WHAT IS RENEWABLE
Renewable energy is energy generated from
natural resources—such as sunlight, wind,
rain, tides and geothermal heat—which are
renewable (naturally replenished).
Renewable energy technologies range from
solar power, wind power,
hydroelectricity/micro hydro, biomass and
biofuels for transportation.
What is Hydropower
Hydropower refers to energy, mostly electric,
which is derived from water in motion. This power
is harnessed and used to drive mechanical devices.
The main advantage of this form of energy is that
it is clean and renewable. Hydropower plants are
actually based on a rather simple concept -- water
flowing through a dam turns a turbine, which
turns a generator.
Relocating people from the reservoir area is the
most challenging social aspect of hydropower,
leading to significant concerns regarding local
culture, religious beliefs, and effects associated
with inundating burial sites. While there can never
be a 100 percent satisfactory solution to
involuntary resettlement, enormous progress has
been made in the way the problem is handled.
Hydroelectric power includes both massive
hydroelectric dams and small run-of-the-river plants.
Large-scale hydroelectric dams continue to be built in
many parts of the world (including China and Brazil),
but it is unlikely that new facilities will be added to the
existing U.S. fleet in the future.
Instead, the future of hydroelectric power in the
United States will likely involve increased capacity at
current dams and new run-of-the-river projects. There
are environmental impacts at both types of plants.
1. Once a dam is constructed, electricity can be produced at a
2. If electricity is not needed, the sluice gates can be shut,
stopping electricity generation. The water can be saved for
use another time when electricity demand is high.
3. Dams are designed to last many decades and so can
contribute to the generation of electricity for many years /
4. The lake that forms behind the dam can be used for water
sports and leisure / pleasure activities. Often large dams
become tourist attractions in their own right.
5. The lake's water can be used for irrigation purposes.
1. Dams are extremely expensive to build and must be built to
a very high standard.
2. The high cost of dam construction means that they must
operate for many decades to become profitable.
3. The flooding of large areas of land means that the natural
environment is destroyed.
4. People living in villages and towns that are in the valley to
be flooded, must move out. This means that they lose their
farms and businesses. In some countries, people are
forcibly removed so that hydro-power schemes can go
5. The building of large dams can cause serious geological
damage. For example, the building of the Hoover Dam in
the USA triggered a number of earth quakes and has
depressed the earth’s surface at its location.
Hydropower stands as the most significant renewable
energy source. It uses the single but very powerful
energy force of moving water. By some comparison, it
competes with the energy produced by fossil fuels and
nuclear power, but is considered much cleaner and
more simplistic. Hydropower remains popular even in
third-world countries, which do not have the resources
to build expensive nuclear generating stations.
Hydropower does not pollute the atmosphere or
Hydropower uses the energy of moving water for a variety
of useful applications.
Hydroelectricity generates electricity by harnessing the
gravitational force of falling water.
In 2006, hydroelectricity supplied around 20% of the
Most hydroelectric power stations use water held in dams
to drive turbines and generators which turn mechanical
energy into electrical energy.
The largest hydroelectric power station in the world is the
Three Gorges Dam in China.
Types of Hydropower
An impoundment facility, typically a large hydropower system,
uses a dam to store river water in a reservoir. The water may be
released either to meet changing electricity needs or to maintain
a constant reservoir level.
A diversion, sometimes called run-of-river, facility channels a
portion of a river through a canal or penstock. It may not require
the use of a dam.
When the demand for electricity is low, a pumped storage facility
stores energy by pumping water from a lower reservoir to an
upper reservoir. During periods of high electrical demand, the
water is released back to the lower reservoir to generate
Large dams have long been promoted as providing
"cheap" hydropower and water supply. Today, we know
better. The costs and poor performance of large dams
were in the past largely concealed by the public
agencies that built and operated the projects. Dams
consistently cost more and take longer to build than
projected. In general, the larger a hydro project is, the
larger its construction cost overrun in percentage
The IHA (International Hydropower Association)
Working Group on Environmental Impact
Assessment (EIA) calls for impact assessment to be
an integral part of the multidisciplinary planning
approach, and to include a strong element of
public consultation. EIAs should cover both
positive and negative impacts both upstream and
downstream of a proposed project.