Presentation on energy, conservation and pollution aimed at KS4&5 pupils

1. Energy - availability, conservation and pollution

2. Kinetic energy and potential energy are considered to be the two forms of energy in physics. In everyday practice, however, terms like electrical energy,
chemical energy, and thermal energy are used. These different forms of energy can be converted from one form to another.
Energy is commonly defined as the capacity of a system or a body to do work. There are many forms of energy (to be describedlater), but any of them can
be used to do work. For example the chemical energy in petrol can be burned in a car engine to make the car move. Electricalenergy can be used to turn a
motor and make machinery move. The thermal energy in the steam used in an electric power plant can partially be converted tomechanical energy in a
turbine and then converted to electrical energy in a generator.
Common Forms of Energy
There are two possible forms of energy in physics, kinetic energy and potential energy. In common usage, however, this is expanded to many possible forms
of energy. Some of the more common forms are described here.
Kinetic Energy is the energy that any moving object has by virtue of its motion. The kinetic energy of a moving object is onehalf of its mass times the square
of its velocity (K.E. = (1/2)mV2).

3. Potential Energy is stored energy that has the potential to do work or be converted to another form. An object that can move downward under
the force of gravity has gravitational potential energy. Also, a compressed spring and a stretched rubber band have potential energy, because
they can do work as they move back to their natural position.
Thermal Energy, commonly simply called heat, is the energy of any object with a temperature above absolute zero, due to the kinetic energy of
its molecules. For a given quantity of material, the higher its temperature, the more thermal energy it has.
Chemical Energy is a particular form of potential energy. It is the energy stored in a chemical that can be released by some reaction of that
chemical. An example is the chemical energy in coal that is converted to thermal energy when the coal is oxidized (burned).
Electrical Energy is energy that is made available due to the flow of an electrical current through a conductor. Electrical energy is actually
energy in transit. For example, it is converted to heat when electrical current passes through a resistor, or it is converted to kinetic energy when
electrical current passes through the windings of an electrical motor, causing the motor to turn.
Mechanical Energy is a term used to refer to the sum of the kinetic energy and potential energy of a system.
A hydraulic turbine
converts the energy of
flowing water into
mechanical energy. A
hydroelectric generator
converts this mechanical
energy into electricity.

4. Energy Conservation and Conversion among the Forms of Energy
The first law of thermodynamics is an expression of the conservation of energy. It states that energy can be neither created nor destroyed (in the absence of
nuclear reactions). Energy can, however, be converted from one form to another and can be used to do work. Some examples of energy conversion are as
follows.
Potential energy to kinetic energy: If a car at rest at the top of a hill is allowed to coast down the hill, most its initial potential energy will have been
converted to the kinetic energy of the moving car at the bottom of the hill. Some of the initial potential energy will have been converted to thermal energy
(heat) due to friction between moving parts.
Chemical energy to electrical energy: A battery contains stored chemical energy that can be converted to electrical energy by connecting an electrical
conductor across the terminals of the battery. The electrical energy will in turn be converted to heat or mechanical energy, depending upon what kind of
device is connected across the terminals of the battery.
Chemical energy to thermal energy: When natural gas is burned in a furnace the chemical energy in the fuel is converted to heat (thermal energy) to keep a
building warm.
Non-Renewable and Renewable Energy Sources
In relatively recent times, the classification of energy sources as either non-renewable or renewable energy sources has become increasingly important. The
huge quantity of the fossil fuels (coal, petroleum, and natural gas) stored underground seemed to provide an infinite supply of readily usable energy when
they were first discovered and put to use. As the rate of use of fossil fuels has mushroomed, however, we've come to realize that there is a finite supply that
is diminishing. As a result, the importance of developing and using renewable energy resources, like solar energy, wind energy, and biomass energy has
become more prominent.

5. Fossil fuels are used extensively in modern industrial countries such as
North America, India, China, Australia, and in Western Europe.
Developing nations in Africa, Southern America and Asia are
increasingly using more and more fossil fuels.
Coal is very common and found all over the world. It is relatively easy
to extract but extremely labour intensive and dangerous. Coal has
been mined for hundreds of years. When burnt, it produces high heat
which is used for cooking, heating and also for creating electricity in
power stations.
Oil is found deep underground in large reservoirs. Holes are drilled
into the ground until the oil is found. It is then pumped out of the
reservoir and transported. Oil can be converted into fuels such as
petrol and diesel and also, through different processes, turned into
the many plastics we have all around us. Oil is found in many countries
and is an extremely valuable resource.
Gas is found underground, usually near oil fields and also in gaps
in rocks. Natural gas is extracted from underground. Since it is very
explosive, transportation over a long distance is dangerous and it is
therefore often used near to the place of extraction. However, it can
be converted to a liquid for transportation and then used as a heating
fuel, and also to create electricity in power plants.
All three fuels take millions of years to produce and therefore can only
be extracted once. They are finite: in time, they will run out. When
they will runout is debatable but with an increasing world population,
increasing personal consumption, and an increasing reliance on power
this time may come quicker than we think.

6. Different renewable energy forms are:
• Solar photovoltaic: The suns rays are converted to
electricity from solar panels.
• Wind: Wind power is used to turn blades on a
turbine and is then converted to electricity.
• Hydroelectricity: Water from a reservoir naturally
flows down-river through turbines which generate
electricity.
• Solar thermal: The suns heat is used to heat water, for
example, for showers and washing.
• Geothermal: Cold water is pumped deep into the
ground and returns hot for heating purposes.
• Wave energy: The power and movement of waves
in the sea are converted into electricity.
• Tidal energy: The power of the daily tide in a river estuary
is used to drive turbines, which then generate electricity.
• Biomass: When living organisms (such as plants) die.
the gases produced are burnt to generate electricity

7. L J Hodgetts 2007
Availability
• Fossil fuels account for 85% of global energy use.
• It is considered that at current annual rates of
production, we have left worldwide, about:
• 155 years of coal
• 40 years of oil
• 65 years of natural gas
Impact
• Burning fuels create waste products
due to impurities.
• Various gasses such as sulphur
dioxide, nitrogen oxide and other
volatile organic compounds can have
a harmful effect upon the
environment.
• The burning of fossil fuels contributes
towards global warming.
Energy demands
• The USA, Canada, Russia and many
European countries have huge energy
demands.
• India and China are growing rapidly in
terms of industry, with plans for
further expansion.
• All of this leads to concerns over
resources and environmental effects.

8. L J Hodgetts

9. Energy - availability, conservation and pollution
Availability
• Fossil fuels account for 85% of global energy use.
• It is considered that at current annual rates of
production, we have left worldwide, about:
• 155 years of coal
• 40 years of oil
• 65 years of natural gas
Impact
• Burning fuels create waste products
due to impurities.
• Various gasses such as sulphur
dioxide, nitrogen oxide and other
volatile organic compounds can have
a harmful effect upon the
environment.
• The burning of fossil fuels contributes
towards global warming.
Energy demands
• The USA, Canada, Russia and many
European countries have huge energy
demands.
• India and China are growing rapidly in
terms of industry, with plans for
further expansion.
• All of this leads to concerns over
resources and environmental effects.

11. UK usage
• In the UK, electricity is the main
source of energy for industry,
commercial and domestic use.
• The North sea gas reserves, which
helped to supply a significant
percentage of our energy needs, are
now dwindling, and importing from
Europe and Russia has increased.
• Renewable energy systems are being
increasingly used to provide small and
large scale, effective, environmental
power.
• www.bwea.com/ukwed/index.asp

12. L J Hodgetts

13. L J Hodgetts
Geothermal energy

14. UK usage
• In the UK, electricity is the main
source of energy for industry,
commercial and domestic use.
• The North sea gas reserves, which
helped to supply a significant
percentage of our energy needs, are
now dwindling, and importing from
Europe and Russia has increased.
• Renewable energy systems are being
increasingly used to provide small and
large scale, effective, environmental
power.
• UK Wind Energy Database

15. Energy production systems
Method Description Advantages Disadvantages Reference
Nuclear Nuclear fission generates heat,
heats water to generate steam,
steam turns turbines, turbines
turn generators, electricity
distributed.
Same cost as coal, no
smoke or carbon
dioxide emissions, lots
of energy from small
amount of fuel.
Radioactive spent fuel,
disposal of waste,
serious potential
effects of accidents.
World Nuclear
Association
Nuclear Institute
www.darvill.clara.net/
altenerg/nuclear.htm
Gas/Coal/Oil Fuel is burnt to generate heat,
heats water to generate steam
, steam turns turbines, turbines
turn generators, electricity
distributed.
Readily available,
ease of transport of
fuel, gas fired stations
very efficient.
Air pollution including
carbon dioxide and
sulphur dioxide, finite
resources, visual
impact of extraction,
large stocks needed
(coal)
www.darvill.clara.net/
altenerg/fossil.htm
www.discoveringfossil
s.co.uk/fossilfuels.ht
m
Hydro-electric Dam is used to trap water,
water released turns turbines,
turbines turn generators,
electricity distributed.
Very low cost once
dam built, no air
pollution, reliable, up
to full power quickly.
Can impact on
environment, (flooded
area, reduced flow at
base), initially
expensive.
www.darvill.clara.net/
altenerg/hydro.htm
www.therenewableen
ergycentre.co.uk/hyd
roelectric-power/
Wind Blades designed to catch wind,
blades turn turbines using
gears, turbines turn
generators, electricity
distributed.
No fuel needed, no
waste or greenhouse
gasses, can be used in
remote areas.
Unreliable, unsightly,
old designs can be
noisy, can harm flocks
of birds.
www.darvill.clara.net/
altenerg/wind.htm
Solar-
photovoltaic
Photovoltaic cells convert light
into electricity.
Low cost after initial
outlay, no pollutants
or waste, predictable.
Very expensive initial
cost, unreliable,
storage system
needed.
www.darvill.clara.net/
altenerg/solar.htm

16. Method Description Advantages Disadvantages Reference
Tidal barrages Barrage built across river
estuary, turbines turn as tide
enters (and when tide leaves),
turbines turn generators,
electricity distributed.
Low cost after initial
outlay, no pollutants
or waste, predictable.
Very expensive initial
cost, environmental
costs – can damage
habitats, only
generates power at
set times of the day.
www.darvill.clara.net
/altenerg/tidal.htm
Wave Motion of waves forces air up
cylinder to turn turbines,
turbines turn generators,
electricity distributed.
Low cost after initial
outlay, no pollutants
or waste, ok for
remote coastal areas.
Unreliable, hostile
environment, high
maintenance, not a
high power output.
www.darvill.clara.net
/altenerg/wave.htm
www.oceanpd.com
Geothermal Cold water pumped
underground through heated
rocks, steam turns turbines,
turbines turn generators,
electricity distributed.
No pollutants or
waste, minor cost of
pumping, resource
“free”, very small
stations, no negative
visual impact.
Only work in certain
locations, can be
unpredictable,
possibility of gas
emissions.
www.darvill.clara.net
/altenerg/geotherma
l.htm
www.renewableener
gyworld.com/rea/tec
h/geothermal
Biomass Fuel (wood, sugar cane, etc)
is burned to generate heat,
heats water to generate
steam, steam turns turbines,
turbines turn generators,
electricity distributed.
Readily available fuel,
can use waste
materials, low cost
process,
Air pollutants,
requires large
amounts of fuel, can
be seasonal.
www.darvill.clara.net
/altenerg/biomass.ht
m
www.biomassenergy
centre.org.uk
http://practicalaction.org/sustainable-design-
technology