Energy and exergy efficiencies in agricultural and utility sectors of Iran compared with other countries

Energy consumption and carbon emissions in Iran have risen rapidly in recent years which is not acceptable regarding environmental regulations. Government officials have been trying to resolve this problem, but so far there has been less success. Exergy analysis method is a powerful tool, which has been successfully used for estimating energy utilization efficiencies of countries. In this study, energy and exergy analysis models for agricultural and utility sectors of Iran are applied. Energy and exergy analysis are performed for two devices (pumps, tractors) in agricultural sector and two subsectors (power plants and hydroelectric) in utility sector. The analyses are based on the actual data presented by ministry of energy officials over the period 1994-2006. The energy and exergy efficiencies in agricultural sector of Iran during 1994-2006 are found to range from 29% to 41.7%, and from 16.9% to 20.2% respectively, and in the utility sector are obtained to range from 33.44% to 39.27%. The result was compared with other countries and it is seen that energy and exergy efficiencies in Iran is higher than some countries and lower than some others. However, it cannot be deduced that one country is better than another, because exergy efficiency depends on different factors like climate, population and structure of energy system and the main differences resulted from the structure of the country. It is seen that exergy efficiency of agricultural sector in Saudi Arabia is higher than that of Iran. However as stated above it can not be concluded that agricultural sector in Saudi Arabia is better than in Iran. It is seen that countries like Saudi Arabia, Iran and Malaysia which the contribution of power plants in electricity generation is about 90%, have low exergy efficiencies in utility sector. This is due to the fact that irreversibilities of thermal power plants are relatively high compared to hydroelectric power plants.