile release, ignition and burnout were studied for the blend fuel. Different ignition behavior was observed depending on the blends composition and the coal rank. The result of this work indicates that the blending of MSW improves devolatization properties of coal. But it was found that the co-combustion characteristics of MSW and coal blend cannot be predicted only from the pyrolytic and or devolatization phenomena as the other factors such as the coal quality also plays a vital role in deciding the blends co-combustion characteristics. The TGA combustion profiles showed that the combustion characteristics of blends followed those of parent fuels in both an additive and non-additive manners. These experimental results help to understand and predict the behavior of coal and MSW blends in practical applications.     

Analysis of energy-efficiency opportunities for the cement industry in Shandong Province,China: A case study of 16 cement plants

In this study, 16 cement plants with New Suspension Preheater and pre-calciner (NSP) kiln were surveyed. Plant energy use was compared to both domestic (Chinese) and international best practice using the Benchmarking and Energy Saving Tool for Cement (BEST-Cement). This benchmarking exercise indicated an average technical potential primary energy savings of 12% would be possible if the surveyed plants operated at domestic best practice levels in terms of energy use per ton of cement produced. Average technical potential primary energy savings of 23% would be realized if the plants operated at international best practice levels. Then, using the bottom-up Electricity Conservation Supply Curve (ECSC) model, the cost-effective electricity efficiency potential for the 16 studied cement plants in 2008 is estimated to be 373 gigawatt-hours (GWh), and total technical electricity-saving potential is 915 GWh, which accounts for 16 and 40% of total electricity use in the studied plants in 2008, respectively. The Fuel Conservation Supply Curve (FCSC) model shows the total technical fuel efficiency potential equal to 7949 terajoules (TJ), accounting for 8% of total fuel used in the studied cement plants in 2008. All the fuel efficiency potential is shown to be cost effective.     

The introduction of electric vehicles in the private fleet: Potential impact on the electric supply system and on the environment. A case study for the Province of Milan,Italy

The study analyses the possible impact of the electric vehicles’ recharging activities on the electric supply system for the Province of Milan and on the global environment with a 2030 time horizon. In particular, the impact on the electric grid is seen both in terms of total electric energy consumption and in power requested to the grid. Because of the long recharging time required by the car batteries, the probability to have thousands of cars contemporary plugged-in at a given time is not negligible. On the other hand, the impact on the environment is seen in terms of CO₂ emissions reduction. Even if, at the moment, the Italian electric energy mix is mainly generated by means of thermal power stations making use of not renewable fossil fuels, the efficiency of these plants is much higher than the efficiency of a vehicle’s engine.     

Conversion of almond shell to activated carbons: Methodical study of the chemical activation based on an experimental design and relationship with their characteristics

The objective of this work is to carry out a methodical study of the preparation conditions of almond shell based chemically activated carbons and its influence on the characteristics of the activated carbons. An experimental design was used to optimize the preparation conditions of activated carbons from almond shell via chemical activation with phosphoric acid. Temperatures from 400° to 800 °C, impregnation ratios in the range 0.5-1.5 and carbonization times varying from 30 to 120 min were defined as continuous parameters to be introduced in a simplex mixture experimental design giving a total of 12 experiments to carry out.The response surface methodology was applied in order to study the influence of all the production parameters on the selected responses. The optimization of all the characteristics of the activated carbons under the same experimental conditions is not possible because the influence of activation temperature, impregnation ratio and activation time is different. However using the response surface methodology it is possible to determine the ranges of each experimental preparation condition to obtain optimal characteristics of the activated carbon.     

Inherent hazards,poor reporting and limited learning in the solid biomass energy sector: A case study of a wheel loader igniting wood dust,leading to fatal explosion at wood pellet manufacturer

Large loaders are commonly used when handling solid biomass fuels. A preventable accident took place in 2010, where the malfunction of a front-end wheel loader led to a dust explosion which killed the driver and destroyed the building. The case offers an opportunity to examine the hazards of solid biomass, the accident investigation and any learning that subsequently took place.The paper argues that learning opportunities were missed repeatedly. Significant root causes were not identified; principles of inherent safety in design were ignored; the hazardous area classification was based on flawed reasoning; the ATEX assessment was inadequate as it dealt only with electrical installations, ignoring work operations; and powered industrial trucks had not been recognized as a source of ignition. Perhaps most importantly, guidelines for hazardous area classification for combustible dust are insufficiently developed and give ample room for potentially erroneous subjective individual judgment. It is a contributing factor that combustible dust, although with great hazard potential, is not classified as a dangerous substance. Accidents therefore fall outside the scope of systems designed to disseminate lessons learned and prevent future accidents.More attention to safety is needed for the renewable energy and environmentally friendly biomass pellet industry also to become sustainable from a worker safety perspective.     

Measuring the social rate of return to R&D in coal,petroleum and nuclear manufacturing: A study of the OECD countries

This paper estimates the social rate of return to research and development (R&D) in the energy manufacturing industry. Our model tries to quantify the positive contribution that lagged R&D has on total factor productivity (TFP) growth in the manufacturing of coal, petroleum products and nuclear fuel for a number of OECD countries. Using a panel of data from the OECD STAN database we are able to obtain results suggesting that R&D has a positive and significant rate of return that varies for each country.     

Field trial results of straw yield with different harvesting methods,and modelled effects on soil organic carbon. A case study from Southern Finland

We estimated the effects of different cutting heights and harvesting strategies on the amounts of harvestable residue biomasses and allocation of residue biomasses in the soil. A case study on regional straw biomass resources was performed with the different crops cultivated in Varsinais-Suomi (Southern Finland) at present (averages of 2003–2012) and in the predicted future warmer climate (scenario RCP 4.5, year 2055). We also estimated, with the help of the Yasso07 model, the effects of different residue incorporation intensities on soil organic carbon (SOC) at present and in the future warmer climate. The results suggested that cutting height has a significant impact on the amount of straw biomass incorporated in the soil and subsequent change in SOC. The impact depended on crop species and variety. When straw is collected and used e.g. in energy production, harvesting practices leaving greater stubble heights could help to maintain soil fertility. The Yasso07 model suggests that in the predicted future warmer conditions, more straw could be collected without decreasing SOC, as mineralization of SOC in the warmer climate is expected to increase less than organic carbon amendments caused by higher crop and root biomasses. Collection and usage of straw as a renewable energy source always decreases greenhouse gas (GHG) emissions in comparison to fossil fuels. However, collecting straw every second year instead of every year, even with higher stubble, would decrease field traffic and spare the soil from compaction and the farmer from extra work, while still significantly decreasing GHG emissions.     

A GIS-based approach for evaluating the potential of biogas production from livestock manure and crops at a regional scale: A case study for the Kujawsko-Pomorskie Voivodeship

In Poland, the promotion of the development of biogas plants was intensified under legal regulations. The potential expansion prompts the need for the assessment of a variety of environmental and geographical constraints as well as technical and economic factors, which ensure socio-economically and ecologically sound biogas development. In this paper, both spatial and non-spatial data were integrated to the GIS model to help determine the optimal sites for installing anaerobic digesters (AD). The focus was placed on animal manure (from cattle and pig populations), and co-substrates such as crop silage. Furthermore, the paper provides insight into the structure of cost and benefits in order to examine what incentive measures suffice to force biogas development and how much biogas feedstock could cost to make investments viable. The techno-economic assessment was carried out for combined heat and power generation and bio-methane injection into the gas grid. The methodology was applied to Kujawsko-Pomorskie Voivodeship.     

The causal relationship between electricity consumption and economic growth in a Gaming and Tourism Center: The case of Macao SAR, the People’s Republic of China

A number of Asian cities decided to establish gaming and resort facilities in order to capitalize on the growing number of gamblers and their family members in Asia. In doing so, they expect to sustain economic growth but, on the other hand, will consume a considerable amount of energy. Nevertheless, the causal relationship between economic growth and electricity consumption in this type of service-oriented territories has never been investigated. Using the historical data obtained from the Government of Macao SAR, we found that electricity consumption and economic growth in terms of gross domestic product are co-integrated for the period of 1999 Quarter 1-2008 Quarter 4. Moreover, vector error correction (VEC) models indicated a lack of short-run relationships but showed that there was a long-run equilibrium relationship between electricity consumption and gross domestic product. The accuracy of VEC models was assessed by using the mean squared error and the mean absolute error. The error analysis shows that VEC models reproduced time series of gross domestic product and electricity consumption in difference form accurately.     

The country-dependent shaping of ‘hydrogen niche’ formation: A comparative case study of the UK and South Korea from the innovation system perspective

This paper reports an international comparison of hydrogen niche formation in the UK and South Korea with special regard to policy development. Hydrogen energy development has provided us with a good example of ongoing phenomena during the early stage of socio-technical transition, in other words, the socio-technical niche. The purpose of the case studies was to see the country dependence in shaping the early stage (the period between the year 2002 and 2005) of hydrogen niche formation from the national innovation system perspective. The findings show certain differences in the background of hydrogen energy policies and the manners of policy development. There also are differences in the R&D activities, including not only the way in which they are performed, but also the strategic focussing of R&D, which have been influenced by R&D systems and the industrial structures of the national innovation systems. Vision-articulating processes and the roles and tendency towards intervention of governments are diverse. The research result will contribute to better understanding of the geography of socio-technical transition with empirical evidence. From that, one will be hinted that the hydrogen future may be diverse in different locations.