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Energy and economic performance of an organic Rankine cycle (ORC) system designed to recycle waste heat of a steam boiler was analysed. Optimisation of ORC system was performed by using the Cycle-Tempo software and the REFPROP program. The selected working fluid was R245fa. For the exhaust gases temperature of 163°C and mass flow rate of 11.83 kg/s, cooling water temperature of 20°C resulted a gross efficiency of 21.02% and a cost of 2987 €/kW, an electricity levelised cost of 102 €/kWh and a payback period of 5.5 years.

The low-enthalpy geothermal sources can be efficiently exploited for heat and power cogeneration by using the KCS-34 Kalina cycle systems. The maximum power for given heat source temperature and cooling temperature is obtained for a certain value of the ammonia-water solution concentration and turbine exit pressure. The Cycle-Tempo simulation software is a very useful tool to investigate variation of some cycle parameters in order to obtain the maximum energy efficiency. In this paper the performance of a KCS-34 Kalina cycle based CHP plant is investigated to exploit a geothermal source with 120°C temperature present in North-West of Romania. It was found that by using the heat and power cogeneration the energy efficiency can be increased from 16.76% to 57.86% in winter and to 33.44% in summer.

The municipal solid wastes (MSW) can be turned into resources through recycling and energy recovery. To obtain the maximum amount of energy, the appropriate technology must be applied to waste treatment. The composition and characteristics of municipal solid wastes are determinant for technologies choice for MSW in a city/region. Municipal authorities from the Galati city proposed a recovery rate of recyclable materials of 60% from MSW and treatment of the post-recycling MSW as follow: biodegradable fraction by anaerobic digestion and the combustible fraction by incineration or gasification. In this study traditional and innovative waste to energy technologies have been analysed and the potential of electrical energy of waste has been estimated. Results show that plasma gasification system of raw MSW coupled with gas turbine engine has almost the same electrical energy production (32.92 GWh/year) as conventional gasification of combustible material from MSW (17.21GWh/year) coupled with anaerobic digestion of organic fraction of MSW (11.65 GWh/year). By recovering and using the landfill gas from the Tirighina landfill, 6.68 GWh of electricity can be produced annually.

This article states the problems with the use of central heating stations, as well as the need to introduce individual heat points. As a result, the authors considered the issue of improving the energy efficiency of heat supply systems in Russian cities while replacing central heating stations with individual heat points. The beneficial effects of the activities are especially noted.