Small Hydropower Plant in Noryangjin Reservoir

 
Hydroelectric power is a type of renewable energy that uses the head (the difference between upstream and downstream water levels) and flow of moving water to produce energy; a small hydropower plant (SHP) in particular is the result of the development of hydroelectric power on a scale serving a small community or with a capacity of up to 10,000kW in general. SHP eliminates pollutants and allows for a constant supply of electricity. They have not been widely adopted in Korea due to difficulties involving the high initial investment cost and plant site selection.

Our Arisu small hydropower plant takes advantage of the kinetic energy of non-pressurized water or head (difference between upstream and downstream water levels) of 24 meters, which is produced in the Amsa purification center and Noryangjin reservoir. This is the first time a waterwheel has been installed in the drinking water supply network to produce hydropower.

Currently, the 103MWh per month generated through this system is being purchased by KEPCO (Korea Electric Power Corporation) for KRW 1.6 million every month. In line with Seoul’s “One Less Nuclear Power Plant” project, the Arisu SHP is expected to play a pivotal role in solving the electricity shortage in the country and reducing CO₂ emissions; thus contributing to the country‘s wider environment preservation initiative.

Installing small hydropower plants: generation capacity of 300 kW (100 kWx3 ea.)

<< Using water flowing from the Amsa purification center to the Noryangjin reservoir, we built the country‘s first small hydropower plant where waterwheel is installed in the drinking water supply network.
<< The Seoul Metropolitan Government sells the electricity from the SHP‘s monthly generation capacity of 103 MWh, earning revenue of KRW 1.6 million every month.
 

Electricity production capacity was not able to meet the rapid increase in electricity demand.

Seoul is moving forward in line with the government‘s renewable energy policies.

Environmental preservation has become a social issue.

Recognizing the economic and social benefits of SHP, many advanced countries around the world have already acquired hydrologic statistics and technology in this field. These countries regard SHP not only as a source of energy, but also as an important energy industry. They have already established an assessment method as to the feasibility of SHP as well as optimal design for plants, streamlined and standardized waterwheels system, and automatic control system, all of which have contributed to the wider adoption of SHP globally.
 • China: 38,500MW, Japan: 1,700MW, Germany: 1,600MW, France: 1,956MW, Italy: 2,233MW
 
Other countries have developed low-head waterwheels since low-head units are much smaller in capacity than the conventional large hydro turbines but just as economically viable.
 • Higher capacity means more economical options. Korea’s capacity is around 1,400kW while other countries are around 1,000kW.
 
Policies and Institutions of Other Countries
Governments around the world have adopted various systems relative to their own situations in terms of demand, supply, generation capacity, and production levels.
 

Domestic Trend
In Korea, as of the end of 2010, SHP generation capacity was 95,220kW at 68 plants, and annual SHP generation at 3.39 million kWh.
 

SHP plants constructed before 2000 were mostly run by IPPs, but the trend reversed after 2001 when the government began various projects including Feed-in-Tariff. Since then, most of the SHP plants have been controlled by municipalities or other public corporations.
Currently, SHP is not utilized to the full extent compared to its high potential. In fact, SHP can be adopted in agricultural reservoirs and sewage treatment plants; hence the huge room for adoption. With RPS now adopted in Korea, SHP is becoming an even more economical option in which many are interested in investing.

Process of Policy Implementation
 • 2012.02.25: Report on measures to implement the lessons learned from the Mayor‘s visit to Japan (pilot project for 1 SHP, 1 PV)
 • 2012.03.13: Report on how to adopt SHP
 • 2012.10.10: Secured budget for investment in SHP (1.231 billion won appropriated by the Korean Ministry of Knowledge Economy)
 • 2013.04.04: Working design
 • 2013.07.02: Service performance
 • 2013.10.16: Permit as utility enterprise (generation 300kW)
 • 2013.08~2014.01: SHP plant construction
 • 2014.01.29: Construction completed

Arisu SHP plant

 • Project Overview
   - Location: Noryangjin Reservoir in Seoul
   - Transmission Pipe: 23.2 km (diameter: 2,200 mm) of water pipes from the Amsa purification plant to the Noryangjin reservoir
   - Water Level: head of purification plant (upstream): 37.79m, head of reservoir (downstream): 12m
   - Waterwheels (3 units): pump-turbine, rated capacity of 94kW, maximum output of 107kW
   - Generators: three-phase induction (capacity: 100kW x 3 units)
   - Operation: Automatic, remote control from the main control center at Noryangjin reservoir
 • Budget: KRW 2.341 trillion (central government: 50% / city government: 50%)
 • Characteristics
   - A natural effective head of 10m is guaranteed.
   - A large amount of water (daily average of 300,000m³) flows to the reservoir.
   - No additional establishments or structures required.
   - There is no impact (noise, vibration, other environmental) on surrounding areas; therefore, low likelihood of civil complaints.

Concerns of potential threat to water quality

There were concerns of oil leaks from waterwheels, which could affect 800,000 households. After thorough inspections including numerous discussion sessions with expert advisory groups, more than 20 site inspections, and analysis of overseas cases, we selected noncorrosive, pump-type waterwheels that can ensure lubricant-free operation, eliminating any possibility of oil leaks.

Other concerns existed. Sudden changes in pressure to the pipeline could cause slime formation that contaminates the water. Moreover, mid-valve operation to increase water flow – a necessary step to compensate for pressure loss when SHP is operating -- can drastically change water velocity, which can also compromise water quality. To prevent such problems, measures included generator pilot operation, real-time monitoring of water quality parameters, and mid-valve adjustments.

1) Meetings on countermeasures in the event of compromised water quality
2) Meetings on countermeasures involving use of emergency valves

Technical issues related to construction
To ensure that the related construction work does not affect households in Seoul, we took advantage of a special piping technology that eliminates the possibility of water interruptions during the construction at 4 sites. We also used pipe sleeves to prevent the pipes from being pushed under pressure and strengthened the support fixtures to be used for water pressure simulation.

To compensate for the limited space in workstations, we had 2 workers in 1 group when carrying materials to pump stations and contracted a company specializing in such operations. Most importantly, all safety and accident-prevention measures were in place with our inspectors, who stayed at the sites throughout the construction period.

Contributing to the energy reduction initiative of the national and Seoul Metropolitan governments

Raising awareness and educating on renewable energy

Seoul’s SHP plant uses water supply pipelines and can be applied to other municipalities in Korea as well as developing countries in Southeast Asia and South America.

Where would more SHP plants be installed in the future?
We are looking into sites with lower head (over 2m) such as Yeongdeungpo Purification Station (200kW) and Samsung Reservoir (30kW).