Renewable and Non-Renewable Energy Sources


1. Energy resources can be divided into two main groups, renewable and non-renewable.


2. Renewable energy sources are energy sources that can be replaces after being used. An example of renewable energy source is solar energy.


3. Non-renewable energy sources are energy sources that cannot be replaced after being used. They will run out eventually. An example of non-renewable energy source is petrol.


4. We can group the various sources of energy into renewable and non-renewable sources as shown below.  

Renewable energy sources

Non-renewable energy sources

* Wind

* Fossil fuels

* Tidal/wave energy

* Radioactive substances (nuclear

* Biomass


* Hydroelectricity


* Geothermal energy


* Solar energy



Renewable energy sources

1. Wind energy

   (a) Wind power is used to turn the blades of large
         windmills or generators to produce electricity,
         or to pump water out of the ground. A high
         wind speed is needed to power wind generators

   (b) Wind generated electricity does not cause air
         pollution. However, it costs more to
         produce than the electricity generated from coal.


2. Tidal/wave energy

    (a) The Earth movement is the source of tidal energy. A dam or barrage is built across
          a river mouth or estuary. Electricity is generated by the flow of water through
          turbines in the dam as the tides rise and fall.

    (b) Waves are caused by wind and partly by
          the tides. The rapid up-and-down
          movement of waves on the surface of
          the sea can also drive turbines to
          produce electricity.

    (c) Although tidal and wave energies do not
          produce pollution, they can cause other
          environmental problems.


3. Biomass energy

    (a) Biomass is plant and animal waste materials that can be used for generating energy.
         This includes using fuel made from sugar cane, biogas of rotting waste and manure
          of livestock.

    (b) Methane gas from biomass is used to generate
          electricity, or is burnt for light and
          heating purposes.

    (c) Converting biomass energy into usable
          energy has many environmental benefits. It
          uses waste materials that are usually
          dumped and uses up methane (a greenhouse

    (d) Fuels such as alcohol can be made from biomass and used as an alternative to
          petrol to power motor cars.

    (e) There are a number of renewable energy projects using biomass. Many of these
          use waste products from agriculture. So, they solve the problem of waste disposal
          and at the same time create energy for use in homes, farms an factories.


4. Water power - hydroelectric energy

    (a) Hydroelectricity is produced from the kinetic energy of water. The movement of
          the water spins turbines which generate electricity.

    (b) Locations with high rainfall and steep mountains are ideal for hydroelectricity. The
          hydroelectric power plant in Kenyir Lake is one of the largest in Malaysia.

    (c) Most hydroelectricity projects require the building of large dams across rivers,
          which can be very expensive.

    (d) The use of hydroelectric energy does not cause
          pollution but the building of the
          large dams affects the ecosystems of the 
          surrounding area. Many cultural sites
          may ne flooded and sometimes people need
          to be resettles elsewhere. There are
          also impacts on fish breeding, loss of
          wildlife habitat and changes in the flow of


5. Geothermal energy

    (a) Geothermal energy uses heat energy from beneath the surface of the Earth.

    (b) Some of this heat finds its way to the surface in the form of hot springs or
          geysers. Other schemes tap the heat energy by pumping
          water through hot dry rocks several kilometres
          beneath the Earth's surface.

    (c) Geothermak energy is used for generating electricity
         and for heating up buildings and water in some

    (d) Geothermal energy is a good source of energy
          because it is clean and can be extracted without
          burning fossil fuels such as coal, gas or oil.


Non-renewable energy sources

1. Fossil fuels

    (a) There are three major forms of fossil fuels, namely coal, petroleum and natural

    (b) They are called fossil fuels because they are formed over millions of years from
           the fossils or remains of dead animals and plants. The fossils are buried under
           dirt and rock. Heat from the Earth and pressure from dirt and rock changes
           these fossils into oil, natural gas and coal. 

    (c) As it takes millions of years to make or renew more fossil fuels, we call them 'non-
          renewable fuels

    (d) Coal

         (i) Coal is our most abundant fossil fuel resource. It
              is a hard, black, rock-like substance.

        (ii) Coal is mainly burned in power stations to generate
              electricity and as a source of
              heat for industry.

       (iii) Burning of coal can produce a lot of carbon dioxide
              and some other toxic gases that can pollute the

    (e) Petroleum

         (i) Petroleum or crude oil is formed in a similar way as coal. But instead of becoming
              a rock, it becomes a liquid trapped between layers of rocks.

        (ii) Petroleum can be made into gas, petrol, kerosene, diesel, oils and bitumen. These
              products are used in homes for heating and cooking, and in factories as a source
              of heat energy. They are also used in power stations to generate electricity and
              to provide fuel for transport.

       (iii) Another common use for petroleum is in producing petrochemicals such as

       (iv) However, the use of petrochemicals like petrol and diesel produces a lot of
              carbon dioxide. It also produces other poisonous gases that are harmful to the
              environment and health.

    (f) Natural gas

         (i) Natural gas is formed in the same way as
              petroleum and is also trapped between
              layers of rock. It is usually found near

        (ii) Natural gas is tapped, compressed and piped
              into homes to be used in stores and
              hot water systems.

       (iii) LPG (Liquefied Petroleum Gas) is made from
              petroleum. It is used for cooking
              and heating at homes, factories and

       (iv) LPG can also be used as an alternative fuel to


2. Radioactive substances like uranium-235 is the main source of nuclear energy. When
    the nuclei of uranium-235 are split apart by nuclear reaction, a tremendous amount of
    energy is released. The energy is used for generation of electricity.


The Uses Of Solar Energy

1. The Sun supplies solar energy which radiates as light energy and heat energy.


2. Solar energy is renewable and can be used continuously as long as the Sun exists.


3. Solar energy cannot be used directly but can be converted to other forms of energy using converters.


4. Figure 6.24 shows how we can harness solar energy for daily uses.


The Need To Conserve Energy

1. It is important to save energy because most of the energy we use comes from fossil fuels. Fossil fuels are non-renewable.


2. At present, we rely heavily on fossil fuels to sustain our daily activities. If we use up all of our fossil fuels, there will not be any left in the future. Our daily activities will be affected.


3. Increased consumption of fossil fuels can cause environmental damage, air pollution and global warming. Conserving energy can slow down or reduce all these negative effects.


4. So it is important for us to learn how to conserve energy. To conserve energy means to find out ways in which we can use less energy and not waste energy.


5. It is also important for us to learn how to manage the energy resources more efficiently.


Ways To Increase Efficient Use Of Energy

1. Efficient use of energy means getting the most use of energy with the minimum waste of energy.


2. The efficient use of energy is the most immediate way to reduce energy use and pollution. 


3. The use of non-renewable energy sources like fossil fuels and nuclear fuels must be planned and managed carefully so that we can get cheaper fuels.


4. We have to develop renewable energy sources like solar, wind, water and biomass energy. With the help of the latest technology, all these energy sources can be used more efficiently without causing much damage to our environment.


5. Some of the ways we can use energy efficiently are:

    (a) Using energy-saving electrical appliances.

    (b) Using fluorescent lamps which are more energy efficient. A compact fluorescent
          light uses 70% less energy and can last up to 10 times longer compared with a
          filament bulb.

    (c) In the kitchen, using pressure cooker and cooking utensils made of goof conductors
          of heat can reduce cooking time and thus reduce the energy used.

    (d) In transportation, use public transport like buses and light rail transit (LRT) to go
          to work instead of using your own car if you are driving alone. Car pooling will also
          help to reduce the use of energy and traffic congestion.

    (e) Any new building should be designed to be more energy efficient. The building
          should be well ventilated, making use of solar technology and making maximum use
          of natural light.