Hydropower harnesses the energy of falling or flowing water to generate electricity. It is the most widely used renewable energy source, accounting for 16% of global electricity. Hydropower does not produce greenhouse gases but it can damage ecosystems and require relocating people when it involves large dams. The main types of hydropower are run-of-river, which uses existing river flow without dams, and conventional dams which store water in large reservoirs and release it to drive turbines.

1. Hydropower
 Hydropower or water power is power derived from
the energy of falling water or flowing water, which
may be harnessed for useful purposes.
 Hydroelectricity is the term referring to electricity
generated by hydropower
 It is the most widely used form of renewable energy,
accounting for 16 percent of global electricity
consumption
 Hydropower is produced in 150 countries, with the Asia-
Pacific region generating 32 percent of global
hydropower in 2010.
 China is the largest hydroelectricity producer
 Paraguay produces 100% of its electricity from
hydroelectric dams, and exports 90% of its production
to Brazil and to Argentina.

2. Types of generating methods
 Conventional (Dams)
 Pumped-storage
 Run-of-the-river

3. Conventional (Dams)
 Most hydroelectric power comes from
the potential energy of dammed
water driving a water turbine and
generator.
 This height difference is called the
head.
 The amount of potential energy in
water is proportional to the head.
 A large pipe (the "penstock") delivers
water to the turbine.

4. Cross section of a Conventional
Hydroelectric Dam.

5. Run-of-the-river
 Run-of-the-river hydroelectric stations
are those with small or no reservoir
capacity
 So water coming from upstream must
be used for generation at that
moment.

6. Micro-hydro

7. Micro-hydro: the basics
 "Run of the river" systems do not require
a dam or storage facility to be
constructed.
 Instead they divert water from the stream
or river and is channelled through a
settling basin
 The water then flows into the Forebay
Tank where it is directed downhill
through a pipe called a penstock.
 When the water reaches the bottom, it
drives a specially designed turbine to
produce the electricity.

8. Advantages of Hydropower
 Renewable, indigenous, non-polluting resource
 Flexibility
◦ Can be ramped up and down very quickly to adapt to changing
energy demands
 Low power costs
◦ Not effected by increases in the cost of fossil fuels
◦ No imports are needed.
◦ Have long economic lives (50–100 years)
◦ Operating labour cost is also usually low, as plants are
automated and have few personnel on site during normal
operation.
◦ Dam serves multiple purposes, providing a useful revenue stream
to offset the costs of dam operation.
 Reduced CO₂ Emissions
◦ Do not burn fossil fuels, they do not produce greenhouse gases
 Produces no direct waste

9. Disadvantages
 Loss of land – for construction of Large reservoirs
leading to submersion, destroying biologically rich and
productive lowland and riverine valley forests.
 Ecosystem damage- Is disruptive to surrounding
aquatic ecosystems both upstream and downstream
of the plant site.
 Relocation- Relocate the people living where the
reservoirs are planned.
 Failure Risks – because hold back large volumes of
water, a failure due to poor construction, natural
disasters or sabotage can be catastrophic to downriver
settlements and infrastructure.
 Flow shortage-Lower river flows will reduce the
amount of hydroelectricity, power shortages in areas
that depend heavily on hydroelectric power.
 Siltation-Negative effect on dams and subsequently
their power stations. Siltation can fill a reservoir and
reduce its capacity to control floods .
 Methane emissions from reservoirs - power plants in
tropical regions