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The paper considers the development of mathematical models of combined heat and power plants that are to be used while modelling the fuel and energy complex. Consideration is given to three methods of combined heat and power plant (CHP) modelling: The first method provides for the simplified modelling based on CHP aggregation in one energy zone; the second method is based on modelling the individual CHP using the accurate parameters of their equipment operation; the third method is based on the use of standard regime diagrams for modelling individual CHP. Analysis of the presented methods of CHP modelling revealed that the third method out of the three methods proposed is most appropriate for mathematical models of fuel and energy complex for studying the fuel and power supply reliability. The experimental part of the paper describes the process of deriving the analytical dependencies of electricity and heat generation versus fuel used by CHP that is obtained by the third method proposed.

Although one of the most harmful factors to health is noise, it is often ignored in life cycle assessment (LCA) studies. Most researches regarding noise inclusion in LCA focus on the problem of transport noise, and very few works consider the impact of noise emitted by other sources. This study addresses the effects of noise generated by cogeneration plants. The main objective is to assess the environmental performance of the noise reduction system by considering the health effects of noise due to steam discharge as well as to compare the environmental loss associated with the production and disposal of a steam silencer with the benefits resulting from its application for noise reduction. A method to determine midpoint and endpoint human health indicators for a composition of noise emitted by intermittent stationary source and background noise is developed. The results indicate that the health benefit due to noise reduction is six orders of magnitude greater than the environmental loss. Human health indicators attributable to noise reduction in the residential zones under consideration span a wide range of disability adjusted life years (DALY)—0.16–136 DALY. The greatest values occur in the densely populated areas located close to the noise source. A formula is proposed to express annoyance of the residents of individual zones depending on their distance to the steam discharge source, its sound power level, and existing background noise level. Uncertainty and sensitivity analyses have been carried out assuming other conditions. Modifications of sound power level, noise reduction efficiency, steam discharge duration, and the silencer lifetime have not affected the overall conclusion drawn.

In developing countries like Pakistan, the capacity shortage (CS) of electricity is a critical problem. The frequent natural gas (NG) outages compel consumers to use electricity to fulfill the thermal loads, which ends up as an increase in electrical load. In this scenario, the authors have proposed the concept of a combined heat & power (CHP) plant to be a better option for supplying both electrical and thermal loads simultaneously. A CHP plant-based microgrid comprising a PV array, diesel generators and batteries (operating in grid-connected as well as islanded modes) has been simulated using the HOMER Pro software. Different configurations of distributed generators (DGs) with/without batteries have been evaluated considering multiple objectives. The multiple objectives include the minimization of the total net present cost (TNPC), cost of generated energy (COE) and the annual greenhouse gas (GHG) emissions, as well as the maximization of annual waste heat recovery (WHR) of thermal units and annual grid sales (GS). These objectives are subject to the constraints of power balance, battery operation within state of charge (SOC) limits, generator operation within capacity limits and zero capacity shortage. The simulations have been performed on six cities including Islamabad, Lahore, Karachi, Peshawar, Quetta and Gilgit. The simulation results have been analyzed to find the most optimal city for the CHP plant integrated microgrid. [ABSTRACT FROM AUTHOR]

Abstract: The scope of the HIGH-COMBI project is the development of high solar fraction systems by innovative combination of optimized solar heating, cooling and storage technologies as well as control strategies, in order to contribute and assist the further deployment of the solar energy market. Within this project, six demonstration plants were installed in four European countries (Greece, Italy, Spain and Austria). The purpose of this article is to assess the result achieved in the technical field of the project and to present the technical aspects of the six innovative demonstration systems realised during the project period. [Copyright &y& Elsevier]

Abstract: The share of electricity produced from renewable energy is constantly increasing in Germany and worldwide. The transformation to an electricity system based on renewable sources is characterised by an increasing need for balancing power in order to compensate power supply from fluctuating sources, such as solar or wind. Biomass, more precisely energy from biogas, has the potential to generate electricity flexible on-demand. A demand-driven biogas production is vital for balancing power generation and can generally be achieved by biogas storing or flexible biogas production concepts. This study analyses and reviews both concepts regarding their ability to facilitate a biogas supply for short-term and long-term balancing power generation. Results show that a demand-driven biogas supply based on a biogas storing concept is, due to the fast availability of biogas (i.e. biomethane), suitable for the generation of positive secondary and tertiary balancing power. Whereas, long-term balancing power can be provided by flexible biogas production as well as by biomethane, which was injected and stored in the natural gas grid. Basically all reviewed biogas supply concepts that facilitate a shutdown of electricity generation by storing or stopping the biogas production can additionally provide negative balancing power. [Copyright &y& Elsevier]

Abstract: The development of industrial ecology has led company managers to increasingly consider their company''s niche in the regional system, and to develop optimization plans. We used emergy-based, ecological-economic synthesis to evaluate two optimization plans for the Jiufa Combined Heat and Power (CHP) Plant, Shandong China. In addition, we performed economic input–output analysis and energy analysis on the system. The results showed that appropriately incorporating a firm with temporary extra productivity into its regional system will help maximize the total productivity and improve ecological-economic efficiency and benefits to society, even without technical optimization of the firm itself. In addition, developing a closer relationship between a company and its regional system will facilitate the development of new optimization opportunities. Small coal-based CHP plants have lower-energy efficiency, higher environmental loading, and lower sustainability than large fossil fuel and renewable energy-based systems. The emergy exchange ratio (EER) proved to be an important index for evaluating the vitality of highly developed ecological-economic systems. [Copyright &y& Elsevier]

Although one of the most harmful factors to health is noise, it is often ignored in life cycle assessment (LCA) studies. Most researches regarding noise inclusion in LCA focus on the problem of transport noise, and very few works consider the impact of noise emitted by other sources. This study addresses the effects of noise generated by cogeneration plants. The main objective is to assess the environmental performance of the noise reduction system by considering the health effects of noise due to steam discharge as well as to compare the environmental loss associated with the production and disposal of a steam silencer with the benefits resulting from its application for noise reduction. A method to determine midpoint and endpoint human health indicators for a composition of noise emitted by intermittent stationary source and background noise is developed. The results indicate that the health benefit due to noise reduction is six orders of magnitude greater than the environmental loss. Human health indicators attributable to noise reduction in the residential zones under consideration span a wide range of disability adjusted life years (DALY)—0.16–136 DALY. The greatest values occur in the densely populated areas located close to the noise source. A formula is proposed to express annoyance of the residents of individual zones depending on their distance to the steam discharge source, its sound power level, and existing background noise level. Uncertainty and sensitivity analyses have been carried out assuming other conditions. Modifications of sound power level, noise reduction efficiency, steam discharge duration, and the silencer lifetime have not affected the overall conclusion drawn. [ABSTRACT FROM AUTHOR]

• Life cycle assessment sheds important light on often hidden environmental impacts. • Construction phase of geothermal plants dominates contribution to most impacts. • Direct emissions dominate results for Global Warming and Acidification potentials. • Mitigation methods are available that reduce environmental impacts significantly. • Geothermal heat and power can have excellent environmental performance. This study applies life cycle assessment (LCA) to examine environmental impacts of generating 1 kW h of energy in a geothermal combined heat and power (CHP) plant based on high temperature geothermal utilization. The Hellisheidi geothermal CHP plant located in SW Iceland, producing 303 MW e and 133–267 MW th in a double flash cycle, is used as a case study for the LCA. The CML-IA baseline and Cumulative Energy Demand (CED) methods are used to perform the life cycle impact assessment (LCIA), providing results for common environmental impact categories investigated in most LCA studies. The impacts associated with joint production processes for electricity and heat are allocated to the two products by energy allocation. The result show that the construction phase of the plant, mainly drilling and casing of geothermal wells along with construction of collection system for geothermal fluid, is largely responsible for most of the impact category results. However, the global warming potential (GWP100), acidification (AP) and the renewable cumulative energy demand from wind, solar and geothermal energy (CED R,w,s,g) are mainly affected by the operational phase of the plant, due to direct emissions of gases (mainly CO 2 and H 2 S) and the extraction of geothermal fluid from ground. To explore the effects of currently installed mitigation methods and operational improvements at the Hellisheidi plant, two operation scenarios are investigated within the study; the first based on a previously published dataset for operating conditions at year 2012 and the second, an updated dataset based on inclusion of implemented mitigation methods until the operating year 2017. Due to carbon capture and storage (CCS) by reinjection of CO 2 using the CarbFix method developed at Hellisheidi, the GWP100 reduced from 15.9 g CO 2 eq/kWh to 11.4 g CO 2 eq/kWh for electricity and 15.8 g CO 2 eq/kWh to 11.2 CO 2 eq/kWh for heat over the 30-year operational time under investigation. Similarly, the SulFix method used for reinjection of H 2 S at Hellisheidi resulted in decreased AP from 9.7 g SO 2 eq/kWh to 3.6 and 3.5 g SO 2 eq/kWh and human toxicity (HTP) from 5.8 and 5.5 g 1,4-DB eq/kWh to 5.1 and 4.8 1,4-DB eq/kWh for electricity and heat respectively. The overall CED resulted in 5.2 kW h (18.7 MJ) of energy demand to produce 1 kW h of either electricity or heat, dominated by the use of geothermal energy as mentioned earlier. Non-renewable energy demand (CED NR) decreased from 6.8 × 10−3 and 5.9 × 10−3 kWh (0.024 and 0.021 MJ) to 5.8 × 10−3 and 5.0 × 10−3 kWh (0.021 and 0.018 MJ), for electricity and heat respectively, by using electrical drills instead of diesel fueled drills for additional wells during the operational time of the power plant. In conclusion, these results indicate a very high environmental performance of the Hellisheidi plant compared to other energy conversion technologies and emphasizes the potential of geothermal energy as a clean energy source for producing electricity and heat. [ABSTRACT FROM AUTHOR]