RENEWABLE AND DISTRIBUTED

ENERGY TECHNOLOGIES
Year/Semester: IV/I
 Apply the knowledge of mathematics, science, engineering fundamentals, and an engineering specialization to the
PO1 solution of complex engineering problems.
Identify, formulate, review research literature, and analyse complex engineering problems reaching substantiated
PO2 conclusions using first principles of mathematics, natural sciences, and engineering sciences.
Design solutions for complex engineering problems and design system components or processes that meet the
specified needs with appropriate consideration for the public health and safety, and the cultural, societal, and
PO3 environmental considerations.
Use research-based knowledge and research methods including design of experiments, analysis and interpretation of
PO4 data, and synthesis of the information to provide valid conclusions.
Create, select, and apply appropriate techniques, resources, and modern engineering and IT tools including prediction
PO5 and modeling to complex engineering activities with an understanding of the limitations.
Apply reasoning informed by the contextual knowledge to assess societal, health, safety, legal and cultural issues and
PO6 the consequent responsibilities relevant to the professional engineering practice.
Understand the impact of the professional engineering solutions in societal and environmental contexts, and
PO7 demonstrate the knowledge of, and need for sustainable development.
PO8 Apply ethical principles and commit to professional ethics and responsibilities and norms of the engineering practice.
PO9 Function effectively as an individual, and as a member or leader in diverse teams, and in multidisciplinary settings.
Communicate effectively on complex engineering activities with the engineering community and with society at large,
such as, being able to comprehend and write effective reports and design documentation, make effective
PO10 presentations, and give and receive clear instructions
Demonstrate knowledge and understanding of the engineering and management principles and apply these to one’s
PO11 own work, as a member and leader in a team, to manage projects and in multidisciplinary environments.
Recognize the need for and have the preparation and ability to engage in independent and life-long learning in the
PO12 broadest context of technological change.
 To understand growing and increasing demands of electrical related technology and design
PSO1 appropriate cost-effective solutions through hardware and simulation
To cater to new challenges in generation and utilization of renewable energy systems for a green
PSO2 tomorrow
 RENEWABLE AND
Name of the Subject:
DISTRIBUTED ENERGY TECHNOLOGIES PO1 PO2 PO3 PO4 PO5 PO6 PO7 PO8 PO9 PO10 PO11 PO12 PSO1 PSO2

Illustrate basic concepts of renewable and

CO1 distributed sources . 3 3 3 3 3
Demonstrate the components of wind energy
CO2 conversion systems. 3 3 3 3 3
Model PV systems and analyze MPPT
CO3 Techniques. 3 3 3 3 3
Illustrate the concept of Energy Production
CO4 from Hydro - Tidal and Geothermal. 3 3 3 3 3
Distinguish between standalone and grid
connected DG systems and design hybrid
CO5 renewable energy systems. 3 3 3 3 3
UNIT - 1
SYLLABUS
Brief idea on renewable and distributed sources - their
usefulness and advantages; Wind Energy Systems:
Estimates of wind energy potential - wind maps -
Instrumentation for wind velocity measurements -
Aerodynamic and mechanical aspects of wind machine
design - Conversion to electrical energy - Aspects of
location of wind farms.
Course Objectives
• To understand the basic concepts on wind energy systems with
concept on aerodynamics, horizontal and vertical axis wind turbines.
• To understand the various relations between speed, power and energy in
the wind systems.
• It provides the knowledge in fundamentals of solar energy systems, various
components of solar thermal systems, applications in the relevant fields and
design of PV systems.
• To understand the Hydel system components and their design concepts. To
get an idea on different other sources like tidal, geothermal and gas based
units.
• To understand the use of various renewable sources as distributed
generators.
Course Outcomes
• Illustrate basic concepts of renewable and distributed sources.
• Demonstrate the components of wind energy conversion systems.
• Model PV systems and analyze MPPT Techniques.
• Illustrate the concept of Energy Production from Hydro - Tidal and
Geothermal.
• Distinguish between standalone and grid connected DG systems and design
hybrid renewable energy systems.
Brief idea on renewable and distributed sources - their
usefulness and advantages
 The electric power system consists of units for electricity production, devices that
make use of the electricity, and a power grid that connects them.

 The aim of the power grid is to enable the transport of electrical energy from the
production to the consumption, while maintaining an acceptable reliability and
voltage quality for all customers (producers and consumers), and all this for the
lowest possible price.

 A sudden change either on the production side or on the consumption side could
endanger the situation we have become so accustomed to.
 Modern society is very much dependent on the availability of cheap and reliable
electricity.
 Several recent blackouts and price peaks have very much shown this.
 There are different reasons for introducing new types of production into
the power system.

 Enabling the introduction of new electricity production is one of the main

reasons for the deregulation of the electricity market.
 The second reason for introducing new types of production is
environmental.
 The third reason for introducing new production, of any type, is that the
margin between the highest consumption and the likely available production
is too small.
-----This is obviously an important driving factor in fast-growing
economies such as Brazil, South Africa, and India.
 Several of the conventional types of production result in emission of carbon
dioxide with the much-discussed global warming as a very likely consequence.

 Changing from conventional production based on fossil fuels, such as coal,

gas, and oil, to renewable sources, such as sun and wind, will reduce the
emission.

 Nuclear power stations and large hydropower installations do not increase

the carbon dioxide emission as much as fossil fuel does, but they do impact
the environment in different ways.

 There is still carbon dioxide emission due to the building and operation even
with these sources, but this is much smaller than that with fossil fuel-based
production.
 The radioactive waste from nuclear power stations is a widely discussed
subject as well as the potential impact of an unlikely but nonetheless serious
accident.

 Large hydropower production requires large reservoirs, which impact the

environment in other ways.

 To encourage the use of renewable energy sources as an alternative, several

countries have created incentive mechanism to make renewable energy more
attractive.
In the last 100 years, the Earth warmed up by
~1° C

100 years is nothing by geological time scales!

Can we predict the past?

Climate change due to natural

causes (solar variations,
volcanoes, etc.)

Climate change due to natural

causes and human generated
greenhouse gases
 CO2 Concentration, Temperature, and Sea Level
Continue to Rise Long after Emissions are Reduced

Sea-level rise due to ice melting: several

millennia

Sea-level rise due to thermal expansion:

CO2 emissions peak centuries to millennia
0 to 100 years

Temperature stabilization:
a few centuries

CO2 stabilization:
100 to 300 years

CO2 emissions
Today 1,000 years
100 years
The possibility / likelihood of global warming is
disturbing …
… but there may be a bigger problem!
 Consumption of Energy Increased by 85%
Between 1970 and 1999
By 2025, Consumption will Triple
Quadrillion Btu
700
History Projections
600

500

400

300

200

100

0
1970 1975 1980 1985 1990 1995 1999 2005 2010 2015 2020
World production of oil and gas is predicted to peak within
10 - 40 years

2010
 Energy conservation and
efficiency can buy time
(a factor of ~2)
but the fundamental problem remains
PREDOMINANCE OF OIL AND GAS
OUT OF GAS
 Potential Sources of Energy when Fossil Fuels
Run Out

?
ROLE OF RENEWABLES IS OF GROWING IMPORTANCE
 MAJOR CHALLENGES IN ENERGY
• Energy security: Fuel supply resources for the future

• Economic growth: Accommodation of the developing nations’ needs

• Environmental effects: Global warming and emission control

• Electricity system reliability: Assurance of integrity of electric power

infrastructure
Advantages of Renewables
Less global warming
Improved public health
Inexhaustible energy
Jobs and other economic benefits
Stable energy prices
Reliability and resilience
RENEWABLES’ ROLE IN THE 2004 U.S. ENERGY SUPPLY
Distributed energy resources
 Distributed energy resources, or DERs, are small-scale electricity supply or
demand resources that are interconnected to the electric grid.

 They are power generation resources and are usually located close to load centers,
and can be used individually or in aggregate to provide value to the grid.

 DERs include a variety of physical and virtual assets.

 Physical DERs are typically under 10 MW in capacity and can consist of diesel or
natural gas generators, micro-turbines, solar arrays, small wind farms,
battery energy storage systems, and more.

 They can be owned and operated by the electric utility, by independent power
producers or by local businesses.

 The utility directs their operation in the same way that it controls the operation of
large central power plants, requesting starts and stops as needed.
Consumer Owned Distributed Energy Sources
What are the Benefits?
 Increased electric system reliability.

 Reduction in amounts of energy lost.

 An emergency supply of power.

 Reduction of peak power requirements.

 Offsets to investments in generation, transmission, or distribution facilities that would

otherwise be recovered through rates.

 Provision of ancillary services, including reactive power.

 Improvements in power quality.

 Reductions in land-use effects and rights-of-way acquisition costs.

 Reduction in vulnerability to terrorism and improvements in infrastructure resilience.

Wind Turbine Energy
Wind Speeds in India
Wind
Wind energy is created when:
 the atmosphere is heated unevenly by the Sun
 some patches of air become warmer than others
 the warm patches of air rise
 cold patches of air rushes-in to fill this void
thus, wind blows
 Wind is described in terms of the direction from which it blows, and is given as compass-
point expressions graduated into 8 or 16 directions clockwise from true north
Instrumentation for Wind Velocity Measurements
 Surface wind is usually measured using a wind vane and a cup or propeller anemometer.
 When a measuring instrument malfunctions, or when no such instrument is available, the
wind direction and speed may be estimated subjectively.
Rotating Anemometers
There are two types of rotating anemometers:
The Cup anemometer, which has three or four cup wheels attached to the rotating axis,
&
The Propeller anemometer, which has propeller blades.

Both types rely on the principle that the revolution speed of the cup or propeller
rotor is proportional to the wind speed.
Cup Anemometers
A cup anemometer has three or four cups mounted symmetrically around a freewheeling
vertical axis.
The difference in the wind pressure between the concave side and the convex side of the
cup causes it to turn in the direction from the convex side to the concave side of next cup.
The revolution speed is proportional to the wind speed irrespective of wind direction.
Wind speed signals are generated with either a generator or a pulse generator.
Generator-type Cup Anemometers
 This type has a small AC generator coupled to its axis.
 The wind turns the cups and the generator to generate a voltage proportional to the
instantaneous wind speed, and the signal is transmitted to the indicator.
 The integrated circuit calculates the average wind speed as the circuit charges and
discharges the capacitor over a certain period.
 This type of anemometer is located in an exposed position on a tower and is connected to
an indicator through cables, and observation from remote locations is possible.
 The greatest distance between the anemometer and the indicator depends on the
electrical resistance of the cable and the design (a model allows a maximum distance of
1,500 m).
 Recent models are equipped with an A/D (analog to digital) converter to allow computer
processing of data tasks.
 The generator-type cup anemometer generates wind speed signals by itself, and can be
used without an electrical supply.
 This type of anemometer does not require a power supply for the main unit, but the
counter takes 3-volt dry-cell batteries
Generator-type Propeller Anemometers
 Figure shows the main part of a generator-type propeller anemometer’s transmitter
sensor.
 It includes a propeller that reacts to wind pressure and turns at a rate corresponding to
the wind speed, an AC generator, a tail assembly and a selsyn motor to generate wind
direction signals.

 To detect the wind direction

and measure the wind speed
accurately, the tail assembly of a
propeller anemometer is
designed so that the propeller
always faces the wind.
 An AC generator connected to
the propeller shaft generates
induced voltages proportional to
the wind speed.
 As shown in figure, these AC voltage signals are rectified to a DC voltage and output as an
analogue voltage signal proportional to the wind speed.

 The analogue voltage signal is transmitted to a wind speed indicator or a recorder in

which a voltmeter is assembled, and the instantaneous wind speed is ascertained.
 Aerodynamic and Mechanical Aspects of Wind Machine Design -
Drag or Lift Design
 Wind turbines are designed based on either aerodynamic Drag or Lift force.
 The wind literally pushes the blades out of the way.

 Slower rotational speeds and high torque capabilities. Useful for providing mechanical
work (water pumping e.g.).
Lift Design
The blade is essentially an airfoil (like wings of
airplanes).

 When air flows past the blade, a wind speed and Lift
pressure difference is created between the upper
and lower blade surfaces.

 The pressure at the lower surface is greater and

thus acts to "lift" the blade.

 The lift force is translated into rotational motion.

 Lift design generally has higher efficiency and is

used in most modern turbines.
Lift & Drag Forces

 The Lift Force is perpendicular to

the direction of motion. We want
α = low
to make this force BIG.

α = medium
<10 degrees

 The Drag Force is parallel to the

direction of motion. We want to α = High
make this force small. Stall!!
Airfoil Shape

Just like the wings of an airplane, wind

turbine blades use the airfoil shape to create
lift and maximize efficiency.

The Bernoulli Effect

Blade Angle

The angle between the chord line of the blade and the wind direction (called angle of
attack) has a large effect on the lift force (see figure below). Typically, maximum lift
force is achieved with 1o to 15o angle of attack.

Angle of Optimal angle of attack

Lift Lift
Attack
Wind

Angle of Attack
Lift/Drag Forces
Experienced by
Turbine Blades
These vectors represent the
forces experienced by an airfoil
wind turbine blade as it
rotates.
Notice that the “apparent
wind” is a combination of the
“real wind” and the “head
wind”.
Well designed blades should
minimize the drag force.
Conversion to Electrical Energy
Many Different Rotors…
Number of Blades – One
• Rotor must move more rapidly to capture
same amount of wind

– Gearbox ratio reduced

– Added weight of counterbalance
negates some benefits of lighter design
– Higher speed means more noise, visual,
and wildlife impacts

• Blades easier to install because entire

rotor can be assembled on ground
• Captures 10% less energy than two blade
design
• Ultimately provide no cost savings
Number of Blades - Two
• Advantages & disadvantages similar to
one blade
• Need teetering hub and or shock
absorbers because of gyroscopic
imbalances
• Capture 5% less energy than three
blade designs
Number of Blades - Three
• Balance of gyroscopic forces
• Slower rotation
– increases gearbox &
transmission costs
– More aesthetic, less noise, fewer
bird strikes
Blade Composition
-Wood
Wood
• Strong, light weight, cheap,
abundant, flexible
• Popular on do-it yourself turbines
• Solid plank
• Laminates
• Veneers
• Composites
Blade Composition
-Metal
• Steel
• Heavy & expensive
• Aluminum
• Lighter-weight and easy to work with
• Expensive
• Subject to metal fatigue
Blade Construction Fiberglass
 Lightweight, strong, inexpensive, good fatigue characteristics
 Variety of manufacturing processes
 Cloth over frame
 Pultrusion
 Filament winding to produce spars
 Most modern large turbines use fiberglass
 Cloth over frame: A wind turbine blade made of a skeleton frame with
flexible carbon fiber cloth running its entire width on top of the blade, being
attached to a mechanized roller positioned at one end of the blade and to a pair of
narrow carbon fiber cloth strips over a roller at the front of the blade.

 “Pultrusion” is a continuous molding process whereby reinforcing fibers are

saturated with a liquid polymer resin and then carefully formed and pulled through
a heated die to form a part.

 “Filament winding” is a process that involves winding filaments under tension over
a rotating mandrel.
 These “scimitar” shaped blades are designed to be efficient while also
reducing NOISE coming off the blades.
Some Wacky Ideas…
Manufacturing Blades

The blade mold (left) is lined with layers of fiberglass, then injected with epoxy resin.
To enhance stiffness, a layer of wood is placed between the fiberglass layers.
The two molds are joined and adhered together using a special liquid epoxy, which
evenly joins the two sides of the blade.
Finally, the whole mold is baked like a cake! 8 hours at 70 degrees centigrade.
Manufacturing Blades

Before delivery, samples of the rotor blades have to go through a variety of static and dynamic
tests.
First, they are subjected to 1.3 times the maximum operating load.
To simulate 20 years of material fatigue, the blades are then mounted on special test beds and
made to vibrate around two million times, before the endurance of the material is again tested
with a final static test.
The blades are painted white, then shipped to wind farms all over the world.
 Advanced Classroom Blade Designs

Cardboard Tube for

Airfoil Blades twisted blades
Wind Turbine Blade Challenge
Students perform experiments
and design different wind turbine
blades
Use simple wind turbine models
Test one variable while holding
others constant
Record performance with a multi-
meter or other load device
Goals: Produce the most voltage,
pump the most water, lift the
most weight
Minimize Drag
Maximize LIFT
Harness the POWER of the
wind!
Aspects of location of wind farms

 The crucial factor in siting a wind farm (also called wind park or wind plant) is the annual
energy production and how the value of the energy produced compares to other sources
of energy.
 Using long-term is data therefore critical.

Data should be collected at a potential site for 2–3 years, after which other questions arise:
What is the long-term annual variability?
How well can we predict the renewable energy production?
  To determine whether historical data from a site is adequate to describe
long-term wind resources at another site, a rigorous analysis should be done.
 The annual hourly linear correlation coefficient should be at least 0.90 between the
reference site and off-site data.

 Wind shear must also be factored in if the heights are different at the two locations.

 If the two sites do not exhibit similar wind speed and direction trends and lack similar
topographic exposures, they will probably not have sufficient correlation value.

 These wind power stations should continue to collect data even after a wind farm is
installed.

 The data improves siting of a wind farm and also provides reference sites for delineating
wind resources for single or distributed wind turbine in the region.
Wind Site Assessment Dashboard (formerly Wind-navigator), a web platform based on
Google Maps, is an interactive tool that includes wind resource maps and world data. The
map provides wind speed data at custom height of 10–140m and a pointer to locate the
minimum and maximum mean annual wind speed.

Vaisala provides a similar interactive wind resource map (map, satellite, hybrid, and terrain
views) and data for much of the world, which features wind speed data for 20m, 50m, and
80m and with Wind GIS Data Layers, resolution is at 90m.
MesoMap:
 This system was developed specifically for near-surface wind forecasting.

 It uses historical atmospheric data spanning 20 years and a fine grid (typically 1–5 km).

 The model provides descriptive statistics utilizing wind speed histograms, Weibull
frequency parameters (statistical Information), turbulence and maximum gusts, maps of
wind energy potential within specific geographical regions, and even the annual energy
production data for a wind turbine of any height for selected sites in a region.
 Wind maps, data compiled by meteorological towers, models, and other criteria
are used to select wind farm locations.
 Further considerations for a wind farm developer are the type of terrain (complex to flat
plain), wind shear, wind direction, and spacing of wind turbines based on predominant wind
direction and availability, land cost, and requirements such as roads, turbine foundations, and
substations.
 In complex terrain, such as mountains and ridges, micrositing is particularly important.
 Satellite and aerial images are used in micrositing and are available from various sources,
some of which are free.
 Zoom Earth has the option of switching among sources, such as Google Maps, Microsoft
VE, and others.
 Although micrositing techniques of wind farm developers are proprietary, satellite images
show the layout of wind farms, and can provide good information about siting from the
images and topographic maps.
 Ocean wind observations provide complementary sources of information for
siting of a offshore wind farm.
The advantages of ocean wind maps are:
 Some satellite wind maps are public domain.
 All offer global coverage allowing observation of large areas without large numbers of
meteorological towers.
 All are accessible in archives spanning several years.
 Accuracy is sufficient for wind resource screening.
 They quantify spatial variations
 They are available at resolutions of 400m, 1.6m, and 0.25 degree.
 Software has been developed for their use.
The major problems with ocean winds are:
 Data are for 10m height and values of wind shear are not known.
 Standard deviations are around 1.2 to 1.5m/s on mean wind speed.
 Data are not available or not as reliable within 25 km of shore.