中国中长期碳减排战略目标初探(Ⅱ)——中国煤炭消费过程的碳排放及减排措施

A Preliminary Study on China′s Long and Medium-Term Strategic Goals for Reducing Carbon Emissions(Ⅱ)——Carbon Emissions during Coal Consumption in China and Solutions

中国能源领域排放的二氧化碳主要来自煤炭,因此煤炭消费过程中的碳减排措施尤为重要。煤炭的主要用户是发电部门,基于应对气候变化的需要,煤电行业的低碳途径不得不考虑采用CCS技术。不论是新建燃煤电厂,还是今后在传统电厂改建过程中增设CCS设施已是大势所趋,预计多数仍将采用MEA法脱除烟气中二氧化碳这一成熟技术。由于MEA法技术经济指标不够先进,估计10~20年内必将出现更先进的脱二氧化碳工艺技术。传统的燃煤锅炉增加CCS的经济效益已经逊于IGCC-CCS,预计2020年后IGCC电厂将成为新建煤电厂的首选方案。20年后采用临氢气化炉与燃料电池FC发电相结合、把高温的热能和甲烷的化学能直接转化为电力的IGFC高效燃煤电厂或将成功应用,IGFC综合能量转化效率比IGCC相对高出1/2~3/4,发展前景不可低估。钢铁、水泥和化工等高耗煤工业部门可通过节能和采用CCS技术降低碳排放,其余用煤的工业部门和分散用户则应考虑节能或用天然气等低碳燃料替代,间接起到减排效果。预计2050年燃煤发电和高耗煤工业总计将排放二氧化碳4.6Gt,如果二氧化碳捕集量是2.9Gt,则净排放量为1.7Gt。加上其他难以捕集二氧化碳的工业、部门及民用煤排放二氧化碳1.0Gt,合计二氧化碳净排放量为2.7Gt（情景A）。如果采用更先进的技术和严格的节能减排措施,可减少煤炭消耗0.31Gt标煤,减少二氧化碳排放0.5Gt,使煤源二氧化碳净排放量减少到2.2Gt（情景B）。无论哪种情景,实施CCS的任务都十分艰巨。

Most carbon dioxide emitted in China′s energy industry comes from coal and thus reducing carbon emissions in the process of coal consumption is very important.The major coal consumer in China is the electricity generating sector.Based on the need for combating climate change,the coal industry has to consider using CCS technology in meeting low-carbon objectives.In the processes of building new coal-fired power plants and expanding or upgrading traditional power plants,adding CCS facilities is an irresistible trend.Most enterprises are expected to adopt the proven MEA technology to remove the carbon dioxide in flue gas.As the MEA technology does not use advanced enough technical and economic indices,more advanced carbon dioxide removing technology is set to come onto the market in the next 10-20 years.For traditional coal-fired boilers,the economic benefits of adding CCS are inferior to using IGCC-CCS.It is predicted that IGCC power plants will become Chin′s first choice in building new coal-fired power plants after 2020.Twenty years from now,IGFC high-efficiency coal-fired power plants may come on line.These power plants can directly convert high-temperature heat energy and the chemical energy of methane to electricity by combining the use of hydrogen gasification furnace and fuel cell power generation.IGFC has an overall energy conversion rate 1/2-3/4 higher than that of IGCC and thus has a very promising development prospect.Big coal consumers such as the iron and steel,cement and chemical industries can reduce carbon emissions by adopting energy-saving and CCS technologies and other industrial coal users and private coal consumers can consider introducing energy-efficient technologies or replacing coal with low-carbon fuels such as natural gas to indirectly reduce carbon emissions.It is predicted that by 2050 the combined volume of carbon dioxide emitted by China′s coal-fired power plants and other large industrial coal consumers will have reached 4.6Gt.If 2.9Gt was captured,the net emission would reach 1.7Gt.If the 1.0Gt of carbon dioxide emitted by other coal-consuming sectors and residential users was included,the combined net emission of carbon dioxide would be 2.7Gt（Scenario A）.If more advanced technologies and strict energy-saving and emission reduction measures were used,China′s coal consumption could drop by 0.31Gt and carbon dioxide emission could drop by 0.5Gt,thus reducing the net coal-derived carbon dioxide emission to 2.2Gt（Scenario B）.The country will face great challenges in implementing CCS under either of the scenarios.