Under the liberalization of the retail electricity market, peer to peer (P2P) energy trading between households in microgrid are more economical. This paper discusses the bidding strategy based on evaluation mechanism for P2P energy trading in microgrid. The main focus is how to reduce the cost of electricity consumption of households and the impact caused by the intermittent and volatility of distributed sources such as photovoltaics (PV) by limiting the selfish behaviors of households in microgrid. Firstly, based on the characteristics of the electricity market, an evaluation mechanism based on the analytic hierarchy process (AHP) for energy auction is proposed to evaluate the energy service level of households and constrain the selfish behavior of households in microgrid. Secondly, the bidding strategy based on evaluation mechanism for P2P energy trading in microgrid is established. Moreover, based on the economic principle, the electricity supply and demand relationship of the household is quantitatively determined by the Household Electricity Supply and Demand Ratio (HESDR) and the energy valuation of household is defined. Finally, through the simulation of actual examples, the effectiveness of the proposed model in reducing the net cost of electricity for households and the impact on the grid are verified.
For the depressurization process of the watersaturated hydrate reservoir, the gas recovery is seriously restrained by the continuous seepage of the surrounding water, resulting in high water production. In response to this problem, the technique of pressureretaining gas injection was used in this work to inhibit water production and enhance gas recovery. The results showed that water production was reduced by hundreds of times and gas recovery reached ~30% by PRGI.
This paper focuses on the optimal dispatching of microgrid with photovoltaic and energy storage. Firstly, considering the constraints of energy storage, interruptible load and transferable load, a multi-objective optimization model of grid-connected microgrid under time-sharing price and demand response is established, aiming at minimizing the operation cost, environmental cost and tie-line power fluctuation of microgrid. Then, aiming at the multi-objective, multi-constraint and non-linear characteristics of the model, an optimization solution method based on non-dominated sorting genetic algorithm-II (NSGA-II) is proposed. Finally, the article simulates the case based on MATLAB and OPENDSS joint simulation platform. The results of the example prove the validity and rationality of the model.
This study proposes a three-dimensional (3-D) model to investigate the detailed characteristics of conjugate conduction-natural convection heat transfer of photovoltaic cells mounted discretely on the bottom wall of a horizontal cabinet. The influences of thermal interaction between air streams inside and outside the cabinet through the conducting walls are explored. Furthermore, the enhancement of cooling performance of photovoltaic cells by using the fins is conducted. Results show that, for the system with 40 photovoltaic cells and Q =10W, the hot spot temperature drop is about 23 ℃ when the fins Nf = 170 are installed onto the cabinet bottom wall.
The steel industry in the European Union, important for the economy as a whole, faces various challenges. These are inter alia volatile prices for relevant input factors, uncertainties concerning the regulation of CO2-emissions and market shocks caused by the recently introduced additional import duties in the US, which is an important sales market. We examine primary and secondary effects of these challenges on the steel industry and stress impacts on European and global level. Particularly, we analyse the impacts of changes in competitiveness on energy demand and CO2-emissions taking transport of raw materials and steel into consideration. By applying information on Human Development Index values (reflecting aspects of life expectancy, education, and per capita income) we show that relocating energy-intensive industries from Europe may not only increase energy demand and global CO2- emissions, but may also affect developing countries.
This paper addresses the issue of social inequality by comparing German household data (gross income, Food‐Energy‐(Watervirtual)‐Nexus expenditures) from 2008 and 2013. The distribution of gross income and of the FE(Wvirtual)‐Nexus related consumption expenditures based on this income is analysed using a three step approach: First, the real distribution is determined, secondly, the dispersion (based on Rawls’ philosophical concept) is analysed, and finally, the normative distribution according to the Atkinson index is calculated to reveal a view on social inequality. The six main household groups were selected for the cross section analysis comparing the social conditions of 2008 and 2013: self‐employed households, public servant households, white‐collar and blue‐collar worker households, unemployed households and retiree households. The three‐dimensional model delivers data about the real and normative distribution of the households’ gross income and consumption expenditures for the time period from 2008 to 2013 considering the inequality perception of society.
Industrial and chemical plants, especially oil refineries, are highly energy-consuming plants. Several energy efficiency interventions are being currently performed: besides gas recovery solutions, also energy recovery in liquid flows can be applied. In this paper, a case study of an Italian oil refinery regarding the use of a Hydraulic Power Recovery Turbine (HPRT), which is installed in a Hydrogen Sulphide (H2S) removal process from the Syngas produced by an Integrated Gasification Combined Cycle (IGCC), is analysed and presented. The real performance data of the process are discussed: on average, 353.4 t/h of liquid SELEXOL can be elaborated by the HPRT with 445.4 m of head. Finally, the recovered electrical energy on a yearly basis is equal to 2966 MWh, or 531 tons of carbon dioxide equivalent. The pay-back period of the intervention ranges indicatively between 6 and 9 years, depending on the discount rate.
The long‐term production of U.S. tight oil is forecast by using a composite model combining the Generalized Weng and Gompertz models. We show that U.S. tight oil production is likely to reach a peak within ten years, between 2019 and 2028, at a production rate between 7 and 13 million barrels per day (Mb/d), depending on the size of the ultimately recoverable resource (URR) estimate. Our most‐likely ‘medium‐case’ URR scenario suggests the peak year is probably around 2025, at a production rate of about 10 Mb/d. Comparing our results with those of the U.S. Energy Information Administration (EIA) suggests that the EIA is over‐optimistic in its long‐term production forecast of U.S. tight oil.
Thermal properties of geopolymer concrete (GPC) are enhanced by adding phase change material (PCM) capsules. The capsules were developed and tested in our previous research. In total, five compositions of GPC cubes were developed for testing, one pure geopolymer as a reference, two compositions by 50% volume substitution of pure geopolymer with the two different PCM capsules and two compositions by 50% substitution of each porous material for comparison. Thermal and structural tests were conducted to investigate the effects of capsules on the properties of produced GPC. The produced thermally enhanced GPC can reduce heat transmission to indoors in the hot climates like the United Arab Emirates and its compressive strength is acceptable for non-loadbearing wall components.
In the conventional downhole heat transfer mode, using the two-phase closed thermosyphon (TPCT) can greatly improve the heat extraction capability from geothermal reservoirs. In this paper, a set of laboratory-scale performance testing device is built for TPCTs with internal tubes and charged with CO2-nanofluids mixed working fluid. Based on the conditions of geothermal reservoir and heating season, experimental investigations are carried out by various heating temperature (50~70 ℃), heating water flow rate (1.0~3.0m3 /h), cooling temperature (5~15 ℃) and cooling water flow rate (1.0~3.0m3 /h). The results show that the increase of heating temperature plays a dominant part in heat transfer performance, but not always be positively correlated due to the increase in temperature difference between the evaporator section and the condenser section. From the perspective of their own structure, outer fins have the most obvious improvement on their performance and another method of reducing the aspect ratio takes second place.