By Dr Kuok King Kuok
With its network of sleepy, meandering rivers and heavy rainfall, Sarawak has all the right characteristics for hydropower generation. The “Land of the hornbills” is criss-crossed by an intricate river system that has served as a means of transportation for hundreds of years. It is so vast that the Sarawak Department of Irrigation and Drainage (DID) divided the river systems into 22 river basins. The longest river is the 560km Rajang, while the Baram at about 466km, is the second longest.
Weather-wise, the state experiences two monsoonal changes: the Northeast Monsoon, also known as the Landas season, brings with it a good amount of rain between November and February; and the Southwest Monsoon which is usually evidenced by hot, humid temperatures. Each year, rainfall is between 3300mm and 4600mm, and sunshine occurs for an average of five to six hours a day.
With upcoming major developments, particularly the Sarawak Corridor of Renewable Energy (SCORE) initiative, the implementation of hydroelectric power dams have been given much emphasis to meet the demands of future domestic, commercial and industrial electricity needs within the state. Currently, Batang Ai and Bakun dams are in operation while the dam in Murum is still under construction. Eight more dams have been proposed: Balleh, Limbang, Lawas, Baram, Belaga, Mejawa, Punan Bah and Pelagus.
However, the potential of micro hydropower, which is capable of producing electricity from 1kw to about 200kw, is still untapped. It was for this reason that a steering committee was set up in early 2009 to conduct a master plan study on the potential for small renewable energy which could be drawn from solar, biomass, wind, tidal and micro hydro, throughout the state. The panel comprised representatives from relevant government agencies of the Ministry of Public Utilities, Ministry of Rural Development, Public Works Department, University Malaysia Sarawak and Sarawak Energy Berhad.
In the study, 40 sites were identified. Rural villages, especially those which were not connected to the State Grid, were surveyed for micro hydropower generation potential. These villages are located in Kapit, Miri, Limbang, Sri Aman, Betong, Sarikei and Bintulu divisions. The findings were presented at the 2010 Third international conference and exhibition on water resources and renewable energy development in Asia. It was found that most of the sites in Kapit Division had limited capacity for micro hydropower. In contrast, the tributaries of Baram river, streams in Betong and Lubok Antu could generate about 50kw to 200kw.
In order to justify the potential for a micro hydropower project, the amount of power that could be obtained from a stream or river has to be determined on-site. The power capacity of a river at any instant is attributed to the water flow volume, and the pressure of falling water or the vertical distance that water drops, described as the “head”. Hydropower sites are broadly categorized as low or high head sites. Higher flow volume and head mean more available power. On the other hand, “low head” refers to a site with less than 10ft (3m) vertical drop, but greater than 2ft (0.61m). In contrast, “high head” refers to a site with a change in elevation greater than 10ft (3m).
Flow volume is measured in cubic feet per second or gallons per minute. The flow data used for assessing the feasibility study of micro hydropower station is the lowest average daily flow of a year. Alternatively, the average daily flow during the period of highest expected electricity demand could be used. However, this may or may not coincide with lowest flows.
Currently, the information on micro hydropower potential throughout Sarawak has yet to be fully assessed. Therefore, more studies need to be carried out to identify sites with micro hydropower potential, power that can be tapped, expected highest electricity demand, and so forth. Once such information has been collected, a micro hydropower potential map could be produced. The map will be of significance in identifying locations which could provide renewable energy that is efficient, reliable, sustainable and affordable for local folk who are not connected to State Grid.
Dr Kuok King Kuok is a lecturer with the Faculty of Engineering, Computing and science at Swinburne University of Technology Sarawak Campus. He is contactable at kkuok@swinburne.edu.my.