Introduction

Large or small hydropower, still far the most important of the renewable energy for electrical power production worldwide, providing 19% of planet’s electricity. However, hydropower on a small scale remains the most effective energy technologies to be considered for rural electrification in less develops country. The advantages of small hydro technology are the system can last for 50 years or more with less maintenance and also environmental friendly.

Malaysian government has launched the Small Renewable Energy Programme (SREP) in 2001, in order to motivate the Independent Power Producer (IPP) in implementing the renewable energy projects in Malaysia. In 2009, there are 5 mini hydropower projects from 17 SREP participants, and one of them is Renewable Power Sdn. Bhd. This mini hydro is operating at Gading Reserve forest, Hulu Selangor with licensed capacity of 2.2MW. The capital cost of this project is estimated to be paid off after 10 years generation. The barriers of this mini hydro are authority issues, short-term profit minded and expensive transmission to the grid. Apart from these challenges, obviously mini hydropower is one of the most potential alternatives energy in Malaysia, suitable to the objective of Fifth Fuel Policy in implementing renewable energy as one energy resource in Malaysia.

Peninsular Malaysia

Tenaga Nasional Berhad operates three hydroelectric schemes in the peninsular with an installed generating capacity of 1,911 megawatts (MW). They are the Sungai Perak, Terengganu and Cameron Highlands hydroelectric schemes with 21 dams in operation. A number of Independent Power Producers also own and operate several small hydro plants. Sungai Perak hydroelectric scheme, with 1249 MW installed capacity: Sultan Azlan Shah Bersia Power Station 72 MW.

Chenderoh Power Station 40.5 MW Sultan Azlan Shah Kenering Power Station 120 MW Sungai Piah Upper Power Station 14.6 MW Sungai Piah Lower Power Station 54 MW Temenggor Power Station 348 MW Sultan Ismail Petra Power Station 600 MW Terengganu hydroelectric scheme, with 400 MW installed capacity: Sultan Mahmud Power Station 400 MW Cameron Highlands hydroelectric scheme, with 262 MW installed capacity: Sultan Yusof Jor Power Station 100 MW Sultan idris Woh Power Station 150 MW Odak Power Station 4.2 MW Habu Power Station 5.5 MW Kampong Raja Power Station 0.8 MW Kampong Terla Power Station 0.5 MW Robinson Falls Power Station 0.9 MW Independent hydroelectric schemes Sg Kenerong Small Hydro Power Station in Kelantan at Sungai Kenerong, 20 MW owned by Musteq Hydro Sdn Bhd, a subsidiary of Eden Inc Berhad.

Sabah and Sarawak Bakun Dam 2400 MW Tenom Pangi Dam at Tenom, Sabah 66MW Batang Ai Dam at Lubok Antu, Sarawak 25 MW Murum Dam in Sarawak 944 MW (Under construction).

Advantages of hydropower in Malaysia

Malaysia has lot of water resources throughout the years. Malaysia covers a land area of 330000 km2 which 58% is lowland areas and 42% is highland areas. In Peninsula Malaysia, we have Titiwangsa, Tahan, Bintang, Kledang and Pantai Timur. In Sarawak, the highlands are Tama Abu, Iran and Kapuas Hulu Ranges while in Sabah, they are Crocker, Maitland nad Brassey. Other than highlands, Malaysia also have has average rainfall of 2450mm in Peninsula, 2630mm in Sabah and 3850mm in Sarawak which contribute to abundance streams and rivers flowing from the highland areas. Suitability catchment for hydro potential is based on 3 factors. They are energy demand, accessibility, and river profile. Other than that, based on hydrology study, average annual rainfall in Malaysia especially in highland sites, the average annual rainfall rate are in range from 1500mm up to 3600mm from 1997 to 2007. Based on the result obtained, location in Malaysia met the requirement for hydro generation. Using this type of energy to generate electricity is not dependent upon the price of uranium, oil, or other types of fuel. This makes electricity costs lower and more stable, one of its most significant advantages.

The pollution created by hydroelectric energy generation is quite minimal. There is some pollution involved in initially constructing the power stations, but this is true of all power plants. It also does not produce radioactive waste or involve the environmental impact of fuel being transported to it. It doesn't require many employees to run a hydroelectric station. According to wikipedia.org, most plants of this type are largely automated. This is another one of the advantages which help keep the cost of hydroelectricity low. Hydroelectric power stations can be set up in almost any size, depending upon the river or stream used to operate them; big enough to power a single home, factory, small town, or large city. Another of its advantages is that hydroelectric is a renewable form of energy, like wind and solar; it does not rely upon finite resources like natural gas or coal to generate power. Hydroelectric stations can operate for many years after they are built. Wikipedia.org states that a number of operational hydro stations were constructed fifty to one-hundred years ago; in contrast to this, IAEA.org indicates that the "design life" of nuclear power plants is generally thirty to forty years. Small hydro electricity generation systems sometimes offer more economic advantages for home owners than solar power, and tend to last longer than solar panels do. Since hydroelectric dams do not burn fossil fuels, they are claimed to not directly produce carbon dioxide. While some carbon dioxide is produced during manufacture and construction of the project, this is a tiny fraction of the operating emissions of equivalent fossil-fuel electricity generation.

One measurement of greenhouse gas related and other externality comparison between energy sources can be found in the ExternE project by the Paul Scherrer Institut and the University of Stuttgart which was funded by the European Commission. According to that study, hydroelectricity produces the least amount of greenhouse gases and externality of any energy source. Coming in second place was wind, third was nuclear energy, and fourth was solar photovoltaic. The extremely positive greenhouse gas impact of hydroelectricity is found especially in temperate climates. The above study was for local energy in Europe; presumably similar conditions prevail in North America and Northern Asia, which all see a regular, natural freeze/thaw cycle (with associated seasonal plant decay and regrowth). Lower positive impacts are found in the tropical regions, as it has been noted that the reservoirs of power plants in tropical regions produce extremely negative amounts of methane. Reservoirs created by hydroelectric schemes often provide facilities for water sports, and become tourist attractions themselves. In some countries, aquaculture in reservoirs is common. Multi-use dams installed for irrigation support agriculture with a relatively constant water supply. Large hydro dams can control floods, which would otherwise affect people living downstream of the project.

Disadvantages of hydropower in Malaysia

Large reservoirs required for the operation of hydroelectric power stations result in submersion of extensive areas upstream of the dams, destroying biologically rich and productive lowland and riverine valley forests, marshland and grasslands. The loss of land is often exacerbated by habitat fragmentation of surrounding areas caused by the reservoir. Hydroelectric projects can be disruptive to surrounding aquatic ecosystems both upstream and downstream of the plant site. Generation of hydroelectric power changes the downstream river environment. Water exiting a turbine usually contains very little suspended sediment, which can lead to scouring of river beds and loss of riverbanks. Since turbine gates are often opened intermittently, rapid or even daily fluctuations in river flow are observed. When water flows it has the ability to transport particles heavier than itself downstream. This has a negative effect on dams and subsequently their power stations, particularly those on rivers or within catchment areas with high siltation. Siltation can fill a reservoir and reduce its capacity to control floods along with causing additional horizontal pressure on the upstream portion of the dam. Eventually, some reservoirs can become full of sediment and useless or over-top during a flood and fail. Changes in the amount of river flow will correlate with the amount of energy produced by a dam. Lower river flows will reduce the amount of live storage in a reservoir therefore reducing the amount of water that can be used for hydroelectricity.

The result of diminished river flow can be power shortages in areas that depend heavily on hydroelectric power. The risk of flow shortage may increase as a result of climate change. Lower positive impacts are found in the tropical regions, as it has been noted that the reservoirs of power plants in tropical regions produce substantial amounts of methane. This is due to plant material in flooded areas decaying in an anaerobic environment, and forming methane, a greenhouse gas. According to the World Commission on Dams report, where the reservoir is large compared to the generating capacity (less than 100 watts per square metre of surface area) and no clearing of the forests in the area was undertaken prior to impoundment of the reservoir, greenhouse gas emissions from the reservoir may be higher than those of a conventional oil-fired thermal generation plant. Another disadvantage of hydroelectric dams is the need to relocate the people living where the reservoirs are planned. In 2000, the World Commission on Dams estimated that dams had physically displaced 40-80 million people worldwide. Some compensation needs to be paid to people that have to be relocated.