It is a consensus of international community to promote the development of low carbon economy in order to face the challenges of climate change. According to the features of nuclear energy, the greenhouse gas (GHG) emission of nuclear energy chain and other energy chain are compared and analyzed, and the results indicate that the GHG emission of nuclear power chain is the least in all types of power generation. The status of nuclear power development and the potential benefit in GHGs emission reduction by developing nuclear power in China are also analyzed. Active nuclear power development is a smart choice for constructing low-carbon energy structure and for addressing global climate changes in China.
nuclear power ; GHG emission ; climate change
Global climate change has become the most important environment challenge of the world. Increasing emissions of greenhouse gas (GHG) due to human activities, which are mainly attributable to energy-related activities, have led to a marked increase in atmospheric GHG concentrations since pre-industrial times [ IPCC, 2007 ]. Since GHGs emission are closely related to energy structure, energy consumption and energy efficiency, control of energy consumption and generating low-carbon energy can greatly contribute to climate change mitigation. Many countries have put forward active steps to achieve energy-related carbon reduction by saving energy, improving energy efficiency, giving priority to the development of nuclear and renewable energy sources, and developing carbon capture and storage (CCS) techniques to mitigate the climate change.
Nuclear energy is produced by controlled nuclear fission and nuclear fusion reactions. The nuclear fission energy produced by thermal neutron reactor is used worldwide in commercial and utility applications. The element 235 U is the main fuel for nuclear fission to produce energy. Shot by a neutron, a 235 U nucleus is split into two lighter nuclei, large amount of energy is released, and multiple neutrons are also released at the same time, which are used to split other 235 U nuclei. This phenomenon is known as a nuclear chain reaction. The nuclear fission doesn’t produce GHG.
The GHG emission in nuclear energy production is a relevant topic when we consider all stages of nuclear fuel cycle, which include mining and milling, conversion, enrichment, fuel fabrication, electricity generation, spent fuel reprocessing, and waste disposal. This fuel cycle is also called nuclear power chain (Fig. 1 ). The nuclear power chain produces GHGs emission indirectly in the construction and the maintenance and operation of the facility, mainly due to the use of fossil fuels and raw and processed materials.
Nuclear power chain system
In the early 1990s, the International Atomic Energy Agency (IAEA) and eight international partners initiated an inter-agency project for comparative assessment of different energy sources. Taking into account the entire upstream and downstream energy chains for electricity generation, nuclear power emits 40 to 100 times CO2 less than currently used fossil-fuel chains, also less than hydro, wind, and biomass (Fig. 2 ) [ Hans and Arshad, 1998 ]. GHGs emission from the nuclear power chain are mainly due to the use of fossil fuels in the extraction, processing, and enrichment of uranium and to fuels used in the production of steel and cement for the construction of reactors and fuel cycle facilities. These emissions, which are negligible relative to those from the direct use of fossil fuels for electricity generation, can be reduced even further by energy efficiency improvements.
CO2 equivalent emissions for different full energy chains
China is one of the few countries that have the entire nuclear industry system. Since 1970s, China began the pre-engineering work of nuclear power construction. By now, three Nuclear Power Plant (NPP) bases in Zhejiang Qinshan, Guangdong Dayawan, and Jiangsu Tianwan have been constructed. Up to 2008, 11 units were in operation (excluding Taiwan, China) and total installed capacity was 9,080 MW, which represented 2% of total electricity generation (Table 1 ). At present, the NPP project under construction in China is 27,080 MW, accounting for 1/3 of the world total (Table 2 ).
|NPP name||Unit||Location||Nominal power(MW)||Reactor type||Date of first connection to the grid|
|Qinshan NPP||Zhejiang Haiyan||310||PWR||1991-12-15|
|Daya Bay NPP||1||Guangdong Shenzhen||2×984||PWR||1993-08-31|
|Qinshan Phase II NPP||1||Zhejiang Haiyan||2×650||PWR||2002-02-06|
|Ling’ao NPP||1||Guangdong Shenzhen||2×990||PWR||2002-02-26|
|Third Qinshan NPP||1||Zhejiang Haiyan||2×700||PHWR||2002-11-19|
|Tianwan NPP||1||Jiangsu Lianyungang||2×1,060||PWR||2006-05-12|
PWR: pressurized water reactor; PHWR: pressurized heavy water reactor
|NPP name||Location||Nominal power(MW)||Reactor type||Construction start date|
|Ling’ao Phase II NPP||Guangdong Shenzhen||2×1,080||PWR(CPR1000)||2005-12|
|Qinshan Phase II extension||Zhejiang Haiyan||2×650||PWR(CNP600)||2006-04|
|Hongyanhe NPP||Liaoning Dalian||4×1,080||PWR(CPR1000)||2007-08|
|Ningde NPP||Fujian Ningde||4×1,080||PWR(CPR1000)||2008-02|
|Fuqing NPP||Fujian Fuqing||2×1,080||PWR(CNP1000)||2008-11|
|Fangjiashan NPP||Zhejiang Haiyan||2×1,080||PWR(CNP1000)||2008-12|
|Yangjiang NPP||Guangdong Yangjiang||2×1,080||PWR(CPR1000)||2008-12|
|Sanmen NPP||Zhejiang Sanmen||2×1,250||PWR(AP1000)||2009-04|
|Haiyang NPP||Shandong Haiyang||2×1,250||PWR(AP1000)||2009-09|
|Taishan NPP||Guangdong Taishan||2×1,750||PWR(EPR)||2009-11|
Date up to November 2009
The GHG emission factors (GGEF) for nuclear power chain and coal power chain in China were calculated and compared in the middle 1990s. The total GGEF of nuclear power chain and coal power chain in China are 13.7 g (kW h)–1 and 1,302.3 g (kW h)–1 , respectively (Table 3 ) [ Ma et al ., 1999 ; Ma et al ., 2001 ]. The GHGs emission from operation of NPPs only account for 14.5% of the total and are mainly due to the use of fossil fuels to maintain operation. The GHGs emission from construction of NPP account for 48.5% of the total and are mainly due to fuels used in the production of cement, steel, copper, etc.. Of the total GHGs emission of coal power chain, 77.9% are due to coal burning of power plant operation, 15.9% are due to coal mining or these can be as high as 21.4% when coal spontaneous combustion is considered in coal production. The total GGEF of coal power chain is two order of magnitudes higher than that of nuclear power chain. The study of GHG emission assessment for different power sources in China in the beginning of the 21th century is not complete yet. However, some preliminary results show that GGEF of both nuclear and coal power chains have declined, but the gap between nuclear and coal power chains becomes larger, which means the carbon reduction effect for nuclear power development would be more significant [ Jiang, 2008 ].
|Power type||Process||Emission factor|
|Coal power chain||Coal production||208.5|
|Coal spontaneous combustion||67.9|
|Coal power plant||1,019.7|
|Nuclear power chain||Mining and milling, conversion, enrichment and fuel fabrication, reprocessing, etc.||7.5|
The carbon reduction effect for nuclear power development is obvious. According to the “Plan of nuclear power development for a middle and long term period (from 2005 to 2020)” [ NDRC, 2007 ] which was approved by the State Council of China in 2007, by 2010 the installed capacity of all operating NPPs will be 40,000 MW and the NPPs under construction will be about 18,000 MW, a total of 58,000 MW, accounting for about 4% of the total electricity generation in China. Based on the capacity of 40,000 MW in the plan, replacing coal power with nuclear power can significantly reduce CO2 emissions by about 450 million tons by 2020. According to the study report titled Scenario Analysis of Energy Demand in China by 2020 by the Energy Institute of the National Development and Reform Commission, the CO2 emission from the combustion of fossil fuels would reach 6.2 billion to 6.6 billion tons by 2020 [ Zhou and Xu, 2004 ]. Then the use of nuclear power replacing fossil fuel would result in about 7.5% of CO2 emission reduction directly. Considering that GHGs emission of nuclear power chain are mainly due to the use of fossil fuels and construction materials, which could be reduced even further by possible energy efficiency improvements in the future, the carbon reduction of nuclear power chain would be greater.
To mitigate climate change, the major energy-related technical actions and measures to control GHGs emission are to adjust energy structure, control the use of fossil fuels, improve energy efficiency, and increase the proportion of nuclear power and renewable energy. China is the second largest power production and consumption country in the world, energy demand is enormous and increasing rapidly but per capita energy consumption is still at a rather low level. Coal power has been the principal part of total national installed capacity of electricity generation in China, which is quite different from the oil and natural gas based energy structure in the developed countries in the world, and the CO2 emission intensity of energy consumption of China is about 30% higher than the average level of the world. To mitigate climate change, China have promised to the international community that by 2020 CO2 emission per unit of gross domestic product will be cut by 40%–45% of the level in 2005 and 15% of the one-time use power will be generated from non-fossil sources [ SC , 2009 ]. Nuclear power is a low-carbon and dense energy source, replacing coal power with nuclear power has an obvious potential in the reduction of GHGs emission. With the increasing demand of GHG emission reduction in the world, active pursuit of nuclear power development in China is a reasonable and effective choice for constructing low-carbon energy structure and responding to global climate changes.
This study was partly supported by the consulting project of Chinese Academy of Engineering entitled “The Key Issues of GHGs Emission for Different Power Energy in China”.