Hydro's Place in Sustainable Energy

My family had a great time today in Lake Caliraya, Laguna, planting trees to reforest a denuded portion of Napocor's ( National Power Corporation of the Philippines) watershed in this area. Caliraya is a man-made lake, home to ~600MW of hydro-electric power. Considering large dams and flooding was done in its construction, this lake is technically not sustainable. It does, however, provide clean electric power ( compared to fossil fuels).

One may ask, "How can hydropower be made sustainable?" The answer is simple in worlds but often difficult in practice. The principle involved is ensuring that a hydropower endeavor must have minimal impact to the immediate ecosystem and community in the site. Traditional large dams involved the impounding of huge volumes of water leading to key issues such as:

1.) Reduction of available water volume for the local community
2. ) Species/Human displacement because of flooding
3. ) Species destruction because of changes in flow characteristics
4.) Water quality changes because of flow characterisitic change

For hydro plants to be sustainable, they must maintain the overall flow characteristics and volume of the river or tributary. Systems known as run-of-river hydro systems do not have dams, but divert some of the water to power station by means of a penstock. After usage, the water is brought back to the river. These are often seen in rural settings in the Philippines and in other parts of South East Asia. Since this technology depends on the normal flow of the river, one much choose sites carefully to ensure consistent power delivery all year round.

Some small hydro plants, use dam technology. For these to be sustainable, they have to first demostrate that their dam is not large ( as defined by the world commission on dams). After this, these plants have to demonstrate that volume or flow changes will not affect local community usage or biodiversity.

Sad to say most of the major hydro plants in the Philippines are not sustainable. We do hope that proposed installations in Panay and Bicol consider sustainability in their designs.

Trivia: The largest hydropower station in the world is the Three Gorges Dam in China. It is projected to be capable of generating 22.5GW of power when all turbines are operational.