Efficiency of household energy utilization in rural China

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1 *Corresponding author: Efficiency of household energy utilization in rural China... Qier An 1,2,3, Haizhong An 1,2,3 *, Lang Wang 1 and Xuan Huang 1,2,3 1 School of Humanities and Economic Management, China University of Geosciences, Beijing, China; 2 Key Laboratory of Carrying Capacity Assessment for Resource and Environment, Ministry of Land and Resource, Beijing, China; 3 Lab of Resources and Environmental Management, China University of Geosciences, Beijing, China... Abstract This paper calculates energy efficiency and exergy efficiency of household energy utilization in rural China. Provincial energy efficiencies and exergy efficiencies for space heating sector, cooking sector and hot water sector are calculated and analyzed. Result shows that national energy efficiencies in space heating, cooking and hot water sector are 27.43, and 13.11%, respectively. Exergy efficiencies are 1.63, 4.42 and 1.16%, respectively. Energy efficiencies in Xinjiang, Tianjin, Beijing and Shanxi are higher than other provinces because of the wide utilization of coal. In eastern China like Shanghai, Jiangssu, Fujian, the proportion of biomass is quite large which results in a low efficiency. Furthermore, exergy efficiencies in southern China are much higher than those of northern China because of the climate differences. Keywords: household energy; energy efficiency; exergy efficiency; rural China Received 15 November 2013; revised 7 March 2014; accepted 11 March INTRODUCTION Rural China has large area and population. The rural household energy consumption is an important part of China s energy consumption. In recent years, the proportion of China s rural population continues to decline, down from 63.78% in 2000 to 48.73% in 2011 [1]. However, the household commercial energy consumption in rural China has increased from million tce in 2000 to million tce in 2011, which has been four times larger in these years. Now the commercial energy utilization in rural China has accounted for more than 40% in national household energy consumption [2]. Household energy has a close relationship with people s daily life. The improvement in household energy utilization means a lot in not only the reduction of energy consumption, but also the improvement of life standard in rural area. Many researches have been made in that topic. Existing papers are mainly about three topics: energy structure and its changes, environmental impact of rural energy utilization and the driving force that make the changes in rural energy. The first topic has achieved most attention. These researches investigate the rural energy structure of China or smaller places based on official statistics or surveyed data, like Zhang et al. [3], Cai and Jiang [4], Wang et al. [5] and Zhou et al. [6]. There are also many papers focus on the environmental impact of Chinese rural energy, like Yao et al. [7] and Liu et al. [8]. Other papers focus on the driving force of energy structure changes in rural China, like Zhang and Guo [9] and Chen et al. [10]. There are some researches about rural energy in other developing countries, particular in India. Ravindranath and Hall [11] examined the experiences of bioenergy in India, focusing on the current situation, comparison between bioenergy and other options for promoting development, the potential for bioenergy and the socioeconomic and environmental impacts of bioenergy. Heltberg et al. [12] discussed domestic energy supply and demand in rural India. Some researchers set up a rural energy database for India and discussed the results based on the analysis of the energy consumption data [13]. A study of eight rural communities in India indicates that levels of energy consumption vary widely among the communities and that consumption depends on socioeconomic and agroclimatic factors [14]. Some researchers compared rural energy utilization between China International Journal of Low-Carbon Technologies 2014, 9, # The Author Published by Oxford University Press. This is an Open Access article distributed under the terms of the Creative Commons Attribution License ( which permits unrestricted reuse, distribution, and reproduction in any medium, provided the original work is properly cited. doi: /ijlct/ctu

2 Q. An et al. and India. Liming [15] analyzed the current status of rural renewable energy in China and India, develops and employs an analysis framework to study the environment, channels, instruments and innovative mechanisms of financing rural renewable energy in China and India, and makes a primary comparison. Pachauri and Jiang compared the household energy transitions between China and India and found that these two countries differ sharply in several respects. Residential energy consumption in China is twice that in India, in aggregate terms [16]. However, there is few papers focus on the efficiency of rural energy utilization in China. Efficiency is so important that we must take it into consideration. The Twelfth Five-Year Plan of China s energy development takes to promote energy efficiency as one of five goals [17]. The Twelfth Five-Year Plan of China s energy technology points that efficiency priority is the basic principle of energy technology development [18]. Along with the social development, more and more people believe that energy conservation is not only about to reduce the energy consumption, but also to improve the energy efficiency, which means to use energy when need and to reduce energy when could. Therefore, energy efficiency is an important topic when talking about rural energy utilization. Motivated by this, this paper tries to investigate the efficiency of energy utilization in rural China. Efficiency can be described by energy efficiency or exergy efficiency. Energy efficiency is based on the first law of thermodynamics while exergy efficiency is based on the second law of thermodynamics. Energy efficiency is popular because it is simple and clear while exergy efficiency takes the quality of energy into consideration and can describe the improve potential of energy systems. In recent years, more and more papers use not only energy efficiency, as well as exergy efficiency to describe efficiency of macroscopic systems, like China [19], transportation sector of Jordan [20], Japanese residential/ commercial sectors [21], agricultural sector of Saudi Arabia [22], Chinese transportation sector [23] and Turkey [24]. This paper also uses energy efficiency and exergy efficiency to analyze the efficiency of energy utilization in rural China. Our aim is to identify the features of efficiencies in different provinces and then provide some information for policy-makers. This paper is organized as follows: the second part is about data and method. In the third section, we calculate energy efficiency and exergy efficiency of three end-use sectors in rural household as well as overall efficiencies. The last part is conclusion, where we review our main findings. 2 DATA AND METHODS 2.1 Data In China, official data about rural energy can be found in three yearbooks: China Energy Statistical Yearbook [25], China Rural Statistical Yearbook [26] and China Rural Energy Yearbook [27]. But, these data cannot support our research about efficiency since it only contains the total amount of energy consumption Table 1. Exergy factor for each energy form. Fuel form Coal 1.06 Biomass 1.19 Electricity energy 1.00 LPG 1.06 Biogas 1.03 Table 2. Exergy quality factor for each end-use sector. Exergy factor End-use sector Exergy quality factor (%) Cooking Space heating 6.8 Hot water Table 3. Energy efficiencies of different end-use sectors by energy form. Coal Biomass Electricity LPG Biogas Cooking (%) Space heating (%) Hot water (%) Table 4. Exergy efficiencies of different end-use sectors by energy form. Coal Biomass Electricity LPG Biogas Cooking (%) Space heating (%) Hot water (%) without how the energy is used in different provinces. Therefore, the data we used in this paper comes from Annual Report on China Building Energy Efficiency [28]. It provides the provincial consumption data of each energy resources in the year of 2008 and the way how these energy resources are used and thus make it possible to calculate the efficiency of energy utilization. There are many impact factors for the efficiency of energy utilization in rural household, like technology and culture. However, in this paper, only energy structure in each end-use sector is considered when calculating energy and exergy efficiencies due to the availability of data. In rural China, there are six end-use sectors in household energy utilization: space heating, cooking, hot water, lighting, space cooling (by air conditioner) and other appliance. Among them, the energy that used for lighting, space cooling and other appliance is electricity for any province so that there is no difference in energy and exergy efficiencies in these three end-use sectors. Therefore, this paper only considers the rest three end-use sectors: space heating, cooking and hot water. 136 International Journal of Low-Carbon Technologies 2014, 9,

3 Efficiency of household energy utilization in rural China Figure 1. Energy structure of space heating in rural area of each province in Figure 2. Provincial energy and exergy efficiency of space heating in Methods Energy efficiency and exergy efficiency are two main methods for assessing the efficiency of a system. Energy efficiency is the ratio between the energy output and the energy input of a system and is based on the first law of thermodynamics. Exergy efficiency is the ratio between the exergy output and exergy input of a system and is based on the second law of thermodynamics. Energy efficiency is easier to calculate and understand, and it also indicates the direction of energy conservation. Exergy analysis overcomes many of the shortcomings of energy analysis, as it considers the quantity and quality of energy resources and thus provides more information than energy efficiency. This paper uses both energy efficiency and exergy efficiency to describe the efficiency of household energy utilization in rural China. Energy efficiency can be calculated using the following equation: h en ¼ useful energy input energy energy loss ¼ input energy input energy ð1þ International Journal of Low-Carbon Technologies 2014, 9,

4 Q. An et al. Exergy efficiency can be calculated using the following equation: h en ¼ useful exergy input exergy exergy loss = input exergy input exergy The energy utilization in rural household is mainly end-use, the energy efficiency of which can be found in references. Thus, the main problem is calculating the exergy efficiency. The exergy efficiency differs from the energy efficiency as follows: for energy resources, the exergy efficiency is less than the energy efficiency because the exergy input is greater due to the exergy factor and the exergy output is lower due to the quality factor. Exergy efficiency can be calculated using the following equation: useful exergy h ex ¼ input exergy useful energy exergy quality factor ¼ input energy exergy factor quality factor ¼ h en exergy factor The exergy factors for each type of energy are listed in Table 1 [29], the quality factors for each end-use sector are listed in Table 2 [30], and the energy efficiencies of different end-use sectors by energy form are listed in Table 3 [30]. Based on Tables 1, 2 and 3, the exergy efficiencies of different end-use sectors by energy form are calculated and listed in Table 4. The weighted mean overall energy efficiency and exergy efficiency are calculated as: h en;overall ¼ X i;k h en;i;k Fr ik h ex;overall ¼ X i;k h ex;i;k Fr ik where h en;overall is the weighted mean overall energy efficiency. The subscript i denotes the ith end-use sector (here, i ¼ 1, 2, 3 which mean space heating, cooking and hot water), and the subscript k denotes the kth energy resource (here, k ¼ 1, 2...5, corresponding to mean coal, biomass, electricity, LPG and biogas). h en;i;k is the energy efficiency of the kth energy resource used in the ith end-use sector, Fr ik in Equation (4) is the ratio of the energy used to the total energy used. h ex;overall is the weighted mean overall exergy efficiency, and h ex;i;k stands for the exergy efficiency of kth energy resource used ith end-use sector. Finally, Fr ik in Equation (5) is the ratio of the exergy used to the total exergy used. ð2þ ð3þ ð4þ ð5þ consumption. There are three energy resources used in space heating: biomass, coal and electricity, their fraction are 34.31, and,0.01%, respectively. So that the national energy efficiency of space heating sector in rural China is calculated to 27.43% while exergy efficiency is calculated to 1.63%. The energy structure in each province changes a lot, as shown in Figure 1. We can hardly see the blue part in Figure 1 since electricity used for space heating in rural China is quite little. There are two main energy resources for space heating: biomass and coal. Jiangsu only consumes biomass for space heating while Henan mainly uses coal. Energy efficiencies for space heating by biomass and coal are 24.1 and 33.8%, respectively. Exergy efficiencies are 1.38 and 2.17%. Different energy structure in space heating results in different efficiencies, as show in Figure 2. Higher the fraction of biomass, lower the energy efficiency and exergy efficiency. Energy efficiency and exergy efficiency in Jiangsu province are 24.1 and 1.38%, which are both the lowest efficiency among 31 provinces. Henan has the highest energy efficiency and exergy efficiency which is and 2.12%, respectively. 3.2 Cooking There are five types of energy used in cooking sector of rural China: biomass, LPG, coal, biogas and electricity. Their fractions are 62.66, 12.10, 13.03, 90.9 and 3.12%. Biomass is the biggest energy for cooking, like in the space heating sector. Coal is the second energy for cooking while its fraction is less than that in space heating sector. The fraction of LPG and biogas are also notable. Energy structure for cooking in rural China is shown in Figure 3. This energy structure in cooking results in a low efficiency. The national mean weighted energy efficiency for cooking is only 15.32% while national weighted mean exergy efficiency is only 4.42%. The energy structure in different provinces changes a lot, as shown in Figure 4. About half of 31 provinces mainly use biomass for cooking, like Shanghai, Jiangsu and Zhejiang. These kind of provinces located in southeast China. In these provinces, the fraction of biomass in cooking is more than 90%. Many provinces use much LPG for cooking, like Tianjin, Jilin and Beijing. In some provinces, the fractions of coal, biomass, LPG and biogas are very close with each other, like Tibet, Shanxi, 3 RESULTS 3.1 Space heating Space heating is the largest end-use sector in rural household energy utilization, which accounts for 70.13% of total energy Figure 3. Energy structure of cooking in rural China in International Journal of Low-Carbon Technologies 2014, 9,

5 Efficiency of household energy utilization in rural China Guangxi, Yunnan and Guizhou. Instead of Shanxi, these provinces all locate in the southwest part of China. The energy efficiencies of biomass, LPG, coal, biogas and electricity for cooking are 10.3, 21.9, 14.4, 27.2 and 59.9% while the exergy efficiency are 2.85, 6.97, 4.47, 8.68 and 19.70%, respectively. Therefore, different energy structure in cooking results in different overall weighted mean energy efficiency and exergy efficiency. Energy and exergy efficiencies in each province are shown in Figure 5. The energy efficiencies are much higher than exergy efficiencies. As the fraction of biomass decrease, the energy and exergy efficiency increase. Tibet has highest efficiency for cooking since people in rural area of Tibet mainly use electricity and biogas for cooking. Its energy efficiency is 32.97% while exergy efficiency is 10.61%. That is a result of policy on biogas. In the year of 2008, Tibet government invested more than 100 million Yuan to help local people build biogas digesters and stoves. After that, more than farmers in Tibet have biogas for free. Shanghai has Figure 4. Energy structure of cooking in rural area of each province in Figure 5. Provincial energy and exergy efficiency for cooking in International Journal of Low-Carbon Technologies 2014, 9,

6 Q. An et al. lowest energy efficiency and exergy efficiency, which are and 3.32%, respectively. The reason for that is people in Shanghai mainly use biomass for cooking. Zhejiang, Jiangsu, Heilongjiang are the some with shanghai. As another example, 84.61% cooking energy in Henan province comes from biomass, 7.07% comes from coal. The efficiency of biomass and coal are both low, so that the cooking efficiency in Henan province is much lower than Tibet. Hebei province is nearly the same with Henan. 3.3 Hot water There are three types of energy in hot water sector: biomass, coal and electricity. Just like space heating sector and cooking sector, the fraction of electricity in hot water sector is still tiny. The fraction of biomass is 85.03% and the fraction of coal is 14.95%. National overall energy and exergy efficiency are only and 1.67%, respectively. According to our data, the energy consumption in Tibet hot water sector is zero. Among the rest 30 provinces, there are Figure 6. Energy structure of hot water in rural area of each province in Figure 7. Provincial energy and exergy efficiency for hot water in International Journal of Low-Carbon Technologies 2014, 9,

7 Efficiency of household energy utilization in rural China Figure 8. Map of (a) energy efficiencies and (b) exergy efficiencies in rural China in International Journal of Low-Carbon Technologies 2014, 9,

8 Q. An et al. 23 provinces mainly use biomass for hot water, as shown in Figure 6. InShanghai,JiangsuandZhejiang,thefractionof biomass in hot water sector are as much as 99.95, and 97.57%. In Anhui, Heilongjiang and Hebei, the fraction of biomass is also striking. In the rest seven provinces, more than half energy comes from coal, like Guangxi, Yunnan, Guizhou andhainan.thesekindofprovincesmainlylocatedinthe southwest China. The energy efficiencies of biomass and coal in hot water sector are 18.2 and 12.2%, respectively, while exergy efficiencies are 1.78 and 1.06%. Therefore, higher fraction of biomass will lead lower energy efficiency and exergy efficiency. Provincial energy efficiencies and exergy efficiencies are shown in Figure 7. It shows that the energy efficiency and exergy efficiency in Shanghai are both the lowest among 30 provinces. The energy efficiency in Shanghai is only 12.23% while exergy efficiency is only 1.07%. On the contrary, the energy efficiency and exergy efficiency in Guangxi, Yunnan and Guizhou are much higher than other provinces. Their energy efficiencies are 17.41, and 16.13%. Their exergy efficiencies are 1.68, 1.57 and 1.51%. 3.4 Overall efficiency In this part, we focus on overall efficiency of rural China as well as each province. After calculating, national overall weighted mean energy efficiency is 23.78% while exergy efficiency is 2.41%. Provincial energy efficiencies and exergy efficiencies can be seen in Figure 8. Figure 8a shows the energy efficiencies of 31 provinces while Figure 8b shows exergy efficiencies of 31 provinces. The color in Figure 8 indicates the efficiencies. Red means lower efficiency and green means higher efficiency. From Figure 8a, we can see that energy efficiency in Xinjiang, Tianjin, Beijing and Shanxi is higher than other provinces. That is a result of widely utilization of coal. The fraction of coal in Xinjiang, Tianjin, Shanxi and Beijing are much higher than any other provinces in China. On the contrary, in the east part of China, like Shanghai, Jiangssu, Fujian, the fractions of biomass are quite large, which result in a low efficiency. This situation may be explained by the energy supply in each part of China. In northern China and Western China, there are lots of coal reserves. Therefore, in those provinces, rural people use coal as their major energy because of the convenience to buy and the reasonable price of coal. On the contrary, in the eastern part of China, there are little coal reserves as well as oil reserves so that local people use more biomass energy. As a result, the energy efficiency in southeastern China is lower than other parts of China. Exergy efficiencies in south China are much higher than north China, as shown by Figure 8b. That is a result of climate change. Cold weather in north China made it necessary to utilize much energy for space heating. The quality of space heating is as low as 6.8%, indicating a lot of exergy has been lost in space heating because of Irreversibility. 4 CONCLUSIONS This paper calculates the efficiency of household energy utilization in rural China. Our main findings are as follows: (1) The national weighted mean energy efficiency in space heating sector is 27.43%, weighted mean exergy efficiency is 1.63%. Jiangsu has the lowest energy efficiency and exergy efficiency in space heating which are 24.1 and 1.38% while Henan has the highest energy efficiency and exergy efficiency which are and 2.12%, respectively. (2) The national mean weighted energy efficiency for cooking is only 15.32% while national weighted mean exergy efficiency is only 4.42%. Tibet has highest efficiency for cooking since people in rural area of Tibet mainly use electricity and biogas for cooking. Shanghai has lowest energy efficiency and exergy efficiency because of widely utilization of biomass for cooking. (3) The national mean weighted energy efficiency and exergy efficiency for cooking are and 1.16%, respectively. The energy efficiency and exergy efficiency in Shanghai are both the lowest. Guangxi, Yunnan and Guizhou have higher energy efficiency and exergy efficiency. (4) National overall weighted mean energy efficiency is 23.78% while exergy efficiency is 2.41%. (5) Energy efficiency in Xinjiang, Tianjin, Beijing and Shanxi is higher than other provinces. That is a result of widely utilization of coal. In the east part of China like Shanghai, Jiangssu, Fujian, the fractions of biomass are quite large, which result in a low efficiency. (6) Exergy efficiencies in south China are much higher than north China because of climate difference. Rural household energy utilization in China is important because of huge amount of energy consumption and close relationship to the living standard of rural people. In this paper, we found that energy efficiencies and exergy efficiencies are very low in rural China, indicating a big necessity and feasibility to be improved. In recent years, china government has been pushing the energy efficiency national wide with increasing effort. The energy utilization structure in rural China has changed a lot after the study year. According to China Energy Statistical Yearbook of 2009 and 2012, the consumption of coal, oil and natural gas in rural household increased a lot with the annual growth rate of 5.18, and 7.24% between 2008 and 2011, respectively [2]. Similarly, the building energy research center of Tsinghua University also points out that the fraction of biomass consumption has decreased in their report on 2012, which focused on rural energy of China [31]. These changes in energy structure will result in an increase in energy efficiency and exergy efficiency. 142 International Journal of Low-Carbon Technologies 2014, 9,

9 Efficiency of household energy utilization in rural China If the developed technology and modern life style is popular in rural China, when rural people do not just use local biomass for space heating, cooking and hot water, the energy efficiency as well as exergy efficiency will increase, indicating that a large amount of energy will be saved. Also, other energy resources like coal, LPG and biogas usually mean cleanness, convenience, safety and little environmental impact. If people in rural area can use those energy in daily life, their living standard will increase. ACKNOWLEDGEMENTS This research is supported by grants from the National Natural Science Foundation of China (Grant No ), the Humanities and Social Sciences planning funds project under the Ministry of Education of the PRC (Grant No. 10YJA630001), the Fundamental Research Funds for the Central Universities (Grant No ), and the Science and Technology Innovation Fund of the China University of Geosciences (Beijing). REFERENCES [1] China Statistical Yearbook. China Statistics Press, [2] China Energy Statistical Year Book, China Statistics Press [3] Zhang LX, Yang ZF, Chen B, et al. Temporal and spatial variations of energy consumption in rural China. Commun Nonlinear Sci Numer Simulat 2009;14: [4] Cai J, Jiang Z. Changing of energy consumption patterns from rural households to urban households in China: an example from Shaanxi Province, China. Renew Sust Energ Rev 2008;12: [5] Xiaohua W, Xiaqing D, Yuedong Z. Domestic energy consumption in rural China: a study on Sheyang County of Jiangsu Province. Biomass Bioenergy 2002;22: [6] Zhou Z, Wu W, Wang X, et al. Analysis of changes in the structure of rural household energy consumption in northern China: a case study. Renew Sust Energ Rev 2009;13: [7] Chunsheng Y, Chongying C, Ming L. Analysis of rural residential energy consumption and corresponding carbon emissions in China. Energ Policy 2012;41: [8] Liu G, Lucas M, Shen L. Rural household energy consumption and its impacts on eco-environment in Tibet: taking Taktse county as an example. Renew Sust Energ Rev 2008;12: [9] Zhang M, Guo F. Analysis of rural residential commercial energy consumption in China. Energy 2013;52: [10] Chen L, Heerink N, van den Berg M. Energy consumption in rural China: a household model for three villages in Jiangxi Province. Ecol Econ 2006;58: [11] Ravindranat NH, Hall DO. Biomass, Energy and Environment: a Developing Country Perspective From India. Oxford University Press, [12] Heltberg R, Arndt TC, Sekhar NU. Fuelwood consumption and forest degradation: a household model for domestic energy substitution in rural India. Land Econ 2000;76: [13] Sinha CS, Sinha S, Joshi V. Energy use in the rural areas of India: setting up a rural energy data base. Biomass Bioenergy 1998;14: [14] Bowonder B, Prakash Rao N, Dasgupta B, et al. Energy use in eight rural communities in India. World Dev 1985;12: [15] Liming H. Financing rural renewable energy: a comparison between China and India. Renew Sust Energ Rev 2009;13: [16] Pachauri S, Jiang L. The household energy transition in India and China. Energ Policy 2008;36: [17] Twelfth Five Year Plan for Energy Development. PRC State Council, [18] Twelfth Five Year Plan for Energy Technology. National Energy Administration, [19] Chen GQ, Qi ZH. Systems account of societal exergy utilization: China Ecol Model 2007;208: [20] Jaber JO, Al-Ghandoor A, Sawalha SA. Energy analysis and exergy utilization in the transportation sector of Jordan. Energ Policy 2008;36: [21] Kondo K. Energy and exergy utilization efficiencies in the Japanese residential/commercial sectors. Energ Policy 2009;37: [22] Dincera I, Hussain MM, Al-Zaharnah I. Energy and exergy utilization in agricultural sector of Saudi Arabia. Energ Policy 2005;33: [23] Zhang M, Li G, Mu HL, et al. Energy and exergy efficiencies in the Chinese transportation sector, 1980e2009. Energ 2011;36: [24] Utlu Z, Hepbasli A. Turkey s sectoral energy and exergy analysis between 1999 and Int J Energy Res 2004;28: [25] China Enrgy Statistical Year Book. National Bureau of Statistics. China Statistics Press, [26] China Rural Statistical Year Book. National Bureau of Statistics. China Statistics Press, [27] China Rural Energy Yearbook. Ministry of Agriculture, Department of Science, Technology and Education. China Agriculture Press, [28] Building Energy Research Center of Tsinghua University Annual Report on China Building Energy Efficiency. China Building Industry Press, [29] Chen GQ, Chen B. Extended-exergy analysis of the Chinese society. Energy 2009;34: [30] Nakicenovic N, Gilli PV, Kurz R. Regional and global exergy and energy efficiencies. Energy 1995;21: [31] Building Energy Research Center of Tsinghua University Annual Report on China Building Energy Efficiency. China Building Industry Press, International Journal of Low-Carbon Technologies 2014, 9,