ep08-strategic thinking on igcc development in china-weidou ni

1、Energy Policy 36 (2008) 111/locate/enpolViewpointStrategic thinking on IGCC development in ChinaHengwei Liu , Weidou Ni, Zheng Li, Linwei MaDepartment of Thermal Engineering, Tsinghua University, Beijing 100084, PR ChinaReceived 28 June 2007; accepted 31 August 2007Available online 2

2、4 October 2007AbstractWith electricity demand growing at a torrid paceabout 15% per year, faster than any other country in the worldChina is fast- tracking the construction of new generation facilities, about 80% of which are coal-red. Chinas total capacity in the reference scenario of World Energy

3、Outlook 2006 (WEO2006) released by the International Energy Agency (IEA) is projected to practically 3.4 times, from 442 GW in 2004 to 1496 GW in 2030, growing at 4.8% per year on average. The vast majority of this huge generation requirement will still be met through the construction of coal power

4、plants. Because new coal power plants built today have a long life cycle and are not easy to upgrade the technologies involved, decisions made now will have a major impact on the coal utilization mode in the coming years. Thus, the future 20 years is the strategic opportunity period of the transitio

5、n of conventional coal utilization. Because the Integrated Gasication Combined Cycle (IGCC) can supply electricity, liquid fuels, hydrogen and other chemicals if needed at low pollution level, and has the potential to make carbon capture and sequestration much easier and cheaper than traditional pul

6、verized coal boiler power plants, it should be the strategic direction for China to meet the requirements of the energy and environmental challenges. This paper makes an overview of Chinas energy and environmental challenges and opportunities, and describes the IGCC technology. It discusses why Chin

7、a should develop IGCC. What are the foundations for China to develop IGCC? What are the rational driving forces to develop IGCC in China? What is the reasonable developing path of IGCC in China?r 2007 Elsevier Ltd. All rights reserved.Keywords: China; IGCC; Sustainable development1. General backgrou

8、ndprimary energy consumption, reaching 2959 Mtce per year- reference scenario (IEA, 2006).1.1. A coal-dominated energy mix will long exist in China1.2. More and more coal will be used for power generation in ChinaChina is the worlds largest producer and user of coal. Due to the greater than 10% econ

9、omic growth in the past 10 years, the Chinese demand for coal grew rapidly. As shown in Fig. 1, both energy production and consumption in China are dominated by coal (NBS, 2007).Although forecasts on Chinas future energy demand vary, they are consistent with regard to coals long-term dominance in Ch

10、ina in foreseeable future. According to the World Energy Outlook 2006 (WEO2006) of the Interna- tional Energy Agency (IEA), Chinas annual primary energy demand is expected to be 4865 Mtce by 2030, twice the countrys energy consumption in 2004. Coal consump- tion is expected to account for around 61%

11、 of the totalIn China, coal is the most important energy resource and it is a resource for all sectors of society except transporta- tion. The use of coal in China is very different from that in the developed countries. The percentages of coal used for power generation in the US, EU, and Japan are 9

12、0%, 60%, and 51%, respectively (Zhou et al., 2005). However, the percentage of coal in China is only 44% in 2005 (NBS and NDRC, 2007), as shown in Fig. 2.From a global perspective, coal will still be the dominant energy for power generation. From now on, the percentage of coal used for power generat

13、ion will be increasing, along with the coal gradually withdrawing from some present sectors. Even if other alternatives for power generationCorresponding author. Tel.: +861062796168; fax: +861062795736.E-mail address: (H. Liu).0301-4215/$- see front matter r 2007 Elsevier Ltd. All

14、 rights reserved. doi:10.1016/j.enpol.2007.08.0342H. Liu et al. / Energy Policy 36 (2008) 111Others 9%Others 8%NG 4%NG 3%Oil 12%Oil 19%Coal 69%Coal 76%Total: 2460MtceEnergy consumptionTotal: 2210MtceEnergy productionFig. 1. Chinas energy mix in 2006.2%China is now the second largest emitter of CO2 a

15、fter the United States. A report last November released by the IEA showed that China would surpass the United States and become the worlds top CO2 emitter by 2009. Most recent estimates by the US Carbon Dioxide Information Analysis Center extend that date up to 2007 (Rosen and Houser, 2007).30%44%1.

16、4. A coal-derived alternative is the way out for mitigating the shortage of liquid vehicle fuel18%6%Heating SupplyTotal Final ConsumptionNow China is facing unprecedented urbanization; every year more than 10,000 thousand farmers ood into cities. Relatively, the auto industry has been developing ver

17、y fast in China in recent years. The production of autos in China was 5.7 million in the year 2005, which made China rank at No. 4 in the world (QICA Statistics, 2005). It is estimated that the amount of autos would reach 130150 million by the year 2020, ranking No. 1 in the world (Chen et al., 2004

18、; Feng, 2005), and reach about 200 million by the year 2030 (DRCSC, 2006). The ratio of the petroleum consumption used in autos in the total consumption of the petroleum is nearly one-third, which is still much lower than the average amount of the world (over one-half). China has already felt the hu

19、ge challenge of the ever- increasing jitter and the safety of petroleum. The amount of crude oil and related products imported in 2006 was about 163 million tons, and the estimated amount will be 450 million tons by 2030. The energy security problem is quite rigorous. Compared with oil, coal reserve

20、s in China are relatively abundant. Now, in China, a universal viewpoint is that China must develop alternative fuels to guarantee energy security in the longer term, and coal- derived fuels are the only choice to mitigate the shortage of oil in a relatively large scale. National statistics show tha

21、t China produced 2.38 billion tons of coal in 2006 and consumed 2.37 billion tons; if 1/8 of the coal production would be used for coal-derived alternative fuels (produc- tion of about 50 million tons alternatives), the problem ofThermal Power CokingOthersFig. 2. Chinas coal consumption mix in 2005.

22、achievethe upper limit of development before2030,coal will still be the most important energy for power generation.1.3. Coal has already been causing severe pollution and huge carbon dioxide (CO2) emission in ChinaThe exploration and utilization of coal have already been causing severe pollution and

23、 ecological degradation. In all, 7080% or more sulfur dioxide (SO2), nitrogen oxides (NOx), mercury (Hg), particulates and CO2 are caused by direct combustion of coal. Currently, about 3040% of Chinas territory, especially the southwest, is suffering from acid rain and respiratory system diseases ar

24、e continuously increasing.Particularly, it is quite difcult to solve the problem of CO2 reduction with direct combustion of coal because of the huge volumetric ow rate of the ue gas and low concentration of CO2 (about 13%). CO2 capture is a high- energy-consumption process, and it will lower the efc

25、iency of the power plants by about 913% percentage points.H. Liu et al. / Energy Policy 36 (2008) 1113vehicle fuel shortage will be mitigated signicantly, without causing an imbalance in energy supply.About 5 years ago, China extensively developed corn- derived ethanol. But corn-derived ethanol cann

26、ot be a reasonable alternative in the long term because, in China, 7% of the world farming land should provide food for 22% of the world population. As far as present technology is concerned, 3.5 tons of corn should be used to produce 1 ton of gasoline. Besides, 0.50.8 tons of coal must be consumed

27、for the fermentation and drying of corn. This means that 10 million tons of gasoline-equivalent alternatives should consume 50 million tons of corn, which is a very large portion of the corn production in China (in 2006, Chinas corn production hit a record 144 million tons). Surely, cassava root, sw

28、eet sorghum and even different kinds of cellulose could be used to produce ethanol, but they have not been commercialized yet, and large-scale collection and transportation under Chinas condition (highly scattered) will be a big problem (Ni, 2007).local and regional environmental protection, and, pe

29、rhaps most important, the need to reduce CO2 emissions because of concerns over global climate change, should be fully considered, or the consequence could be that China would lock into a coal-based energy system where future reductions in oil import, emissions of CO2 and other environmental polluta

30、nts would lead to signicant cost and efciency penalties.New and cleaner coal-based power generation technol- ogies have been emerging since the 1990s. In particular, the Integrated Gasication Combined Cycle (IGCC) technol- ogy that involves the gasication of coal or of other solid hydrocarbons to pr

31、oduce a synthesis gas for cogeneration of power and other products has brought a hope for coal to play a role in sustainable development.3. Description of IGCC technology3.1. How does IGCC work? (IHI, 2007; Xu, 2006; COAL21, 2006)2. OpportunitiesAs shown in Fig. 4, IGCC is a power generation process

32、 combining two leading technologies. The rst technology is called coal gasication, which transforms coal (and other fuels) to a synthetic gas (syngas). The second technology is called combined cycle, which is one of the most efcient means of generating electricity.Chinas energy infrastructure is exp

33、anding at an unprecedented speed. About 278 GW of new power generation capacityincluding 101.17 GW in 2006were added from 2001 to 2006 (NBS, 2007), which is more than the total installed capacity of Japan (261 GW in 2004) or of Russia (220 GW in 2004). Chinas electricity demand in the reference scen

34、ario of WEO2006 is projected to practically3.4 times, from 2237 TWh in 2004 to 7624 TWh in 2030, growing at 4.8% per year on average. The vast majority of this huge generation requirement will be met through the construction of coal power plants, as shown in Fig. 3. Because new coal-red power plants

35、 built today have a long life cycle and it is not easy to upgrade the technologies involved, decisions made now will have a major impact on the coal utilization mode in the coming years.Therefore, the future 20 years is the strategic opportunity period of the transition of traditional coal utilizati

36、on. The increasing shortage of oil, more strict requirements forCoal gasification: The gasication portion of the IGCC plant produces a clean syngas which fuels the combus- tion turbine. Coal is combined with oxygen in the gasier to produce the syngas, consisting mainly of carbon monoxide and hydroge

37、n. The gas is then cleaned by a gas cleanup process. After cleaning, the syngas is used in the combustion turbine to produce electricity. Combined cycle: This portion consists of a combustion turbine/generator, a heat recovery steam generator, and a steam turbine/generator. The exhaust heat from the

38、 syngas-red combustion turbine is recovered in the heat recovery steam generator (exhaust-heat boiler) toFig. 3. Chinas power generation-reference scenario (IEA, 2006).4H. Liu et al. / Energy Policy 36 (2008) 111Fig. 4. Typical components of an IGCC power generation system (IHI, 2007).3.2.2. Product

39、s flexibilityAlong with electricity production,produce steam. This steam then passes through a steam turbine to power another generator, which produces more electricity. The combined cycle is more efcient than conventional power-generating systems because it re-uses waste heat to produce more electr

40、icity.IGCC is able toco-produce other commercially desirable products that result from the process. Some of these products include steam, oxygen, hydrogen, fertilizer feed stocks and FischerTropsch fuels. Usually, this type of IGCC is called polygeneration. Technically, the power generation part of

41、polygeneration is similar to that of IGCC.The block diagram of a polygeneration system is shown in Fig. 5.The syngas (CO+H2) via coal gasication after cleaning is used for the production of chemicals, liquid fuels (FT liquid, methanol, dimethyl ether (DME), etc.) and electric power. All the energy o

42、w, material ow and exergy ow of these processes are coupled together and optimized. In comparison with stand-alone production, the benets in capital investment, cost of unit products and pollution reduction (sulfur, Hg and particulates) are very signicant (more than 10%). At the same time, the syste

43、m is quite exible. It can adjust the peak valley of its products according to the market demand.The liquid fuels produced by polygeneration, especially methanol and DME, are suitable alternatives for vehicle fuels, and can signicantly mitigate the shortage of oil in China. Furthermore, methanol can

44、be used to produce olen and propane (MTO and MTP); thus, coal chemistry will partially play the role of traditional petroleum chemistry to reduce the consumption of oil. DME has a physical property close to that of liqueed petroleum gas (LPG), except for its use as an alternative for diesel oil, and

45、 it is an excellent civil fuel, providing clean energy to residents.This polygeneration system is open. Under the concrete circumstance of China, in the coal-abundant areas, this system is quite benecial, and it could implemented step by step or phase by phase according to the technical advancement

46、and availability of capital investmentfor example, for the rst phase, only co-production of power,3.2. Why consider IGCC?IGCC is an advanced technology that representsthecleanest of currently available coal technologies. Advan- tages of IGCC over current conventional coal-based power generation syst

47、ems include the following.3.2.1. Higher efficiency and lower emissionsThe most striking difference between an IGCC and a pulverized coal (PC) power plant is the higher efciency potential of the former. Net efciency for IGCC in existing plants is around 4043% (LHV) and 3841% (HHV). Recent gas turbine

48、s would enable this to be bettered, and future developments should take efciencies beyond 50% (Henderson, 2007).For traditional pollutants such as NOx, SO2, particulate matter (PM) and Hg, IGCC is inherently lower polluting (about 1/10) than the current generation of traditional coal- red power plan

49、ts: the desulfurization rate is 99%, SO2 emission is about 25 mg/N m3 (the Chinese standard is1200 mg/N m3), the denitrication rate is 90%, nitrogen oxide emission is 1520% of that of conventional power plants (Zhao et al., 2006).Unlike the ordinary coal-redpowerplants,and theIGCCdoes not need to de

50、al with low-concentration pollutants in a large volume of ue gas. In a coal IGCC system,the gas coming out of the gasier (syngas) is under high pressure and contains higher concentrations of pollutants than the exhaust gas of coal combustion does. Therefore, the cost of removing pollutants is compar

51、atively lower.H. Liu et al. / Energy Policy 36 (2008) 1115Fig. 5. Block diagram of a polygeneration system (Ni, 2007).3.3.1. Higher costIGCC facilities areheat and methanol; the other products could be arranged later.more expensive to build thanconventional coal plants. Only recently have suppliers

52、begun to emerge that can offer comprehensive, integrated designs with packaged systems and compatible equipment. Today, the construction cost of a coal IGCC plant is more than $1500/kW (Jiao, 2007).3.2.3. Pathway to carbon capture and storageIn an IGCC plant, the coal is reformed using steam to make

53、 a synthetic gas, then high-concentration and high- pressure CO2 can be separated and is relatively easier to be captured, which can be utilized for enhanced oil recovery or enhanced coalbed methane recovery. Thus, the cost will3.3.2. Lower reliabilityThe reliability is currently being considered as

54、 the most important process-related problem of IGCC plants. The availability of current IGCC power plants is only about 80%. Although the availability of IGCC has signicantly increased in recent years, it is still lagging behind PC technology. The industry is encouraging suppliers to offer performan

55、ce contracts for next-generation IGCC plants, but for now the risk of reduced reliability and availability add signicant cost to the projects nancing.Besides the most critical obstacles for commercialization of IGCC technology mentioned above, IGCC has other shortcomings, such as the long constructi

56、on period and little operating experiences.be much less than capturing conventional power plants.the CO2 from ue gas of3.2.4. Higher fuels flexibilityIGCC plants can burn any high hydrocarbon fuel, including low- and high-sulfur coal, anthracite, and biomass, which is suitable for China to utilize i

57、ts 20% or more high-sulfur coal resources.3.2.5. Lower water requirementIGCC systems only for power generation use less cooling water and are desirable in the event that the power station is located in an area lacking adequate water. Water requirements are typically 1/31/2 less for IGCC applica-3.4.

58、 IGCC worldwidetions than for conventional coal generation (Lin 2005; Zhao et al., 2006; Xu, 2006).IGCC also has other benetsfor example, coaletal.,The research and development of IGCC technology started in the 1970s. About 10 IGCC plants were constructed worldwide in 1990s, one of the typical four commercial coal-red plants in operation are Wabash River, Tampa, Buggemun, and Puertollano IGCC power plants. The rst two (Wabash River and Tampa) of these projects are in the US and were implemented with the nancial s