Approach to Highly EfficientPower Generation
TOSHIMITSU ICHINOSE*1

MASASHI HISHIDA*2
EISAKU ITO*3

With elaborate countermeasures against global warming becoming a major issue, highly efﬁcient thermal power plants with huge
CO2 emissions are an important problem calling for an immediate solution. This paper outlines an approach toward highly efﬁcient,super critical-pressure, coal-ﬁred boiler plants, IGCC and GTCC, capable of effective utilization of coal and natural gas, the mainenergy sources for thermal power.

1. Introduction

2. Change in power generation by thermal power
plants(1) Change in fuel power generation
Figure 1 shows the change in fuel power generation1of the world. Power generation is increasing aroundthe world and will increase further. It is consideredthat natural gas thermal power generation will have thehighest increase rate (4.2%) until 2030 followed by coal
thermal power generation (2.6%). These two are selected
for environmental performance (CO 2 emissions fromnatural gas is 40 % less than from coal) and economic
performance (the price of coal is less than half that ofnatural gas).
*1 Nagasaki Research & Development Center, Technical Headquarters*2 Nagasaki Shipyard & Machinery Works*3 Takasago Research & Development Center, Technical Headquarters 77

14000
Power generation (TWh)With elaborate countermeasures against global warming
getting important, the reduction of CO 2 emissions fromthermal power plants using fossil fuels is strongly demanded.
T he industrial sector, including power plants, like thetransportation and civilian sectors, consumes a huge amountof fossil energy, equivalent to about one third of the world’s
total fossil energy consumption. It is estimated that the total
value of power generation will increase continuously for thenext 20 - 30 years, keeping that ratio intact. Highly efﬁcient
thermal power plants are an extremely important issue as
countermeasure against CO2 emissions.
As the increase in world energ y demand causes anincrease in CO2 emissions, the countermeasures against CO2emissions always involve the problem of cost performance.
The adequate technical veriﬁcation of highly efﬁcient power
plants may prove an excellent and effective means in terms ofthe general cost (economic) performance in spite of its initialcost. With the present and future world power generation
as a background, this paper outlines the approach to highly
efficient coal and natural-gas firing plants, which are themain thermal power plants.

: Coal-fired thermal power: Natural-gas firing
thermal power: Hydro power

12000
10000

: Nuclear power: Oil-fired thermalpower: Renewable energy, etc.

Annual averageincrease rate (%)
1980-2005 2005-2030
3.5
2.6
Coal
5.3
4.2
Natural gas
1.2-1.2
Petroleum

8000
6000
4000
2000
01971

1980

1990

2000 2005 20102020

2030

YearFig. 1 Change in fuel power generation in the world
The world power generation shows a sharp increase, with the main
plants using coal and natural gas.

(2) Change in fuel consumption for power generation byregion
Figure 2 shows the change in f uel consumption
for power generation in regions around the world. 1
Approximately 80% of the increase in fuel consumption
in the future will be in developing countries, with Asia
alone accounting for approximately 50 % (with Chinaand India accounting for about 40%). This indicates thatcountermeasure against CO 2 emissions in developing
countries is an urgent need.
(3) Transition of fuel prices
Figure 3 shows the change in fossil fuel prices overthe last ten years. 2 With the world power generation
showing an upward trend from 2000, fuel prices other
Mitsubishi Heavy Industries, Ltd.
Technical Review Vol. 45 No. 1 (Mar. 2008)

6000
5000

: Central and South America: Middle East
: Africa: Oceania

7: LPG: Crude oil: LNG

6
CIF price (Yen/Mcal)

Fuel consumption for power generation(million tons of petroleum equivalent): Asia: North America: Europe OECD
: Europe Non-OECD

Annual averageincrease rate (%)
1980-2005 2005-2030
1.9
1.9
World
4.5
2.9
Asia
1.0
1.1
North America

4000

5432101997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007

3000

Year

2000

Fig. 3 Change in fuel prices
Prices of fuel including coal rose sharply from the middle of 2004,
when dependency of developing countries in Asia on energy
increased, with the prices estimated to keep rising in the future.

1000
01971

: Anthracite coal
: Metallurgical coal
: Steam coal

1980

1990

2000 2005 2010

2020

2030

Year

1.6 times larger, in 2030. More than half of the increase
will be in Asia, followed by North America and Europe.
One measure for reducing CO 2 emissions is to improvethe efficiency of existing and newly built thermal power
plants, calling for the urgent development of effective
technology in this ﬁeld.

Fig. 2 Change in fuel consumption for power generation byregion
Most of the increase in power generation is in developing countries,
with Asia alone accounting for approximately 50%.

The main fuels used in thermal power plants are coaland natural gas, and the high-efﬁciency use of these two isindispensable for CO2 reductions.
In coal-ﬁred power plants, with plant capacity increasing,
the use of high-temperature, high-pressure steam conditions
is expected to improve the thermal energy efficiency. The
efficiency of the state-of-the-art thermal power with ultra
super critical (USC) conditions is 43% (gross power plant
efficiency, HHV base), capable of reducing CO 2 emission

Increase during 2005 - 2030
60 550146000

1021
OthersOthers8000

20Europe

10000

40

Asia

12000

NorthAmerica

14000

3. Approach to high-efﬁciency plants(%)

CO2 emissions(million tons of carbon equivalent)

than coal began to rise, and since the middle of 2004,
when the dependency on energ y of the developing
countries in Asia increased, a sharp rise has been seen in
the prices of all fuels including coal. Since it is thoughtthat prices will keep rising in the future, highly efﬁcientplants are also important to reduce power generation
costs.
(4) Change in CO2 emissions
Figure 4 shows the change in world CO 2 emission
levels.1 It is said that as a result of the use of fossil fuels
CO2 emissions will increase from 7.5 billion tons of carbon
equivalent in 2005 to 11.7 billion tons, approximately

EuropeNorth America

4000Asia

200001971

1980

1990

2000 2005 2010

2020

2030

Year

Fig. 4 Change in world CO2 emissions
Emission to increase in 2030 to 1.6 times of the level in 2005, with more than half of theincrease attributed to Asia.

Mitsubishi Heavy Industries, Ltd.
Technical Review Vol. 45 No. 1 (Mar. 2008)

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State of burningof 100 NOx A-PMburner
Fig. 5 USC coal-ﬁred thermal power plant (600 MW Unit Hirono
No. 5 Thermal Power Station of the Tokyo Electric PowerCompany.)
With the world’s highest level steam condition of 24.5 MPa and600°C, the unit ensures high efﬁciency power generation

Fig. 6 250 MW class air-ﬁred IGCC demonstration unit (Built byClean Coal Power R&D Co., Ltd.)This is a promising new technology using highly efﬁcient coal being
currently high efﬁciency and high reliability are veriﬁed.

intensity by 3 - 4% compared with conventional plants. TheHirono No. 5 Thermal Power Station of the Tokyo ElectricPower Company, which started operation in July 2004, shownin Fig. 5, has a main steam pressure of 24.5 MPa and amain steam temperature and reheated steam temperatureof 600°C, the highest levels in the world, ensuring highly
ef f icient power generation. 3 In order to withstand thehigh-pressure, high-temperature steam, the steam turbine
uses high-temperature material and cooling technology inaddition to a two casing turbine for the first time for a 600
MW turbine, and 48-inch steel ISB (integral shroud blade)blades. Further, the boiler has a vertical tube type furnace
using high-temperature material and riﬂed tubes in addition
to the latest, sophisticated technology such as low NOx
combustion using an A-PM (advanced pollution-minimum)
burner and an MRS (Mitsubishi rotary separator) pulverizer,
and low unburned combustion technology. As improved
steam conditions are the key to highly efficient coal-fired
thermal power, there is a move in Japan to promote, as anational project, 700°C A-USC technology, similar to thedrive for the next-generation advanced ultra super criticalpressure plant in Europe and America, whose efficiency

is estimated to be 46% (gross power plant efficiency, HHVbase).
On the other hand, another highly efﬁcient use of coal is
the Integrated Coal Gasification Combined Cycle (IGCC)
where the gasiﬁcation of coal by partial combustion is used toproduce combustible gas such as CO and H 2 , for combustion
in a gas turbine. Large-scale projects for 300 MW ClassO 2 -fired IGCC (for manufacturing chemical product rawmaterials) are already under way in some foreign countries.
In Japan the development of a ir-f ired IGCC for power
generation with higher efficiency and higher reliability is
being promoted. Figure 6 shows an external view of the250 MW class air-fired IGCC demonstration facility built
by Clean Coal Power R&D Co., Ltd. established jointly by
Japanese power companies under government subsidy.4 The
power generation efﬁciency of the IGCC using 1,500°C classG-type gas turbine is 48 - 50% (net power plant efficiency,
LHV base), and its commercialization is eagerly awaited.
The generation efficiency of gas turbine combined cycle(G T CC) power generation using natural gas has been
continuously improved by raising the gas turbine inlet
temperature, such as 1,100°C (D-type), 1,350°C (F-type)Fig. 7 1,500°C class GTCC plant (Kawasaki Thermal Power Station
No. 1 Series of Tokyo Electric Power Company)
Highly efficient power plant employing state-of-the-art G-type gas
turbineMitsubishi Heavy Industries, Ltd.
Technical Review Vol. 45 No. 1 (Mar. 2008)9and 1,500°C (G -t ype). T he ef ficiency has reached thelevel of 58 - 60 % (net power plant efficiency, LH V base)with a 1,500°C class GTCC. Figure 7 shows an externalview of the Kawasaki Thermal Power Station No.1 Series(single shaft combined plant × 3) of Tokyo Electric Power
Company, where a 1,500°C class, 50 Hz M701G2 is installed. 5
A national development project is under way of a 1,700°Cclass gas turbine for further enhanced ef ficiency since
the high-efficiency GTCC not only uses natural gas, but isalso effective as a CO 2 countermeasure. Mitsubishi Heavy
Industries, Ltd. (MHI) is taking part in this project, aiming
at producing equipment with 62 - 65% efﬁciency (net power
plant efﬁciency, LHV base).

contribute to environmental preservation. The status quoof the technical development of individual plants and theirdegree of contribution will be explained in the continued
report for your reference.
References

4. Conclusion

1. Asia/World Energy Outlook 2007 issued by the Institute of Energy
Economics, Japan
2. Trade Statistics of Japan (Ministry of Finance)
3. Momma, H. et al., Commencement of the Commercial Operationof 600 MW Unit, “Hirono No.5 Thermal Power Station of The
Tokyo Electric Power Co., Inc.”, Mitsubishi Heavy Industries
Technical Review Vol.41 No.5 (2004)
4. The web site of Clean Coal Power R&D Co., Ltd.
5. Tsukagoshi, K. et al., Operating Status of Uprating Gas Turbinesand Future Trend of Gas Turbine Development, Mitsubishi HeavyIndustries Technical Review Vol.44 No.4 (2007)

As described above, because of the huge CO 2 emissions
from thermal power plants and in view of the increasing
world demand for energy in the future, it is utterly vitalto make earnest and immediate ef for ts to reduce CO 2emissions. MHI is taking positive steps towards improving
the efficiency of coal-fired and natural gas burning plants
which are closely related to the CO 2 problem, in order toToshimitsu Ichinose

Masashi Hishida

Eisaku ItoMitsubishi Heavy Industries, Ltd.
Technical Review Vol. 45 No. 1 (Mar. 2008)10