22MEX01 Renewable Energy Sources

Unit II Solar Energy and Wind Energy

Solar Energy: Solar Radiation Measurements of Solar Radiation and Sunshine - Solar Thermal Collectors Flat Plate and Concentrating Collectors - Fundamentals of Solar Photo Voltaic Conversion Solar PV Systems-Types- Design of a Standalone Solar PV System - Solar PV and Thermal Applications - Building Integrated Solar- Challenges Economics- Leadership in Energy Environment Design (LEED) Certification.

Wind Energy: Basic Terms Types - Horizontal Axis Wind Turbine-Vertical Axis Wind Turbine - Building Integrated Wind Turbines - Wind Turbine Generator and its Performance - Wind Turbine Applications - Recent Developments in Offshore Wind Turbines and Energy Storage - Hybrid Systems - Challenges - Economics.

• Energy produced and radiated by the sun, more specifically the term refers to the sun’s energy that reaches the earth.
• The amount of energy received in unit time on a unit area perpendicular to the sun’s direction at the mean distance of the earth from the sun is called solar constant.

HOW MUCH SOLAR ENERGY?

The surface receives about 47% of the total solar energy that reaches the Earth. Only this amount is usable.

TYPES OF SOLAR RADIATION

• Direct or Beam Radiation:

solar radiation that has not been absorbed or scattered reaches the ground directly from the sun.

• Diffuse Radiation

solar radiation received from the sun after its direction has been changed by reflection and scattering by reflection.

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SOLAR RADIATION GEOMETRY

• Declination
• Hour angle
• Solar azimuth angle
• Altitude angle
• Zenith angle

• Declination angle (δ)

- It is a angle between a line extending from the centre of the sun to the centre of earth and projection of this line upon the earth’s equatorial plane.

• Hour angle (ὠ)

- It is a angle through which the earth must turn to bring the meridian of point directly in line with sun’s rays.

• Altitude angle

- It is a vertical angle between the projection of the sun’s rays on horizontal plane and the direction of sun’s rays.

• Zenith Angle

It is a complimentary angle of sun’s altitude angle. It is a vertical angle between the sun’s rays and line perpendicular to horizontal plane through the point.

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SOLAR RADIATION MEASUREMENT

• Pyrheliometer

- It collimates the beam radiation to determine the beam intensity as a function of incident angle.

- The Angstrom pyrheliometer

- The abbot silver disc Pyheliometer

- Eppley Pyheliometer

• Pyranometer

- It is a instrument used to measure total or global radiation over a hemispherical field of view

- Eppley Pyranomoter

- Yellot Solarimeter

- Moll-Gorczyheski solarimeter

- Velochme Pyranometer

SOLAR COLLECTORS

• Solar collector

- It is a device for collecting solar radiation and transfer the energy to a fluid passing in contact with it.

- Non Concentrating Collectors.

- Concentrating Collectors

• Non concentrating Collectors

- Flat plate collectors

1. Liquid collectors

2. Air collectors

3. Collectors with porous absorber

FLAT PLATE COLLECTOR

• Concentrating Collectors

- Parabolic trough collector

- Mirror Strip reflector

- Fresnel Lens collector

- Compound parabolic Concentrator

- Flat plate Collector with adjustable mirrors

PARABOLIC TROUGH COLLECTORS

FRESNEL LENS COLLECTOR

COMPOUND PARABOLIC CONCENTRATOR

SOLAR PHOTO VOLTAICS

PHOTO VOLTAIC EFFECT

• The generation of an electromotive force as the result of ionizing radiation.
• Energy conversion devices used to convert sunlight to electricity by the use of the photovoltaic effect is called solar cells.
• Combination of these solar cells are called solar module or solar array.

COMPONENTS OF PV SYSTEM

• Solar Array
• Blocking Diode
• Battery Storage
• Inverter/Converter
• Appropriate switches and circuit breakers

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PV CELLS MATERIALS

• Monocrystalline Silicon

- Czochralski Method.

- Efficiency 20%

• Polycrystalline silicon
• Gallium arsenide
• Amorphous silicon
• Cadmium telluride

PV CELL MANUFACTURING PROCESS

WORKING

On Grid PV System

OFF Grid PV System

Hybrid PV System

SOLAR ENERGY APPLICATION

• Solar water heating
• Space heating
• Space cooling
• Solar distillation
• Solar pumping
• Agricultural and Industrial process heat
• Solar furnace
• Solar cooking
• Solar production of hydrogen
• Solar green house
• Thermal electric conversion

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SOLAR WATER HEATING

Components of Solar water heating system

• Flat plat collectors
• Storage tank
• Circulation system and auxiliary heating system
• Control of system

Types

• Natural circulation solar water heater (Pressurized)
• Natural circulation solar water heater (Non-Pressurized)
• Forced circulation water heater

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SOLAR HEATING SYSTEM

• Passive Heating System

- Direct Gain

- Thermal Storage Wall

- Attached Sun space

- Roof Storage

- Convective loop

• Active Heating system

PASSIVE SPACE HEATING SYSTEM

SPACE COOLING

• Absorption air conditioner

- Lithium bromide Water

- Ammonium Water

• Intermittent absorption cooling

Leadership in Energy Environment Design (LEED) Certification.

• Leadership in Energy and Environmental Design (LEED) Certification is a globally recognized green building certification system developed by the U.S. Green Building Council (USGBC). It provides a framework for healthy, highly efficient, and cost-saving green buildings.
• To promote sustainable building and development practices through rating systems that recognize projects that implement strategies for better environmental and health performance.

LEED Examination Procedure

Types of LEED Credentials LEED

• Green Associate Entry-level credential for understanding green building principles.
• LEED Accredited Professional (LEED AP)Advanced credential with specialization

LEED Green Associate Exam

Duration: 2 hours

No. of Questions: 100 multiple-choice

Format: Computer-based

Pass mark: 170 out of 200

Topics: LEED Process, Integrative Strategies, Energy, Water, Materials, Location & Transportation, Indoor Environmental Quality

LEED Accredited Professional (LEED AP)

• Duration: 4 hours (2 parts)
• Green Associate (2 hrs)
• AP with Specialty (2 hrs)
• 100 questions per part
• Specializations: BD+C, ID+C, O+M, ND, Homes

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How winds created ?

Wind turbine

• A wind turbine is a device that converts kinetic energy from the wind, also called wind energy, into mechanical energy in a process known as wind power.
• If the mechanical energy is used to produce electricity, the device may be called a wind turbine or wind power plant.

Basic components of wind turbines

Basic Terms in Wind Energy

• Wind Speed – Velocity of wind flow
• Air Density (ρ) – Affects power output
• Swept Area (A) – Area covered by rotating blades
• Tip Speed Ratio (TSR) – Blade tip speed / wind speed
• Cut-in Speed – Minimum wind speed to generate power
• Rated Speed – Speed at which turbine produces max power
• Cut-out Speed – Max safe operating speed

Types of wind turbine

Horizontal axis wind turbine

• Horizontal axis using two aerodynamic blades.
• Horizontal axis propeller type using single blades.
• Horizontal axis multi blade type
• Dutch type
• Sail type

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Dutch type wind mill

Sail type wind mill

Vertical axis wind mill

• Savonius rotor
• Darrieus rotor type

Savonius rotor �

Darrieus rotor type�

Building Integrated Wind Turbine

Recent Developments in Offshore Wind Turbines and Energy Storage

Floating Offshore Wind Turbines

Suitable for deep waters (>60 m depth)

Hybrid System

Performance of Wind Turbine

Energy conversion Process

• The process is based on aerodynamic lift and drag forces, similar to an aircraft wing. When wind flows over the airfoil-shaped blade, it causes a pressure difference between the upper and lower surfaces.
• This pressure difference produces a lift force, which has a tangential component that makes the rotor turn.The rotational kinetic energy of the rotor is transferred via a shaft to a generator.
• The rotor slows down the wind as it passes through, extracting some energy. According to Betz’s Law, a maximum of 59.3% of wind’s kinetic energy can be captured.

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