Air, Earth, Fire and Water ~ An
Introduction to Environmental
Science
Unit 2 ~ Renewable Energy
Unit 2 ~ Renewable Energy
Introduction to Renewable
Energy
• As fossil fuels are being used up it is
urgent that we find something to replace
them to satisfy our energy needs.
• Renewable energy is the way forward.
• By using different types of renewable
energy in different areas we could provide
for all of our future energy needs.
Unit 2 ~ Renewable Energy
Energy
• Energy cannot be created or destroyed; it
can only change from one form to another.
• There are many different forms of energy
such as: Kinetic, Potential, Nuclear,
Chemical, Electrical, Magnetic, Heat,
Sound
Unit 2 ~ Renewable Energy
Renewable Versus Non-Renewable
Energy
• A renewable source of energy is one
which is derived from resources which are
replaced or regenerated e.g. biomass,
water or wind.
• A non-renewable source of energy is one
which will become depleted in time e.g.
fossil fuels
Unit 2 ~ Renewable Energy
Renewable Versus Non-Renewable
Energy
• We usually burn fossil fuels in order to
convert their chemical energy to heat, light
and other forms of energy.
• Renewable sources of energy include
hydroelectricity, wind energy, tidal energy,
solar energy, and biomass.
Unit 2 ~ Renewable Energy
Hydroelectricity
• Hydroelectricity involves building a dam
across a river to form a lake. Water flowing
through the dam turns a generator to
produce electricity.
Unit 2 ~ Renewable Energy
Hydropower
http://www.canren.gc.ca/school/index.asp?CaId=181&PgId=1075
Unit 2 ~ Renewable Energy
Hydropower in Ireland ~
Ardnacrusha Co. Clare
Unit 2 ~ Renewable Energy
Wind power and wind farms
www.eas.asu.edu/~holbert/eee463/WIND.HTML
• Wind energy involves the wind turning
large wind turbines, which generate
electricity.
Unit 2 ~ Renewable Energy
Wind Power
http://www.canren.gc.ca/school/index.asp?CaId=183&PgId=1079
Unit 2 ~ Renewable Energy
Wind power in Ireland
Arklow
West of Ireland wind farm
(photo:GE Energy)
Unit 2 ~ Renewable Energy
Tidal power
• Tidal energy involves building a dam
across an estuary to form a lake. This lake
fills and empties as the tide rises and falls.
The water flowing through the dam
generates electricity.
• Another way uses underwater turbines.
home.clara.net/darvill/altenerg/tidal.htm
Unit 2 ~ Renewable Energy
Harnessing the tide
Tidal power plant St. Malo/Bretagne
Unit 2 ~ Renewable Energy
Solar energy
• There are several ways to harness the sun’s
energy.
• It can be trapped by solar panels and used to
heat water.
• The sun can be focused onto a boiler and used
to generate steam to produce electricity.
• The light energy can be converted into electricity
using solar cells (photovoltaic cells).
Unit 2 ~ Renewable Energy
Many ways to harness the sun
Unit 2 ~ Renewable Energy
The biomass solution
• Biomass is plant matter and can be used as
several ways.
• Sugar cane or sugar beet or whey bcan be
fermented to make bio-alcohol which can be
used instead of petrol.
• Biodiesel is made from vegetable oils, like
rapeseed oil, which can be used in unmodified
diesel engines.
• Fast growing crops like elephant grass or willow
can be used as solid fuel for boilers.
Unit 2 ~ Renewable Energy
Biomass Systems
http://www.canren.gc.ca/school/index.asp?CaId=191&PgId=1071
Unit 2 ~ Renewable Energy
Biomass in Ireland
Elephant grass
Rapeseed
Unit 2 ~ Renewable Energy
From Carbery to cars
Whey → Bioethanol → E85
Unit 2 ~ Renewable Energy
Energy from the Sun
The sun’s energy can be harnessed in 2
main ways:
• Solar panels that heat up in the suns light
to produce electricity
• Solar cells that use light to produce
electricity.
Unit 2 ~ Renewable Energy
Harnessing Light Energy
• Visible light is only part of the
electromagnetic spectrum. Radiation from
the sun is not monochromatic - it is made
up of a range of different wavelengths, and
therefore energies.
• Light can be separated into different
wavelengths, and we can see them in the
form of a rainbow.
Unit 2 ~ Renewable Energy
Trapping sunlight in silicon
• Silicon can only trap a certain wavelength
of light and turn it into electricity.
• Sunlight has a wide range of wavelengths
– some are absorbed and the others pass
straight through.
Unit 2 ~ Renewable Energy
Harnessing Light Energy
• Only a certain amount of energy,
measured in electron volts (eV) and
defined by our cell material (about 1.1 eV
for crystalline silicon), is required to knock
an electron loose.
• We call this the band gap energy of a
material.
• The devices are known as solar cells or
photovoltaic cells.
Unit 2 ~ Renewable Energy
Solar Cells
• Solar cells are known as photovoltaic or
photoelectric cells.
• They convert light directly into electricity
• Solar energy is free - it needs no fuel and
produces no waste or pollution.
• Photovoltaic (PV) cells are made of
special materials called semiconductors
such as silicon.
Unit 2 ~ Renewable Energy
How do photovoltaic cells work?
• Semiconductors are materials which have a conductivity
between conductors (generally metals) and nonconductors or insulators (such as most ceramics).
• Semiconductors can be pure elements, such as silicon
or germanium, or compounds such as gallium arsenide
or cadmium selenide.
• In a process called doping, small amounts of impurities
are added to the pure semiconductors causing large
changes in the conductivity of the material.
• When light strikes the cell, a certain portion of it is
absorbed within the semiconductor material.
Unit 2 ~ Renewable Energy
How do photovoltaic cells work?
• This means that the energy of the
absorbed light is transferred to the
semiconductor.
• The energy knocks electrons loose,
allowing them to flow freely.
• This flow of electrons is a current, and by
placing metal contacts on the top and
bottom of the Photovoltaic cell, we can
draw that current off to use externally.
Unit 2 ~ Renewable Energy
How solar cells work
http://www.bbc.co.uk/science/robots/techlab/sub2.shtml
Unit 2 ~ Renewable Energy
Solar Energy Systems (1)
http://www.canren.gc.ca/school/index.asp?CaId=182&PgId=1077
Unit 2 ~ Renewable Energy
Solar Energy Systems (2)
http://www.canren.gc.ca/school/index.asp?CaId=182&PgId=1077
Unit 2 ~ Renewable Energy
Solar Panels to produce hot water
http://www.canren.gc.ca/school/index.asp?CaId=182&PgId=1077
Unit 2 ~ Renewable Energy
Renewable Energy Sources in
Ireland
• Activity: What area in Ireland would be the
best for different types of renewable
energy sources?
Unit 2 ~ Renewable Energy
Renewable Energy Sources in
Ireland
• Can you think of Irish examples of
renewable energy?
• Wind Power
• Hydropower
• Biomass
• Solar Panels
• Solar Cells
Unit 2 ~ Renewable Energy
Renewable energy in Ireland
• Ireland is producing more and more of its
energy from renewable resources.
• How does Ireland compare with other
countries in Europe?
Unit 2 ~ Renewable Energy
Worldwatch Guide of Renewable Energy
Usage and Targets for the Future
Unit 2 ~ Renewable Energy
Biodiesel in Ireland
www.agri-energy.co.uk
Unit 2 ~ Renewable Energy
Some Irish wind farms
www.hibernianwindpower.ie/windfarms/overview.htm
Unit 2 ~ Renewable Energy
Conclusion – a lot done, much
more to do!
• In 1990 renewable energy was 1.9% of Ireland’s
primary energy supply – by 2006 it had reached
4.5% (wind 2.7%, hydro 1.2%)
• In 2006 we produced 1,622 GWh from wind, with
782 MW installed capacity
• Landfill gas contributed 108 GWh in 2006 and
hydropower 724 GWh
www.sei.ie/
Unit 2 ~ Renewable Energy