Development of the Ultra High Efficiency Thermal Power Generation Facility

Toshihiro Sano Thermal Power Department Tokyo Electric Power Company 1-5-3 Uchisaiwai-cho, Chiyoda-ku, Tokyo 100-0011, JAPAN Phone: +81-3-6373-4001, Fax: +81-3-3596-8530, E-mail: [email protected]

Abstract In order to combat global warming, attention has been increasingly shifting towards nuclear and renewable energy such as wind and solar power generation as feasible power resource alternatives. The electric power suppliers of Japan are aiming to increase the amount of nuclear and non- power generation by over 50% of total power generation by 2020. However, this does not translate into the complete eradication of the traditional model as the remaining half will still be fossil fuel-based thermal power generation. Given these circumstances, Japan has aggressively implemented of further measures to enhance the efficiency of thermal power generation.

Key Words: High Efficiency, Power Generation, Combined Cycle Power Generation

1. Introduction actively adopted. The combined cycle generation 1.1 Thermal Power Generation realizes high thermal efficiencies and possesses The conviction that global warming prevention superior environmental properties and rapid load and the generation of and renewable adjustment capability. The 1,500 deg-C class gas energies such as wind and solar power are is of the highest class of inextricably linked is an idea that has recently been in the world at 59% (LHV: Low Heating Value) and gathering force. Regardless, thermal power is already under commercial operations. generation still remains as the major source of power supply and accounts for approximately 60% 45% 43% of all power generated in Japan. Thus, enhancing Japan 41% Nordic France the efficiency of thermal power generation has been Countries 39% UK/Ireland deemed indispensible in order to achieve CO2 37% USA

South Korea emissions reduction. Further, as Japan is a country 35% Germany Australia with few natural resources and is largely dependant Thermal Efficiency(%) - LHV 33% 31% India China on imports for its energy resources, the impact of 29% 1990 1992 1994 1996 1998 2000 2002 2004 2006 the recent rise in fuel prices has been extreme. For *Source: INTERNATIONAL COMPARISON OF FOSSIL POWER EFFICIENCY AND CO2 INTENSITY (2009) (ECOFYS) the effective utilization of fossil fuels, technology Fig.1 International Comparison of thermal power generation efficiency for improving the efficiency of the thermal power generation has become increasingly important from Figure 1 is an international comparison of the both environmental and economical perspectives. efficiency of thermal power generation. From the In Japan, the combined cycle generation facility, 1990s, Japan has attained the highest level of which combines gas and steam , has been

－1－ thermal efficiency, a level it still maintains along security through utilizing the “best mix” of power with UK/Ireland. This has been achieved via the sources. We have diversified our power and fuel enthusiastic introduction of the highly efficient sources where we were previously dependent combined cycle power generation from the mid mainly on oil-fired thermal power generation. 1980s along with the state of the art efficient steam is available in abundance and is relatively power generation facilities (/Turbine). The inexpensive and LNG has superior environmental same can also be said for UK/Ireland, where performance. Thus coal-fired thermal power and combined cycle power generation was introduced the LNG combined cycle are the two main sources utilizing the resources from the gas of our thermal power generation. Further fields of North Sea since the 1990s after the technological development to increase the thermal deregulation of electric utilities. efficiency and subsequent aggressive implementation are desired for these two different 1.0 technologies. ）

/kWh 0.8 2 Fuel for power generation 1.2 Improving Efficiency of Thermal Power kg-CO

（ 0.6 Generation 0.4 Figure 3 depicts the output trend of steam

Construction/Operation 0.2 conditions and the efficiency of TEPCO’s thermal of facilities power generation. In the late 1950s, the main CO2 Emission intensity intensity Emission CO2 0.0 Coal OilLNG Photovoltaic Nuclear source was steam power generation with its thermal LNG Combined Wind *Source: Report of Central Research Institute of Electric Power Industry efficiency being around 39% (LHV). After the Fig.2 Lifecycle CO2 emission Second World War, Japan’s thermal power generation increased in efficiency and capacity. Figure 2 depicts the lifecycle CO2 emissions from This was achieved via repeated improvements of different types of power sources. It shows the the steam conditions ( and ) by amount of CO2 emitted during the process of bringing in and absorbing the latest technologies burning fuel to generate power, as well as the from and the United States. In the 1970s, amount of CO2 emissions from all other types of the capacity and efficiency reached 1,000MW and energy usage, such as from the extraction of raw 43%, respectively. Japanese technology for thermal materials, construction of power generating efficiency improvement has since then surpassed facilities, fuel transportation and refining, and plant that of its technological forefathers. At present, the operations and maintenance. Liquefied Natural Gas efficiency of the latest coal-fired Ultra Super (LNG) has the smallest CO2 emission per calorific Critical (USC) thermal power plant has reached value, and the combined cycle power generation 45%. has a 20 to 30% higher thermal efficiency In 1985, TEPCO has introduced its first combined compared to the steam power generation. That is cycle power generation. Its thermal efficiency of why LNG-fired combined cycle thermal generation 47% has largely surpassed that of the conventional has the least CO2 emissions intensity among all steam generation at that time. Further, for the thermal power generation. combined cycle, the firing temperature which is After the two oil crises, which highlighted our equivalent to the steam conditions for the vulnerability due to our nation’s lack of energy conventional steam power generation was increased. resources, we have strived to enhance our energy The Advanced Combined Cycle (ACC) with an

－2－ efficiency of 54% was introduced. The firing generate . Then, the steam is cooled until temperature was increased from 1,100 deg-C to it condenses into at the condenser and is then 1,300 deg-C. Further, in 2007, the “More Advanced resent to the boiler. Sea water is the primary cooling Combined Cycle” (MACC) with a firing source for the condenser. Various types of fuel not temperature of 1,500 deg-C commenced only coal, oil, and LNG, but also extremely heavy commercial operations. Its thermal efficiency residual oil (such as asphalt) can be used for the reaches 59%. Now, the total capacity of the boiler. Recently, there are also approaches to combined cycle generation of TEPCO is utilizing bio mass fuel by mixing them with coal at approximately 13,000MW and accounts for one coal-fired thermal power plants. third of TEPCO’s total thermal generation capacity.

As a result of the vigorous implementation of the Stack Boiler Turbine Fuel Storage combined cycle generation, the average efficiency Tank Gas Flue Steam Generator of TEPCO’s thermal power generation was 46.9% LNG Carrier Vaporizer (LHV) in the fiscal year 2009, which is amongst the

Air top levels in Japan. Water Fuel Gas Electricity

In this paper, the features of the steam and Cooling Water combined cycle generation and the trend of the latest efficiency improvement technologies have Fig.4 Outline of Steam Power Generation been introduced. 2.2 Transition of Steam Power Generation and 1,000MW Steam Power Generation 1000 Output its Environmental Measures 800 710MW 600 In 1960s, with the further development of the 600 Combined Cycle Power Generation 500 400 350 350 360 380 Japanese economy, many power stations were built 175 265 165MW Unit Output (MW) Output Unit 200 125MW to meet the rapid growth of electricity demand. As 0

Steam Temperature (deg-C) oil became increasingly cheap and redundantly 24.1MPa 24.5MPa 25 Steam Condition 600 600℃ available, fuel for thermal power generation was 20 566℃ 566℃ 550 converted from coal to heavy and crude oil. After 15 538℃ 16.6MPa

12.5MPa experiencing the two oil crises in the 1970s, the Steam Pressure (Mpa) Pressure Steam 10 500

) weakness of Japans energy policy, which relied 65 Thermal 61% Combined Cycle Power Generation 59% 60 Efficiency almost exclusively on Middle East oil resources, 55 54% 55% 50 47% 44.6% 45.2% had become apparent. From the viewpoint of 45 42.2% 42.7% 43.2% 40 39.4% Steam Power Generation energy security, in order to realize the “best mix” of

Gross Efficiency (LHV% Efficiency Gross 35 1950 1960 1970 1980 1990 2000 2010 2020 power sources, nuclear, LNG thermal and coal Fig.3 Output, Steam Condition and efficiency trend of thermal power generation were introduced as TEPCO’s thermal power generation substitutes to oil-fired thermal generation. In 1970, the Minami Yokohama Power Plant was 2. Development of a Steam Power Generation the first in the world to utilize LNG as a source of Facility fuel for power generation. At that time, social 2.1 Features of the Steam Power Generation controversy concerning was beginning For steam power generation, as shown in Figure 4, to peak. The utilization of LNG as a fuel source had fuel is burned in the boiler to produce high since then proliferated given its superior dust and temperature and high pressure steam. This steam sulfur oxide (SOx) emissions-free environmental rotates the and the generator to

－3－ characteristics. 2.3 Implementation of Efficiency Improvement On the other hand, coal-fired thermal power Technology for Steam Power Generation generation became necessary in order to comply Thermal efficiency for steam power generation with strict environmental regulations borne from was improved by increasing its capacity and anti-pollutant environmental legislation. However, temperature and the pressure of steam conditions. given its abundance in many diverse sources, coal By increasing its capacity and enlarging the is being reconsidered, especially in the politically equipment, the thermal efficiency increases. This is stable countries of the Pacific Rim. because the radiation loss from the surface of the Japan leads the world not only in thermal boiler relatively decreases and also the decrease of efficiency but also in technologies that support or the tip loss of the steam turbine caused by the steam work in concert with environmental measures. As passing through the gap between the rotating blades shown in figure 5. Japan’s NOx and SOx emissions and the casing without producing power. The unit intensity is the lowest in the world. As for counter capacity increased from around 350MW in the measures against SOx emissions, the use of 1960s, to 600MW in the 1970s and has now low-sulfur heavy oil and high quality coal and the reached 1,000MW. Figure 6 reveals the incremental installation of the wet lime-gypsum method high temperature and pressure improvements of steam performance desulfurization unit for coal- power generation in Japan. The steam conditions fired thermal power generation were implemented. improve in the order of sub-critical, Super Critical In considering NOx emissions, excluding those (SC) and Ultra Super Critical (USC) steam originating from the fuel, NOx is also produced conditions. When water is pressurized above a through the oxidation of within the certain pressure and heated to increase its atmosphere during combustion. These type of temperature, there is a phenomenon where the emissions are known as thermal NOx. The major water suddenly changes to steam. This point is countermeasures against NOx emissions are called the critical point of water (22.12 MPa, realizing reductions via the improvement of the 374.15 deg-C). Steam conditions over this critical combustion method and the implementation of a pressure are called SC and within SC, steam low-NOx burner and removal by installing a conditions with the temperature exceeding 566 catalysis flue gas denitration facility. The major deg-C are classified as USC. countermeasures against dust emitted from burning P

oil and coal, is the installation of an electrostatic ) precipitator. First SC Unit deg-C T （

[g/kwh] SOx Emmision Intensity NOx Emmision Intensity 4

3.5 3.4 3.2 3.3 3.1 3 2.9

2.5 Steam Temperature Main Steam Pressure(MPa)

2 1.6 1.5 1.4 1.4 1.2 1.2 Year of commercial operation 1 0.8 0.8 0.7 0.6 0.5 Fig.6 Trend of Steam Temperature and Pressure for Japanese 0.2 0.2 0.14 0.18 0 Steam Power Generation Canada France Germany Italy UK USA 6Nations Japan TEPCO ('05) ('05) ('05) ('05) ('05) ('05) Average ('07) ('08) ('05) Source：OECD [Environmental Data Compendium 2006/2007] and IEA[Energy Balances of OECD Countries 2008 Edition] Fig.5 International Comparison of SOx, NOx emission intensity

－4－ Steam Condition With the introduction of SC steam conditions, the Station Name Output Year of commercial Company Unit No. Pressure Temperature operation boiler has developed from the traditional drum MW MPa deg-C Tomato-Atsuma 4 Hokkaido 700 25.0 600/600 Jun-02 Noshiro 2 Tohoku 600 24.1 566/593 Dec-94 circulating type to the one-through type which Haramachi 1 Tohoku 1,000 24.5 566/593 Jul-97 Haramachi 2 Tohoku 1,000 24.5 600/600 Jul-98 consists only of groups of many long tubes. Due to Hitachinaka 1 Tokyo 1,000 24.5 600/600 Dec-03 Hitachinaka 2 Tokyo 1,000 24.5 600/600 Dec-13(Schedule) the SC steam conditions where the water suddenly Hirono 5 Tokyo 600 24.5 600/600 Jul-04 Hirono 6 Tokyo 600 24.5 600/600 Dec-13(Schedule) changes into steam when it reaches a certain Hekinan 3 Chubu 700 24.1 538/593 Apr-93 Hekinan 4 Chubu 1,000 24.1 566/593 Nov-01 temperature, the drum which acts as a kettle has Hekinan 5 Chubu 1,000 24.1 566/593 Nov-02 Nanao Ohta 1 Hokuriku 500 24.1 566/593 Mar-95 Nanao Ohta 2 Hokuriku 700 24.1 593/593 Jul-98 been eliminated. Water entering a tube will be Tsuruga 2 Hokuriku 700 24.1 593/593 Sep-00 Maizuru 1 Kansai 900 24.5 595/595 Aug-04 preheated, evaporated and super heated and steam Maizuru 2 Kansai 900 24.5 595/595 Aug-10(Schedule) Misumi 1 Chugoku 1,000 24.5 600/600 Jun-98 will come out of the exit of the tube. Tachibanawan 1 Shikoku 700 24.1 566/593 Jun-00 Reihoku 2 Kyushu 700 24.1 593/593 Jun-03 After the 1970s, the steam conditions had not Matuura 2 J-Power 1,000 24.1 593/593 Jul-97 Tachibanawan 1 J-Power 1,050 25.0 600/610 Jul-00 changed for quite a while, but the effort to improve Tachibanawan 2 J-Power 1,050 25.0 600/610 Dec-00 Isogo 1 J-Power 600 25.0 600/610 Apr-02 efficiency continued via capacity enlargements Isogo 2 J-Power 600 25.0 600/620 Jul-09 and the development of the highly efficient steam Fig.7 USC Power Stations in Japan turbine blades. From the 1980s, construction of coal- fired power generation was promoted in order 2.3.1 Example of USC Power Plant in Japan -1 to take advantage of the abundant and cheap coal. In order to enhance energy security and minimize However, as coal-fired power generation required generation costs, TEPCO’s coal-fired Hitachinaka more in-house loads in order to operate the Unit One (1,000MW) commenced commercial equipment necessary for environmental measures operations in December 2003. For TEPCO, it had and have more CO2 intensity compared to the LNG been about 30 years since the last large scale and oil-fired power generation, there was an coal-firing power plant was constructed. In order to increasing demand towards efficiency increase the thermal efficiency and decrease CO2 improvements via increasing its steam conditions. emissions, the USC steam conditions of 24.5MPa, Further, with the development of new materials 600/600 deg-C was adopted. It achieved a thermal able to resist high , the USC efficiency of 45% (LHV) which is the highest class technology was realized. The first coal-fired USC in terms of coal-fired steam power generation levels. plant for TEPCO is the Hitachinaka Maximum efforts were put forth towards Unit One which commenced operations in 2003. environmental preservation. Highly efficient and Further, in 2004, the Hirono Power Station Unit reliable denitrifying facility and electrostatic Five began commercial operations. Currently, two precipitator and desulphurization facility had been more units, namely, Hitachinaka Unit Two and installed for the flue gas treatment. Further, woody Hirono Unit Six are under construction. Further, the fuel which is a kind of natural and spread of coal-fired USC power generation has renewable energy is scheduled to be utilized as fuel expanded throughout Japan and now accounts for for Unit One from fiscal year 2012. When half of all coal-fired generation in the nation. Figure implemented, it would reduce the annual CO2 7 shows the number USC Power Stations in Japan. emission by about 110 kilo tons. The construction of Unit Two (1,000MW) has started in October 2009. Commercial operations are scheduled to commence from December 2013. Although the Unit Two’s steam conditions are the same as those for Unit One, operability

－5－ improvements and operating cost reductions are eliminate the boiler recirculation pump being made. It will also be able to cope with more ・ Tandem compound steam turbine different types of coal than Unit One. Figure 8 is a ・ Two cylinder steam turbines made up of high bird’s eye depiction of Units One and Two. and intermediate combined turbine cylinders and a single low-pressure turbine cylinder ・ World's longest 48-inch last stage steel blades for 3,000 rpm turbines Further, due to the limited land space and shallow surrounding sea areas, it was difficult to dock coal carrier ships. Thus, the Onahama Coal Center was built as coal transshipping station 30 km south of the power station. Coal from the carrier ship is initially unloaded and stocked at the Onahama Coal Center and then transported to its final destination via a designated domestic vessel. The operation of Fig.8 Hitachinaka Power Station the Coal Center was started in conjunction with the operations of Unit Five. The overview of Hirono 2.3.2 Example of USC Power Plant in Japan -2 Unit Five is shown in Figure 9. TEPCO’s Hirono Power Station was a heavy oil- fired steam power generation plant located at Hamadori along the coast of the Fukushima Prefecture. Units Five and Six have been constructed in an extension area of about 14ha which is extremely small for a coal-fired steam power generation unit. With these two units, the total output of Hirono Power Station will come to 4,400MW making it TEPCO’s second largest thermal power station. Units Five and Six will also possess the highest global standards of thermal efficiency, steam conditions and environmental Fig.9 Hirono Power Station measures the same as Hitachinaka Power Station. When the master plan was put together during the 3. Development of a Combined Cycle Power 1990s, the electricity liberalization and competition Generation Facility 3.1 Features of the Combined Cycle Power with the IPPs had begun. In order to reduce Generation construction and operational costs, optimizations The which is the heart of the current of the following facility were thoroughly combined cycle power generation was previously implemented: used as an independent prime mover for power ・ Size reduction of the boiler by limiting generation. Compared to steam power generation, the variety of design coal the gas turbine can easily change its load of a ・ Simplifying the number of duct systems into a certain amount and is capable of rapid starts and single system stops. Although it is also capable of adjust to ・ Optimization of the start up system in order to

－6－ demand fluctuations, its efficiency was significantly necessary to inject steam into the combustor to low compared to steam power generation due to the reduce the temperature to control NOx emissions. large energy loss of high temperature exhaust gas. With the development of the dry low NOx That is why it was used only during emergencies or combustor, the reduction of NOx emissions and peak hours in Japan. improvement of thermal efficiency was achieved But in foreign countries, many of them were simultaneously. Air and fuel was pre-mixed in order implemented as they are easy to construct within a to realize a uniform flame to reduce the thermal short period of time, construction costs are low and NOx without water and steam injections. Currently, there are minimal location restrictions as there is no all of TEPCO’s combined cycle power generation need for vast amounts of cooling water for the units are equipped with the dry low NOx condenser and operations are relatively easily combustors and the catalysis flue gas denitration managed compared to steam power generation. facility in line with the normal practice for the During this period, the firing temperature has steam power generation. Thanks to the combination increased to 1,100 deg-C, a resulting level of the two technologies, NOx emissions from the considered to be satisfactory and reliable. Figure 10 combined cycle generation are controlled within outlines the structure of the combined cycle several ppm which is extremely low. generation. The exhaust gas from the gas turbine, Further, environmentally speaking, the combined after rotating the gas turbine, is lead to the cycle power generation is superior. As power output recovery steam generator to produce steam to rotate is shared amongst the gas turbine and the steam the steam turbine. Although the temperature of the turbine, the thermal effluent from the condenser of steam is limited to 600 deg-C due to material the steam turbine is about 50-60% lower compared constraints for steam power generation, the to that of steam power generation of the same combined cycle generation can effectively utilize capacity. the energy of the fuel, by utilizing the thermal The features of the combined cycle generation is energy in high temperature regions at the gas that it is able to start and stop within a very short turbine and the low temperature regions at the time frame taking advantage of the mobility of the steam turbine. gas turbine. The load curve of the combined cycle power generation is shown in Figure 11. Where Air Fuel Exhaust Gas Exhaust Gas around three hours is necessary for a 1,000MW

Gas Turbine Power HRSG steam power generation unit to reach base load Generation Gas Generator Air Fuel Compressor Turbine operations from start up after an eight hour stop, it Steam Exhaust Gas Generator Generator Turbine only takes around one hour for the combined cycle Boiler Steam Power generation unit from the same eight hour stop. Generation Gas Compressor Turbine Cooling Cooling 100 Water Water Combined Cycle Power Condenser Condenser Generation Pump 100 Fuel Pump ) % )

Fig. 10 Outline of Combined Cycle Power Generation ( %

( d

e d e a p o S L When the first combined cycle power generation was introduced, it had the wet diffusion combustor. 0 0 Though the combustion of the diffusion combustor GT Start Synchronize Base Load is very stable, as it has a high temperature region, Aprox 60 Minitues the thermal NOx was easily developed and it was Fig.11 Start up Schedule of C/C Power Generation

－7－ 3.2 Efficiency Improvement Technologies for the history of increasing the firing temperature of Combined Cycle Power Generation the gas turbine. The combined cycle power The combined cycle generation has been generation can be categorized into three distinct introduced throughout the world with the generational phases with this firing temperature. recognition of the 1,100 deg-C class gas turbine. Within TEPCO, in order to distinguish these three The thermal efficiency of the 1,100 deg-C class generation phases, we call the first generation phase combined cycle is 47% (LHV) and surpassed the with the 1,100 deg-C class, CC (Combined Cycle), efficiency of the steam power generation by over the second generation phase with 1,300 deg-C class, 3-4% at that time. Thus, large combined cycle ACC (Advanced Combined Cycle) and the third power plants for utilities were built in many places generation phase with 1,500 deg-C class, MACC in Japan since 1984. (More Advanced Combined Cycle). Figure 13 Since then, with dramatic thermal efficiency and shows the 1,100 deg-C and 1,300 deg-C combined environmental feature improvements achieved by cycle power plants of TEPCO. increasing its firing temperature and developing the dry low-NOx combustor, LNG combined cycle Yoko- Futtsu Shina- power plants were built in sequence through out hama Chiba 1 Chiba 2 Futtsu 3 1&2 gawa 1 Japan. Now, there is a 1,500 deg-C combined cycle 7&8 Number of Unit 14 8 4 4 4 3 power plant with one of the world’s highest thermal Unit Output (MW) 165 350 360 360 380 380 efficiency rates of 59% (LHV) already in Group Output (MW) 2,000 2,800 1,440 1,440 1,520 1,140 commercial operation. Figure 12 is the heat balance Design Thermal 47.2 54.1 54.2 54.2 55.3 55.3 diagram of the latest 1,500 deg-C class combined Efficiency (%LHV) Year of Commercial 1986 / 1998 2000 2000 2003 2003 cycle power generation. Operation 1988

Condenser GT Type 9E 9FA M701F 9FA 9FA+e 9FA+e Turbine Steam ３３％ Fig.13 TEPCO‘s CC and ACC power stations ５３％ ２０％ Electricity Heat Recovery Energy ５９％ Just after the World War II, the buckets of the gas Gas Turbine

Fuel (LNG) Fuel ３９％ turbines were made of steel and used without any １００％ cooling or coatings. The gas turbines for the CC ６１％ GT Exhaust GT power generation increased its firing temperature to 1,100 deg-C by utilizing the technologies employed H ５３％ R in aviation engines such as nickel super alloy, blade S ８％ G cooling technology and thermal barrier coatings. Since then, the combined cycle power generation Exhaust Gas has become economically feasible and has spread Fig.12 Heat Balance Diagram of MACC widely throughout the world. Further, for TEPCO, Futtsu Power Station Groups One and Two The most important indicator for the combined (2,000MW) commenced operations in 1985 and cycle power generation is the firing temperature of achieved a thermal efficiency rate of 47% (LHV). the gas turbine which dominates the thermal Further, for the ACC power generation, the efficiency of the combined cycle power generation. construction of a 1,300 deg-C class gas turbine was The history of improving the efficiency of the realized through several technical developments. combined cycle power generation can be said to be Concerning the material technology, enhancement

－8－ Kawasaki 1 Shin-Nagoya 8 Futtsu 4 Sakaiko of high temperature creep strength was created by (Tokyo) (Chubu) (Tokyo) (Kansai) improving the crystal structure and chemical Number of Unit3435 components of the nickel supper alloy for buckets. Unit Output (MW) 500 400 507 400 Group Output (MW) 1,500 1,534.4 1,520 2,000 As for the cooling technology, a cooling efficiency Design Thermal about 59 about 58 about 59 about 58 increase was realized by adopting the return flow Efficiency (%LHV) Year of Commercial 2007-2009 2008 2008-2010 2009-2010 cooling with a sophisticated cooling passage within Operation the turbine buckets compared to the one through GT Type M701G2 M501G 9H M501G Kawasaki 2-1 Himeji No.2 Kawasaki 2- Goi 1 cooling of the previous 1,100 deg-C class gas (Tokyo) (Kansai) 2,3 (Tokyo) turbine. With the realization of the 1,300 deg-C Number of Unit1623 class gas turbine, the thermal efficiency of ACC Unit Output (MW) 500 486.5 710 710 Group Output (MW) 1,920 2,919 1,920 2,130 power generation dramatically increased to 54% Design Thermal about 59 about 60 about 61 about 61 (LHV). Starting from the Yokohama Power Station Efficiency (%LHV) Year of Commercial 2013 2013-2015 2016-2017 2021-2023 Group Seven and Eight (2,800MW), many ACC Operation power plants were constructed. Further GT Type 1,500℃-class 1,600℃-class 1,600℃-class 1,600℃-class technological improvements for the thermal barrier Fig.14 Latest Combined Cycle Power Stations in Japan coating to protect the buckets from the hot exhaust gas were made after ACC power generation was 3.2.1 Kawasaki Power Station Group 1 and 2 implemented. TEPCO’s Kawasaki Power Station Group One As for the MACC power generation, additional commenced its commercial operations from June high temperature strength enhancement of the 2007. It was the first 1,500 deg-C class MACC metallic material and usage of steam which has a power generation in Japan and achieved a thermal higher cooling ability than air for the cooling of efficiency of 59% (LHV) which is the highest level combustors, buckets and nozzles allows for the in the world. Group One (500MW x 3 stages, total further increase of the firing temperature. With the 1,500MW) implements the MHI’s 701G2 gas 1,500 deg-C gas turbine, the thermal efficiency of turbine. The key features of this gas turbine are that the MACC power generation reached 59% (LHV). the combustors are steam cooled. In February 2009, TEPCO’s Kawasaki Power Station Group One and the entire Group One began commercial operations Futtsu Power Station Group Four commenced and from February 2010, steam from Group One commercial operations from 2007 and 2008, was supplied to 10 companies in the Chidori-Yako respectively. Furthermore, the implementation of a industrial complex of Kawasaki City. 1,600 deg-C class More Advanced Combined Along with the construction of Group One, Cycle 2 (MACC 2) power generation which has demolition of the former One to Six units was done increased its firing temperature with the bucket at the same time. After the demolition, construction cooling and coating technology improvement has of Group Two was started from October 2009. The been planned for the Kawasaki Power Station 2-1 Stage which is the first of the Group Two will Group Two and the replacement of the Goi Power be MACC power generation (500MW x 1 stage) Station. Figure 14 shows the latest ultra-high following Group One and is planned to be efficient combined power stations in Japan. commercially operated from February 2013. On the other hand, Stages Two and Three of Group Two are planned to be the 1,600 deg-C MACC2 (710MW x 2 stages, Group Two total 1,920MW) with a thermal efficiency rate of 61% (LHV). They

－9－ are scheduled to begin commercial operations from 2016 and 2017, respectively. Figure 15 depicts the future Kawasaki Power Station Groups One and Two.

Fig.16 Futtsu Power Station

3.3 Effective Use of Coal From an energy security and economical perspective, as coal is available in abundance and is Fig.15 Kawasaki Power Station relatively inexpensive, it is considered to be a promising fuel source for both now and in the 3.2.2 Futtsu Power Station Group 4 future. However, it is not possible to burn coal in At Futtsu Power Station, Groups One and Two the combustor of the gas turbines. The use of coal (2,000MW) which are the pioneering CC within was limited to such activities as pulverized coal- Japan, and Group Three ACC power generation fired steam power generation. (1520MW) are under commercial operations. The technology to improve the thermal efficiency Further, adjacent to Group Three, Group Four of coal-fired power generation is called the MACC power generation facilities (507MW x 3 “Integrated Coal Gasification Combined Cycle” stages, total 1520MW) are under construction. (IGCC). Coal is gasified at the gasification furnace Group Four implements GE’s 9H gas turbine. The which enables it to be used as fuel for an efficient key features of the 9H gas turbine is that it adopts gas turbine combined cycle power generation. steam cooling for the 1st and 2nd stage buckets and Figure 17 is an outline of the IGCC. nozzles. The commercial application of the IGCC with a Construction of Group Four was started from 1,500 deg-C class gas turbine is assumed to have a September 2004. The first gas turbine and the heat net efficiency rate between 48 to 50% (LHV). At recovery steam generator were delivered on site in present, the demonstration of the IGCC is on going August and September of 2006, respectively. The as a national project. This project is located in commissioning of Stage One, the first of the Group Nakoso of Fukushima Prefecture and managed by Four, was started in November 2007. After various Clean Coal Power R&D CO., LTD. (CCP), an tests and tuning such as change over of the steam institution which funded mainly by TEPCO supply for the bucket and nozzle steam cooling together with nine other Japanese Utilities and which is special for the 9H type, Stage One J-power. The air blown IGCC, which is unique to commenced commercial operations in July 2008. Japan, has a higher net efficiency compared to the The entire commercial operations of Group Four blown IGCC of USA and Europe. The CCP are scheduled for October 2010. A bird’s eye view was established in June 2001. After three years of of Futtsu Power Station is shown in Figure 16. design and environmental impact assessment and

－10－ another three years of construction and fired power generation” and IGCC and Advanced commissioning of the 250MW IGCC with a 1,200 Ultra Super Critical power generation (A-USC) for deg-C class gas turbine was started from 2007. It the “high efficient coal fired generation” was has achieved a net efficiency rate of 42.9% (LHV) chosen for this program. The 1,700-deg-C class gas and has successfully operated continuously for turbine is expected to be applied to not only the 2,039 hours in 2008. Currently, it is in its third year LNG-fired combined cycle power generation but of testing and is accumulating a great deal of also to IGCC power generation. know-how. TEPCO has dispatched numbers of It is strongly desired that the issues connected to engineers to CCP in order to acquire experience in each technical development be resolved and further construction, operations and maintenance for the implementations of thermal efficiency preparation of the commercialization of the IGCC. improvements be steadily realized.

Fig.17 Outline of IGCC

4. Future Prospects The electric power suppliers of Japan are aiming to increase the rate of nuclear and non-fossil fuel power generation to over 50% of the total power generation by 2020. However, this means that the remaining half will still be fossil fuel-based thermal power generation. Further, thermal power generation’s role in adjusting to the fluctuation of solar and wind power generation output affected by the weather will still be significant. Further efficiency improvements of the thermal power generation are necessary in order to meet increasing environmental and economical demands while maintaining a stable supply of energy. In March 2008, the Resource and Energy Agency in the Ministry of Economy, Trade and Industry, announced the “Cool Earth - Innovative Energy Technology Program”. Out of the 21 prioritized technologies, 1,700 deg-C class combined cycle power generation for “high efficient natural gas

－11－