Volume 6 hydro power 6 10 – hydropower development in japan

Volume 6 hydro power 6 10 – hydropower development in japan Volume 6 hydro power 6 10 – hydropower development in japan Volume 6 hydro power 6 10 – hydropower development in japan Volume 6 hydro power 6 10 – hydropower development in japan Volume 6 hydro power 6 10 – hydropower development in japan Volume 6 hydro power 6 10 – hydropower development in japan

T Hino, CTI Engineering International Co., Ltd., Chu-o-Ku, Japan

© 2012 Elsevier Ltd

6.10.1.2 The Start of Long-Distance Transmission of Electric Power and Large Hydropower Dams

6.10.1.5 Electric Power Shortages and the Postwar Reorganization of Electric Power

6.10.1.7 Hydropower Dams from the Rapid Economic Growth Period to the Stable Growth Period

6.10.1.7.1 Electric power demand and the roles of hydropower dams during the rapid economic growth period

6.10.1.7.2 The redevelopment of hydropower by consistent hydropower development in a river system

6.10.1.7.3 Hydropower development centered on pumped-storage-type hydropower

6.10.4.1.2 Features of the project area

6.10.4.1.4 Effects of the benefits

6.10.4.2 Sediment Flushing of Reservoir by Large-Scale Flashing Facilities in the Kansai Electric Power Company

6.10.4.2.2 Features of the project area

6.10.4.2.5 Results of the mitigation measures

6.10.4.3 Reservoir Bypass of Sediment and Turbid Water during Flood in the Kansai Electric Power Company

6.10.4.3.2 Features of the project area

6.10.4.3.5 Results of the mitigation measures

6.10.4.4.2 Features of the project area

6.10.4.4.5 Results of the mitigation measures

Relevant Websites

6.10.1 Outline of the History of Hydropower Development in Japan

Hydropower production that began with waterwheels on small rivers has expanded to include the run-of-river type, conduit type, dam and conduit type, and dam type

During the last half of the 1880s in Japan, hydropower production appeared as an economical power production method to replace coal-fired thermal power production, meeting the growing electric demand The first hydropower was run-of-river type with small-scale intake weirs installed to stabilize the intake water level In about 1900, the construction of large-scale hydropower plants

in mountainous regions far from demand regions began in response to progress in long-distance electric power transmission technology From about 1910, the hydro-first/thermal-second stage arrived, and the construction of hydroelectric stations as part of dam regulation pond construction began In the 1920s, dam–conduit-type hydropower plants appeared, providing a base load supply in response to soaring demand for industrial electric power

Although the end of Second World War was followed by a temporary surplus of electric power, its demand soared because of shortages of power source, and postwar rehabilitation Such circumstances triggered demand for the immediate start of work to establish the postwar electric power development system Advanced thermal power stations were being constructed to provide electricity to meet rising demand, and provide base load On the other hand, large-scale hydropower plants that were intended to meet the peak demand for electric power, increased in importance, spurring their construction

The hydro-first/thermal-second electric power structure continued until 1962 and was followed by the advance of thermal power and nuclear power, but even after 1960, reservoir and regulating pond-type hydropower plants continued to be developed as valuable peak supply power The concept of river hydropower development is to construct groups of hydropower plants appro­priately from upstream to downstream to efficiently produce hydropower from the overall river perspective, and is called Consistent Hydropower Development in a River System The oil shock of 1973 was followed by large-scale pumped-storage electric power production as part of valuable clean energy and as power to respond to peak electric power production

6.10.1.1 The Start of Hydropower Production

Hydropower production was first developed for in-house use by the spinning and mining industries The first electric power station developed to provide commercial electric power was constructed in Kyoto: the Keage Power Station (1892) that used water drained from Lake Biwa Its power was used to operate the first electric street cars in Japan

Demand for electric power for lighting began in 1887 and records of electric power demand for factories appeared in 1903, when Japanese industry finally modernized

Early electric power projects were primarily intended to supply electric power for lighting from thermal power stations During this period, transportation within Japan was inconvenient and transporting coal was costly, so it was difficult to produce thermal power in inland regions of Japan Therefore, most power produced in such regions was hydropower In other words, hydropower development began in regional cities close to hydropower zones

6.10.1.2 The Start of Long-Distance Transmission of Electric Power and Large Hydropower Dams

After the Russo-Japan war, the Japanese economy underwent rapid growth Because electric power demand was also expanded rapidly by the Russo-Japan war, the electric power industry acquired an important position in Japanese industry This growth of electric power demand grew in two areas: spreading electric lighting in homes and the electrification of power provision in factories

The earliest hydropower plants in Japan were extremely close to their demand regions, and their generator output and transmission voltage were both low However, in 1899, the transmission of 11 kV for 26 km and the transmission of 11 kV for

22 km were achieved in the Chugoku and Tohoku Regions, respectively, permitting longer distances between hydropower plants and consumption regions, thereby contributing greatly to electric power production projects in Japan Later, electric power companies worked to increase transmission voltages, lengthen transmission distances, and to develop high-capacity hydropower plants

Table 1 Oldest hydropower plants in each region

Maximum Maximum Beginning

Table 2 Large-scale hydropower plants constructed by the beginning of the twentieth century

Name of power

plant

Name of river system

Dam or water resource

Beginning of operation

Maximum output (kW)

Voltage (V)

Distance (km) Komabashi

Yaotsu

Yatsuzawa

Shimotaki

Sagami Kiso Sagami Tone

Lake Yamanaka Lake Maruyama Sosui Oono Desanding Basin Kurobe Dam

1907.12 1911.12 1912.7 1912.12

No 1

intake weir

Source: Electric Power Civil Engineering Association

During this period, intake facilities used to generate electric power also changed as low fixed water intake weirs that could take in the flow rate in the dry season were replaced by dams with gates, and these were expanded to include dams with regulating ponds Large-scale hydropower plants developed in this way are shown in Table 2

Of these, the Shimotaki Power Station in the northern Kanto Region supplied power to Tokyo at that time, providing almost the entire demand (∼40 million to 80 million kWh yr− 1) to run trams in Tokyo

In addition, the Yatsuzawa Power Station (Tokyo Electric Power Company, Inc (TEPCO), 1912) in western Kanto was not only a high-capacity dam but also a conduit type with a large regulating pond (effective capacity: 467 000 m3) It was an epoch-making type of dam at that time

The development of large-scale hydropower plants had a number of important impacts on the management of the electric power industry First, it allowed a drop in the price of electricity, because hydropower could be produced more cheaply than thermal power Second, it permitted companies to meet the daytime demand for power for industry, in addition to the nighttime demand for lighting power

Because most hydropower plants were the conduit type at that time, it was impossible to control daytime and nighttime flow rates This means that when an appropriate customer could not be found, it was impossible to produce power using the daytime flow rate when demand for electric power was lower than at night, and this encouraged a rise in electric power production costs Electric power companies attempted to obtain daytime demand by lowering their daytime electricity charges, contributing to the profitability of industries that used this cheap electric power (Figure 1)

During this phase, the structure of electric power production facilities underwent a sharp change, from thermal-first/ hydro-second to hydro-first/thermal-second Hydro surpassed thermal power in 1911, ushering in the age of hydro-first/ thermal-second in the Japanese electric power industry: for about a half century from 1911 to 1960

6.10.1.3 The Development of Dams and Conduit-Type High-Capacity Hydropower Production

During the Taisho Period (1912–26), the Japanese economy was affected by worldwide economic growth, resulting in lively growth of about 5% per annum of Japan’s manufacturing industries, until the start of the Second World War The growth of the electrochemical industries and the machinery and iron and steel sectors after the First World War was remarkable To support production, these industries required an abundant and low-priced supply of electricity The electric power supply grew explosively at a rate in excess of 20% per annum, and the first shortage of electric power since the establishment of the industry occurred during a drought in 1918 Other reasons for the rapid development of hydropower were the successful introduction of long-distance power transmission, permitting the development of large hydropower production in mountainous regions, and the flourishing of industries that used

Demand for industry

Demand for household

Figure 2 Changes of electric power production at the early stage Source: Electric Power Civil Engineering Association

low-priced electric power available at times when electric power demand was low Operating thermal power stations in parallel to supplement hydropower production during dry seasons ensured stable electric power and encouraged the expansion of the electric power industry This gave the industry the idea of effectively using a quantity of water in excess of the flow rate in the dry season by creating complementary hydropower–thermal power systems, and increased the maximum intake to approximately the average water flow rate

Under these circumstances, companies that planned and conducted large-scale hydropower development were established, one after another They developed the rich hydropower of mountainous areas and constructed high-voltage transmission lines to supply electric power to cities One example was the successful transmission of 154 kV for 238 km, from the Suhara Power Station (Kansai Electric Power Co., Inc (KEPCO), 1922) in Chubu to the Osaka Substation in Osaka (now the Furukawabashi Substation), in 1923 The achievement and spread of long-distance electric power transmission, by increasing voltage, spurred hydropower development

in mountainous regions, with particularly remarkable development of high-capacity hydropower beginning in the late Taisho Period (1912–26)

An example is the Oi Electric Power Station that includes the Oi Dam (PG, 53.4 m) in Chubu Region The Oi Electric Power Station, a dam–conduit-type power station developed on the Kiso River, was completed in 1924 It was originally planned as a conduit type, but it was converted to a dam type that can respond to peak demand, making it the first power station to include a large-scale dam constructed in Japan The maximum output of this power station was equivalent to half of the entire electric power demand in Aichi Prefecture at that time

The Shizugawa Power Station (KEPCO), which includes the Shizugawa Dam in Kyoto Prefecture, developed in 1924, provided more than 10% of all electric power used in Osaka Prefecture at that time When it was developed, the Osaka–Kyoto–Kobe Metropolitan Region was particularly short of electric power, so its development made a big contribution to the supply of electric power in the region

Taisho Period

6.10.1.4 The Increased Use of River Water as an Energy Source

During the early Showa Period (1926–45), large-capacity hydropower development continued in response to the results of economic evaluations of two approaches that began to spread in the late Taisho Period, making the maximum intake quantity approximately the average water flow rate and using thermal electric power as supplementary power during dry seasons At the same time as national government control of industry strengthened, mining and manufacturing industry production soared, and metal,

Table 3 Hydropower plants representing each region after the First World War

Maximum output (kW)

Beginning of operation HEPCO

Nokanan Kamiasou Hosobidaani Shizugawa

Oi Taishakugawa

30 22.4 35.2 53.4 62.1

chemical, and machinery industries grew at a particularly rapid rate Electric power companies responded to trends in the manufacturing industry by devising and implementing the concept of successively developing hydropower plants mainly from the downstream reaches of large-scale rivers

Of these, the development of hydropower on the Kurobe River in Hokuriku Region began with the completion of the Yanagawara Power Station (1927), and moving upstream, was followed by the Kurobegawa No 2 Power Station (1936) supplied

by the Koyadaira Dam (PG, 54.5 m), then the Kurobegawa No 3 Power Station (1940) supplied by the Sennindani Dam (PG, 43.5 m)

When the national government took control of electric power, continued surveys moved upstream, but because it was followed shortly by the Second World War, hydropower development ended with the construction of the Kuronagi No 2 Power Station (1947) on a tributary The later successive development of the Kurobe River is described later

As successive developments were carried out along the river, dams used exclusively to produce hydropower were constructed separately at locations in the river basin where topographical conditions suited hydropower development, advancing the use of river water as an energy source

In the 1920s, on the Oi River System in Chubu Region, the water intake dam, the Tashiro Dam (PG, 17.3 m), was constructed as the furthest upstream dam located 160 km from the river mouth, and hydropower plants (Tashiro River No 1 and No 2 Power Stations) were developed, carrying the water into the Hayakawa River on the Fuji River System This hydropower was transmitted to the Metropolitan Tokyo area The power produced by these power stations was equivalent to about three times the demand by Tokyo at that time

In the middle reaches of the Oi River and on the Tenryu River, dam-type hydropower plants were constructed, forming the core electric power development of each river system at that time The maximum output of the Oigawa Power Station was so massive that

it equaled approximately half of the contract kilowatts for all electric power in Shizuoka Prefecture at that time The Yasuoka Dam (PG, 50.0 m), the first dam constructed on the Tenryu River to produce electric power, was also completed during that period

during that period

6.10.1.5 Electric Power Shortages and the Postwar Reorganization of Electric Power

The end of the Second World War was followed by a temporary surplus of electric power, because electric power consumption was halved from its former level by stagnation of manufacturing activities caused by the wartime destruction of manufacturing plants As

a consequence of the spread of electric heaters to heat people’s homes in response to shortages and soaring prices of coal, petroleum, and gas, and of the spreading use of electric power that could be obtained easily and cheaply as a power source to restore manufacturing, electric power demand soared Annual energy supply that was down to 19.5 billion kWh in 1945 had leaped to 29.4 billion kWh in 1947

However, new electric power sources were not developed, as little work was done to restore electric power systems damaged by the war and to continue projects initiated before the war Later, at the end of 1949, approval was given for hydropower development

at 33 locations, with an intended production of 1180 MW, as hydropower development funded by the US Economic Rehabilitation Fund

The system of state control of the electric industry that had been implemented through Japan Power Generation and Transmission Co Inc., during the war, ended with the 1951 breakup of the electric power industry into the current nine regional companies as an occupation policy of moving away from Japan’s overcentralized economy That year, the Korean War that boosted electric power demand was accompanied by an extremely severe drought in the autumn, resulting in an unprecedented electric power crisis At that time, frequent power failures made candles a standard form of emergency lighting

in homes

Such circumstances triggered demand for the immediate start of work to develop a large-scale hydroelectric source In 1952, the Electric Power Development Promotion Act was enacted Under this law, the Electric Power Development Co., Ltd (J-POWER) was

Table 4 Hydropower plants representing each region before the Second World War

Sumatagawa 34.8 Source: Electric Power Civil Engineering Association

founded with government funding, to establish a power source development system with the primary task of directly investing government funds in regions where development was difficult This law also stipulated that the Electric Power Development Coordination Council would prepare long-term basic plans for electric power and annual implementation plans, including all electric power development projects conducted by electric power companies and public bodies In these ways, the postwar electric power development system was established

6.10.1.6 Development of Large-Scale Dam-Type Hydropower Plants

When the growth of hydropower production in Japan began, it was centered on run-of-river-type hydropower plants that required relatively little initial funding, and until the 1950s, the decline in hydropower production during the drought season was supplemented by thermal power production In the late 1950s, of the hydropower plants at approximately 1460 locations, only about 40 were equipped with reservoirs that could regulate their flow

Thermal power stations operating after the war were powered by coal, but their electric power production efficiency and profitability both fell remarkably because of delayed supplies of coal, a decline in its quality, and a rise in its price As a result, the construction of dam-type hydropower plants was reemphasized as a way of increasing water usage and overcome the seasonal imbalance

More advanced thermal power stations were being constructed to provide electricity to meet rising demand in response to the postwar rehabilitation of industry, and with these stations providing base load, large dam-type hydropower plants that were intended to meet the peak demand for electric power, increased in importance, spurring their construction Table 5 shows the major hydropower dams that were completed during this period

An example is the Sakuma Power Station that became the key to promoting electric power development

The Tenryu River carries a large volume of water as a result of the heavy snow and rain that fall in its mountainous middle reaches

as it flows through the Chubu Region As a result, the region had sought development for many years dating back to the Taisho Period Following a severe drought in 1951, electric power had to be developed very quickly, so J-POWER, which was founded in

1952, decided to develop electric power at Sakuma

The Sakuma Power Station was designed to handle peak loads and J-POWER also developed electric power resources at the reregulating reservoir, further downstream at Akiha

The Sakuma Dam is a concrete gravity dam with a height of 155.5 m and reservoir capacity of about 330 million m3 The maximum output of the Sakuma Power Station is 350 000 kW, equivalent to 2.3% of the total electric power output in Japan

at that time Its annual electric power production of about 1.5 billion kWh has been the largest in Japan from the time

it was completed until now, and a pioneer in large-capacity reservoir-type hydropower plants The power it produces has been shared by Chubu Electric Power Co (CEPCO) and TEPCO, thus making a major contribution to stabilizing supply and demand in the Tokyo–Yokohama area and Nagoya area and to the economical operation of advanced thermal power plants

6.10.1.7 Hydropower Dams from the Rapid Economic Growth Period to the Stable Growth Period

6.10.1.7.1 Electric power demand and the roles of hydropower dams during the rapid economic growth period

The development and spread of household electrical appliances was a particularly remarkable aspect of the process of postwar economic growth in Japan, as washing machines, television sets, and refrigerators spread rapidly in homes during the late 1950s This was followed by a revolution in consumption of the so-called three Cs: cars, coolers (home air conditioners), and color televisions

Economic growth was accompanied by a rapid growth in energy demand Beginning about 1948, a series of large-scale oil fields were discovered in the Middle East and technological progress encouraged a switch from coal to petroleum in the industrial world Demand for electric power also increased so that, as shown in Figure 3, from the 1950s to 1965 the quantity of electric power consumed soared almost as rapidly as the annual 10% increase in the mining and manufacturing industry’s production index During this period, electric power companies were compelled to ensure energy supplies by means of large-scale electric power

Table 5 Large-scale hydropower dams in the 1950s

EPCO

Source: Electric Power Civil Engineering Association

6.10.1.7.2 The redevelopment of hydropower by consistent hydropower development in a river system

On major river systems in Japan, hydropower development was started in the 1920s by constructing dams in the central and downstream reaches of rivers, where it was easy to construct electric power stations Thereafter, large-scale hydropower development shifted upstream From about 1960, the construction of hydropower plants resumed from the upstream reaches to the central and downstream reaches of each river system, and electric power plants were developed or redeveloped in the central and downstream reaches of rivers to efficiently utilize the head drop and water quantity Good examples are the Kiso River, Hida River, Oi River, Agano River, Sho River, and Kurobe River

Below, the Kurobe River, which is the location of the Kurobe Dam (VA, 186.0 m), the highest dam in Japan, is introduced as an example of Consistent Hydropower Development in a River System

As mentioned above, until the 1940s, electric power stations were constructed on the Kurobe River in a series of steps, thus taking advantage of the head drop of river water from the old Yanagawara Power Station to the Kurobegawa No 3 Electric Power Station (Table 7 and Figure 5)

After the Second World War, an age when electric power production had shifted to advanced thermal power while hydropower played a role as a large reservoir-type peak load supply, the KEPCO responded by preparing a plan to construct a dam to form a large reservoir at the furthest upstream part of the Kurobe River, which was to play a pivotal role in the Consistent Hydropower Development in a River System The Kurobe Dam, which attracted attention as one of the century’s giant projects, was completed

in 1963 and was the product of the finest civil engineering technology in Japan at that time The Kurobegawa No 4 Hydropower Station that takes water from the reservoir at the Kurobe Dam began operating in 1961, prior to the completion of the Kurobe Dam The completion of the Kurobe Dam with its total reservoir capacity of approximately 200 million m3 improved the downstream flow regime remarkably To use its capacity effectively, the new power stations located downstream were constructed in succession, completing the entire Consistent Hydropower Development on the River (Figure 5) In this way, the Kurobe River became a

Figure 4 Change in hydropower generation capacity and its share in the whole generation capacity Source: Electric Power Civil Engineering Association

N

34 66

60

20 20 6

Totalhydropowergenerationcapacity

Total Hydropowergenerationcapacity includingpomped-storage

Table 6 Hydropower dams completed around 1960

Output power Name of dam Owner River system Dam height type Name of power station (MW) Start of operation

Table 7 Consistent hydropower development on the Kurobe River

Development in the lower reach

Large-scale reservoir development in the upper reach

Redevelopment in the lower reach

Kurobegawa No 4 P.S (Kurobe Dam) Shin-Kurobegawa No 2 P.S (Koyadaira Dam) Shin-Kurobegawa No 3 P.S (Sennindani Dam) Otozawa P.S (Dashidaira Dam)

Shin-Yanagawara P.S (Dashidaira Dam) Unazuki P.S (Unazuki Dam)

Source: Electric Power Civil Engineering Association

power-source river with a series of peak power stations that took full advantage of the head drop of more than 1300 m from the Kurobe Dam reservoir water level (elevation 1448 m) to the Otozawa Power Station (elevation 131.1 m)

6.10.1.7.3 Hydropower development centered on pumped-storage-type hydropower

In the late 1950s, high-capacity, advanced thermal power stations took over the base load supply of electric power, with peak adjustment handled by large-scale reservoir-type hydropower plants

During the 1960s, rapid urbanization and a rise in the people’s standard of living driven by rapid economic growth resulted in a remarkable increase in office and home electricity demand for air conditioners This trend shifted the annual maximum power demand, which had formerly been on winter evenings, to the daytime during summer The summer peak exceeded the winter peak

in 1968

This summer peak created a new demand pattern, marked by a sharpened peak during the day, a pattern that was beyond the adjustment capacity of reservoir-type power stations, thereby creating a need for pumped-storage power stations that are better suited to adjusting the gap in daytime and nighttime electric power demand

In 1960, the Resources Council of the Science and Technology Agency of the Prime Minister’s Office issued a policy statement calling for the diversification of energy supply sources In the recommendation concerning the survey of pumped-storage electric power production, it called for hydropower surveys of pumped-storage power station locations in order to establish a power source development approach that treats thermal, nuclear, and pumped-storage power stations as harmonized sources

Under these circumstances, the electric power companies also studied policies to promote hydropower development from a new perspective, thus establishing large-scale redevelopment plans for pumped-storage power stations, both standalone and as part of comprehensive development projects

A pumped-storage power station requires two reservoirs: an upper and a lower reservoir Until about 1970, many were constructed as mixed pumped-storage power stations that could also produce ordinary hydropower where the inflow of river water to the upper reservoir was sufficient However, as the number of available economical locations declined, the development of pure pumped-storage power stations at locations where either no water or extremely little water flows into the upper reservoir began

to flourish, beginning with the station at Numappara (J-POWER, 1973) in the early 1970s This was made possible by the development of new technologies: a steel penstock with a head drop in the 500 m class and high-capacity reversible pump-turbines Many efforts to reduce energy dependency on petroleum were initiated following the first and second oil shocks in 1973 and

1979, then in 1980, the Act on the Promotion of Development and Introduction of Alternative Energy was enacted, shifting priority

to the construction of nuclear power stations

Power Station and Head Drop after the completion of the Kurobe Dam

Kurobegawa No.4 Kurobe Dam

72.00 m 3 /s

Kurobe River (longitudinal profile)

Sennindani Dam

Shin−Kurobegawa No.3 46.00 m 3 /s

Kurobegawa No.3 33.60 m 3 /s

Shin−Kurobegawa No.2 Koyadaira Dam

46.00 m3/s

Kurobegawa No.2 47.20 m 3 /s

Shin−

Otozawa 74.00 m3/S 50.92 mYanagaware 3 Dashidaira Dam

Figure 5 Schematic view of hydropower generation on the Kurobe River Source: KEPCO

Because both total electric power demand and the annual maximum demand stopped rising, almost all plans for new pumped-storage power plants have either been postponed or cancelled since the 1990s

Output from pumped-storage hydropower plants at the end of 1960 was only 58 MW (0.3% of total electric power production output), but it had grown to 3390 MW (5.8% of total electric power output) by 1970 Then, its output increased by about

20 000 MW from 1970 to 2001, as its share of all power production facilities rose from about 6–11% (Figure 6)

The structure of power supply by power source is shown in Figure 7, revealing that in recent years, the base load supply has been provided by run-of-river hydropower, nuclear power, and coal-fired thermal power, load fluctuations during the daytime are handled by liquefied natural gas (LNG) and by LPG thermal power plants, and short-term peaks are supplied by dam-type hydropower and pumped-storage power

6.10.2 Current State of Hydropower in Japan

6.10.2.1 Primary Energy in Japan

Resource-poor Japan is dependent on imports for 96% of its primary energy supply; even if nuclear energy is included in domestic energy, dependency is still at 81% Thus, Japan’s energy supply structure is extremely vulnerable Following the two oil crises in the 1970s, Japan has diversified its energy sources through increased use of nuclear energy, natural gas, and coal, as well as the promotion of energy efficiency and conservation (Figure 8)

Pumped Storage Capacity

Figure 8 Share of primary energy % Source: IEA/Energy Balances of OECD Countries 2003–04 (2006 Edition)

Figure 6 Change in the capacity of pumped-storage power generation Source: METI

Time of the day

SUPPLY SOURCE Peak supply

Daily load curve

Hydropower (Reservoir type)

Pumped storageThermal power (Oil)

Middle

(LNG, PG, other gas) Thermal power (Coal) Nuclear power

Hydroelectric power is one of the few self-sufficient energy resources in resource-poor Japan Hydroelectric power is an excellent source in terms of stable supply and generation cost over the long term Hydroelectric power saw a rebirth in development following the oil crises of the 1970s Although steady development of hydroelectric power plants is desired, Japan has used nearly all available sites for the construction of large-scale hydroelectric facilities, and so recent developments have been on a smaller scale

6.10.2.2 Development of Hydroelectric Power in Japan

generation, two-thirds of the total was already developed

6.10.2.3 Hydroelectric Power Development

hydro-first/thermal-second electric power structure continued in early 1960s and was followed by advanced thermal and nuclear power, but even after 1960, reservoir- and regulating pond-type hydropower plants continued to be developed as valuable peak supply power (Figures 11 and 12)

Table 8 Potential hydroelectric power

Maximum output Annual power generation

Figure 9 History of electric power development

Total installed capacity

Figure 10 History of electric power generation

Figure 12 Hydroelectric generation Source: Hand Book of Electric Power Industry, 2009, Japan Electric Association

Most of large-scale conventional hydropower stations shown in Table 9, with maximum capacity excess 100 MW, were developed from 1950 to 1980 These hydropower stations have scale merit; therefore, they were given priority to smaller ones

6.10.2.4 Development of Pumped-Storage Power Plant

As the gap in demand between daytime and nighttime continues to grow, electric power companies are also developing pumped-storage power generation plants to meet peak demand The share of pumped-storage generation facilities of the total hydroelectric power capacity in Japan is growing year by year

Table 9 Large-scale conventional hydroelectric power stations (>100 MW)

Name

Total maximum (MW)

output

Year of operation

Maximum (MW) output

Okutadami Tagokura Sakuma Kurobegawadaiyon Ariminedaiichi Tedorigawadaiichi Miboro Otori Hitotuse Shinanogawa Shimokotori Kinugawa Nakatugawadaiichi Maruyama Otozawa Wadagawadaini Ariminedaini Yomikaki Kiso Akimoto Shinkurobegawadaisan Hiraoka

Electricity is normally supplied at a constant frequency However, this frequency is not constant since it declines when supply capacity falls short of demand and increases in excess of demand The adjustment of generation output in response to demand fluctuations is thus an important way of ensuring the supply of high-quality power of a stable frequency

Pumped-storage power plants reach maximum output within 3–5 min of start-up and their output can be adjusted in a matter of seconds (Figures 13 and 14 and Table 10)

Though both the share of installed capacity of hydroelectric power in total installed electric power and the share of electric generation are only 17% and 7%, respectively, hydroelectric power is one of the few self-sufficient energy resources in resource-poor Japan So, even smaller hydroelectric power plant, its steady development is required in Japan (Figure 15)

The CO2 emissions from hydropower are emitted only for constructing and repairing the facilities Hydropower stations do not emit CO2 during operation

Approximately 70 million tons of CO2 was reduced by the use of hydropower in fiscal 2006 Without power supply from hydropower stations, the CO2 emissions in Japan would have been increased by about 6% compared to the level in fiscal 1990 Today, hydropower is viewed as a clean and renewable energy that emits zero CO2 and is effective for preventing global warming The benefits of hydropower production, which is one type of recyclable energy, are that it is purely domestic, recyclable resource that can be recovered, produces low emissions of CO2, has a long service life, contributes to regional development, and its technologies are established

Figure 14 The share of installed capacity of hydroelectric power Source: Hand Book of Electric Power Industry, 2009, Japan Electric Association

Table 10 Pumped-storage power stations (>500 MW)

Plant name

Maximum (MW) Okutataragi

Okumino Sintakasegawa Ookochi Okuyoshino Tamahara Matanogawa Sintoyone Imaichi Okukiyotu Shimogo Shiobara Kazunogawa Okuyahagi–Daini Numappara Azumi Nabara Honkawa Tenzan Okukiyotu-Daini Omarugawa Oobera

Fuel and combustion Equipment and operation

Figure 15 The CO emissions

Medium and small hydropower development will make a great contribution to ensuring valuable domestically produced energy, and will go beyond merely producing power to create regional industries centered on hydropower generation, and so on, by providing other functions that contribute to autonomous development of the region

6.10.3 Hydropower in Japan and Future Challenges

6.10.3.1 Energy Situation in Japan and Hydropower

Just before the first oil shock, oil provided the highest percentage of Japan’s primary energy, accounting for 77% of all energy Later, the oil shocks led to the introduction of nuclear power, LNG, coal, and so on, so that by 1998, Japan’s dependency on oil was down

to about 52%

The percentage of primary energy provided as electric power was 41% in 2000, while other forms were sent directly to consumers

as fuel With the exception of the small supplies provided by new energy sources (about 1%), energy, other than electricity, is produced almost entirely from fossil fuels To prepare for the depletion of fossil fuels and to stop global warming, hydrogen and other secondary energy media should be developed If hydrogen energy becomes a replacement fuel for oil energy in the near future, electric energy will be needed to produce hydrogen, and in order for this to be as independent of fossil fuels as possible, nuclear power, new energies, and hydropower must be developed

Next, an examination of the breakdown of electric power sources shows that it used to be mainly hydropower, but from about 1962, hydropower was surpassed by thermal power Fuels used to produce thermal power are oil, coal, LNG, and so on At peak production times, more than 60% of all electric power was produced from oil The oil shocks were followed by the development of electric power sources such as nuclear power, coal, LNG, and so on, as substitutes for the oil that is high-priced and its supply is unstable

As shown in Table 11, nuclear power now accounts for 31% of annual electric power production Incidentally, hydropower accounts for 9% of annual electric power production (Table 11)

The share of oil used for electric power production is low at 9% Its electric power production cost is high and it generates a lot of

CO2 Therefore, the use of oil will continue to decline in the future

Nuclear power, which is the largest source, generates almost no CO2 and its production cost is the lowest, but recent accidents at nuclear power plants have made it difficult to boost nuclear power, and ensuring safety and back-end measures are other challenges The second-largest source, LNG, provides relatively low-cost power and is considered the cleanest among fossil fuel sources, but

it produces a lot of CO2: between 500 and 600 g kWh− 1

Coal, which is the third largest source of electric power, ensures superior fuel supply stability and cost, but it produces

975 g kWh− 1 of CO2, the largest of any energy source

The fourth source is hydropower, which produces extremely small quantities of CO2, even less than new energy sources, is clean, and as energy produced entirely in Japan, offers a very stable supply Although hydropower’s initial investment costs are relatively high, its long-term cost is low To develop future hydropower plants, it is necessary to reduce costs and protect the environment In addition, it is important that efficient maintenance be performed continuously to extend the equipment’s lifetime in existing hydropower systems, which offer long-term cost superiority

New energies still provide less than 1% of electric power generation, but under the Renewable Portfolio Standard Act, electric power companies are now legally required to provide a certain percentage of their power by wind power, waste material power, or other reusable energies, and this is expected to promote the development and spread of these technologies Nevertheless, to develop these in the future, their costs must be reduced and they must supply electricity more stably

6.10.3.2 Hydropower in Japan and Future Challenges

The following will be important as policies to restrict emissions of CO2, thereby lowering dependency on fossil fuels while responding to the anticipated increase in energy consumption:

Table 11 Comparison of electric power sources

Ratio of generated energy Generation cost Unit CO2 discharge Electric power sources (as of end of FY 2002) (Yen kWh− 1) (g-CO2 kWh− 1)

1 Restricting energy consumption and saving energy

2 Developing and adopting recyclable energy (hydropower, wind power, geothermal, photovoltaic, hydrogen, wave power, seawater temperature difference power, biofuel, etc.)

The benefits of hydropower production, which is one type of recyclable energy, are that it is a purely domestic recyclable resource that can be recovered, produces low emissions of CO2, has a long service life, contributes to regional development, and its technologies are established Its negative impacts are that it is expensive and that it may affect the natural environment

Japan produces 1076 � 106

MWh of electric power, of which 94 � 106

MWh is hydropower Including existing hydropower, Japan’s potential hydroelectricity equals 135 � 106 MWh

It is presumed that hydropower will be implemented as described below

At this time, construction at almost all locations suitable for large-scale development has been completed, and in this century, it will be necessary to maintain, manage, and prolong the life of dams and hydropower plants that have already been constructed

Future development will presumably be done by introducing power production technologies that are kind to the environment and suited to locations with short falls and low flow rates, thereby developing hydropower plants that take advantage of unused small falls, including that at dams other than hydropower dams, while reducing production costs Hydropower is a clean 100% domestically produced recyclable energy, and will naturally be passed on to future generations

as a valuable asset

Medium and small hydropower development will make a great contribution to ensuring valuable, domestically produced energy, and will go beyond merely producing power to create regional industries centered on hydropower generation, and so on, by providing other functions that contribute to autonomous development of the region A trend toward using small falls effectively, mainly on agricultural channels and rivers at a scale ranging from a few tens of kilowatts to a few hundred kilowatts, has emerged Hydropower generation during this century will probably meet the demands of the times from various perspectives, including resolving global environmental problems

6.10.4 Successful Efforts in Japan

6.10.4.1 Large-Scale Pumped-Storage Power Plants in Tokyo Electric Power Company

Pumped-storage-type power plants have been developed in Japan since 1930 Tokyo Electric Power Co., Inc (TEPCO) has nine pumped-storage power plants with approximately 10 000 MW in total, including two under construction They have contributed to stable operation of a huge power network in Kanto district including Tokyo metropolitan area, functioning as peak load power sources, storage of electric power, spinning reserve, voltage support ability to control reactive power, and black start capability for power network recovery

6.10.4.1.1 Outline of the project

Pumped-storage power generation uses two adjustment reservoirs that are located at different elevations and are connected together

by conduits together with reversible pump-turbines, to utilize surplus electricity generated during the low-demand small hours and weekends to pump water from the lower adjustment reservoir up to the upper adjustment reservoir so that the water can be used to generate electricity during the daytime peak demand hours and/or in the event of an emergency Tokyo Electric Power Company (TEPCO) currently owns a total of nine pumped-storage power plants (including two under construction), which are being operated by TEPCO to meet the daytime peak electricity demand Table 12 and Figure 16 show a list of TEPCO’s pumped-storage power plants and their locations, respectively (Table 13)

Table 12 TEPCO’s pumped-storage power plants

Kazunogawa 1600 1999 Partially commissioned Pure

Figure 16 Locations of TEPCO’s pumped-storage power plants

Table 13 Main facilities of Tokyo Electric Power Company’s pumped-storage power plants

Upper dam and adjustment reservoir Lower dam and adjustment reservoir

Total

6.10.4.1.2 Features of the project area

TEPCO is supplying electricity to approximately 42.8 million people in its service area that covers most of the Kanto Region including the Tokyo metropolitan area The total area of the service area is approximately 39 500 km2 The total amount of electricity sales and the peak demand in fiscal year 2009 were about 280 billion kWh and 60 million kW, respectively To ensure that TEPCO will be able to supply electricity in a stable, uninterrupted manner for the years to come, it is striving to achieve, taking into consideration the anticipated global energy demand trends, the most efficient mix of energy resources which best accommodates the hourly, daily, and seasonal fluctuations of electricity demand and is best from the standpoints of economics, environmental protection, and securing stable sources of fuel procurement The pattern of daily electricity usage in the summertime in TEPCO’s service area is as follows (Figure 17): The demand starts increasing sharply at around 6.00 a.m and continues to increase up until the lunch hour when it dips slightly It starts increasing again at 1.00 p.m and continues to increase up until around 2.00 p.m when

Power source requirements

Suitable power sources Operational requirements

Peak

Middle

Base

Sharp fluctuations

The duration of power

generation operation is short

Large daily fluctuations

The duration of power

generation operation is

relatively long

Negligible fluctuations

Power is generated all day

Load adjustment capability Hot reserve and frequent start/

stop capability

Capable of being activated and deactivated at a relatively high frequency during the day or of otherwise being adjusted so that similar effects can be achieved

Capable of continuous 24 h operation

Low fixed costs

Relatively high variable costs can

be tolerated as long

as this requirement

is satisfiedaBoth variable and fixed costs are relatively low

Low variable costs

Relatively high fixed costs can be tolerated as long as this requirement is satisfied

Pumped-storage- and pondage-type hydropower, gas turbine

Oil and LNG-fired thermal power

Coal-fired thermal power

Run-of-river-type hydropower Nuclear power

a ‘Variable costs’ mainly refers to fuel costs and ‘fixed costs’ mainly refers to depreciations and interests on the construction cost

it peaks It then decreases gradually up until around 6.00 p.m when it starts to decrease sharply The demand continues to decrease until it reaches the bottom at around 4.00 a.m when it starts increasing again To accommodate this variation in an economical and efficient manner, it is necessary to develop dedicated power sources for each of the peak, middle, and base demand portions explained in Table 14 and use them in combination

6.10.4.1.2(ii) History of pumped-storage power plant development in TEPCO

After the Second World War, Japan’s electricity demand increased sharply as the Japanese economy developed rapidly into an autonomous economy, but thermal power plants were used as the primary means to accommodate the sharp increases in electricity demand, with pondage- and reservoir-type hydroelectric power plants (which have high adjustment capabilities) developed as peak load power sources At the time, thermal power plants were improving their thermal efficiencies thanks to the development of high-temperature, high-pressure equipments, which were considered to be optimal power sources to meet the electricity demand which was increasing at a rate of more than 10% per year, because of their large capacities and short construction periods As a result

of the accelerated development of thermal power plants, the share of thermal power relative to the total amount of electricity generated surpassed the share of hydropower by the early 1960s, signaling the advent of the so-called ‘era of thermal electricity’ Hydroelectric power plants continued to be developed and used as important peak load power sources, but as the number of sites suitable for hydroelectric power plant development decreased as a result of progressive exploitation of economical sites, mixed pumped-storage hydroelectric power stations started to be developed Mixed pumped-storage hydroelectric power plants are pondage-type hydroelectric power plants added with pumped-storage power generation systems to enable them to make large-scale daily adjustments to meet peak demand Examples include the Yagisawa Power Plant (Tone River, 240 MW, operational since 1967)

Costs increase when operating Costs increase due to higher vari­

hours are short due to the use of able costs resulting from extended storage generation, to meet power operation of pumped storage

need for larger regulating reservoirs Costs increase, since excess capa­

to accommodate longer city during nighttime and weekend

Percentage of pumped storage facilities

in Gunma Prefecture, the Azumi Power Plant (Shinano River, 623 MW, operational since 1970) in Nagano Prefecture, and the Shin-Takasegawa Power Plant (Shinano River, 1280 MW, operational since 1969) in Nagano Prefecture From around the second half of the 1970s, the need for mixed pumped-storage hydroelectric power plants started to increase as the summertime peak electricity demand increased sharply due to sharp increases in the cooling- and air-conditioning-related consumption of electricity However, because the number of suitable sites for mixed pumped-storage power plant development had decreased as a result of progressive exploitation of sites where natural river flows can be utilized effectively, pure pumped-storage hydroelectric power plants started to be developed Because pure pumped-storage hydroelectric power plants essentially have no river water inflow into their upper adjustment reservoirs and generate power using water pumped up from their lower adjustment reservoirs only, they can

be sited without the need to consider river system conditions as long as the heads are sufficiently large The scales of pumped-storage power plant development projects and the proportion of the pumped-storage capacity as a percentage of the total capacity of the entire power network are determined based on the results of a power network system analysis that aims to minimize the power generation cost of the entire power network taking into consideration the above-mentioned pattern of daily electricity usage in TEPCO’s service area The current optimal proportion of the pumped-storage capacity as a percentage of the total capacity of the entire power network in TEPCO’s service area is estimated to be about 10–15% (Figure 18) In line with the increases in electricity demand in recent years, the Tamahara Power Plant in Gunma Prefecture (1200 MW, head = 518 m, operational since 1982), the Imaichi Power Station in Tochigi Prefecture (1050 MW, head = 524 m), the Shiobara Power Station in Tochigi Prefecture (900 MW, head = 338 m), the Kazunogawa Power Station in Yamanashi Prefecture (1600 MW, head = 714 m), and the Kannagawa Power Station in Gunma Prefecture (2820 MW, head = 653 m, currently under construction) were planned and constructed sequentially to maintain the proportion at the optimal level

6.10.4.1.3 Benefits

6.10.4.1.3(i) Functions of pumped-storage power plants

Pumped-storage power plants play a wide range of roles in power network system, including such functions as peak supply source, storage of electricity, hot reserve capacity, phase modification function, and power source for black start for power network system recovery

6.10.4.1.3(i)(a) Peak load power source For the peak portion of the demand, it is desirable to use a power source whose fixed costs are low even if it means relatively high variable costs, because the duration of power generation operation is short Pumped-storage power plants are lowest-cost power plants in terms of fixed costs because they can be constructed at a low unit construction cost per kilowatt and comprise long-life structures such as dams and conduits In terms of fuel costs, which make up the bulk of the total variable costs of a power plant, approximately 30% of the fuel consumed to run a pumped-storage power plant

is wasted in the form of losses due to the upward and downward transport of water in the waterway and losses of reversible pump-turbines and generator-motors, but the pumped-storage power plant can be run at a lower total fuel cost by using low-cost electricity generated by nuclear power as a power for pumping water than that for a coal-fired thermal power plant Figure 19 shows the relationship between the annual operating hours and energy costs (i.e., fixed costs plus variable costs) by power plant type As is

Figure 18 Optimal proportion of the pumped-storage capacity as a percentage of the total capacity of the entire power network

Pumped storage Thermal

Figure 19 Relationship between the annual operating hours and annual costs

clear from the figure, the economical approach is to use nuclear power and thermal power for the base and middle demand portions, respectively, because the annual operating hours for these portions are long For the peak demand portion, however, pumped-storage hydropower generation is the lowest cost, because the annual operating hours is short In addition, the peak portion of the electricity demand is characterized by sharp load fluctuations and thus requires a power source that has an excellent load adjustment capability and is also capable of frequent start/stop These operational requirements can only be met by pumped-storage hydroelectric power plants, which can adjust their outputs quickly and can start/stop in a matter of minutes Because of these economic and operational characteristics, pumped-storage hydroelectric power plants have been developed and used as peak load power sources

6.10.4.1.3(i)(b) Storage of electricity Because electricity demand changes daily, weekly, and seasonally, it is convenient to utilize the cheaply available electricity generated by nuclear and coal-fired thermal power plants (whose variable costs are low) during the low-demand hours such as midnights and weekends to operate pumped-storage power plants, so that low-cost electricity can be stored in the form of water in upper adjustment reservoirs, and it can be used as a generator during peak load hours of weekdays to reduce the overall electricity supply cost, saving the use of power sources that are higher cost in terms of fuel costs (such

as oil-fired thermal power plants)

6.10.4.1.3(i)(c) Hot reserve capacity To ensure stable, uninterrupted supply of electricity, it is necessary to provide for unexpected demand increases and unscheduled power source outages, as well as output reductions by having sufficient reserve capacities in place In general, it is desirable to achieve this with power sources whose fixed costs are low even if it means relatively higher variable costs, because the operating hours is much less than that in the case of ordinary power generation In addition, a reserve capacity should be capable of being activated instantly in the event of a power source failure or other emergency to make up for the lost capacity to ensure that the supply of electricity is not disrupted or reduced Because these requirements, which are similar

to those for peak load power sources, are best satisfied by pumped-storage power plants, it is best to use pumped-storage power plants as hot reserve capacities

6.10.4.1.3(i)(d) Phase modification and frequency Control Functions Because of parallel capacitance increases in power networks due to the increase of long overhead and underground transmission lines, voltage rises and drops occur at receiving ends when the load is low and high, respectively These phenomena are usually controlled by means of shunt reactors and power condensers installed in substations, but electricity utilities can also use pumped-storage power plants as synchronous phase modifiers that adjust power network voltages by operating generator-motors without load and adjusting magnetic field currents

to provide or absorb reactive power In addition, the recent development of variable-speed pumps has enabled pumped-storage power plants to be used as a means of power network frequency control (AFC, automatic frequency control) during nighttime