Micro Hydro

SURVEY OF MICRO-HYDRO POTENTIAL IN SARAWAK

INTRODUCTION

There are great potentials for micro-hydro power in Sarawak, especially for the many scattered communities who have no access to the power grid.
The vast networks of rivers and streams found in the rugged terrains amongst the scattered rural population within the vast land area of provide great potentials for this kind of sustainable renewable energy.

MAPPING AREAS

A total of 104 sites/settlements in 8 divisions throughout the state of Sarawak as per Figure below was visited and surveyed in this mapping works, namely;

• Samarahan Division
• Sri Aman Division
• Betong Division
• Sarikei Division
• Kapit Division
• Bintulu Division
• Miri Division
• Limbang Division

Figure: The State of Sarawak

Each of these 8 divisions actually have its sources of water tributaries from the mountain ranges that stretch from the South to the North of Sarawak that flows into the main rivers in the state as follows:

Figure: Sarawak’s terrain

The rural population is scattered either along the river upstream or in the highlands which are far off from the power grid. These areas are accessible either by boats or travelling through logging roads. Almost all settlements are located either near to or along the rivers or streams. The distances of the potential source of hydro power ranges from less than a kilometre to almost 5 kilometres. At present most of these settlements are using small generator sets as source of power for their electricity.

TECHNICAL APPROACH

The technical approach to this survey/mapping was to collect data as well as to record the locations of the settlements, their potential sources and calculate the power producing potential of every source within each of the settlement. No other feasibility assessments were done. The minimum and maximum water levels in all streams/rivers were based on the information or experiences from local dwellers/settlers. This also includes the adverse dry weather conditions during the period of May to October 2009.

Locations of settlements are identified by use of Geographic Information System equipment, the portable handheld Global Positioning System (GPS) unit. It determines the latitude and longitude of the locations. The GPS unit is also used in trekking the routes of each source from the settlements by giving its estimated distances and in determining the estimated hydraulic head of the source.

The calculation of power potential of the streams/rivers requires two values: the flow rate and the hydraulic head corresponding to the elevation difference between the upstream and the downstream ends of the reach. The flow rate was calculated based on the average speed across the stream/river and its average cross sectional area. The power potential values are gross power values based on the estimated flow rates obtained during the day of survey.

 The subsections that follow describe the details of the various aspects of the technical approach in the calculation of the power potential and data analysis in producing the mapping.

THEORY

The calculation of the stream flow rate, hydraulic head and subsequently, power potential is based on the data and information being collected on the ground during the day of survey. That could mean that the water flow at that time could either be between the minimum and maximum range of flow.

Flow Rate Calculations

The flow rate was calculated using the average cross sectional area of the stream and the average velocity across that cross sectional area of stream. The velocity of stream was taken using s stream flow meter. The flow meter consists of an impeller which rotates and a counter will count the number of impeller revolutions per minute.

The flow speed is given by the following formula;

V = 0.000854 C + 0.05

Where
V = velocity in metres/second
C = counts per minute (impeller rotations/minute)
The estimated flow rate is calculated using the equation;
Q = A x V
Where
Q = estimated flow rate in cubic metres/second
A = average cross sectional area of stream in square metre
V = average velocity of stream in metre/second

POWER POTENTIAL CALCULATION

The power potential of a stream was calculated using the hydraulic head and the estimated flow rate. The hydraulic head associated with each stream was obtained using elevation data from the handheld GPS unit. It provides the elevation data at the upstream and the downstream ends of reach. The difference of these elevation values was the hydraulic head for the flow.
 

The following equation was used to calculate the power potential;

P = g x Q x H

Where
P = Power in kilowatts
g = accelaration due to gravity, 9.81 metre/second2
Q = estimated flow rate in cubic metres/second
H = hydraulic head in metre

DATA

All data collected are in both hardcopy and also stored in the GPS memory. These data will be logged into a spatial database management system with the assistance of the GIS section. The data are then transformed into a mapping data which will show the locations of the micro hydro resources and potential.

SITES SURVEYED & DATA ANALYSED

The following are the settlements that have been surveyed for potential micro hydro

For further details log on website :
http://www.sarawakenergy.com.my/index.php/r-d/micro-hydro