• Energy Research

Abstract In contrast to the ever-increasing focus on China's CO2 emissions, little attention has been given to its CH4 emissions, the second largest greenhouse gas. Presented in this paper is a comprehensive assessment of the CH4 emissions in Mainland China by source and region based on the latest statistical data and research literatures available. The total CH4 emission in China 2007 is estimated as 38.6 Tg, one and a half times of that in USA. Even by the lower IPCC global warming potential (GWP) factor of 25, it corresponds to 964.1 Mt CO2-eq, in magnitude up to one seventh of China's CO2 emission and greater than the nationwide gross CO2 emissions in Australia, Canada, and Germany in 2007. As the leading emission source, energy activities are responsible for 45.3% of the total emission, agricultural activities contribute a comparable share of 40.9%, followed by waste management of 13.8%. Among all the 11 major emission sources, coal mining (38.3% of the total), enteric fermentation (21.4%) and rice cultivation (14.4%) essentially shape the CH4 emission profile for China, quite different from that for USA which is characterized by prominent emissions from enteric fermentation, municipal solid waste landfill and natural gas leakage. The Western and Central areas contribute 70.9% of the total nationwide emission and Shanxi is the largest regional CH4 emitter with an amount of 4.6 Tg. The five regions of Xizang (Tibet), Shanxi, Qinghai, Ningxia, and Guizhou are identified with the largest emissions per-capita and emission intensities. In contrast to the focused areas of CO2 emission reduction mainly in the energy-intensive eastern regions, the mitigation potential of CH4 emissions in the western and central regions is huge by integrating emission quantity and structure with emission per-capita and emission intensity at the regional level. Corresponding policy-making implications for CH4 emission mitigation in China are addressed.

Abstract The concept of exergy has been applied to ecological evaluation, resource accounting and environmental impact assessment. As a suitable indicator for ecological evaluation, exergy analysis presents a unified thermodynamic measure of objective evaluation of resources and environment with exergetic unit. A case study of water quality assessment using exergy analysis is presented. Compared with other existing methods, exergy accounting provides a unitary and objective measure for water pollution as a result of the application of the thermodynamic concept to water quality assessment.

Abstract It’s anticipated that future expansion of energy industry in China will inevitably exert enormous pressure on water use both at home and abroad, due to the globalized energy supply chains. Therefore, this study aims to systematically evaluate the global water use embodied in China’s energy supply chains (i.e., energy supply, demand and international trade) in a unified framework by using a global multi-regional input-output analysis. The results reveal that China's direct water withdrawal by energy sectors (i.e., coal, oil, gas, petroleum and electricity) amounts to 117 billion m3 in 2011, of which foreign demand mainly from USA, EU28 and Japan drives one quarter. From energy demand side, only water roughly equivalent to one fifth of direct water withdrawal of energy sectors is embodied in China’s final demand of energy sectors, indicating that energy sectors transfer large amounts of water embodied in intermediate use to downstream sectors. Regarding water use embodied in China's energy trade, China mainly imports from XSU (Rest of Former Soviet Union), Russia and Korea, and exports to Vietnam, Singapore and XEA (Rest of East Asia). Although much of the discussion around China’s energy-water nexus is focused on local perspective, our findings highlight the importance to consider the impacts of China’s globalized energy supply chains on worldwide water use when formulating policy.

Abstract As a possible contribution to the exergy-based approach in systems ecology, the account of the exergy utilization in a society is considered a basic vision of the third stage of the universal hierarchy of exergy as the fundamental natural resource, on the national or regional scale just next to the first two stages on the global and terrestrial scales, and thus may provide a basis for the ecological systems analysis diagnosis of the socioeconomics. In the light of the scarcity and usefulness of exergy and in part as development of the exergy account scheme initiated by Milia and Sciubba and illustrated by Ertesvag, the concept, diagram and implications of the systems account of societal exergy utilization are presented and illustrated, as a complement to the cross-sectional account scheme initiated by Wall. A systems account of societal exergy utilization is carried out for China 2003. The society system, supported by domestic natural resources and import from and export to other countries or regions, is diagrammed with seven independent and complimentary sub-systems of extraction sector, agriculture sector, conversion sector, industry sector, tertiary sector, transportation sector, and domestic sector. The exchange and utilization of resources and products was quantified in terms of exergy between the sectors of the society and between the sectors and the natural environment or other countries or regions. The total societal exergy use amounts to 66,525 PJ, of which 25.1% is used in the industry sector, 24.6% in the domestic and households, 21.4% in conversion, 10.4% in agriculture, 7.8% in tertiary, 6.2% in extraction and 4.5% in transport. The ecological efficiency defined for the production sectors as the exergy outflow divided by the inflow is estimated as 92.9% for the extraction sector, 44.6% for the agriculture sector, 30.0% for the conversion sector, 27.7% for the industrial sector, 18.0 for the transportation sector, 41.9% for the tertiary sectors, respectively. Net input of resource exergy to the Chinese society amounted to 66.17 EJ, which is 50.90 GJ per capita, 5.64 MJ per GDP Yuan, or 2.99 MJ per M2 Yuan.

Abstract On the basis of Odum's ecological economic measure of emergy as embodied solar energy, a system account of biomass resource exploitation by agriculture in China 2004 is developed in this paper, which supplements a former study on corresponding long-term historical trends during 1978 to 2000 (Chen et al., 2006. Emergy-based analysis of the Chinese agriculture. Agriculture, Ecosystems and Environment 115, 161–173). The aggregate fluxes and indicators for biomass resource exploitation in China 2004 are calculated and illustrated when compared with those for 2000 to elucidate the latest status of the Chinese agriculture as the exploitation sector for biomass resource. Data sources and algorithm are presented in detail as basic references for related analysis involving the ecological economy of biomass exploitation in agriculture.

Abstract To investigate the greenhouse gases emission from enteric fermentation and manure management of livestock and poultry industry in China, the present study presents a systematic estimation of methane and nitrous oxide emission during 1949–2003, based on the local measurement and IPCC guidelines. As far as greenhouse gases emittion is concerned among livestock swine is found to hold major position followed by goat and sheep, while among poultry chicken has the major place and is followed by duck and geese. Methane emission from enteric fermentation is estimated to have increased from 3.04 Tg in 1949 to 10.13 Tg in 2003, an averaged annual growth rate of 2.2%, and methane emission from manure management has increased from 0.16 Tg in 1949 to 1.06 Tg in 2003, an annual growth rate of 3.5%, while nitrous oxide emission from manure management has increased from 47.76 to 241.2 Gg in 2003, with an annual growth rate of 3.0%. The total greenhouse gas emission has increased from 82.01 Tg CO2 Eq. in 1949 to 309.76 Tg CO2 Eq. in 2003, an annual growth rate of 2.4%. The estimation of livestock methane and nitrous oxide emissions in China from 1949 to 2003 is shown to be consistent with a linear growth model, and the reduction of greenhouse gas emission is thus considered an urgent and arduous task for the Chinese livestock industry.

This second part is the continuation of the first part on fossil fuels and energy minerals. The major renewable energy sources and forest products entering the Chinese society from 1980 to 2002, including sunlight, wind power, tidal power, wave power, geothermal power and heating, biomass, hydroelectric resource and forestry products, are calculated and analyzed in detail in this paper. The solar exergy inputs from solar photovoltaics and solar collectors, including water heater, solar oven and solar building, are calculated and discussed. The development of the wind power plant is presented. Major tidal power plants, which are still working, are addressed. Wave power devices and plants are introduced. Geothermal resources, mainly for power generation and heating, associated with distribution, are depicted. The utilization of biomass, embracing firewood, straw and biogas, which served as the main obtainable local resources for private consumption and production in the rural areas, is illustrated. Development of hydroelectric resources as complement to scarce fossil fuels is represented, of which the small hydropower project adapted for rural areas is emphasized. Finally, forest products from timber forest and economic forest are presented, with the forestation, reproducing, tending areas and sum of odd forestation trees being manifested.