Sarawak hydro power potentials said to be more than 20,000MW and by year 2020 a whooping 7500MW of the state power will be generated by water. While governments have been tapping these vast natural resources to feed the power hungry, heavy-pollution aluminium industry, the rural poor had not been able to reap any benefits from it.
This is partly because of the cost involves in building large hydro power dam. The good news is that you don’t need millions to light up your own home using this free natural resource. In Sarawak an NGOs had built a micro-hydro at Long Lawen, Belaga – lighting a longhouse of more than 700 people (pdf) at over USD $53, 428.00 or less than hundred dollar per person.
Here is how typical micro-hydro works?
The power available in a river or stream depends on the rate at which the water is flowing, and the height (head) which it falls down. Hydro schemes are classified by the output power which they produce as approximately:
Large scale: 2 MW and above
Mini: 100 kW to 2 MW
Micro: 5 kW to 100 kW
Pico: less than 5 kW
but the basic approach is similar for all.
The core of a micro-hydro scheme is the turbine, which is rotated by the moving water. Different types are used, depending on the head and flow at the site (see box). For example, Ashden Award-winner Practical Action Peru uses Pelton, Francis and Cross-flow turbines. The turbine rotates a shaft, which is often used to drive an electrical generator.
Most micro-hydro systems are ‘run-of-river’ which means that they don’t need large dams to store water. However, they do need some water-management systems.
A small dam in the river bed directs the water to a settling tank. This allows silt to settle out of the water, and the clean water to flow into a canal or a pipe to a second settling tank called the ‘forebay’, which is sited above the power house.
The canal or pipe can be fairly long, 1 km or more, if a suitable stream is distant from where the power is required. The outlet from the forebay has a screen to trap silt and floating debris. Water flows out into a pipe called the ‘penstock’, which is made as steep as possible to transfer water to the turbine. Water leaving the turbine is led back to the stream through the outlet pipe or ‘tail-race’
Micro-hydro can bring electricity to remote communities for the first time, replacing kerosene for lighting, providing TV and communications to homes and community buildings, and enabling small businesses to start.
Micro-hydro schemes are already benefiting many remote Kenyah communities in Belaga district see video below.
Around the world it had light up the Himalayas and Andes, as well as in hilly parts of China, Sri Lanka and the Philippines. In the developed world, micro-hydro schemes supply power to existing mains electric grids.