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Highlights: [•] Electrical power reduces with temperature, heat recovery remains almost constant. [•] Thermal-to-electrical power ratio increases with ambient temperature. [•] Not only the density of sucked air decreases but also its volumetric flow. [•] Putting a limit to shaft speed causes TIT to decrease with ambient temperature. [•] Power reduction with ambient temperature more than doubles that of great GTs. [Copyright &y& Elsevier]

This paper describes a test bench that has been designed to implement the fogging inlet air cooling technique to a 100 kWe Microturbine (MGT) and reports the power and efficiency increase of the machine. Indeed, one of the main issues of MGTs, which has also been observed and documented in large sized gas turbines, is their strong sensibility to inlet air temperature. One of the most interesting technology in terms of low plant complexity to limit the MGTs performance loss is the high pressure fogging. Although cooling down the inlet air temperature with this technique has already been analyzed for medium/large gas turbines systems, there are very limited reports available on MGTs and few experimental data are documented. Results show that the machine’s electric power gain depends on ambient humidity and it ranges from 5% to 13% (corresponding to an inlet temperature drop between 4 and 10 °C) in the location where the plant is installed. Power enhancement corresponds to 1.03 kW for each Celsius degree of inlet air temperature reduction. As regards the electric conversion efficiency, the increase reaches about 0.41%/°C. Being the inlet air saturation the thermodynamic limit, the absolute power and efficiency gains are the higher, the hotter and drier the climate is. [ABSTRACT FROM AUTHOR]

Abstract: The study considers the “renovation” (as defined by Italian legislation) of an electricity-generating plant using biogas produced in a managed landfill as the primary energy source. The landfill, located in the Marche region (central Italy), receives about 100 kt y−1 of urban and industrial residues. The plant is endowed with two 470 kW (e) internal combustion engines and has been in operation since 1998. At the end of its lifecycle it is scheduled for decommissioning. Public incentives for energy production from renewable sources, which the plant enjoyed in the first eight years of activity, have also expired. The study examines the main legal, technical and economic options available to the landfill management, in particular considering the new Italian and EU incentives for energy generation from renewable sources. Five configurations are considered for the replacement of the existing engines, three at the original site (a single combustion engine with/without incentives, and a plant with microturbines), and two involving the construction of new plants at a separate site (a cogeneration plant with a combustion engine and one with microturbines). The study provides data that may be a useful basis for other similar cases and for simulations. [Copyright &y& Elsevier]

In the contest of European and National choices regarding energy and mobility policies, the goal of this paper is to introduce reasonable guidelines for the local promotion of electric mobility in an area of central Italy and possibly to extend the methodology to other regions/countries. In fact, the path towards car electrification is started worldwide, but the rate of increase of electrically powered cars will depend primarily on charging stations availability. In this respect, utilities that manage/own local grids may be key actors by investing on infrastructures and thus locally creating the conditions for the spreading of electric cars. A techno-economic analysis of the investment of a local utility has been performed taking into account medium- and long term-forecasts of electricity and fuel prices, as well as electric cars market share and economic risk. The study proved that an investment in urban charging station infrastructure in Italy can be profitable even without incentives, with a payback period of 4–5 years. The results of the analysis have been exploited by an Italian utility which owns/manages the local electric grid in two municipalities. The first steps of the plan implementation, which started in 2014, are reported in the paper. [ABSTRACT FROM AUTHOR]

Microturbines (MGTs) are power generation devices showing very interesting performance in terms of low environmental impact, high-grade waste heat and very low maintenance cost. One of the main issues that affect the output of MGTs is their strong sensibility to inlet air temperature. Both in literature and in practical applications, several solutions have been applied to control the inlet air conditions and reduce the sensibility of this kind of machines to ambient conditions. One of the most interesting technology is the refrigerating vapour compression technique. This solution has already been used for medium/large GTs, but there are very limited inlet air cooling applications on MGTs and few experimental data are documented. This paper describes a test bench that has been designed to apply the direct vapour expansion technique to a 100 kWe MGT and reports the power and efficiency augmentation of the machine when operating in hot summer days. The chiller was designed to treat the MGT’s air flow rate under specific working conditions and cool the inlet air temperature down to 15 °C. Thanks to the reduction of the inlet air temperature, the MGT showed a benefit in terms of electric power gain up to 8% with respect to the nominal power output in ISO conditions while the electric efficiency increased by 1.5%. Results indicate that an almost linear trend can be obtained both in the electric power increase and in the electric efficiency increase as a function of the inlet air temperature when the chiller operates under nominal working conditions. When the IAC device operates at a higher temperature or a higher humidity than the design one, the gain is limited; in some working conditions with high relative humidity, most of the beneficial effect can even be lost. [ABSTRACT FROM AUTHOR]

Abstract: In this work, artificial neural networks (ANNs) were applied to describe the performance of a micro gas turbine (MGT). In particular, they were used (i) to complete performance diagrams for unavailable experimental data; (ii) to assess the influence of ambient parameters on performance; and (iii) to analyze and predict emissions of pollutants in the exhausts. The experimental data used to feed the ANNs were acquired from a manufacturer’s test bed. Though large, the data set did not cover the whole working range of the turbine; ANNs and an artificial neural fuzzy interference system (ANFIS) were therefore applied to fill information gaps. The results of this investigation were also used for sensitivity analysis of the machine’s behavior in different ambient conditions. ANNs can effectively evaluate both MGT performance and emissions in real installations in any climate, the worst R 2 in the validation set being 0.9962. [ABSTRACT FROM AUTHOR]