Utilization Exergy Efficiency Research Articles

Analyzing the Energy Utilization Efficiency of Renewable Energy Resources. Part 2: Exergy Analysis Method

Exergy analysis is a powerful tool in the design, simulation and performance evaluation of thermal and thermo chemical systems. A particular thermo dynamical system is the society of a country or a region. This method of exergy analysis has recently been used with an increasing interest to assess the energy utilization efficiencies of countries. Part 2 of the present study, which consists of two parts, analyzes the energy utilization efficiency of renewable energy resources (RERs) by using exergy analysis, while energy analysis of RERs has been presented in Part 1. Turkey, with a projected population of 76,840,418 in 2010, is analyzed as an application country. RERs studied are used in the Turkish conversion, residential-commercial and industrial subsectors. Total exergy inputs are projected to be 7,400.34 PJ, while RERs production values are expected to be 580.20 PJ. The energy and exergy efficiency values for the RERs of Turkey are projected to be 60.99% and 44.30% in 2010, respectively. Besides this, total energy and exergy utilization efficiency values for those are forecasted to be 49.85 and 27.94% in the same year, respectively. The present study has clearly indicated the necessity of the planned studies towards increasing RERs utilization efficiency in the subsectors studied, and especially the critical role of policymakers in establishing effective energy-efficiency delivery mechanisms throughout the country.

Assessment of the energy and exergy utilization efficiencies in the Turkish agricultural sector

This study deals with evaluating the energy and exergy utilization efficiencies in the Turkish agricultural sector over a 12-year period from 1990 to 2001. In the energy and exergy analyses, two main energy sources, namely fuels and electricity, are taken into consideration, while the sectoral energy and exergy efficiencies are compared for this period. These main energy sources include diesel for tractors and other vehicles, and electricity for pumps. Overall energy utilization efficiencies are obtained to vary between 29.1 and 41.1%, while overall exergy utilization efficiencies are found to range from 27.9 to 37.4% in the analysed years, respectively. It may be concluded that the present technique proposed here may be used as a useful tool in analysing and evaluating the energy and exergy utilization efficiencies, identifying energy efficiency and/or energy conservation opportunities and dictating the energy strategies of countries. Copyright © 2005 John Wiley & Sons, Ltd.

Assessment of the energy utilization efficiency in the Turkish transportation sector between 2000 and 2020 using energy and exergy analysis method

Energy and exergy utilization efficiencies in the Turkish transportation sector over the period from 2000 to 2020 are evaluated in this study. A comparison of the overall energy and exergy efficiencies of the Turkish transportation sector with the other countries is also presented. Energy and exergy analyses are performed for four transport modes, namely roadway, railway, airway and seaway, while they are based on the actual data for 2000 and projected data for 2020. Roadway appears to be the most efficient mode when compared with railway, air and seaway. It is projected that about 15% of total energy resources will be used in this sector during 2020. The energy utilization efficiencies for the Turkish transportation sector range from 23.71% in 2000 to 28.75% in 2020, while the exergy utilization efficiencies vary from 23.65% to 28.85% in the same years, respectively. Exergetic improvement potential for this sector is estimated to be 700 PJ in 2020, with an average increase rate of 4.5% annually between 2000 and 2020. Road transport and oil-fuelled combustion engines offer the principal scope for exergetic improvement in the coming decades. It may be concluded that the methodology used in this study is practical and useful for analyzing sectoral energy and exergy utilization to determine how efficiently energy and exergy are used in the sector studied. It is also expected that this study will be helpful in developing highly applicable and productive planning for energy policies.

Estimating the energy and exergy utilization efficiencies for the residential–commercial sector: an application

The main objectives in carrying out the present study are twofold, namely to estimate the energy and exergy utilization efficiencies for the residential–commercial sector and to compare those of various countries with each other. In this regard, Turkey is given as an illustrative example with its latest figures in 2002 since the data related to the following years are still being processed. Total energy and exergy inputs in this year are calculated to be 3257.20 and 3212.42 PJ, respectively. Annual fuel consumptions in space heating, water heating and cooking activities as well as electrical energy uses by appliances are also determined. The energy and exergy utilization efficiency values for the Turkish residential–commercial sector are obtained to be 55.58% and 9.33%, respectively. Besides this, Turkey's overall energy and exergy utilization efficiencies are found to be 46.02% and 24.99%, respectively. The present study clearly indicates the necessity of the planned studies toward increasing exergy utilization efficiencies in the sector studied.

Analysis of energy and exergy use of the Turkish residential–commercial sector

This study presents the analysis of the energy and exergy utilization of the Turkish residential–commercial sector (TRCS) in the years of 2000 and 2020 and compares the results obtained with those of other countries available in the literature. This analysis is done based on the actual data for 2000, while the projected energy data for 2020 are used in the calculations. Total energy and exergy inputs are calculated to be 3527.20 PJ and 3469.62 PJ in 2000, while they are projected to be 12,898.51 PJ and 12,636.99 PJ in 2020, respectively. Annual fuel consumptions in space heating, water heating and cooking activities as well as electrical energy uses by appliances are determined for 2000, while they are forecasted from 2004 to 2020. The energy efficiency value for the TRCS is found to be 55.60% in 2000, and is expected to be 65.53% in 2020. The exergy efficiency value for that is obtained to be 8.02% in 2000, with a projected value of 10.07% in 2020. Turkey's overall energy and exergy utilization efficiencies in the same years are also found to be 44.91% and 24.78% in 2000, with the projected values of 55.15% and 30.44% in 2020, respectively. The present study clearly indicates the necessity of the planned studies towards increasing exergy efficiencies in the sector studied and especially the critical role of policymakers in establishing effective energy-efficiency delivery mechanisms throughout the country. It may be concluded that the current methodology is useful for analyzing the sectoral energy and exergy utilization, giving energy saving opportunities.

Turkey's sectoral energy and exergy analysis between 1999 and 2000

This study analyses sectoral energy and exergy utilization in Turkey between 1999 and 2000. Total energy and exergy utilization efficiencies are calculated to be 43.24 and 24.04% in 1999, and 44.91 and 24.78% in 2000, respectively. In order to calculate these efficiency values, Turkey is subgrouped into four main sectors, namely utility, industrial, transportation and commercial-residential. The energy efficiency values are found to be 23.88, 30.10, 68.97 and 57.76% in 1999, and 23.71, 30.11, 68.81 and 57.05% in 2000 for transportation, utility, industrial and commercial-residential sectors, respectively. Besides this, the exergy efficiency values are obtained to be 23.80, 30.28, 35.97 and 8.12% in 1999, and 23.65, 30.47, 35.51 and 8.02% in 2000 for the same order of sectors. The present study has clearly shown the necessity of the planned studies towards increasing exergy efficiencies in the sectors studied. Copyright © 2004 John Wiley & Sons, Ltd.