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Abstract District heating (DH) enables the utilisation and distribution of heating from sources unfeasible for stand-alone applications and combined with cogeneration of heat and power (CHP), has been the cornerstone of Denmark’s realisation of a steady national primary energy supply over the last four decades. However, progressively more energy-efficient houses and a steadily improving heat pump (HP) performance for individual dwellings is straining the competitive advantage of the CHP–DH combination as DH grid losses are growing in relative terms due to decreasing heating demands of buildings and relatively high DH supply temperatures. A main driver for the DH water temperature is the requirements for domestic hot water (DHW) production. This article investigates two alternatives for DHW supply: (a) DH based on central HPs combined with a heat exchanger, and (b) a combination of DH based on central HPs and a small booster HP using DH water as low-temperature source for DHW production. The analyses are conducted using the energyPRO simulation model and are conducted with hourly varying factors; heating demands, DH grid losses, HP coefficient of performance (COP) and spot market prices in order to be able to analyse the relative performance of the two options and their performance over the year. Results are also compared to individual boilers and individual HPs. The results indicate that applying booster HPs enables the DH system to operate at substantially lower temperature levels, improving the COP of central DH HPs while simultaneously lowering DH grid losses significantly. Thus, DH performance is increased significantly. Additionally, performance for the DH HP with booster combination is considerably better than individual boiler or HP solutions.

Abstract The use of photovoltaic solar power generation is rising as worldwide energy demand increases. Therefore, reliability, safety, life cycle, and improved efficiency of photovoltaic plants have all become a major concern in research nowadays. In this context, monitoring systems are necessary to guarantee the required operating productivity and to avoid overpriced maintenance costs. This paper studies the non-ideal operating conditions for grid-connected photovoltaic plants and proposes an anomaly detection methodology that combines the advantages of the 2-sigma, short-window simple-moving average control charts with shading strength and irradiance transition parameters to detect early deviation in photovoltaic plant operational data. The key aspect of proposed methodology is that it requires neither historical data for model training procedure nor parameters from previous simulation. Only instantaneous meteorological and electrical parameters are required. The efficiency of the condition monitoring methodology has been validated through experimental results conducted in actual operating conditions. Results demonstrated that the proposed methodology is effective to identify non-ideal operating conditions for grid-connected photovoltaic plants, i.e., (i) normal operating condition, (ii) natural dynamic shading, (iii) artificial dynamic shading, and (iv) artificial static shading. Moreover, a low-cost and non-invasive internet-of-things-based embedded architecture is proposed to monitor photovoltaic plant operation in real-time.

Abstract Numerous efforts have been done for achieving the maximum penetration of renewable energy sources (RESs) in the autonomous grids of Greek islands, which never exceeded 10%, despite the exceptional wind and solar potential. Large fluctuations on demand during summer, winter, and 24-h period in combination with the technical restrictions of diesel generators of the existing conventional power stations are a major concern of power supply system. Reversing the roles of diesel generators and wind farms (WFs), to use WF as the basic energy source and diesel generators as stand-by system changed in fact the whole philosophy of energy supply systems in islands and created perspectives for the fundamental reformation of the conventional energy supply systems in autonomous grids. In fact, methods of contemporary interim medium term energy storage are investigated for hybrid systems in order to adjust the stochastic behavior of wind energy to the demand, to provide the system with guaranteed power. This Wind–Hydro Plants in combination with the most adequate RES forming an Renewable Energy Supply System (RESS), increase further the economical penetration of RES into autonomous grids up to 90% or even 100% and simultaneously reduce drastically the fuel costs. Furthermore, a supergrid is examined and compared with RESS as another efficient way for achieving higher penetration of RES.

Abstract Anaerobic digestion of animal by-products was investigated in batch and semi-continuously fed, reactor experiments at 55 °C and for some experiments also at 37 °C. Separate or mixed by-products from pigs were tested. The methane potential measured by batch assays for meat- and bone flour, fat, blood, hair, meat, ribs, raw waste were: 225, 497, 487, 561, 582, 575, 359, 619 dm 3 kg −1 respectively, corresponding to 50–100% of the calculated theoretical methane potential. Dilution of the by-products had a positive effect on the specific methane yield with the highest dilutions giving the best results. High concentrations of long-chain fatty acids and ammonia in the by-products were found to inhibit the biogas process at concentrations higher than 5 g lipids dm −3 and 7 g N dm −3 respectively. Pretreatment (pasteurization: 70 °C, sterilization: 133 °C, and alkali hydrolysis (NaOH) had no effect on achieved methane yields. Mesophilic digestion was more stable than thermophilic digestion, and higher methane yield was noticed at high waste concentrations. The lower yield at thermophilic temperature and high waste concentration was due to ammonia inhibition. Co-digestion of 5% pork by-products mixed with pig manure at 37 °C showed 40% higher methane production compared to digestion of manure alone.

Abstract Biomass is an important renewable energy source that holds large potential as feedstock for the production of different energy carriers in a context of sustainable development, peak oil and climate change. In developing countries, biomass already supplies the bulk of energy services and future use is expected to increase with more efficient applications, such as the production of biogas and liquid biofuels for cooking, transportation and the generation of power. The aim of this study is to establish the amount of Ghana's energy demand that can be satisfied by using the country's crop residues, animal manure, logging residues and municipal waste. The study finds that the technical potential of bioenergy from these sources is 96 PJ in 2700 Mm3 of biogas or 52 PJ in 2300 ML of cellulosic ethanol. The biogas potential is sufficient to replace more than a quarter of Ghana's present woodfuel use. If instead converted to cellulosic ethanol, the estimated potential is seven times the estimated 336 ML of biofuels needed to achieve the projected 10% biofuels blends at the national level in 2020. Utilizing the calculated potentials involves a large challenge in terms of infrastructure requirements, quantified to hundreds of thousands of small-scale plants.

Four different municipal solid wastes (dog manure, horse manure, apple pomace waste and tea waste) and an industrial by-product (NovoGro) were used to produce solid fuel pellets. The mixtures followed a raw material to NovoGro ratio of 50:1. The pellets diameters varied between 4 and 5 mm, and the average length was 20 mm. The dog manure, horse manure, apple pomace waste and tea waste pellets were denoted as DN, HN, AN and TN, respectively. The combustion characteristics of the pelletized fuels were investigated, such as total moisture, ash content, calorific value and ash fusion point, etc. The physicochemical properties were analyzed by using a number of analytical techniques including X-ray fluorescence spectrometry (XRF), X-ray diffraction spectrometry (XRD), scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR). The results of the mechanical, thermal and morphological properties show that the raw materials were effectively combined with the NovoGro binder; furthermore, the DN, HN and TN pellets exhibited excellent mechanical and thermal properties, including high calorific values (>16.30 MJ/kg), high resistance to mechanical shock (>99%), high volatile matter contents, optimal softening temperatures and optimal ash contents. However, the high K, Ca, and Si contents of the AN can form low-melting-point eutectics, which can cause slagging. Moreover, the AN materials had large particle sizes, and high cellulose and hemicellulose contents led to high total moistures, low softening temperatures and low calorific values. The AN was not suitable for use as a fuel. The results suggested that NG is an effective binder for pelletization of biomass and showed the feasibility of using municipal solid wastes for energy production.

Abstract In this article, we investigate the intergenerational transmission of sustainable consumption practices. Whereas previous studies have used self-reported attitudes and behaviour, this study uses data on actual energy consumption for space-heating and hot water combined with extensive panel data from Danish administrative registers. The paper shows significant intergenerational correlations between the energy consumption patterns of adults and their mothers, also when controlling for the energy consumption of the mother-in-law, where possible. Furthermore, it shows that the intergenerational correlation is slightly stronger for adults with lower income levels. These results suggest that energy consumption practices are shared and reproduced within the family. Following theories of practice, the intergenerational similarities in energy consumption practices refer to bodily learned practices that are indirectly transmitted and negotiated through family relations. In this way, these findings also contribute to a better understanding of how practical understanding regarding how to perform practices is transmitted within more ordinary aspects of consumption that play a less obvious role in distinction. To ensure more sustainable consumption practices in the future, this paper points to the importance of the role of family relations and the transmission of embodied practices.

Empirical greenhouse gas (GHG) flux estimates from diverse peatlands are required in order to derive emission factors for managed peatlands. This study on a drained fen peatland quantified the annual GHG balance (Carbon dioxide (CO2), nitrous oxide (N2O), methane (CH4), and C exported in crop yield) from spring barley (SB) and reed canary grass (RCG) using static opaque chambers for GHG flux measurements and biomass yield for indirectly estimating gross primary production (GPP). Estimates of ecosystem respiration (ER) and GPP were compared with more advanced but costly and labor-intensive dynamic chamber studies. Annual GHG balance for the two cropping systems was 4.0 ± 0.7 and 8.1 ± 0.2 Mg CO2-Ceq ha(-1) from SB and RCG, respectively (mean ± standard error, n = 3). Annual CH4 emissions were negligible (<0.006 Mg CO2-Ceq ha(-1)), and N2O emissions contributed only 4-13 % of the full GHG balance (0.5 and 0.3 Mg CO2-Ceq ha(-1) for SB and RCG, respectively). The statistical significance of low CH4 and N2O fluxes was evaluated by a simulation procedure which showed that most of CH4 fluxes were within the range that could arise from random variation associated with actual zero-flux situations. ER measured by static chamber and dynamic chamber methods was similar, particularly when using nonlinear regression techniques for flux calculations. A comparison of GPP derived from aboveground biomass and from measuring net ecosystem exchange (NEE) showed that GPP estimation from biomass might be useful, or serve as validation, for more advanced flux measurement methods. In conclusion, combining static opaque chambers for measuring ER of CO2 and CH4 and N2O fluxes with biomass yield for GPP estimation worked well in the drained fen peatland cropped to SB and RCG and presented a valid alternative to estimating the full GHG balance by dynamic chambers.

Climaps.eu is an online atlas providing data, visualizations and commentaries about climate adaptation debate. It contains 33 issue-maps and 5 issue-stories. Each of the maps focuses on one issue in the adaptation debate and provides.The atlas is addressed to climate experts (negotiators, NGOs and companies concerned by global warming, journalists…) and to citizens willing to engage with the issues of climate adaptation.It employs advanced digital methods to deploy the complexity of the issues related to climate adaptation and information design to make this complexity legible.