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This slide is the presentation of the various renewable sources.
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Renewable Energy Sources
What is Renewable Energy? Renewable resources are natural resources that can
be replenished in a short period of time.
A renewable resource is a natural resource that can be re-made or re-grown at a scale comparable to its consumption
Nonrenewable / Fossil Fuels1. Coal2. Liquid Hydrocarbons- Petroleum (oil)3. Natural Gas
HOW ARE FOSSIL FUELS MADE ???
Coal, petroleum, and natural gas are considered nonrenewable because they can not be replenished in a short period of time
Why Renewable Energy?Conventional fuels are having high energy value, low cost, easily transportable etc.,But…
Why Renewable Energy?
Problems with Fossil Fuels Limited Supply- At projected consumption rates, natural
gas & petroleum will be depleted by the end of the 21st century
Global Warming - Burning fossil fuels produces large amounts of CO2, which is the main green house gas
Impurities are major source of pollution For e.g.; SO2 travels on air currents & falls with
precipitation as acid rainMakes one country rely on other countries for their
energy needs
RENEWABLE RESOURCES Solar Wind Biomass Water Geothermal OTEC Tidal and Wave
Solar Energy
9
What is Solar Energy?
Energy produced by the sunClean, renewable source of energyHarnessed by solar collection methods such as solar cells, solar Collectors etc.Converted into usable energy such as electricity, heat etc.
Photovoltaic (solar) panel
Set of solar panels
Solar Energy Conversion Systems Solar Photovoltaic System – PV Cell
Solar Energy Electrical Energy Solar Thermal Energy Conversion SystemSolar Energy Thermal Energy
ORSolar Energy Thermal Energy Electrical Energy
Solar Photovoltaic System
© NASA/NREL
Solar cells (or photocells) turn light energy from the Sun directly into direct current electricity. Once the solar cell is built it produces no pollution and requires little maintenance.
This makes solar cells ideal for use in remote locations where maintenance is difficult and other sources of electricity would be expensive.
Solar cells
Solar cells suffer from a low efficiency. This is because only light with enough energy causes an electron to be released which is only about 25% (maximum) of all sunlight.
Producing enough electricity to power a town would require a very large area of solar panels but covering the roof of a house can meet the annual electricity needs of the household.
Efficiency of a solar cell
n-type semiconductor
p-type semiconductor
+ + + + + + + + + + + + + + + - - - - - - - - - - - - - - - - - -
Depletion Zone
Photo voltaic Cell
Photovoltaic System
Typical output of a module (~30 cells) is ≈ 15 V, with 1.5 A current
PV Technology Classification
Amorphous Silicon PV Cells Efficiency is less around 5% Makes 13% of PV market
Multi Crystalline PV Cells Efficiency is less around 10 to 15% Accounts for 90% of crystalline Si market
Mono Crystalline PV Cells Operating efficiency 20 to 25%
Applications of PV Water Pumping: PV powered pumping systems are excellent
,simple ,reliable – life 20 yrs Commercial Lighting: PV powered lighting systems are
reliable and low cost alternative. Security, billboard sign, area, and outdoor lighting are all viable applications for PV
Consumer electronics: Solar powered watches, calculators, and cameras etc.
Telecommunications Residential Power: A residence located more than a mile
from the electric grid can install a PV system more inexpensively than extending the electric grid (Over 500,000 homes worldwide use PV power as their only
source of electricity)
Solar Thermal Energy Conversion SystemsPassive SystemActive system (Solar Thermal Collectors)
Solar Thermal Collectors
• Non focussing Collectors (Flat plate collector)
• Focussing Collectors
• Line focussing
• Point Focussing
Flat Plate Collector
Solar water heater
Thermal storage
Steam power plant – a recap
Line focussing- parabolic Collector
© Warren Gretz/NREL© Warren Gretz/NREL
Point Focussing
© Bill Timmerman/NREL
Point Focussing
Solar power stations use the energy from the sun to heat water to make steam, which is then used to drive a turbine.
Some solar power stations use a series of mirrors called heliostats to reflect light onto a boiler.
Solar power stations
© Sandia National Laboratory/NREL
Other Solar devicesSolar StillSolar Air HeaterSolar Water PumpSolar CookerSolar dryer
Solar still
WIND ENERGY
Uneven heating of earth’s surface and rotation
Turbine Evolution
Used for Pumping water Grinding grain
Mainly used for Generating Electricity
Types of turbinesVAWT – Vertical Axis Wind Turbine
Drag is the main force
Nacelle is placed at the bottom
Yaw mechanism is not required
Lower starting torque
Difficulty in mounting the turbine
Unwanted fluctuations in the power output
HAWT – Horizontal Axis Wind Turbine
Lift is the main force
Much lower cyclic stresses
95% of the existing turbines are
HAWTs
Nacelle is placed at the top of the tower
Yaw mechanism is required
Two types of HAWTDOWNWIND TURBINE
UPWIND TURBINE
A Typical HAWT
Offshore turbines – coastal development
Offshore turbines
More wind speeds
Less noise pollution
Less visual impact
Difficult to install and maintain
Energy losses due long distance transport
Disc type wind turbineMuch more efficient than HAWT
Requires less height
Low noise
Works in any wind direction
BIOMASS
Biomass Sources
Direct combustion
Thermo chemical
Gasification
Pyrolysis
Bio Chemical Conversion
Digestion
Fermentation
Conversion of Biomass
Solid Fuel Combustion Biomass was the first fuel
mankind learned to use for energy, Burning wood for warmth and cooking
Direct combustion of solid matter where the biomass is fed into a furnace where it is burned. The heat is used to boil water and the energy in the steam is used to turn turbines and generators.
Animal Dung
Wood
Gasification A process that uses heat, pressure, and steam to convert materials directly into a gas composed primarily of carbon monoxide and hydrogen.
GasificationTypical raw materials - coal, petroleum-based
materials, and organic materials.
The feedstock is prepared and fed, in either dry or slurried form, into a sealed reactor chamber called a gasifier.
The feedstock is subjected to high heat, pressure, and either an oxygen-rich or oxygen-starved environment within the gasifier.
Pyrolysis Heat is used to chemically convert
biomass to Gaseous liquid and solid fuels.
Biomass is heated to 500oC to 900 oC in a closed vessel in the absence of Oxygen
Pyrolysis can perform almost all form of organic materials
Digestion Decomposition of organic matter by anaerobic bacteria in an oxygen-starved environment.
Anaerobic digesters compost (or “digest”) organic waste in a machine that limits access to oxygen encouraging the generation of methane and carbon dioxide by microbes in the waste. This digester gas is then burned as fuel to make electricity.
Digestion
Fermentation Unlike other renewable energy sources, biomass
can be converted directly into liquid fuels— bio-fuels— for our transportation needs (cars, trucks, buses, airplanes, and trains)
The two most common types of bio-fuels are ethanol and bio-diesel
Ethanol – An additive to gasoline
Bio-diesel - made by combining alcohol with vegetable oil, animal fat etc.
Hydropower
Water power• Converts Potential
energy of water to mechanical energy and then to electrical energy
• One of the main source of energy after conventional energy
• In india, approximately 22% of energy is from hydel power
Water power
Water power- working of turbine
Impulse Turbine (Pelton Wheel) High Head, Low discharge
Mixed flow Reaction Turbine (Francis Turbine) Medium Head, Medium discharge
Axial flow Reaction Turbine (Kaplan Turbine ) Low Head, High discharge
Water Turbines
GEOTHERMAL ENERGY
Steam power plant – a recap
Geothermal
• The thermal energy contained in the interior of earth is called Geothermal Energy• Use heat to make steam
which rotatesturbine for electrical generation
Geothermal Energy
Ocean Thermal Energy Conversion (OTEC)
MAIN COMPONENTS OF AN OTEC SYSTEM
The temperature at the top of sea and that at the bottom of sea has a temperature difference of 20 degrees
A steam power cycle is operated between the top surface (the source) and the bottom of the sea (sink)
Working of OTEC plant
1. Open cycle
Water is the working fluid Desalinated water can be produced
2. Closed cycle
Ammonia can be used as a working fluid
Tidal and Wave Energy
Wave Energy
Wave Energy Conversion
Wave Energy Conversion
Tidal PowerNo dam, but a turbine alone is needed for energy conversion
Tidal Energy
Renewable energy resources are the only solution for a sustainable world
Solar energy is clean energy which makes no pollution, no harm to environment
In remote areas, the only solution for energy is solar power Most of the Renewable energy resources are pollution free
and nature friendly Solar, Biomass, Hydel and Wind energy has very good
potential and they are the fastest growing renewable energy sources
Conclusions
Conclusions (contd..) The future looks bright for Renewable energy because
technology is becoming more advanced and efficient Initial Cost is high (Cost may not be a factor in many
occasion..!) intermittent supply
Energy storage equipments are needed Must be coupled with other sources of electricity
It is best suited if using as a hybrid energy source
Save energy, save earth
Thank you
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