"Work, of course," Kao Cheng-yi, director of Taiwan Power Company's "Pumped Storage Project Office" at Shuili, Nantou, says proudly.
Director Kao, his 460 Taipower colleagues, and 3,000 construction engineers and workers have worked, and lived, at Sun-Moon Lake since May, 1981, when they started work on the Minghu Pumped Storage Project. Their efforts involve the construction of a 60 meter tall concrete gravity dam, a 1,000 megawatt underground power plant, and two 2.4 kilometer long, 7 meter wide water tunnels.
And, they have a right to be proud of themselves. Twenty two months after the construction started, the project, with an estimated completion time of 60 months, is already 52 percent complete. At this point, they estimate that they will finish the whole project in 44 months, well ahead of the 48-month schedule.
Storing power in the form of water in the highlands at times when it is abundant, and releasing it into energy in the dry season, is a time-proven concept. It has been vigorously applied to this nation's energy master plans in conjunction with the nuclear power plants which have come on stream in recent years. The concept makes use of periods of surplus power to pump water to a high reservoir. The water is discharged for power generation to meet peak power loads, often on the same day.
In Taiwan, night power consumption has been only 60 percent of the daytime rate in recent years. Since power generation by large-capacity nuclear and thermal power plants cannot be greatly reduced to efficiently pace such energy-use shifts, pumped storage power plants to absorb periodic surplus and help meet peak power consumption needs are an imperative.
The Minghu Project will use Sun-Moon Lake, with its elevation of 750 meters, as a natural upper reservoir. Lakewater will flow down through two underground tunnels to a power house, generating up to 1,000 MW of power per hour, or more than three times the power generating capacity of all Taiwan in 1945. The water will be routed from the generators to the Shuili River, to be stored behind the new dam in a lower reservoir, then to be pumped back to Sun-Moon Lake at times of excess electricity generation, mostly by energy from nuclear power plants.
"Constructing a hydropower plant can be like warring against nature, which can be very ruthless," comments Director Kao, who is an ecologist by training.
Mother Nature too often shows her fierce side during hydropower plant construction. Statistics compiled by a Japanese engineering firm show an average of one accidental death for every square kilometer of construction work in such projects.
There is no room for carelessness. In the excavation of one tunnel for example, every square meter of upper tunnel surface had to be able to withstand 120 metric tons of pressure. Every worker on such a construction site must understand that any little miss on the job may lead to underground disaster.
To gauge the scale of the project, we toured the construction site, from the lowest point up.
The Shuili River flows quietly through the verdant lushness of Nantou, an inland county famous for the variety of its fruits and the beauty of its women. Two small power plants, Takuan and Chukung, built some 50 years ago, stand quietly on the river bank, marking the approach to the busy construction site for the dam, only a few hundred yards upstream.
Concrete-mixer trucks pull up to the river bank at a rate of 3 to 5 minutes per load. Each truck "barrel" holds only three cubic meters of concrete. To fill the 57.5 meter tall, 169.5 meter long dam, will eventually require 173,000 cubic meters of concrete-more than 55,000 truckloads.
"Hwaah!" With a thunderous rush, a batch of small dried concrete chunks is poured over the roadside.
"These concrete pieces are harder than ordinary paving rock. Still, not good enough for the dam," explained one red-hated young inspector. Top-grade stone for the dam is hauled in from the Chou-sui River area, about 40 kilometers away. The cement is trucked from Shinchu in northern Taiwan.
The dam's foundation was excavated downward from both river banks, 20 extra meters of it under conditions of great danger and hardship because of an unexpectedly large fault, about 9 to 14 meters deep and traversing both banks of the dam site.
Some 375,300 cubic meters of earth, rocks, trees, and whatever have been excavated from the dam area. However, one feature remain on the site: a small Earth God temple, just one meter tall, still stands safely at the top of the site, a guardian symbol of safety for all workers in the area.
Now halfway completed, the dam will later be provided with two sluiceways for the flushing of sediments and for passing flood waters. They will also permit the discharge of sufficient river runoff to serve downstream population needs.
To catch debris before it can enter the lower reservior, thus reducing its effective capacity, a debris control dam will be built two kilometers upstream.
From the left bank or the Shuli River, one can enter the water-exit ends of the tunnels. In the entrance area are signs reading "Safety First," "No Smoking," "Watch For Falling Rocks," and "NT$500 Fine for Not Wearing Safety Hats." And sure enough, the underground world is one of hat parades. By the color of the hats, one can tell who these people are: red hats are Taipower personnel, in charge of inspection and overall construction; blue hats are workers from the Retired Servicemens Engineering Agency, responsible for all underground engineering work; yellow hats are workers of China Engineering Consulting Company, responsible for the aboveground engineering work; and green hats are Japanese technicians, in charge of installing the mechanical equipment.
Wearing safety hats is only one part of a "Zero Fault" safety drive for the project. Almost halfway through the construction, the campaign has been marred by a fatal lift accident, costing the lives of two red hats.
Adjacent to the tunnel exits under the mountain mass, one enters a huge mushroom-like space, more like an indoor coliseum than the power house it is intended to be. At this stage, the 21 meter wide, 40 meter high, and 127 meter long giant cave is luminous with spotlights for the several hundred workers manning three eight-hour shifts for reinforcement work on the cave walls and ceiling; the installation of mechanical equipment has just started.
The cave, bigger than a football field, will be just big enough for four 250 MW pump-turbines and four motor-generators. One is in awe to think that by 1985, this installation will be able to generate more than three times the power generated by all 30 power plants built by the Japanese during their long occupation of the island. Taipower has grown 40 times in power generating capacity, for a total of 11,870 MW, one of the largest energy capabilities in Asia.
The underground power house and the upper reservoir are connected by the 2.4 kilometer long water-routing tunnels, 50 meters apart, and probably the most difficult part of the whole construction project.
The RESA excavation teams met with such difficulties as soft earth and fault plains. Most of the engineers still remember the bad experience with the water pockets they encountered as they excavated for the Teh-chi dam. They had to exercise extraordinary care in forging ahead. On the days of hardest going, the work could be pushed ahead by only a meter a day. Average excavation progress was 4.5 meters per day.
In order to shorten this overall construction period, three working "faces" were arranged for each tunnel. From each face, construction work could push upstream and downstream simultaneously. Because of high internal tunnel pressures reaching 12 kilograms per square meter, concrete linings of up to 65 centimeters were implanted.
In order to avoid the "water hammer" effect caused by fluctuations under the turbine load, two surge tanks have been built at the ends of pressure relief tunnels.
The 100 meter tall, 30 meter wide tanks, standing lonely in the wilds of the mountain range, are, in effect, safety relief valves.
On one side the tunnels are connected with inclined penstocks which feed water to the generators. Each will be able to pass 380 cubic meters of water per second-enough to fill any Olympic size pool in three seconds.
On the other side, the tunnels are connected to an intake structure on the west shore of Sun-Moon Lake, consisting of two separated gate shafts and equipped with two wheel gates.
Instead of opting for underwater excavating and construction, the project construction department decided to relocate the existing highway along the lake shore to the mountain side, utilizing the rim of the spur as a natural cofferdam, then removing it to divert the lake water after completion of the intake structure.
Dry land operations are more economical, and the project's office staff is very "budget conscious." "For each day of construction," said T.P. Pan, "Taipower has to payout over NT$10 million. Moreover, in order to cope with the ever-increasing peak load demand in an economical way, we cannot let this equipment sit idle."
Officials concede that it is a very expensive project. Taipower is investing US$1,000 to develop each kilowatt of power, since the total project will cost NT$31 billion (US$775 million). They also emphasize, however, that the operating cost of the finished plant will be very low, and they expect to retrieve the cost in 10 to 20 years since the plant will replace the expensive fuel burning generators otherwise used to buttress peak power consumption hours. "Just think how much the Minghu project will help to reduce power system expansion," said deputy director Pan.
From the bank of the Shuili River to the shores of Sun-Moon Lake, the construction site covers an area of 500 hectares, most of which was covered with virgin woods until the project team arrived. Along some 40 kilometers of project roads constructed for all project purposes, are the scattered dormitories of the engineers and construction workers.
A good many of the workers have been at Sun-Moon Lake for more than two years now, going home only on Sun days. Their dormitaries are equipped with such facilities as televisions, reading rooms, tennis courts, and recreational sports equipment. Still, many feel there is not a whole lot to do on off hours, except possibly to work more.
Pan Ping-sheng, who has drifted from one hydropower construction site to another since he joined Taipower in the 50's, said he has not spent one third of the period with his family.
The lack of family life, however, in Pan's, and in many others' cases is compensated by a sense of achievement. The two stages in the Sun-Moon Lake pumped storage project, when completed, will be able to generate 2,600 MW of power, excelling the 2,300 MW of the pumped storage project in Bath County, Virginia, up to now, the largest in the world.
The peace and quiet of beautiful Sun-Moon Lake is now disrupted only at its west corner, where the bulldozers roam the shore, tug boats shuttle back and forth, and concrete mixers circle the pouring sites. In two years, the grounds will be restored to the way they used to be. Most of the new structures we see today at the lakeshore will be submerged in the lakewater, and the staff and workers will have moved on to new construction sites.
People in the future will probably not notice, when they receive their monthly electricity bills, that the charge is the lowest among all Asian countries. However, the Minghu Pumped Storage Project will remain a monument to the Republic of China's power planners and construction teams.