In the next years distributed poly-generation systems are expected to play an increasingly important role in the electricity infrastructure and market. The successful spread of small-scale generation either connected to the distribution network or on the customer side of the meter depends on diverse issues, such as the possibilities of technical implementation, resource availability, environmental aspects, and regulation and market conditions. The aim of this approach is to develop an economic and parametric analysis of a distributed generation system based on gas turbines able to satisfy the energy demand of a typical hotel complex. Here, the economic performance of six cases combining different designs and regimes of operation is shown. The software Turbomatch, the gas turbine performance code of Cranfield University, was used to simulate the off-design performance of the engines in different ambient and load conditions. A clear distinction between cases running at full load and following the load could be observed in the results. Full load regime can give a shorter return on the investment then following the load. In spite combined heat and power systems being currently not economically attractive, this scenario may change in future due to environmental regulations and unavailability of low price fuel for large centralized power stations. Combined heat and power has a significant potential although it requires favorable legislative and fair energy market conditions to successfully increase its share in the power generation market.

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Geopolitical issues give rise to problems in the smooth and continuous flow of oil and natural gas from the production countries to the consumers’ development countries. In addition, severe environmental issues such as greenhouse gas emissions, eventually guide the consumers to fuels more suitable to the present situation. Alternative fuels such as biogas and coal gas have recently become more attractive because of their benefits, especially for electricity generation. On the other hand, the use of relatively low heating value fuels has a significant effect to the performance parameters of gas turbines. In this paper, the impact of using four fuels with different heating value in the gas turbine performance is simulated. Based on the high efficiency and commercialization criteria, two types of engines are chosen to be simulated: two-shaft simple and single-shaft recuperated cycle gas turbines. The heating values of the four gases investigated, correspond to natural gas and to a series of three gases with gradually lower heating values than that of natural gas. The main conclusions drawn from this design point (DP) and off-design (OD) analysis is that, for a given TET, efficiency increases for both engines when gases with low heating value are used. On the contrary, when power output is kept constant, the use of gases with low heating value will result in a decrease of thermal efficiency. A number of parametric studies are carried out and the effect of operating parameters on performance is assessed. The analysis is performed with customized software, which has been developed for this purpose.

Environmental concerns related to climate change are forcing many countries to consider implementing cogeneration of heat and power with centralized heating systems (i.e. district heating networks) which are becoming increasingly widespread in many countries. Combined heat and power (CHP) or cogeneration is the simultaneous production of electricity and useful thermal energy. The big interest this technology is receiving, both globally and locally, has its reason in the chance of reducing fuel consumption by enhancing energy production processes. The considerable amount of waste heat associated to traditional power stations is transformed into useful heat, which can be sent through the district network to houses and buildings for heating or cooling. Considering the pollution district heating reduce local pollutants such as dust, sulphur dioxide and nitrogen oxides by replacing exhausts from individual boilers. In addition to the reduced use of fuels, far more effective pollution prevention and control measures can be taken in central production facilities.The purpose of this paper is to present the results of the investigation for the installation of a small-scale CHP plant for District Heating purposes in a small municipality in Northern Greece.Initially the heat and electricity demands were estimated based on a combination of historical consumption data, the construction features of the buildings and the weather conditions in the region.A pipe network was designed and sized appropriately and the utilization of a CHP plant was studied.Additionally, a number of various fuel options were considered such as natural gas, oil, pulverised coal and biomass from crop and forest residues, and also animal waste. The availability in biomass in the local region was estimated and it was found that it could cover a small percentage of approximately 5% of the required heating power.Finally, a techno-economic analysis was carried out and the CO 2 reduction benefits were estimated.

Coal gas and biofuels as alternative fuels have recently become more attractive, because of their benefits, especially in electrical power industry. The major obstruction to their use is the relatively low calorific values. This paper presents a comprehensive simulation method for calculating the adiabatic temperature of various fuels when they are used in combustion chambers under constant pressure. The adiabatic temperature is presented as a function of combustion fuel air ratios and the fuels low calorific values. In addition, the utilization of various gaseous fuels in single shaft and two shaft gas turbine engines is analyzed. This analysis includes the design point (DP) and off-design (OD) performance of the two engines. The calorific values of the four gases investigated correspond to natural gas (NG) and to fuels with significantly lower calorific values than that of NG (coal synthetic gases, biofuels). Two main conclusions are drawn from this analysis. Firstly, for both single shaft and two shaft engines and for a given turbine entry temperature (TET), both power and thermal efficiency are increasing when fuels with decreasing calorific value are burnt. Secondly, for both single shaft and two shaft engines and for a given power, the thermal efficiency is slightly reduced.