Pico Hydros make great damges
By Raveendra Kariyawasam
A belief that ‘small’ hydropower systems are a source of clean energy with little or no environmental impact is driving a growing interest in mini, micro, and pico hydropower systems that can generate from less than 5 kilowatts up to 10 megawatts of energy.
Hydropower may appear to be the cleanest and most versatile of renewable energy sources, but experience shows that optimism about its potential can be misplaced.
Hydropower uses water to generate carbon-free electricity. Fossil-fuelled power plants and coal power plants, nuclear power plants produce gases and/or ash emissions into the air. After 1950 hydropower became popular in many countries including Brazil, China, Sri Lanka, India, and Malaysia. Many small and large-scale dams have been built through natural waterways. In Sri Lanka, Randenigala, Rantambe, Victoria are some examples of this.
When building the above-mentioned dams the Government of Sri Lanka (GOSL) made many outlandish claims including that there would be a surfeit of electricity in Sri Lanka such that we would be in a position to export the excess to India through the Kanya Kumari. Of course, this never happened and people understood this to be another falsehood of the government. Successive governments have a record of false claims with regard to the effectiveness of “development” projects that seem to achieve nothing and in many cases have destroyed extant national assets and the environment.
The GOSL has accelerated micro-hydro projects using many catchment areas and inviting private companies to build and operate hydropower plants and sell the electricity to the national grid. This is called Energy Trade.
One example of the dire consequence due to the installation of hydropower in Sri Lanka is our experience with the Laxapana waterfall. The construction of a private hydropower plant above 200 meters of this waterfall has degraded the ecosystem in the area and is currently facing a threat of completely drying up as the explosions made during the construction work has made the rocks of the waterfall loose. The banks of the Maskeliya River that supplies water to the waterfall have also collapsed due to these explosions. It seems that in searching for solutions to the growing energy demand the GOSL and its partners are paying scant attention to the environmental degradation their activities cause.
Egypt’s High Aswan Dam has become an iconic symbol of these kinds of projects and highlights the detrimental environmental impacts it has engendered. “Projects like these fundamentally altered river ecosystems, often fragmenting channels and changing river flows. Natural lakes take hundreds of years to evolve from oligotrophic (low in nutrients) to eutrophic (rich in nutrients) status. But man-made reservoirs underwent this transition within a few years, degrading water quality, harming fisheries, bringing siltation and invasion by weeds, and creating environments suitable for mosquitoes and other disease vectors”, a study has shown
In a report on the Environmental Implications of Renewable Energy Sources, the International Energy Agency (IEA) notes: “Small-scale hydro schemes (SHS) tend to have a relatively modest and localised impact on the environment. These arise mainly from construction activities and from changes in water quality and flow on ecosystems (aquatic ecosystems and fisheries) and on water use”.
According to the International Energy Agency, the world has not experienced any major problems from ‘small’ hydropower plants simply because the world has used them economically to earn money without thinking about the ecological impact.
The same situation is arising in Sri Lanka. the private company has been involved in energy trade. the government institutes such as CEA and other responsible officers and institutes make EIA and all legal documents to them, continue ecological degradation without previse or post proper environmental assessment.
The International Energy Agency (IEA) and other research institutes have identified many ecological impacts of micro-hydropower in the world. Constructions of micro or macro hydropower plants can badly affect aquatic ecosystems. Interrupting water flow, barriers to animal movement, water loss from evaporation and loss of biodiversity from the sacrificed portion of the river are a few of the devastating results. With smaller dams, storage is an increasingly important problem that may require the construction of more low-head systems than anticipated. Reservoirs silting up or becoming overloaded with nutrients are other common problems.
According to the IEA, methane generation occurs largely where water and sediment meet, and this means that a shallower water body is likely to release more methane per unit area than a deeper water body. Shallow reservoirs are not unlike paddy fields which are known to contribute substantially to methane emissions, a greenhouse gas 25 times more potent than carbon dioxide.
The IUCN in its report on small-scale hydropower plants said in 2012 that ecosystems were under threat
Small hydropower plants cause damage to the ecosystem. A study carried out by the University of Sheffield in the United Kingdom showed that small hydropower plants have caused damage to ecosystems, destroying aquatic fauna and flora.
There are many other studies showing the damage caused by small-scale hydropower plants and the Ministry of Environment must pay heed and conduct thorough assessments before granting approvals and must work hard to revive aquatic ecosystems already destroyed.
As a tropical country, we have enough sunshine and wind. These are the ideal renewable energy sources the government must exploit