Search

In the framework of promotion of energy efficiency and renewable energy sources in Croatia it is aiming at achieving the objectives of energy policy that includes sustainable energy development, energy supply security and competitiveness of energy systems. In order to make a final conclusion it is necessary to identify the key factors and by scientific evidence minimize conflicting opinions in the pricing of fuel, limiting climate change and the use of various forms of energy, the possibilities of import or export of energy, all in accordance with national interests. Although the consumption of electricity in Croatia is small, inefficient usage of electricity brings structure of its available resources into a state of exhaustion. In the paper, but not entering in the structure of production and consumption, by applying regression models, the relationship between the amount of production, imports, exports and the availability of electricity to its final consumption in the Republic of Croatia is determined. Descriptive statistical analysis in this paper is reduced to the determination of the analytical expression that in some sense the best presents empirical data on the variables shown for comparison. By simple linear regression model and multiple regression model the relationship between production, import and export of electricity are represented i.e. the total availability and its consumption. Based on obtained size it will be determined whether and in how much regression model is representative. The calculated parameters have provided a clear picture about the relationship between studied variables. [ABSTRACT FROM AUTHOR]

Croatia has enormous renewable energy potential, particularly solar, but it is underperforming with regard to its use both for electricity production and heating. Paper focuses on the reasons therefor by analyzing the policy with regard to environment, subsidies, the role of international financial institutions, monopoly dimension of power utility companies, as well as social dimension. The author presents proposals for changing the status quo in order for Croatia to catch up with regard to securing reasonable solar and other renewable energy share in its energy supply. Apart from the state as regulator which has various instruments at its disposal to implement thoroughly the renewable energy use, local authorities should assume central role and responsibility for solarizing their territories and generating the energy locally from other renewable energy sources available on their territory. Municipal utility companies would thus add electricity production to their regular activities and could provide installation and maintenance services for individual energy generating systems within the territory of their competence. [ABSTRACT FROM AUTHOR]

Abstract: Many of the modern practices in waste management at the same time represent means of reduction of greenhouse gas (GHG) emissions. The main focus in this paper is given to the measures for recovering energy from municipal solid waste (MSW): Utilization of landfill gas for electricity production, Utilization of refuse derived fuel (RDF) in cement industry, Thermal treatment (Incineration) of MSW, Mechanical-biological treatment, and to one measure without energy recovery – Landfill gas flaring, for all of which it was found that could generate substantial GHG emission savings. The economic side of the implementation of these measures, considering the GHG emission reduction, is analysed in order to determine the priority between them. With respect to the cost-effectiveness, marginal costs (expressed as € per ton of reduced or avoided CO2eq) are calculated for all the measures. It was determined that around 1 million tons of CO2 can be avoided in 2020, which is 2.7% of projected GHG emissions in Croatia, while the energy that could be recovered from waste is 8.3 PJ in 2020, which represents about 3% of the total final energy consumption in 2008. The measures Utilization of landfill gas for electricity production and Landfill gas flaring showed the greatest economic benefit. [Copyright &y& Elsevier]

Abstract: In the Republic of Croatia, there are several sources of medium-temperature geothermal water in the range of 90–140°C, with which it is possible to produce electricity in binary plants, either with the Organic Rankine Cycle (ORC) or with the Kalina cycle. In the literature, the Kalina cycle is viewed as more thermodynamically favourable than the ORC; i.e., the Kalina cycle has a higher thermal efficiency and produces more power. However, the Croatian experience with a medium-temperature geothermal source with the relatively high temperature of geothermal water (Velika Ciglena, 175°C) is that the ORC is thermodynamically better than the Kalina cycle. In this paper, a comparison between the ORC and the Kalina cycle is performed based on energy analysis results for a medium-temperature geothermal source with a relatively lower temperature (Lunjkovec–Kutnjak, 140°C). Additionally, in this case the ORC has better thermal efficiency (First Law efficiency) – 13.5% vs. 12.8% – and accordingly higher net power – 2225.5kW vs. 2101.4kW. This difference is explained by the relatively high average annual temperature of the cooling air in the condenser (15°C), which has a more unfavourable influence on the condensing pressure in the Kalina cycle than in the ORC (6.35bar vs. 0.68bar). [Copyright &y& Elsevier]

Abstract: In the Republic of Croatia there are some medium temperature geothermal sources by means of which it is possible to produce electricity. However, only recently concrete initiatives for the construction of geothermal power plants have been started. Consequently, the paper provides proposals of the possible cycles for the Republic of Croatia. On the example of the most prospective geothermal source in the Republic of Croatia detailed analysis for the proposed energy conversion cycles is performed: for Organic Rankine Cycle (ORC) and Kalina cycle. On the basis of analysis results both the most suitable cycle for selected and for other geothermal sources in the Republic of Croatia are proposed. It is ORC which in case of the most prospective geothermal source in the Republic of Croatia has better both the thermal efficiency (the First Law efficiency) and the exergetic efficiency (the Second Law efficiency): 14.1% vs. 10.6% and 52% vs. 44%. The ORC gives net power of 5270kW with mass flow rate 80.13kg/s, while the Kalina cycle gives net power of 3949kW with mass flow rate 35.717kg/s. [Copyright &y& Elsevier]

We discuss an approach to minimizing the group variability of generation in a system of intermittent renewable sources using the portfolio theory. The total variability of a system that can be modeled using various parameters as goal-functions is minimized given any desired level of expected long-term generation. An extensive analysis was carried out on a set of time series of measured generation data obtained from twenty wind plants in Croatia over five years in one hour and fifteen minutes, time resolutions. The choice of the goal function most relevant for the operational (and economic) consequences of short-term variability is discussed. [ABSTRACT FROM AUTHOR]