Renewable Energy

1. Unit-I
Introduction of Renewable Energy
BY
R.ARULJOTHI
M.Tech( 2nd YEAR)
15EE302
Under the guidance of
DR. N.P. SUBRAMANIAM, M.E.,Ph.D.,
ASSISTANT PROFESSOR
DEPARTMENT OF ELECTRICALAND ELECTRONICS
ENGINEERING
PONDICHERRY ENGINEERING COLLEGE

2. Overview
• Introduction
• Need of Renewable Energy
• Types of Renewable Energy
• Storage Devices
• Photocatalysis via Water Splitting
• Microgrid

3. Renewable Energy-Introduction
• Renewable energy is generally defined as energy that is collected
from resources which are naturally replenished on a human
timescale.
• The source of energy which is freely available from nature and
never exhausting and continuous renewed are called Renewable
Energy Sources.
• Renewable energy is energy generated from natural resources
such as sunlight, wind, rain, tides and geothermal heat ,which are
renewable (naturally replenished).
• Renewable energy technologies range from solar power, wind
power, hydroelectricity/micro hydro, biomass and biofuels for
transportation.
• Renewable energy is energy that is generated from natural
processes that are continuously replenished. This includes
sunlight, geothermal heat, wind, tides, water, and various forms
of biomass. This energy cannot be exhausted and is constantly
renewed.

4. Need of Renewable Energy
• Conventional energy sources fixed and limited
• Cost, Demand and Supply increase
• Conventional energy sources can’t be regenerated
• Transportation of coal, petroleum difficult and costly
• Associated with hazards and fire
• Transmission and Distribution costly of Conventional energy sources
• Conventional energy sources produces pollution
• Conventional energy sources are owned by few country
• Energy security of conventional energy sources very less.

5. Types of Renewable Energy
• Solar Energy
• Wind Energy
• Biomass
• Hydropower
• Nuclear power
• Geothermal energy
• Ocean energy

6. Solar Energy
• Solar power is the conversion of sunlight into electricity either directly by
using photo voltaic or concentrated solar power.
• A solar cell, or photovoltaic cell (PV), is a device that converts light into
electric current using the photoelectric effect.
 Advantages
• Non-polluting: Solar energy is an alternative for fossil fuels as it is non-
polluting, clean and reliable
• Solar energy is a renewable source of energy as it can be used to produce
electricity as long as the sun exists.
 Dis-Advantages
• The primary disadvantage of solar power is that it obviously cannot be
created during the night.
• The power generated is also reduced during times of cloud cover
(although energy is still produced on a cloudy day).
 Applications
• Solar water heater
• Solar water pump
• Solar furnaces
• Traffic light, Street light and railways signal
• Solar cooker

7. Wind Energy
• Wind energy is a form of solar energy.
• Wind energy(or wind power) describes the process by which wind is used to
generate electricity.
• Wind turbines convert the kinetic energy in the wind into mechanical power.
• A generator can convert mechanical power into electricity.
 Advantages
• It's a clean fuel source.
• Wind energy doesn't pollute the air like power plants that rely on combustion of
fossil fuels, such as coal or natural gas.
 Dis-Advantages
• Direction and motion of wind not continuous
• Unpredictable
• In interior region not suitable
• Uneven speed cause difficulty to generate Electrical Energy
 Applications
• Generate Electrical energy by wind mill
• Water pump for irrigation
• Flour mill
• Run machine without electric power

8. Biomass
• Biomass is organic matter derived from living, or recently living
organisms.
• Biomass power is carbon neutral electricity generated from renewable
organic waste that would otherwise be dumped in landfills, openly burned,
or left as fodder for forest fires.
• In biomass power plants, wood waste or other waste is burned to produce
steam that runs a turbine to make electricity, or that provides heat to
industries and homes.
 Advantages
• Biomass used as a fuel reduces need for fossil fuels for the production of
heat, steam, and electricity for residential, industrial and agricultural use.
• Biomass fuel from agriculture wastes maybe a secondary product that adds
value to agricultural crop.
 Dis-advantages
• Research is needed to reduce the costs of production of Biomass based
fuels.
• Expensive
• Require More Land

9. Geothermal Energy
• Geothermal energy is the energy obtained from the earth(geo) from the hot
rocks present inside the earth.
• It is produced due to the fission of radioactive materials in the earth’s core
and some places inside the earth become very hot. These are called hot
spots.
• They cause water deep inside the earth to form steam.
• As more steam is formed, it gets compressed at high pressure and comes
out in the form of hot springs which produces geothermal power.
 Advantages
• Maintenance cost of geothermal power plants is very less.
• Geothermal power plants don't occupy too much space.
• Unlike solar energy, it is not dependent on the weather conditions.
• It is non-polluting and environment friendly.
 Dis-advantages
• Total generation potential of this source is too small.
• There is always a danger of eruption of volcano.
• Installation cost of steam power plant is very high.

10. Nuclear Energy
• Nuclear power is the use of nuclear reactions that release nuclear energy to
generate heat, which most frequently is then used in steam turbines to
produce electricity in a nuclear power plant.
• The term includes nuclear fission, nuclear decay and nuclear fusion.
• Nuclear energy is a powerful source of energy, generated during a nuclear
reaction, by change in the nucleus of an atom. The source of nuclear energy
is the mass of the nucleus and energy generated during a nuclear reaction is
due to conversion of mass into energy.
 Advantages
• Nuclear power produces very less amount of pollution.
• Very small amount of raw material is required.
• It is a very reliable source of energy
 Dis-advantages
• The danger of accidental discharge of radio activity also exists.
• Nuclear power stations are always at the risk from terrorist attack.
• Proliferation of nuclear technology increases the risk of nuclear war too.

11. Tidal Energy
• Tides are the waves caused due to the gravitational pull of the moon and
also sun(though its pull is very low). The rise is called high tide and fall is
called low tide.
• During high tide, the water flows into the dam and during low tide, water
flows out which result in turning the turbine.
 Advantages
• It is an inexhaustible source of energy.
• Tidal energy is environment friendly energy and doesn't produce
greenhouse gases.
• As 71% of Earth’s surface is covered by water, there is scope to generate
this energy on large scale.
• Maintenance costs are relatively low.
• The life of tidal energy power plant is very long.
• The energy density of tidal energy is relatively higher than other renewable
energy sources.
 Dis-Advantages
• Cost of construction of tidal power plant is high.
• The actual generation is for a short period of time.
• There are very few ideal locations for construction of plant and they too are
localized to coastal regions only.

12. Storage Devices
• Energy storage is the capture of energy produced at one time for use at a later time.
• A device that stores energy is sometimes called an accumulator.
• There are two types of storage devices in Electrical Method
 Capacitor
 Battery
• A capacitor (originally known as a 'condenser') is a passive two-terminal electrical
component used to store energy electrostatically.
• Practical capacitors vary widely, but all contain at least two electrical conductors
(plates) separated by a dielectric (i.e., insulator).
• A capacitor can store electric energy when disconnected from its charging circuit, so
it can be used like a temporary battery, or like other types of rechargeable energy
storage system.
• Capacitors are commonly used in electronic devices to maintain power supply while
batteries change.

13. • An electric battery is a device consisting of one or more electrochemical
cells with external connections provided to power electrical devices such as
flashlights, smartphones, and electric cars.
• The range and diversity of batteries used as a source of electrical power is
truly enormous, reflecting the immense range of uses of electrical power.
They range in size from tiny button cells storing milliwatthours of energy
and delivering microwatts of power to giant load levelling batteries, the size
of buildings, storing megawatthours and delivering megawatts.
Application / Requirement Battery type
Low power, low cost consumer applications
Low power Primary and Secondary cells. Leclanché,
Alkaline, NiCad, NiMH, Lithium primary, Lithium
secondary.
Power tools, cordless equipment NiCad, NiMH, Lithium Ion
Small devices, hearing aids, watches, calculators,
memory back up, wireless peripherals.
Primary button and coin cells, Zinc air, Silver oxide,
Lithium Thyonyl Chloride and other Lithium
primaries
Industrial traction batteries Lead acid, Nickel Iron
Other traction batteries, robots, bicycles, scooters,
wheelchairs, lawnmowers
Lead acid, Nickel Zinc, NiMH, Lithium Ion
Very high power, load levelling.
Pumped, renewable electrolyte
Flow batteries

14. Photocatalysis via Water Splitting
• Photocatalytic water splitting is an artificial photosynthesis process with
photocatalysis in a photoelectrochemical cell used for the dissociation of
water into its constituent parts, hydrogen and oxygen , using either artificial
or natural light. Theoretically, only solar energy (photons), water, and a
catalyst are needed.
• Most of the energy that we use comes from fossil fuels,
• Problem with fossil fuel:
A. Production of greenhouse gases
B. The amount of fossil fuel on the Earth is limited
• To replace or reduce the use of fossil fuels, several alternative energies
have been developed.
• These energy sources include
A. wind.
B. hydropower.
C. solar.
D. geothermal.

15. • Hydrogen is the ideal fuel for the future.
• it is clean, energy efficient, and abundant in nature.
• While various technologies can be used to generate hydrogen, only some of them can be
considered environmentally friendly.
• solar hydrogen generated via photocatalytic water splitting
A. low-cost
B. clean hydrogen production.
• Photocatalytic water splitting is another promising technology to produce “clean” hydrogen.
• Compared with thermochemical and photobiological water-splitting techniques, it has the
following advantages:
• Reasonable solar-to-hydrogen efficiency;
• Low process cost;
• Small reactor systems suitable for household applications, thus providing for a huge market
potential.
Mechanism of photocatalytic
water splitting

16. Types of Photocatalytic Water-Splitting Reaction
(1) Photochemical-cell reaction.
(2) Photoelectrochemical-cell reaction.
The mechanism basically involves 4 major steps:
(1)generation of electron-hole pairs.
(2)oxidation of water by photo-generated holes
(3)transfer of photo-generated electrons
(4) reduction of H+ by photo-generated electrons.

18. • Pt/SrTiO3:Rh and WO3, used as H2-photocatalyst and O2-photocatalyst,
respectively
• ion-exchange membrane allows the transport of protons, As well as the
exchange of the mediator ions (Fe2+/Fe3+) in solution

19. Future Prospects of Photocatalytic Water Splitting
• Over the past few decades, several semiconductor materials and
photocatalytic systems have been developed for the water-splitting
reaction under UV and visible-light irradiation.
• It has been observed that photo-generated charge separation,
prevention of water-splitting backward reaction
• utilization of a large fraction of the incident energy are the essential
requirements for achieving high photo-conversion efficiency.
• The development of new technologies requires collaboration of
many streams with a strong theoretical background for a better
understanding of the hydrogen production mechanism in order to
come up with a low-cost and environmentally friendly water-
splitting process for hydrogen production.

20. Microgrid
• It is a small-scale power supply network that is designed to provide power
for a small community.
• It enables local power generation for local loads.
• It comprises of various small power generating sources that makes it highly
flexible and efficient.
• It is connected to both the local generating units and the utility grid thus
preventing power outages.
• Excess power can be sold to the utility grid.
• Size of the Microgrid may range from housing estate to municipal regions.
Microgrid Components
• Distributed Generation
• Loads
• Immediate storage
• Controller
• Point of Common Coupling

21. Typical Microgrid is shown below:

22. Microgrid Operating Modes
Grid Connected Mode:
• Utility grid is active.
• Static switch is closed
• All the feeders are being
• supplied by utility grid.

23. Microgrid Operating Modes
Island Mode:
 Utility grid is not supplying power
 Static switch is open.
 Feeder A, B, C are being supplied
by Microsources.
 Feeder D (not sensitive )
is dead.

24. Conventional Grid vs. Microgrid
 Efficiency of conventional grid is very low as compared to Microgrid.
 Large amount of energy in the form of heat is wasted in conventional
grid.
 Power sources in case of Microgrid (often referred to as Microsources)
are small and are located in close proximity to load.
• Microgrid encourages the use of the renewable energy sources.
• Large land use impacts are avoided.
• CO2 Emissions are reduced.
Environmental Aspects

25. Advantages & Disadvantages
Advantages
• A major advantage of a Microgrid, is its ability, during a utility grid
disturbance, to separate and isolate itself from the utility seamlessly with
little or no disruption to the loads within the Microgrid.
• In peak load periods it prevents utility grid failure by reducing the load
on the grid.
• Significant environmental benefits made possible by the use of low or
zero emission generators.
• The use of both electricity and heat permitted by the close proximity of
the generator to the user, thereby increasing the overall energy efficiency.
• Microgrid can act to mitigate the electricity costs to its users by
generating some or all of its electricity needs.
Dis-Advantages
• Voltage, frequency and power quality are three main parameters that
must be considered and controlled to acceptable standards whilst the
power and energy balance is maintained.
• Electrical energy needs to be stored in battery banks thus requiring more
space and maintenance.
• Resynchronization with the utility grid is difficult.

26. References
• Chi-Hung Liao, Chao-Wei Huang, and Jeffrey C. S. Wu. Hydrogen
Production from Semiconductor-based Photocatalysis via Water
Splitting. Catalysts 2012, 2, 490-516.
• Midilli, A.; Ay, M.; Dincer, I.; Rosen, M.A. On hydrogen and
hydrogen energy strategies I:
• Current status and needs. Renew. Sustain. Energy Rev. 2005, 9, 255–
271.
• Parida, B.; Iniyan, S.; Goic, R. A review of solar photovoltaic
technologies. Renew. Sustain.Energy Rev. 2011, 15, 1625–1636.
• Kishore VVN, Renewable Energy Engineering and Technology, Teri
Press, New Delhi, 2009.
• John Twidell, Anthony D. Weir, A., Renewable Energy Sources,
EFN Spon Ltd, 2nd edition, 2006.