1. Homework

2. Negative impacts non- renewable energy has caused.
fossil fuels give out carbon dioxide into the air, radioactive energy because
mining uranium and then turning it into plutonium takes up a lot of power
and releases carbon dioxide in to the air.

3. Hydropower

4. 5 Questions
Q1:How much money does it take to maintain a hydroelectric dam? Hydroelectric dams
are temporary features. They will eventually fill up with gravel and silt from the river.
This is very expensive to remove. Otherwise the maintenance is things like removal of
debris that may damage the turbines. The actual maintenance of turbines and generators
is small - occasionally bearings need replacement and so on
Q2: How much money does the hydroelectric dam make?
about $0.04 per Kilowatt
Q3: How long have people been using water power? For many
centuries water mills were used to grind corn, but obviously
not to produce electricity.
Q4: How many water turbines are there in the Hoover dam? there are 17 water turbines in
the Hoover dam
Q5: Who first used water for energy? Early uses of waterpower date back to Mesopotamia
and ancient Egypt, where irrigation has been used since the 6th millennium BC and water
clocks had been used since the early 2nd millennium BC.

5. How does Hydropower work?
Hydroelectric dams work by converting the movement or falling of water into useful forms of energy
such as electricity. Some examples of this are watermills which powered machinery such as sawmills,
irrigation which used gravity, and dams which use falling water to power turbines. Hydroelectric dams
use a reservoir to create potential energy from the dammed water. This water flows through an intake
and into a large pipe called a penstock. The penstock feeds water into a turbine which powers a
generator. Many dams will have multiple reservoir tanks which are held at the top of the dam. During
low electricity usage the turbines will power pumps to fill these tanks. Then during peak electricity
demand the tanks will be dumped onto the turbines to increase their production potential. The dam
generator consists of a turbine powered by water flowing through the wicket gate. This gate can be
opened more or less to determine the rate of flow through the turbine and thus the amount of power
generated. The turbine is attached by a shaft to an electric generator. Hydroelectric dam generators are
quite large.

7. Example

8. Pros Cons
Pros and Cons Once a dam is
constructed, electricity
The high cost of dam
construction means that
can be produced at a they must operate for
constant rate. many decades to become
profitable.
Dams are designed to last
many decades and so can Animals can die because
contribute to the they can’t migrate up
generation of electricity river or down river
for many years / decades.
The lake that forms
behind the dam can be
used for water sports and The flooding of large
leisure / pleasure areas of land means that
activities. Often large the natural environment
dams become tourist is destroyed.
attractions in their own
right. More money.
Pros and cons Hydropower is a fueled
by water, so it's a clean
The building of large
dams can cause serious
fuel source. Hydropower geological damage. For
doesn't pollute the air like example, the building of
power plants that burn the Hoover Dam in the
fossil fuels, such as coal, USA triggered a number
oil or natural gas. of earth quakes.
Fish populations can
be impacted if fish
cannot migrate
The lake's water can be upstream past
used for irrigation
impoundment dams to
purposes.
spawning grounds or if
they cannot migrate
downstream to the
ocean.

9. Bibliography
Wikipedia http://en.wikipedia.org/wiki/Hydropower#History
Wiki answers http://wiki.answers.com/Q/
What_are_the_advantages_and_disadvantages_of_hydro-electric_power
Renewable energy index http://renewableenergyindex.com/hydro/how-do-
hydroelectric-dams-work
Googlehttps://www.google.co.nz/
Google pictures https://www.google.co.nz/imghp?hl=en&tab=wi