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Energy efficiency is a key target of the European Union policy. The “Europe 2020 strategy” quantitative targets account an increase by 20% of the energy efficiency by the end of 2020. The attention to power sources optimization and energy waste reduction leads European Countries to develop subsidy strategies to drive the energy market towards efficiency enhancement. According to this trend, energy efficiency of residential buildings has significantly grown in Italy in the last years. Combined production of electric and thermal power is a notable example of efficiency enhancement awarded by the CAR ( Cogenerazione ad Alto Rendimento ) Italian subsidies system. In these circumstances, the optimization of the ensemble between power generators and thermal storages becomes crucial to satisfy in an efficient way thermal power requirement independently from electric power production. The purpose of this paper is to find the optimal power plant design of power generators and thermal storages in order to minimize daily management costs and environmental impact. The power plant layout in analysis consists in a micro-CHP (Combined Heat and Power) and an absorption chiller both coupled with respective thermal storages. Through this evaluation, it is possible to identify the optimal coupling of the devices as a function of the load requirements and understand the great influence of their sizing on the energy management benefits. The analysis is performed with reference to cold and warm thermal load required by a residential case study. The performance analysis takes place in representative days of different seasons and the results are extended on an annual base. The power request profiles are developed on the basis of literature data. The results are compared on an economic basis considering the NPV (Net Present Value) index, evaluated using as the benchmark a standard plant layout composed by a water boiler and an electric chiller. [ABSTRACT FROM AUTHOR]

The increasing need for energy and cost efficient solutions for thermal and electric supply is giving new life to CHP plants, even for small power sizes. It is renowned that the optimal application of a CHP plant is to satisfy as much as possible both the electricity and the thermal requirements of the loads, but the frequent applicative context, especially for residential and/or tertiary buildings, is unbalanced towards the thermal needs, so that the sizing of the CHP is determined by the electric loads, at least in the Italian tariff structure context, with the consequence that the generator is relatively small and, consequently, the installation costs represent a consistent part of the capital investment. The increasing level of the performance of the electric heat pump can sensitively minimize the former issue: the combination between a CHP and an EHP can led to a larger size of the co-generative unit, whose exceeding power output can feed the heat pump so that to efficiently satisfy most of the thermal loads of the plant. In this paper an application case referred to an office building is presented: the optimal size of the system will be discussed, and the economic results (in terms of PBT and NPV) of the management of the plant compared with other commonly exploited solutions: • Conventional supply, with the heat produced by a gas boiler, the cooling from an electric chiller, and the electricity purchased by the grid; • Optimal sizing of the CCHP based on the heating loads duration curve, with the engine operated in thermal-led; • Optimal sizing of the CCHP based on the electric loads duration curve, with the engine operated in power-led. The environment performance will be discussed as well, focusing on the comparison between the different solutions in terms of equivalent CO 2 emissions and primary energy consumptions. [ABSTRACT FROM AUTHOR]

The present paper describes an energy efficiency project (and relevant authorities proceedings) related to a 100 MWe CHP located within an industrial facility in Italy (COD 1996). The CHP plant supplies steam and electricity to the industrial process, whilst the extra electric-energy generation is sold to the grid. Main project target was to increase the global operating and economic indicators by: • Modifying the plant in order to cope with different thermal needs from the industrial process; Obtaining the incentives named TEE – Titoli di Efficienza Energetica , related to the CAR scheme; • Reducing CO 2 emissions (“Quote CO 2” ). • Increasing the CHP global efficiency; As several European CHP plants are nowadays facing operation/performance limitations due to different actual thermal loads (typically lower) compared to the design ones; the project has hence the aim to combine the need of a plant retrofit and the eligibility for the CAR incentives, providing a financial support to the retrofit, which corresponds, in project case, to a PBT of less than 2 years. The project and iterations with GSE are still ongoing. [ABSTRACT FROM AUTHOR]

Mauritius has a long tradition of using cogeneration systems for electricity generation. Bagasse, a by-product of sugar cane is burnt in high temperature and pressure boilers to produce superheated steam to be used for combined heat and power generation. Steam is fed in condensing extraction steam turbine coupled with an alternator to produce electricity and the exit low pressure steam of the turbine is used for the processing of sugar with flexibility to be employed also in distillery and refinery activities. Multi-criteria analysis of such bio-refinery inputs and outputs is conducted considering Energy, Engineering, Economic, Environmental and Ethical dimensions like sustainability, equity and democratization of the energy sector. Due to the reduction of price obtained for the sale of sugar to the European Union, the sugar industry has to re-engineer itself to move towards the flexi-factory concept for its survival. Production of high value-added refined sugar/special sugars, dehydrated ethanol for transport and power use and green electricity are constrained by a host of factors from climatic conditions to the price of sugar on the world market through the grid power costs itself dependent on world oil and coal prices. Environmental standards are also to be considered. The aim of this paper is to optimize the cogenerated energy systems of the cane flexi-factory by a holistic energy systems analysis. Actual parameters of a flexi-factory are used to calculate the energy efficiency of each components parts of the system as well as social, economic and environmental benefits. Policy implications crucial to the future viability of such complex energy systems; these are fully discussed in relation to national and international objectives. [ABSTRACT FROM AUTHOR]