2. ❑ Biomass is organic material that comes from recently dead plants
and animals.
❑ Biomass contains energy that once came from the Sun. Plants
convert energy from the Sun into chemical energy. This process is
called photosynthesis.
❑ Animals that eat plants use and store this energy in their own
bodies. Fossil fuels are not considered as biomass.
❑ Wood, waste from crops, landfill gas, and municipal solid waste are
some of the common types of biomass. In Canada, industrial wood
waste is the most common type of biomass.
7. Biomass is produced in the photosynthesis process
solar energy into biomass energy.
which converts the
Photosynthesis process only occurs in green plants.it is the process of
combining the carbon dioxide from the atmosphere with water plus light
energy to carbohydrates produce(sugars,starches,celluloses etc.)and
oxygen.
6O2+C6H12O6
6CO2 + 6H2O + light energy
8. ❑ Biopower technologies convert renewable biomass fuels into heat and
electricity using processes similar to those used with fossil fuels.
❑ There are three ways to release the energy stored in biomass
to produce biopower:
❖ Burning,
❖ Bacterial decay,
❖ Conversion to gas/liquid
10. ❑ Most electricity generated from biomass is produced by direct
combustion.
❑ Biomass is burned in a boiler to produce high-pressure steam. This
steam flows over a series of turbine blades, causing them to rotate.
The rotation of the turbine drives a generator, producing electricity.
❑ Biomass can also serve as substitute for a portion of coal in an
existing power plant furnace in a process called co-firing
(combusting two different types of materials at the same time).
11. 2. BACTERIAL DECOMPOSITION (ANAEROBIC DIGESTION)
❑ Organic waste material, such as animal dung or human sewage, is
collected in oxygen-free tanks called digesters.
❑ Here, the material is decomposed by anaerobic bacteria that
produce methane and other byproducts to form a renewable natural
gas, which can then be purified and used to generate electricity.
3. CONVERSION TO A GAS OR LIQUID FUEL
❑ Biomass can be converted to a gaseous or liquid fuel through
gasification and pyrolysis. Gasification is a process that exposes
solid biomass material to high temperatures with very little oxygen
present, to produce synthesis gas (or syngas)—a mixture that
consists mostly of carbon monoxide and hydrogen.
12. ❑ The gas can then be burned in a conventional boiler to produce
electricity. It can also be used to replace natural gas in a combined-
cycle gas turbine.
❑ Pyrolysis uses a similar process to gasification but under different
operating conditions.
❑ In this scenario, biomass is heated at a lower temperature range
but in the complete absence of oxygen to produce a crude bio-oil.
This bio-oil is then substituted for fuel oil or diesel in furnaces,
turbines, and engines for electricity production.
13. ❑ Some biomass plants generate electricity by burning methane.
❑ Methane is a gas that can be collected from landfills.
❑ These plants use a slightly different process than plants that burn
solid biomass.
❑ The products of burning methane, instead of steam, cause the
turbine to spin. As with solid biomass, the rotation of the turbine
drives a generator.
❑ Generators are devices that generate electricity. Generators convert
mechanical energy into electrical energy. First a force from the water
vapour or gas makes the rotor turn.
14. ❑ The rotor has a coil of wire that spins inside a fixed magnet around
it, called the stator.
❑ The rotation creates a magnetic field which forces electrons to move
along the wire. This generates electric current. We call this
electromagnetic induction. The metal wire constantly moves inside
the magnet. This creates a continuous flow of electrons, generating
electricity.
15. ❑ Unlike other types of renewable energy resources, biomass plants
can generate power all the time. They don’t rely on intermittent
things such as wind or sun. This makes electricity from biomass
reliable.
❑ To make biomass renewable, the consumed plant material needs to
be replaced as quickly as it is used. This may be through growing
new crops or planting trees. If this were to happen, then burning
biomass would not increase greenhouse gas levels. But if it does
not, then burning biomass would increase greenhouse gas levels.
❑ Another advantage of using biomass is that it can prevent some
types of waste from going to landfills.
16. Disadvantages of Biomass Electricity Generation
❑ Burning biomass produces similar greenhouse gases to burning
fossil fuels. These greenhouse gases contribute to rising global
temperatures. Burning biomass also releases other pollutants into
the air. These pollutants include particulate matter, nitrogen oxides,
sulfur and dioxide. Air pollution can cause respiratory issues, heart
disease, cancer, and other health issues.
❑ Biomass-generated electricity can also impact the environment in
other ways. For example, cutting down trees can lead to
deforestation. Growing plants to use as biomass can impact soil
quality and water usage. These plants take up space where wild
plants could have grown.
18. TIDAL ENERGY
Introduction
❑ Tidal energy is produced by the surge of ocean waters during the
rise and fall of tides.
❑ Tidal Energy or Tidal Power as it is also known, is another form of
hydro power that exploits the vast energy source of the oceans tides
to generate electricity.
❑ Tidal Energy is a “sustainable energy source”, as the Earth uses the
gravitational forces of both the moon and the sun everyday to move
vast quantities of water around the oceans and seas producing
tides.
19. ❑ As the Earth, its Moon and the
Sun rotate around each other in
space, the gravitational
movement of the moon and the
sun with respect to the earth,
causes millions of gallons of
water to flow around the Earth’s
oceans creating periodic shifts
in these moving bodies of water.
These vertical shifts of water are
what we call “tides”.
Alignment of the Moon and Sun
on Tidal Energy
20. ❑ When the earth and the moons gravity lines up with each other, the
influences of these two gravitational forces becomes very strong and
causes millions of gallons of water to move or flow towards the
shore creating a “high tide” condition.
❑ Likewise when the earth and the moons gravity are at 90o to each
other, the influences of these two gravitational forces is weaker and
the water flows away from the shore as the mass of water moves to
another location on the earth, creating a “low tide” condition.
21. ❑ When the moon is in perfect alignment with the earth and the
sun, the gravitational pull of the moon and sun together becomes
much stronger than normal with the high tides becoming very high
and the low tides becoming very low during each tidal cycle. Such
tides are known as spring tides (maximum). These spring tides
occur during the full or new moon phase
❑ The other tidal situation arises during neap tides (minimum) when
the gravitational pull of the moon and the sun are against each
other, thus cancelling their effects. The net result is a smaller pulling
action on the sea water creating much smaller differences between
the high and low tides thereby producing very weak tides
22. ❑ The time taken for a tidal cycle to happen is about 12 hours and 24
minutes (called the “diurnal cycle”) between two consecutive high
tides allowing Oceanographers and Meteorologist to accurately
predict the ebb and flow of the tides around the oceans many years
in advance.
❑ Therefore Tidal Energy can be considered as a renewable energy
source as the oceans energy is replenished by the sun as well as
through tidal influences of the moon and suns gravitational forces.
24. ❑ Since the position of the earth and the moon with respect to the sun
changes throughout the year, we can utilise the potential energy of
the water contained in the daily movement of the rising and falling
sea levels to generate electricity.
❑ The generation of electricity from tides is similar in many ways to
hydro-electric generation we looked at in the hydro energy tutorials.
The difference this time is that the water flows in and out of the
turbines in both directions instead of in just one forward direction.
25. Tidal Energy Generation
Tidal energy, just like hydro energy transforms water in motion into a clean
energy. The motion of the tidal water, driven by the pull of gravity, contains
large amounts of kinetic energy in the form of strong tidal currents called
tidal streams.
The daily ebbing and flowing, back and forth of the oceans tides along a
coastline and into and out of small inlets, bays or coastal basins, is little
different to the water flowing down a river or stream.
Tidal generators are designed to produce power when the rotor blades are
turning in either direction. However, the cost of reversible electrical
generators are more expensive than single direction generators.
26. Different Types of Tidal Systems
❑ Tidal Barrage – A Tidal Barrage is a type of tidal power generation
that involves the construction of a fairly low dam wall, known as a
“barrage” and hence its name, across the entrance of a tidal inlet or
basin creating a tidal reservoir..
❑ A tidal barrage generates electricity using the difference in the
vertical height between the incoming high tides and the outgoing low
tides. As the tide ebbs and flows, sea water is allowed to flow in or
out of the reservoir through a one way underwater tunnel system.
❑ The one disadvantage of Tidal Barrage Generation, is that it can
only generate electricity when the tide is actually flowing either “in”
or “out” as during high and low tide times the tidal water is
stationary.
27. ❑ Tidal Stream– A Tidal Stream Generation system reduces some of
the environmental effects of tidal barrages by using turbine
generators beneath the surface of the water. Major tidal flows and
ocean currents, like the Gulf Stream, can be exploited to extract its
tidal energy using underwater rotors and turbines.
❑ Tidal stream turbines generate tidal power on both the ebb and flow
of the tide. One of the disadvantages of Tidal Stream Generation is
that as the turbines are submerged under the surface of the water
they can create hazards to navigation and shipping.
❑ This is basically a fixed wing called a Hydroplane positioned on the
sea bed.
28. Advantages of Tidal Energy
❑ Tidal energy is a renewable energy resource because the energy it
produces is free and clean as no fuel is needed and no waste bi-products
are produced.
❑ Tidal energy has the potential to produce a great deal of free and green
energy.
❑ Generally tidal energy is not expensive to operate and maintain compared
to other forms of renewable energies.
❑ Low visual impact as the tidal turbines are mainly if not totally submerged
beneath the water.
❑ Low noise pollution as any sound generated is transmitted through the
water.
❑ High predictability as high and low tides can be predicted years in
advance, unlike wind.
29. Disadvantages of Tidal Energy
❑ Tidal energy is not always a constant energy source as it depends
on the strength and flow of the tides which themselves are effected
by the gravitational effects of the moon and the sun.
❑ Tidal Energy requires a suitable site, where the tides and tidal
streams are consistently strong.
❑ Must be able to withstand forces of nature resulting in high capital,
construction and maintenance costs.
❑ High power distribution costs to send the generated power from the
submerged devices to the land using long underwater cables.
❑ Danger to fish and other sea-life as they get stuck in the barrage or
sucked through the tidal turbine blades.
