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.
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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.
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.
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