1. Energy Conversion & Management 40 (1999) 1129±1140
Estimation of energy consumption for each process in the
Japanese steel industry:
a process analysis
Y. Sakamoto a,*, Y. Tonooka b, Y. Yanagisawa c
a
Research Institute of Innovative Technology for the Earth (RITE), 9-2, Kizugawadai, Kizu-cho, Souraku-gun, Kyoto,
619-02, Japan
b
Faculty of Economics, Saitama University, Shimo-okubo 255, Urawa, Saitama, 338, Japan
c
Faculty of Engineering, Global Environment Engineering Program, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku,
Tokyo, 113, Japan
Received 6 July 1998; accepted 21 December 1998
Abstract
The energy consumption for each process in the Japanese steel industry is estimated by a statistical
process in order to evaluate the possibility of reducing energy consumption. The speci®c energy
consumption for each product is estimated and also for crude steel produced from an integrated steel
plant route and an electric arc furnace route. The speci®c energy consumption is compared. The energy
consumption can be estimated from the production amounts of products for each process and for crude
steel. The energy consumption of blast furnaces is the largest and that of rolling and piping is the next
largest. The speci®c energy consumption of crude steel produced from an integrated steel plant route is
approximately 2.6 times as high as that of an electric arc furnace route. # 1999 Elsevier Science Ltd.
All rights reserved.
Keywords: Speci®c energy consumption; Steel industry; Reduction
1. Introduction
Recently, the phenomenon of global warming caused by greenhouse gases from fossil fuel
* Corresponding author. Tel.: +81-774-75-2304; fax: +81-774-75-2317.
E-mail address: sakamoto@rite.or.jp (Y. Sakamoto)
0196-8904/99/$ - see front matter # 1999 Elsevier Science Ltd. All rights reserved.
PII: S 0 1 9 6 - 8 9 0 4 ( 9 9 ) 0 0 0 2 5 - 4

2. 1130
Table 1
Annual fuel consumption of each production process in 1994
Iron
and steel production process
Iron making Steel making
BOFa EAFb
Y. Sakamoto et al. / Energy Conversion & Management 40 (1999) 1129±1140
Fuel type Unit Total Sintering Pelletizing Blast Other Ferroalloy Forging Casting Rolling Private Miscellaneous Coke Others
furnace furnace production and power production
Piping generation
Petroleum fuel
Kerosene kl 421,707 ± ± ± ± 2291 210 83,190 30,754 17,021 99,514 65,052 55,976 ± 67,699
Diesel oil kl 36,520 ± ± ± ± 501 1786 23 159 131 8091 2 16,499 11 9317
A kl 636,118 1801 ± 439 1665 7097 9897 42,822 75,603 24,436 271,053 82,378 76,020 465 42,442
heavy oil
B kl 10,066 44 ± ± ± 2454 ± 1901 110 139 4973 ± 254 ± 191
heavy oil
C kl 1,267,304 1547 2382 39,039 ± 19,060 209 3260 35,618 18 660,207 453,733 13,274 ± 38,957
heavy oil
Hydrocarbon oil kl 107,995 ± ± 1602 3 ± ± ± ± ± ± ± ± 106,390 ±
LPGc ton 628,635 1438 ± 14,347 ± 1137 53,561 2349 23,396 7737 239,844 152,747 81,891 24 50,164
Petroleum coke ton 636,643 ± ± 397,005 ± 10,308 ± 11,434 ± 36 ± ± 27 215,458 2375
Non-petroleum fuel
Material coal ton 40,726,243 ± ± 1,860,187 ± ± 9 ± ± 19 ± ± 48 38,865,980 ±
Other coal ton 8,146,274 756,986 70,532 5,684,376 23,409 324,542 260,455 3855 ± ± ± 838,415 ± ± 183,704
Coke ton 35,428,384 4,016,722 40,097 30,396,806 19,897 383,981 153,557 170,716 ± 78 43 ± 157,180 59,266 30,041
Tar ton 193,240 1788 ± 136,592 ± 9 ± ± ± ± 15,886 6640 1294 30,789 242
COGd 1000 m3
9,705,932 148,262 47,517 1,433,428 453 2695 290,743 29,252 30,915 1925 3,932,544 1,695,371 419,454 1,589,007 84,366
BFGe 1000 m3
78,753,737 67,543 ± 28,491,859 25,607 1099 5455 730 1308 ± 1,421,151 32,752,038 314,807 15,652,050 20,090
BOFGf 1000 m3 4,406,050 20,082 ± 1,149,023 309 4550 4017 3413 6244 ± 1,310,124 1,631,808 32,073 190,239 54,168
EAFGg 1000 m3
6248 ± ± ± ± 6248 ± ± ± ± ± ± ± ± ±
LNGh ton 481,298 ± ± ± ± 11,352 ± 6363 12,749 2211 334,096 42,694 64,707 ± 7126
3
City gas 1000 m 544,536 3270 ± 12,672 128 57 2715 12,827 3966 4908 261,548 76,116 121,268 1221 43,840
3
Oxygen 1000 Nm 7,184,032 ± ± 1,757,692 15,468 51,225 3,980,737 953,731 3442 6376 118,955 ± 286,598 ± 9808
Electricity 1000 kWh 66,732,696 3,264,549 243,438 4,660,395 22,931 2,545,976 3,362,715 14,865,570 537,056 453,004 18,765,949 1,291,996 12,360,190 993,268 3,365,659
a
Basic oxygen furnace.
b
Electric arc furnace.
c
Lique®eld gas.
d
Coke oven gas.
e
Blast furnace gas.
f
Basic oxygen furnace gas.Ã.
g
Electric arc furnace gas.
h
Lique®ed natural gas.

3. Y. Sakamoto et al. / Energy Conversion & Management 40 (1999) 1129±1140 1131
combustion has become a worldwide problem. Emissions of CO2 from fossil fuel combustion is
a serious problem throughout the steel industry. The Japanese steel industry consumed
approximately 13±15% of the total energy among all Japanese industry in 1990 [1].
In order to evaluate the possibility of reducing energy consumption, exact estimation of the
amount of energy consumed in each production process is necessary. However, reports in
which energy consumption for each process, product and production route are simultaneously
evaluated are few to date. This is due to the small amount of data in detail for each
production process.
In this study, in order to perform an exact estimate of energy consumption for each
process in the Japanese steel industry, a process analysis was adopted using statistical data.
The speci®c energy consumptions (SECs) for each product and for crude steel produced from
integrated steel plants (ISPs) and electric arc furnace (EAF) routes were estimated and
compared.
To present the countermeasures of energy consumption taken in the Japanese steel
industry, the next generation of Japanese steel making methods is introduced brie¯y.
Furthermore, reduction of energy consumption was estimated in the Japanese steel industry
by about 2010.
2. Methodology
2.1. Outline of methodology for estimating energy consumption of each process
The Yearbook of Statistics on the Iron and Steel Industries [2] is published by the Japanese
national government (Ministry of International Trade and Industry, MITI) as a listing of
statistical data on the Japanese iron and steel industries.
In these statistics, the Japanese iron and steel industries are divided into 14 processes and are
described according to the input±output balance of products, fuel, raw materials and electricity
for each process. As an example of the data we used in this report, Table 1 and Table 2 show
the annual fuel and electricity consumption of each process in 1994 and the annual steel
production in 1994.
In this report, in order to obtain more exact estimation than those in other recent estimates,
Table 2
Annual steel production in 1994
Production (ton/year)
Production route Common steel Special steel Total
ISP 57,419,064 (71.6%) 9,805,187 (54.3%) 67,224,251 (68.4%)
EAF 22,816,793 (28.4%) 8,253,519 (45.7%) 31,070,312 (31.6%)
Total 80,235,857 (100%) 18,058,706 (100%) 98,294,563 (100%)

4. 1132 Y. Sakamoto et al. / Energy Conversion & Management 40 (1999) 1129±1140
the amount of energy consumption was estimated by adding some improvements based on
Tonooka's and Harada's methodologies [3,4] and using the above statistics.
As the fundamental estimation methodology in this report, energy consumption was
estimated from mass and energy balances of fuel, products and electricity for the 14 processes
shown in Table 1 and by summing these consumptions of energy (in detail see Section 2.2).
This methodology has the following characteristics:
1. All forms of energy were considered as primary energy. In particular, electricity was
Fig. 1. Schematic ¯ow to estimate energy consumption.

5. Y. Sakamoto et al. / Energy Conversion & Management 40 (1999) 1129±1140 1133
classi®ed into purchased and generated electricity. The calori®c value of purchased electricity
was estimated from the Japanese electricity con®guration [5], while that of the generated
electricity was estimated from input amounts of fuel and purchased electricity for private
power generation.
2. Energy consumption for each process was estimated from mass and energy balances of fuel,
products and electricity. These values were separately described as fuel (petroleum fuel and
non-petroleum fuel), raw materials and electricity. The SEC (GJ/ton-product) which is
expressed in terms of thermal energy per ton of each product was estimated from the
obtained energy consumption for each process.
Consequently, even in countries with a large di€erence in energy consumption con®guration
(e.g. the fuel consumption and the electricity con®gurations), it is possible to compare energy
consumptions for each process and product.
Steel is made via two large production routes. One is the ISP route, which produces pig iron
in blast furnaces with iron ore and coke as the major charged raw materials and produces
crude steel in basic oxygen furnaces. The other is the EAF route, which produces crude steel in
EAFs from scrap as the major charged raw material. For crude steel (cs) produced via these
two productions routes, the SEC (GJ/ton-cs) which is expressed in terms of thermal energy per
ton of crude steel was estimated.
2.2. Estimation procedure
For the 14 processes, energy consumption and SEC per ton of each product were
estimated by calculating mass and energy balances for fuel (19 kinds), products (including
by-product, e.g. scrap, dust, slug, etc.) and electricity (two kinds, not divided into two kinds
in statistics). However, another furnace process which does not produce pig iron for
steelmaking use was included in the blast furnace process, because the amount of fuel
consumption, electricity and production amount (pig iron) are extremely small compared
with those of another process.
The amount of generated electricity was allocated to the processes of the ISP route
(sintering, pelletizing, coke production, blast furnace, basic oxygen furnace, and rolling and
piping). All electricity that was consumed from private power generation sources was classi®ed
as purchased electricity in order to avoid an in®nite loop.
Fig. 1 shows the schematic ¯ow to estimate energy consumption.
2.2.1. Energy consumption and SEC
1. For each process, mass and energy balances for the amounts of each fuel and electricity are
calculated.
2. Energy consumption is calculated by multiplying balanced amounts of each fuel and
electricity by each calori®c value (high heating value (HHV)) [5,6]. The calori®c values in
these calculations were 9.134 MJ/kWh [5] (conversion eciency 39.4%) and 10.978 MJ/kWh
(conversion eciency 32.5%) for purchased and generated electricity, respectively. The latter

6. 1134 Y. Sakamoto et al. / Energy Conversion & Management 40 (1999) 1129±1140
was calculated by dividing the amount of energy consumption for private power generation
by the amount of generated electricity. The amount of energy consumption was calculated
by multiplying the balanced amounts of each fuel and purchased electricity by each calori®c
value.
3. SEC is calculated by dividing the amount of energy consumption for each process by the
production amount for each product.
2.2.2. SEC of crude steel for each production route
The major energy and material ¯ows in steel making, for estimation of the SEC of crude
steel, were de®ned as shown in Fig. 2 where crude steel was classi®ed into common and
special steel produced from the ISP and EAF routes. These values were estimated from the
amount of energy consumed in each process in the preceding estimation. Since the
consumption amounts of products, fuel, raw materials and electricity of ferroalloy production
and rolling and piping are not divided into statistics for each production route, these
Fig. 2. Major energy and material ¯ows in steel making.

7. Y. Sakamoto et al. / Energy Conversion & Management 40 (1999) 1129±1140
Table 3
Annual energy consumption of each production process in 1994
Petroleum fuel Non-petroleum fuel Electricity SEC
Production process (PJ/year) Total (GJ/ton-prod) Prod
Sintering 0.2 146.0 35.8 182.0 (8.4%) 2.1 Sinter ore
Pelletizing 0.1 4.2 2.7 7.0 (0.3%) 1.9 Pellets
Blast furnacea 16.0 889.0 51.4 956.4 (44.1%) 13.0 Pig iron
Ferroalloy production 1.7 21.7 23.3 46.7 (2.2%) 53.2 Ferroalloys
BOF 3.1 À13.9 36.9 26.1 (1.2%) 0.4 BOF cs
EAF 5.4 12.7 135.8 153.9 (7.1%) 5.0 EAF cs
Forging 6.7 1.6 4.9 13.2 (0.6%) 24.7 Forgings
Casting 2.0 0.4 4.1 6.5 (0.3%) 18.4 Castings
Rolling and Piping 53.5 133.3 187.5 374.3 (17.3%) 4.2 Final steel products
Private power generation 31.7 189.8 À221.5 0.0 (0.0%) 0.0b Generated electricity
Miscellaneous 10.2 26.4 112.9 149.5 (6.9%) 1.5 All cs
Coke production 11.5 179.6 10.9 202.0 (9.3%) 7.5 Cokes
Others 8.7 10.9 30.7 50.3 (2.3%) 0.5 All cs
Total 150.8 1601.6 415.5 2167.9 (100%) 22.1 All cs
a
Including other furnace.
b
(GJ/kWh). Prod: product. cs: crude steel.
1135

8. 1136 Y. Sakamoto et al. / Energy Conversion & Management 40 (1999) 1129±1140
amounts were allocated to each process from the production amounts of crude steel
produced from each route.
3. Results and discussion
3.1. Energy consumption and SEC
Table 3 shows the annual energy consumption and SEC for each production process in the
Japanese steel industry in 1994. Blast furnaces comprise the largest energy-consuming process
(956.4 PJ/year). The amount of energy consumption from this process accounted for 44.1% of
the total energy consumption (2.168 EJ/year), those of rolling and piping and coke production
follow (374.3 and 302.0 PJ/year) and account for 17.3 and 9.3% of the total energy
consumption, respectively. The amounts of energy consumption of the primary processes of the
ISPs route (i.e. blast furnace, coke production and sintering) accounted for 61.8% of the total
energy consumption. The SEC of ferroalloy is the largest (53.23 GJ/ton-prod), and those of
forgings and castings follow (24.66 and 18.37 GJ/ton-prod), because the production has the
various kinds for various special steels production and their small production amount. The
overall SEC for all crude steel is 22.05 GJ/ton-cs.
Fig. 3 shows the fraction of consumed energy by source type in the Japanese steel industry
in 1994. Energy consumption from combustion of non-petroleum fuel is the largest and
accounts for 73.9% of the total energy consumption.
Fig. 3. Fraction of consumed energy by source type.

9. Y. Sakamoto et al. / Energy Conversion & Management 40 (1999) 1129±1140 1137
The amount of energy consumption of the primary process of the ISP route accounted for
75.8% of the total energy consumption, and in the case of including by-product gases (COG,
BFG and BOFG) in coal fuel, the amounts of energy consumption of combustion of coal fuel
account for 98.9% of that of the ISPs. Consequently, the amount of energy consumption from
combustion of ISP coal accounted for 55.4% of the total energy consumption.
Table 4 shows the SEC of each steel for two production routes. The SECs of common steel,
special steel and the average value of the ISPs route are approximately 2.8, 2.4 and 2.6 times as
large as those of the EAFs route's. The reason for this is that the major charged raw material
for the EAF route is scrap, which has been already reduced.
The EAF route produced 31.6% of the total crude steel production in 1994 (see Table 1). By
about 2010, the EAF industry expects the percentage of crude steel produced by EAFs to rise
to 40% of Japanese steel production by developing a large size EAF which can produce large
size shapes. If its percentage rises to 40% as an ideal case, the overall SEC for all crude steel
will fall by 0.611 GJ/ton-cs. The reduction of energy consumption will be approximately 126.0
PJ/year and will account for 5.8% of the total energy consumption.
3.2. Countermeasures for reduction of energy consumption in the Japanese steel industry
From the preceding estimate, it was found that the energy consumption of the primary
processes (blast furnaces, coke production and sintering) of the ISP route was extremely large
in the Japanese steel industry. As a countermeasure for reduction of energy consumption,
besides introduction of new technologies, increasing the production ratio of EAF steel would
be a signi®cant measure.
On the other hand, several new technologies are being developed by the Japanese steel
industry. A new generation of steel making process to replace the blast furnace process
presently used, called the Direct Iron Ore Smelting Reduction (DIOS) process is being
developed by the Japanese steel industry with national support.
Fig. 4 shows a comparison of the DIOS process and the current blast furnace process. This
process can replace coke ovens, sintering machines and blast furnaces. Furthermore, it makes
possible ¯exible production in response to demand ¯uctuations.
The development of a pilot plant producing 500 ton-pig iron/day has been completed.
Currently, a construction plan for a commercial plant to produce 3000 ton-pig iron/day is
being promoted. The amounts of energy consumption of this plant will be reduced by
Table 4
SEC of each crude steel for two production routes
Production route SEC (GJ/ton-cs)
Common steel Special steel Average
ISP 24.3 26.7 24.6
EAF 8.7 11.3 9.4

10. 1138 Y. Sakamoto et al. / Energy Conversion & Management 40 (1999) 1129±1140
Fig. 4. Comparison of DIOS process and blast furnace process.

11. Y. Sakamoto et al. / Energy Conversion & Management 40 (1999) 1129±1140 1139
approximately 3±4% from that of the current blast furnace process as reported. Furthermore,
the production cost (per pig iron) will fall by approximately 19% from that of the blast
furnace process [7].
By this estimate, the overall SEC of crude steel produced by the DIOS process will fall by
approximately 0.598 GJ/ton-cs. For the case of 100% production by the DIOS process used
instead of the current blast furnace process, the reduction of energy consumption would be
approximately 40.2 PJ/year.
The Japanese steel industry expects that approximately 20% of the number of current coke
ovens, sintering machines and blast furnaces will be replaced by the DIOS process by about
2010. The reduction of energy consumption will be approximately 8.0 PJ/year.
4. Conclusions
In this report, the energy consumption for each process in the Japanese steel industry was
estimated by a statistical process analysis to evaluate the possibility of reducing energy
consumption.
The SEC for each product and for crude steel produced from the ISP and EAF routes was
estimated.
The energy consumption could be estimated from the amount of product for each process
and for crude steel. The energy consumption of blast furnaces was the largest, and that of
rolling and piping was the next largest.
The average SEC of crude steel produced from the ISP route was approximately 2.6 times as
high as that of the EAF route.
By about 2010, reduction of energy consumption in the Japanese steel industry will reach
approximately 133 PJ/year through an increase in the production ratio of EAF steel and
through development of the next generation steel making process.
Acknowledgements
This work was sponsored by New Energy and Industrial Technology Development
Organization (NEDO). The authors are grateful to NEDO.
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