POWER GENERATION USING SOLAR POWER PLANT
Parth Amin
B.E., Gujarat University, India, 2007
PROJECT
Submitted in partial satisfaction of
the requirements for the degree of
MASTER OF SCIENCE
in
ELECTRICAL AND ELECTRONIC ENGINEERING
at
CALIFORNIA STATE UNIVERSITY, SACRAMENTO
SUMMER
2010
POWER GENERATION USING SOLAR POWER PLANT
A Project
by
Parth Amin
Approved by:
__________________________________, Project Advisor
John C. Balachandra, Ph.D.
____________________________
Date
__________________________________, Second Reader
Preetham B. Kumar, Ph.D.
____________________________
Date
ii
Student: Parth Amin
I certify that this student has met the requirements for format contained in the University
format manual, and that this project is suitable for shelving in the Library and credit is to
be awarded for the Project.
__________________________, Graduate Coordinator
Dr. Preetham B. Kumar
Department of Electrical and Electronic Engineering
iii
________________
Date
Abstract
of
POWER GENERATION USING SOLAR POWER PLANT
by
Parth Amin
Pursuing the commitment of California State to generate at least 20 percent of
total generated energy from the renewable source by the year 2010 rather than 2017,
many new power plants based on renewable energy sources are being set up in California
[1].
This project is focused on the generation of electrical energy from solar
intensity. by setting up a solar power plant is in the Redding, California region.. The
choice of the place comes from the fact that it has favorable weather and farmlands
within the region, which can easily supply the required intensity and load for Solar Power
plant.
This project report describes the design aspect of solar power plant which is
application based as well as based on other designs used in similar power plants. The
report first explores the main blocks of this project. The report then explains the
requirement of non-polluting energy sources. Moreover, it explains how to collect solar
insolation and how it generates the output power in the form of electrical energy. The
iv
report then includes about concept of tracking circuit and different technologies used for
the same, then goes on to explain the data acquisition system.
In the end, the aspect of generation of electrical power from the solar plant is
explained along with calculations and simulation. The simulation has been done in
Matlab© through writing a program code. Moreover, the generated power using glycol as
a coolant has compared in the last part of this report.
_______________________, Project Advisor
John C. Balachandra, Ph.D.
_______________________
Date
v
ACKNOWLEDGMENTS
Before going into the details of this project, I would like to add a few warm words
for the people who gave me support, directly or indirectly to complete this project. It was
my pleasure that Dr. John. C. Balachandra allowed me to work on this project with him. I
must thank him for providing me all the necessary resources and help to finish this
project. His experience in this field helped me a lot in finishing my work. I must say
without his continuous help, guidance and support, this project would not have been
successfully completed.
I also want to thank Dr. Preetham Kumar for being a committee member for my project. I
am again thankful to Dr. John C. Balachandra for reviewing my project report and giving
his valuable suggestions. Finally, but importantly, my wholehearted thanks go to all
faculty members of Electrical Engineering and Computer Science Department for helping
me finish my graduation at California State University, Sacramento.
vi
TABLE OF CONTENTS
Page
Acknowledgments……..……………………………………………………………………
vi
List of Tables.………………………………………………………………………………. ix
List of Figures………………………………………………………………………………. x
Chapters
1. INTRODUCTION ……………..………………………………………………………… 1
1.1Project Goal…….....…………..…………………………………….……………….... 1
1.2Need of a Solar Power Plant...……………………………………….......…….…….... 2
1.3Advantages of Solar Energy ..............……….……………………..….……….…….... 4
2. SOLAR INSOLATION …….……………...………………………………………..…… 5
2.1Block Diagram …………………….………..……………………..………….…….... 5
2.2What is Solar Insolation.……….…………………………………..………….…….... 6
2.3Solar Insolation in Redding (California).…………………………..………….…….... 8
3. TRACKING CIRCUIT……………..…………………………………………………….. 12
3.1 Concept of Solar Power.......................................................................……….…….... 12
3.2 Parabolic Errors...................................................................................……….…….... 15
3.3 Sopogy (SopoNova and MicroCSP)…................................................……….…….... 18
4. DATA ACQUISITION SYSTEM.………………………………………………………. 23
4.1 Functional Blocks …………………………………………………………….……. 23
4.2 Sensor ………………………………………………………………………………. 24
4.3 Signal Conditioning Circuit ………………………………………………………… 25
4.4 Analog MUX ……………………………………………………………………….. 25
4.5 Sample and Hold Circuit ………………………………………………………………26
4.6 A to D Converter ……………………………………………………………………. 26
4.7 Analog to Digital Converter IC – MCP 3204 ………………………………............. 26
4.8 Main Features of MCP 3204 ……………………………………………………….
27
5. CALCULATIUONS……………………………………………....……………………… 30
5.1 Maximum Power………………................................................................................... 30
5.2 Average Power………...………................................................................................... 33
5.3 Comparison of Power………...……… ........................................................................ 36
6. SIMULATION………………………………………………………………………….….37
vii
6.1 Simulation Overview……............................................................................................ 37
6.2 Simulated Results and Graphs...................................................................................... 40
7. GLYCOL AND GENERATED POWER...………………………………………………. 46
7.1 Types of Glycol…………............................................................................................ 46
7.2 Comparison of Different Glycols................................................................................. 47
7.3 Simulation Results Using Glycol................................................................................. 51
8. CONCLUSION ………………………………..…………………………………………. 54
References ………………………...………………………………………………………… 55
viii
LIST OF TABLES
Page
1.
Table 2.1 Solar Insolation Level of Main Cities in California …...………..…
2.
Table 2.2 Solar Insolation Level of California’s Different Places …………… 9
3.
Table 5.1 Generated Energy Comparison…….………..…………………….
36
4.
Table 6.1 Power Distribution Chart (summer)…………..…………………
43
5.
Table 6.2 Power Distribution Chart (winter & rainy)………………………
44
6.
Table 7.1 Comparisons of Ethylene Glycol, Propylene Glycol & Corn Glycol. 50
7.
Table 7.2 Temperature vs. Power (Without using Glycol)……………………..51
8.
Table 7.3 Temperature vs. Power (Using Glycol)…………………………… 52
9.
Table 7.4 Comparison of Generated Power…………………………………….53
ix
7
LIST OF FIGURES
Page
1.
Figure 1.1 Distribution charts of different Energy Resources …………..…
2
2.
Figure 1.2 Increase Rate of Gasoline Price ($) in California ………………
3
3.
Figure 2.1 Block Diagram of The Project……………..……………… ….
5
4.
Figure 2.2 Redding’s Climate From Dawn to Dusk …….……………
10
5.
Figure 2.3 Redding’s Insolation Level Hour-by-Hour ………..……… …..
10
6.
Figure 2.4 Redding’s Climate Condition …………………………………..
11
7.
Figure 3.1 Incidence Angle of Fresnel Mirror ……………………………..
13
8.
Figure 3.2 Fresnel Mirrors’ Plates ………………………………………
13
9.
Figure 3.3 Descriptions of Potential Optical Errors in Parabolic Collectors... 16
10.
Figure 3.4 Modeling of Potential Optical Errors in Parabolic Collectors…… 18
11.
Figure 3.5 SopoNova 4.0 Mirror ……………………………………………
20
12.
Figure 3.6 MicroCSP Concentrated Power ………………………..…..
21
13.
Figure 3.7 MicroCSP Solar Process Heat …………………………….
22
14.
Figure 3.8 MicroCSP Applications ……...…………………………………
22
15.
Figure 4.1 Block diagram of Data Acquisition System ……………… …
24
16.
Figure 4.2 Clock Cycle …………………………………………………….
28
17.
Figure 6.1 Temperature Calculation (Daytime wise) of Summer Season Only. 40
18.
Figure 6.2 Temperature Calculation (Daytime wise) of winter season only…. 41
19.
Figure 6.3 Generated (output) Power vs. Temperature…………………….
20.
Figure 7.1 Freeze Points Comparison of Different Glycols………………….. 49
x
42
1
Chapter 1
INTRODUCTION
1.1 Project Goal
This project discusses the generation of electrical energy in the form of output
power by using solar energy as a source. The main concept is to track the sun to get
maximum intensity at a concentrated point, and this concentrated solar intensity is
required to heat the flowing liquid to generate steam. Through the generated steam, the
steam turbine will start producing the output power in the form of electricity. Pressure
sensors take care of the generated steam and will continuously be monitored to avoid any
accidents.
This project uses different lenses and mirrors to gather maximum insolation at one point.
This way we can get use of the best qualities of different mirrors. Moreover, this solar
power plant uses the unit lens mirror (only one of particular dimension) to get the output.
In addition to this, project involves the concept of data acquisition system, whose output
is given to the control system. This way we can proceed to the calculation part and after
that, we can go for simulation process of output power.
2
1.2 Need of a Solar Power Plant
The solar power plant is the next generation for this world. As we are running out
of the fuel sources, it is required and necessary to find some other source and the answer
to this dilemma is the sun. From the sun, we can get tremendous amount of energy free of
cost, and, moreover, from the following figure-1, we can see that each energy source has
its own storage capacity, while the solar has unlimited amount of energy.
Figure 1.1 Distribution charts of different Energy Resources [2]
3
We all know that the price of gasoline (petroleum) is going higher and higher day by day.
In last one to two years, it has increased drastically. One of the reasons of this issue is we
are having less amount of fuel than in the past. In the following figure-2, we can see the
increase rate of gas price particularly in California Region, USA.
Figure 1.2 Increase Rate of Gasoline Price ($) in California [3]
Thus, we decided to move to any other energy resource, which can exist forever. And
solar power plant comes in the picture. This project report explains how much power we
can generate through a solar power plant and within what time span we can generate that
power. In the following section, the application of solar resources is discussed.
4
1.3 Advantages of Solar Energy
Some of the advantages of solar energy are as follows:
1. It is a renewable source.
2. It is independent.
3. It is non-polluting (Environmental Friendly).
4. Free of cost (Saves money).
5. Available in any weather condition
6. It does not require any maintenance and has a long life.
5
Chapter 2
SOLAR INSOLATION
2.1 Block Diagram
The block diagram of this project is shown below, which has several blocks. The
main blocks and the figure are as follows:
Figure 2.1 Block Diagram of the project
Main Units of the Block Diagram
1. Tracking Circuit
2. Pressure Sensor
3. Data Acquisition System
6
4. Display (LCD)
5. Control System
6. Control Valve
Some of the above-mentioned parts will be discussed in the later part of the project report
while the remaining are included in the other sections (not discussed separately). Now, let
us discuss about Solar Insolation in the following section.
2.2 What is Solar Insolation?
There is a term known as Solar Insolation Level which is defined as the amount of
solar radiation incident on the surface of the earth. In simple terms, it means how much
sunlight is shining down on us. By knowing the insolation levels of a particular region we
can determine the size of solar collector that is required. An area with poor insolation
levels will need a larger size of solar collector than an area with high insolation levels.
Once you know your region’s insolation level you can more accurately calculate collector
size and energy output.
The values of solar insolation are generally expressed in KWh/m2/day. This is the
amount of solar energy that strikes a square meter of the earth’s surface in a single day.
Of course, this value is average to account for differences in the day’s length. There are
several units those are used throughout the world.
7
The conversions based on surface area are as follows:
1 KWh/m2/day = 317.1 btu/ft2/day = 3.6MJ/m2/day
The raw energy conversions are:
1KWh = 3412Btu = 3.6MJ = 859.8 Kcal [10]
Table 2.1 shows typical solar insolation levels in two main cities in California.
State City
CA
CA
Latitude Longitude Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
Los
34° N
118° W
Angeles
San
38° 31' 121° 30'
Francisco N
W
Year
Avg
3.09 4.25 5.09 6.58 7.29 7.62 7.45 6.72 6.11 4.42 3.43 2.72 5.40
2.35 3.33 4.42 5.95 6.84 7.39 7.55 6.51 5.75 3.92 2.65 2.06 4.89
Table 2.1 Solar Insolation level of main cities in California [5]
Solar energy is available everywhere on Earth, in varying amounts. Solar
radiation that reaches the earth’s surface in an unbroken line is direct, while sunlight
scattered by clouds, dust, humidity and pollution is called diffused. The sum of the direct
and diffused sunlight is global-horizontal insolation. Concentrating solar technologies,
which use mirrors and lenses to concentrate sunlight, rely on direct radiation, while PV
(Photovoltaic) cells and other solar technologies can function with diffused radiation.
Insolation is a term referring to the amount of solar radiation that strikes the
planet’s surface over some period – a minute, hour, day, month or year. NREL (National
Renewable Energy Laboratory) has developed insolation estimates for the U.S. based on
8
solar measurements taken at a number of stations throughout the country, as well as
computer modeling that uses meteorological data to predict insolation at a large number
of sites.
According to NREL’s measurements, the nation’s most plentiful solar resources
are found in the Southwest. California, Nevada, Arizona, New Mexico, Utah, Colorado
and Texas, and they possess some of the best insolation values in the world. According to
DOE (Department Of Energy), “enough electric power for the entire country could be
generated by covering about nine percent of Nevada – a plot of land 100 miles on a side –
with parabolic trough systems.”
In all, the U.S. has a relatively abundant supply of solar resources. A 1 kW solar
electric system in the U.S. can generate an average of more than 1,600 kWh per year,
while the same system in southern Germany (which installs eight times as many PV
systems as the U.S.) would be able to generate only about 1,200 kWh per year, due to
that nation’s weaker insolation. A 1 kW system installed in parts of Nevada, Arizona,
New Mexico and far West Texas can produce 2,100 kWh per year. [4]
2.3 Solar Insolation in Redding (California)
Table 2.2 is the Solar Insolation Level Chart for California. in which, we can
figure out that ,in California, a place called Inyokern has highest Solar Insolation levels
which are:
9
8.7 KWh/m2/day, which is Highest
6.87 KWh/m2/day, which is Lowest
7.66 KWh/m2/day, which is Average
Inyokern, CA is 380 Miles away from Sacramento, CA towards south side.
State
City
Solar
Insolation
High
Low
Level
Avg.
(KWh/m2/day)
California
California
California
California
California
California
California
California
Santa Maria
Riverside
Davis
Fresno
Los
Angeles
Soda
Springs
La Jolla
Inyokern
6.52
6.35
6.09
6.19
5.42
5.35
3.31
3.42
5.94
5.87
5.1
5.38
6.14
5.03
5.62
6.47
5.24
8.7
4.4
4.29
6.87
5.6
4.77
7.66
Table 2.2 Solar Insolation level of California’s different places [6]
Now, let us discuss Redding’s climate condition and what the insolation level is
of Redding from dawn to dusk i.e. 12 hours a day.
10
Darkness
Dawn
Sunshine
Dusk
Figure 2.2 Redding’s climate from dawn to dusk [7]
Variable
I II III IV V VI VII VIII IX X XI XII
Insolation, kWh/m²/day 1.86 2.79 3.93 5.19 6.39 7.33 7.42 6.55 5.11 3.45 2.05 1.64
Figure 2.3 Redding’s Insolation level hour-by-hour [7]
11
Temperature
Period
Rain
Min(F)
Avg (F)
Max(F)
Avg (inch.)
January
37.4
46.2
54.9
8.0
July
68.1
83.3
98.4
0.2
Average Annual Precipitation - 39.4 inches
Average Annual Snowfall - 4.8 inches
Figure 2.4 Redding’s Climate Condition [8]
AVAILABILITY OF CLEAN WATER IN REDDING, CA
Clean (ground/surface) Water: 30,000 ac-ft./year to 80,000 ac-ft./year
Location: Redding Basin, Shasta County [9]
Therefore, average insolation level in Redding, CA, USA is 7.33 KWh/m²/day in
normal environment. As we have enough level of insolation, favorable weather and
farmlands within the region, we have decided to study the installation of a solar power
plant in Redding, CA.
12
Chapter 3
TRACKING CIRCUIT
3.1 Concept of Solar Power
Solar power plant is similar to other conventional power plants; the only
difference is that it uses the sunrays as a source of energy, which is inevitable, and most
efficient and economical source of energy.
Energy from sun comes to earth in forms of sunrays, and in solar power plants we
use this energy for power generation. Fresnel Mirrors are the heart of this whole power
plant. By using Fresnel Mirrors, we can concentrate all the sunrays falling on to it to one
particular point. Concentrating solar collectors use shaped mirrors or lens to provide
higher temperatures those flat plate collectors. By concentrating all these rays, we can get
extremely high temperature at this point with the help of this high temperature we can
convert liquid into vapour form. [11]
Fresnel diffraction mirror is a kind of atomic mirror, designed for the seculars
reflection of neutral particles coming at the grazing incidence angle, as shown in the
following figure:
13
Figure 3.1 Incidence angle of Fresnel Mirror [11]
Here in our case we are using water as a liquid and due to high temperature, this water
gets converted into steam.
Figure 3.2 Fresnel Mirrors’ plates [11]
With the help of this steam and closed-loop circulation principle, energy conversion from
one form to another can be possible. The pressure of this resulting steam measured by the
means of pressure sensor and this value is stored in a temporary register and displayed on
the LCD.
14
Steam pressure should not be increased or decreased from pre-defied values, and
if it does, then it should be automatically compensated. This can be done by monitoring
the developed logic which we have used in a microcontroller based circuit for the
regulation of the desired pressure as required to be operated in the plant.
Tracking circuit is needed for automatic positioning of sunrays to a dish. This
circuit constantly tracks the sun in accordance to get maximum sunrays falling
perpendicular on the aperture surface of the dish. With the help of this Fresnel Mirror
(lens) all rays are concentrated at one particular point, which is achieved by following the
sun by turning around its length-axis. This is sufficient to provide a line focus.
A black absorber tube is located in this focus line, surrounded by a glass
envelope. The space in between is evacuated to prevent heat losses by convection or
conduction. A heat transfer medium inside the absorber tube receives the heat and
transports it to the Collector tube from where it is fed to the power block, and due to high
concentration, we can get very high temperature there. Now as we have kept one glass
enveloped tube at this point and liquid is passing through it, due to high temperature this
water gets converted into steam. We have used glass tube with surface colored black so
that it prevents heat loss, and use feedback system so that we can increase efficiency.
A Fresnel lens is a type of lens invented by French Physicist Augustin-Jean
Fresnel Originally developed for lighthouses. The design enables the construction of
lenses of large aperture and short focal length without the weight and volume of material,
15
which would be required in conventional lens design. Compared to earlier lenses, the
Fresnel lens is much thinner, thus passing more light and allowing lighthouse to be
visible over much longer distances. [11]
3.2 Parabolic Errors
There are some errors related to parabolic mirror (dish). Therefore, we are not
using parabolic mirrors in this project, and instead we are using Fresnel mirrors and for
that, we will use Sopogy Inc. using SopoNova4.0 and MicroCSP technologies. In the
next section, we will discuss about Sopogy Inc. and its technologies. However, in this
section we are discussing errors related to parabolic mirror (dish).
The following figure 3.3 is an illustration of the different types of potential errors
that may be encountered in parabolic Collectors:
(1) Materials:
- Specularity of the reflective material
(2) Fabrication:
-Local slope errors: waviness of the reflector surface
- Profile errors: The average shape of the reflector (obtained by averaging the
local slope errors) may differ from a part
-Misalignment of the reflector
-Mislocation of the receiver tube
16
(3) Operation:
-Tracking errors: initial poor quality or degradation of equipment
-Profile errors due to wind loading and/or weathering
-Degradation of reflector surface due to dust, dirt and general weathering
-Misalignment of the receiver due to sagging or buckling and other thermal or
thermal cycling effects [12]
Figure 3.3 Descriptions of Potential Optical Errors in Parabolic Collectors [12]
17
In the analysis of statistical or random errors, errors are assumed independent
stochastic processes, and their occurrences are represented by normal probability
distributions. The distribution of energy directed toward the receiver is then obtained by
convolution as shown in the following Figure 3.4. The random errors include the
following:
(1) Apparent change in the sun's width due to atmospheric effects,
(2) Scattering at the reflector due to its optical properties or random slope errors and
(3) Random misalignment.
Non-random errors are deterministic, and the can have a greater impact on the operation
of the collector. They account for the gross errors in the manufacture/assembly and/or
operation on the collector. This can be the result of either misdirecting the central ray
from the reflector surface or misplacing the receiver or both. [12]
The non-random errors are identified as follows:
(1) Reflector profile errors due, for example, to deflection or severe waviness of the
reflector surface causing a permanent change in the location of the (ideal) focus of the
reflector,
18
(2) Consistent misalignment of the collector with the sun due, for example, to a constant
tracking error or rotation of the collector’s vertex-to-receiver axis during assembly, and
3) misalignment of the receiver with the effective focus of the collector. [12]
Figure 3.4 Modeling of Potential Optical Errors in Parabolic Collectors [12]
3.3 Sopogy (SopoNova and MicroCSP)
Sopogy, Inc. is a solar thermal or equipment designer and manufacturer with its
Research and Development team located in Honolulu, HI, with a California Bay Area
19
office supporting its US, European markets, and a technical engineering team located in
Asia. Sopogy targets the distributed generation, industrial process heat, and absorption
chiller air condition markets. [13]
In January 2008 Sopogy was named the "Venture Capital Deal of the Year," Sopogy is
installing a 500-Kilowatt plant on the Big Island at the Natural Energy Laboratory of
Hawaii Authority with plans for a 10MW plant on other islands.
The company's name origin comes from industry key words. The "SO" comes from
Solar, the "PO" comes from "Power" and the "GY" comes from "Energy and
Technology." Sopogy is "Solar Power Technology."
In July 2008 Sopogy was awarded the New Product of the Year Award from the National
Society of Professional Engineers for its SopoNova 4.0 product. This was the first solar
technology to have received the prestigious award. Past recipients include Boeing for the
777 and Mercedes Benz for the M-Class. [13]
In September 2008 Sopogy was selected as a finalist for Platt's Global Energy Awards,
recipient of the 2008 Business Leadership Award for Innovative Company of the Year by
Pacific Business News, and as the recipient of Hawaii Governor's Innovation Award.
In March 2009, Sopogy's SopoNova 4.0 product was selected as the Winner of Plant
Engineering Magazine's Product of the Year 2008 Gold Award. [13]
20
Figure 3.5 SopoNova 4.0 Mirror [13]
Micro CSP is One of the Technologies used for the concentration of solar power. Sopogy
coined the term "MicroCSP" in which Concentrating Solar Power (CSP) collectors are
based on the designs used in traditional Concentrating Solar Power systems found in the
Mojave Desert but are smaller in collector size, lighter and operate at lower thermal
temperatures usually below 600 °F (316 °C). This technology uses the basic parabolic
mirror. These systems are designed for modular field or rooftop installation where they
are easy to protect from high winds, snow and humid deployments [14]
SopoNova 4.0 is a concentrating parabolic trough solar collector designed for
distributed generation installations that include rooftops. The technology operates
similarly to conventional parabolic trough systems used in California since the mid
1980's but modified to reduce the physical size and is similarly manufactured to
21
fluorescent lighting luminaries. The unique aspects of SopoNova 4.0 include
unassembled the collector ships flat, Integrated 270 degree tracking, Integrated stands,
and custom controls. [13]
The working of the MicroCSP is as follows.
Figure 3.6 MicroCSP concentrated power [14]
MicroCSP technology harnesses solar energy in a revolutionary collector. The
solar power enters the panel and is reflected from precise mirrors onto focal point called a
receiver where heat transfer fluid is circulated. [14]
Heat transfer fluid passes through a series of MicroCSP collectors called an array.
This Process is shown in the following figure. This process raises the fluid temperature
and achieves a mass flow creating solar process heat.
22
Figure 3.7 MicroCSP Solar Process Heat [14]
This process has some applications as shown in the following figure. Solar
process heat enables partner technologies such as electrical turbines, absorption air
conditioning and steam creation. Cogeneration is also achieved by combining multiple
thermal technologies enabling a number of returns from one renewable energy input.
Figure 3.8 MicroCSP Applications [14]
23
Chapter 4
DATA ACQUISITION SYSTEM
4.1 Functional Blocks
The purpose of any data acquisition system is to acquire analog signals & present
them to the MCU (Expand?) in a form that can be manipulated (i.e. in the form of logic
1 or 0). The main parts of any general data acquisition system consist of the following
components:
1. Transducers (sensors)
2. Analog Multiplexer.
3. Signal Conditioning (Amplification, Filtering...)
4. Sample and Hold Circuit.
5. Analog to Digital Converter.
6. Microcomputer System.
7. Digital to Analog Converter.
8. Actuator.
24
Figure 4.1 Block diagram of Data acquisition system
4.2 Sensor
Sensor is used to convert one form of energy into another. Here our sensor
converts the sensed pressure to appropriate current output. We are using a special
pressure sensor for that which is manufactured by IFM-ELECTRONICS pa3022. The
specification of that sensor is as follows:
25
Operating Voltage:
9 to 30v
Output current
:
4 to 20mA
Measuring range :
0 to 100bar
Response time
1.5ms
:
Other unique features are that it can withstand reverse polarity protection and also high
voltage protection. This sensor gives the output in 4-20 mA range that is given to the next
stage of the block.
4.3 Signal Conditioning Circuit
This block is needed to convert the output signal in an appropriate form so that
controller can understand that signal. The output of sensor is not always in specific range
and in order that is necessary for microcontroller, so the signal conditioning circuit acts
as a bridge between pressure sensor and microcontroller. In our case this circuit converts
4 to 20mA current signal to a voltage signal of 0 to 5V.
4.4 Analog MUX
Analog multiplexer is used when there is more than one input signal. If we are
using more than one solar dish then this signals should be multiplexed using this analog
multiplexer.
26
4.5 Sample and Hold Circuit
This is one of the most important parts of the data acquisition system. Sample and hold
circuit is necessary to keep signals constant while converting an analog signal to digital
signal with desired resolution.
4.6 A to D Converter
A to D converter is necessary to make the output of sample and hold circuit
compatible with microcontroller. The output of sample and hold circuit is given to the A
to D converter. This converts analog data to digital since the microcontroller understand
that form only. Serial ADC(expand?) is used here to output the data in serial fashion in a
single clock cycle. Data is obtained out serially by either using SPI(expand?).
4.7 Analog to Digital Converter IC – MCP 3204
The MCP- 3204 is a programmable ADC to provide two pseudo- differential
input pairs or four single-ended inputs. Non-linearity is specified at 1 LSB (expand?).
Communication with the devices is done using a simple serial interface compatible with
the SPI protocol. Low current Design permits operation with typical standby and active
currents in the order of nano-amperes.The MCP3204 ADC is a 12-bit serial ADC which
converts the analog input signal to a 12 bit Digital output Data.
27
4.8 Main Features of MCP 3204
1.
12-bit resolution so more accurate.
2.
SPI Serial Interface Modes.
3.
Analog inputs programmable as single-ended or differential pairs.
4.
On chip sample and hold circuit so no need of extra circuitry.
5.
Single supply Operation(2.7 to 5.5 V)
6.
4 or 8 input channels.
Analog inputs for channels 0-4 are treated as independent input channels
configured in a single-ended mode. The CS/SHDN pin is used to initiate communication
with the device when pulled low and will end conversion and put the device in low power
standby when pulled high. The pin must be pulled high between conversions. The SPI
Clock is used to initiate a conversion and to clock out each bit of the conversion as it
takes place. The Serial Data is sent to the input port to configure data into the device. The
Serial data output pin is used to shift out the results of A/D conversion. Data will always
change on the falling edge of each clock as the conversion takes place. The IC employs a
conventional SAR architecture. With this architecture a sample is acquired on an internal
sample/hold capacitor for 1.5 clock cycles starting on the fourth rising edge of the serial
clock after the start bit has been received. Following this sample time, the device uses a
collected charge on the internal sample and hold capacitor to produce a serial 12 bit
digital output code. Communication with the device is done using a 4-wire SPIcompatible interface. For the A/D converter to meet specification, the charge holding
28
capacitor must be given enough time to acquire a 12 bit accurate voltage level during the
1.5 clock cycle sampling period.
For each device, the reference input (Vref) determines the analog input voltage
range. As the reference input is reduced, the LSB size is reduced accordingly. The
theoretical digital output code produced by the A/D converter is a function of the analog
input signal and the reference input as shown below.
Digital output code = 4096*Vin / Vref.
Where,
4096 is because of 12-bits (= 212)
Vin = Analog input voltage
Vref = Reference voltage
Figure 4.2 Clock Cycle
29
In this clock cycle above in Figure 4.2, basic working of this ADC is shown. Here
we are using only one channel so we will make D0 and D1 permanently 00. after that
there is mode selection bit and one start bit.
The first clocked received with CS low and Din high will constitute a start bit.
The SGL/DIFF bit follows the start bit and will determine if the conversion will be done
using single ended or differential input mode.
The next three bits (D0,D1,D2) are used to select the input channel configuration.
The device will begin to sample the analog input on the fourth rising edge of the clock
after the start bit has been received. The sample period will end on the falling edge of the
fifth clock following the start bit.
After the D0 bit is input, one more clock is required to complete the sample and
hold period. On the falling edge of the next clock, the device will output a low null bit.
The next 12 clocks will output the result of the conversion with MSB first as shown in
the figure.
The time between the end of the sample period and that of all 12 data bits have
been clocked out should not exceed more than 1.2ms. Thus minimum clock frequency
should be 10 kHz.
30
Chapter 5
CALCULATIONS
5.1 Maximum Power
Depending on the readings, there is a maximum output power we can generate
and the other parameter is an average output power. Maximum power will be generated
when there is maximum solar insolation level while the average power is the power
generated by average value of solar insolation level. There are also some other
parameters related to the power that we will discuss in this section in the form of
calculations. Our main goal is to generate an output power.
Target Output = X amount of energy generated in KW/m2/day or MW/m2/day
Input = Solar Insolation Level in W/m2/day
Input = Length and Width of Fresnel Mirror (or any other concentrator) in m2
Input = Area in mile sq or sq ft or m2 [15]
Solar Insolation Level (Radiation level) = 10.20 KWh/m2/day
= 10.20 / 12
= 850 W/m2/day
Solar Insolation Level (Radiation level) = 850 W/m2/day (got from the reading)
31
Solar to thermal efficiency = 60% of Solar Insolation Level
= 850*0.60
= 510 W/m2/day
Losses (in Pipes, fitting or etc.) = 10% of Solar to thermal efficiency
= 510*0.10
= 51 W/m2/day
Thus, available power we have at this stage is 459 W/m2/day
Thermal to electric efficiency = 20%
= 0.459*0.20 (KW)
= 0.09180 KW
Now, Area of 1 Panel (of Fresnel mirror) = length * width m2
= 3.66*1.52
= 5.56 m2
Thus, average output power per panel = electrical power generated * area of a panel
= 0.09180*5.56
= 0.512 KW
Now, we have center to center spacing of 2.59m of 1 panel and area of one panel is
32
5.56 m2. So, we can calculate daily panel output power of only one panel which is
2.56KWh/Panel/Day.
Now, we have total 365 days in a year. So, our annual output power will be as
follows:
Annual panel output Power = daily panel output power * 365 days
= 2.56 * 365
= 934 KWh/Panel/Day
Now, if we want to generate 250KW of power in one day then we can do as follows:
0.512 KW/day in 1 panel
250 KW/day in (?)
Thus,
(250KW * 1) / 0.512 KW
= 489 Panels
Moreover, if we increase the area of 1 panel then we can also make efficient changes in
output power. It means there is another way to get the desired output power in one day by
means of area of one panel and number of panels. Now, we will move to calculate the
average output power.
33
5.2 Average Power
Now, we have different reading of solar insolation level and we have average insolation
level as well. So, from that average insolation level we can calculate the average output
power.
Solar Insolation Level (Radiation level) = 7.33 KWh/m2/day
= 7.33 / 12
= 611 W/m2/day
Solar Insolation Level (Radiation level) = 611 W/m2/day (got from the reading)
Solar to thermal efficiency = 60% of Solar Insolation Level
= 611*0.60
= 366 W/m2/day
Losses (in Pipes, fitting or etc.) = 10% of Solar to thermal efficiency
= 366*0.10
= 36.6 W/m2/day
Thus, available power we have at this stage is 329.4 W/m2/day
Thermal to electric efficiency = 20%
= 0.3294*0.20 (KW)
34
= 0.06588 KW
Now, Area of 1 Panel (of Fresnel mirror) = length * width m2
= 3.66*1.52
= 5.56 m2
Thus, average output power per panel = electrical power generated * area of a panel
= 0.06588*5.56
= 0.367 KW
Now, we have center to center spacing of 2.59m of 1 panel and area of one panel is
5.56m*m. So, we can calculate daily panel output power of only one panel which is
1.83KWh/Panel/Day.
Now, we have total 365 days in a year. So, our annual output power will be as
follows:
Annual panel output Power = daily panel output power * 365 days
= 1.83 * 365
= 668 KWh/Panel/Day
35
Now, if we want to generate 250KW of power in one day then we can do as follows:
0.367 KW/day in 1 panel
250 KW/day in (?)
Thus,
(250KW * 1) / 0.367 KW
= 681 Panels
Thus, we can separately check the final output generated power from two different
calculations. Moreover, we can increase the output power by using a catalyst like glycol.
We will discuss the glycol part later. In the upcoming section we will do comparison of
Maximum power and average power.
36
5.3 Comparison of Power
Different Parametes
Solar Insolation(W/m2/ day)
Solar To Thermal Efficiency (60%)
Losses In Pipe, Fitting etc. (10%)
Available Energy(W/m2/ day)
Thermal To Elec. Efficiency(20%)
Avg O/P per Panel (KW)
Length of Panel ( m)
Width of Panel (m)
Center To Center Spacing (m)
Area of One Panel (m2)
Daily Panel O/P (KWh/Panel/Day)
Annual Panel (KWh/Panel/ Year)
Electrical Energy Generated
No. of Panels Required For 250 KW
(Electrical Energy In KW or MW)
Maximum
Average
850
510
51
459
20
0.512
3.66
1.52
2.59
5.57
2.56
934
0.512
489
611
366
36.6
329.4
20
0.367
3.66
1.52
2.59
5.57
1.83
668
0.367
681
Table 5.1 Generated Energy Comparison
37
Chapter 6
SIMULATION
6.1 Simulation Overview
Now, we are in the phase of simulation. In this chapter, we will discuss the whole
simulation process. In this process, the provided inputs will be taken into consideration
and output file will generate respective graphs according to the inputs and provided
conditions. Thus, by this process, we can estimate our outcome and compare it with our
desired one. In addition to these, simulated power system will give us an idea of corner
cases as well where our handy calculations cannot reach. So, in other words, we can say
that by doing this process we can check our whole system and its working along with its
generated graphs and other outputs. Now, let us look at the procedure and some
assumptions.
We will take outputs at three different times of a day.
a.8am
b.12pm
c.4pm
Assumptions
38
1) Measurements are done assuming that 1 Acre of land can maximum produce
1MW of electricity.
2) Atomic conditions considered as following:
- Sunny
-
Cloudy
3) Seasons accounted for are:
- Summer
-
Winter
-
Rainy
Now, we will see the partial program/code written to get simulated (generated output
Power) results.
Note that this program is just a part of main program.
Insolation.m
function [out]= insolation(g,y);
c=ones(1,9);
d=ones(1,9);
d=y*c;
x = linspace(8,16,9);
for i=1:9
r(i)=(d(i)-(x(i)-12)^2);
39
end
if (strcmp(g,'summer')|| (strcmp(g,'winter')))
plot (x,r)
mean(r)
cov(r)
else
out='wrong season';
end
q=[117 110.33 68 38.5]
w=[.512 .367 .217 .021]
plot(q,w)
end
This program was written using MATLAB software. This was just a partial
program of the main program used for simulation. After doing the whole simulation
process, output graphs (for different inputs and conditions) are generate as follows:
40
6.2 Simulated Results and Graphs
Figure 6.1 Temperature Calculation (Daytime wise) of summer season only
In this graph, you can see the temperature Vs time. The noticeable thing here is
that this is for the summer season. The reason behind this is that more the temperature we
can generate better the output power will be produced. Therefore, we can see that in
summer season, at noon (12pm) we can get maximum temperature and thus the power. In
the morning time (around 8:00am to 10:00am), also we have good heat and same in the
41
evening time (around 4:00pm). Now let’s see for the other seasons in the following
graph.
Figure 6.2 Temperature Calculation (Daytime wise) of winter season only
This is a graph for winter and rainy seasons. If we look at the temperature in
these two seasons, we can see that temperature is very less compared to summer season
but not bad. This means that significant power can still be generated. So, it is good that
now we can actually see this condition by simulation process. Moreover, if we want to
42
generate more amount of power in these two seasons, then we can keep our plant (circuit)
on for more time compared to the summer season. It has other solutions as well without
keeping it on for more time like increasing the area of one panel or increasing the number
of panels. Now, the following graph is the generated output power (for one panel) for
different temperatures. This graph gives us the idea of exact power generated at particular
temperature. This is the final output of the simulation process and the best part of
simulation process. It is as follows:
Figure 6.3 Generated (output) Power Vs Temperature
43
If we want, some other information then we just have to run the simulation in
MATLAB by entering different input values and output graph will produce the result.
Now let us produce the output values and charts with different conditions. It is as
following:
Summer Season:
Climate Conditions (Summer)
% of Output Power(MW/Acre)
Season
Time
Summer
Summer
Summer
Summer
Atmosphere
Cloudy
Sunny
Sunny
Cloudy
8
12
16
16
0.25
0.7
0.5
0.35
Table 6.1 Power Distribution Chart (summer)
44
This gives the power distribution same as we discussed previously but this one is
in the form of chart. Now, let us discuss the same for winter and rainy seasons.
Winter and Rainy Seasons:
Climate Conditions (Winter & Rainy)
Season
Winter
Winter
Winter
Rainy
Atmosphere
Cloudy
Sunny
Cloudy
Cloudy
% of Output Power(MW/Acre)
Time
8
12
16
16
0.3
0.65
0.325
0.1525
Table 6.2 Power Distribution Chart (winter & rainy)
45
Thus for the above-mentioned discussion we can generate power in different
season. However, power will be generated according to the season and climate conditions
as well.
46
Chapter 7
GLYCOL AND GENERATED POWER
7.1 Types of Glycol
Glycol (C3H8O2) is mainly used to increase the efficiency of the generated power
and as a coolant in cooling systems for power plants. So, Glycol is basically a catalyst. In
solar water heating applications, glycol is used to keep the heat transfer solution (water +
glycol) from freezing at night in cold climates. Even in warm climates, water can freeze
overnight causing damage to the solar thermal system as well as the structure it is
installed upon. For this reason, all reputable solar contractors will automatically use a
glycol-water mix as the heat transfer medium. In southern climates a 33% glycol solution
is typical, with 50% being the norm in colder climates.
Glycol is an anti-freeze solution. In common use there are three primary types of glycol:
1) Ethylene glycol (monoethylene glycol (MEG), 1, 2-ethanediol),
2) Propylene glycol and
3) Corn glycol
Ethylene glycol is used for automotive anti-freeze. It is a highly toxic substance and is
not used for solar thermal applications due to the danger of poisoning. But in solar
47
thermal applications, propylene glycol (propane-1,2-diol) is used because it is non-toxic.
Due to its similar properties to ethylene glycol, propylene glycol has quickly become the
solar industry norm. [16]
7.2 Comparison of Different Glycols
There are different types of Glycol. One is better than other in one way or other.
From the research, we can say that corn glycol is better than others. The reasons are as
follows:
Corn glycol is a non-toxic, safe glycol with antifreeze properties that has the same
molecular formula as propylene glycol (C3H8O2). This environmentally friendly, or
green glycol, is our solar glycol of choice for thermal transfer. This renewable glycol is
an excellent heat transfer fluid for solar hot water heaters and provides a safer, more
efficient solution than the propylene glycol. [16]
Only through a special catalytic process are chemical engineers able to turn corn into
propylene glycol. To actually create this thermal transfer fluid, the corn is broken down
into lactic acid, and by utilizing copper ions as a catalyst, with hydrogen gas present,
transform the chemical make-up of the lactic acid into propylene glycol. Corn glycol has
been shown in studies to actually be a more efficient form of propylene glycol as a heat
transfer solution.
48
Not only is the corn glycol formed in this process considered a green glycol, the
approach itself is more environmentally friendly, resulting in fewer pollutants and
unwanted byproducts like alcohols. The method of creating propylene glycol is less
efficient and harmful to the environment due to its use of petroleum based starting
materials. The starting materials for corn glycol are renewable, making this the method of
choice for producing thermal transfer fluid. [16]
As far as the safety of this new corn glycol, with its extremely low toxicity,
propylene glycol is recognized as being a safe for food additive purposes. With this safe
glycol, we can rest a bit easier knowing children and animals cannot cause fatal harm to
themselves if small amounts are ingested, or, if some glycol accidentally finds it’s way
into potable water. Using renewable resources to make non-toxic anti-freeze, an
important chemical with a plethora of applications, is a wonderful “green” scientific
advancement.
If you are looking for an environmentally friendly, safe, non-toxic, solar glycol
mix for your solar hot water applications, corn glycol is the medium of choice. Make sure
to place your order for our special SPP formula of corn glycol to fuel your thermal
transfer applications today. The SPP solar glycol has better viscosity, better heat transfer,
better anti-corrosive values protection, proper PH and best of all its 100% renewable.
There are graphs and comparison plots shown below. [16]
49
Figure 7.1 Freeze Points Comparison of different Glycols [16]
50
Table 7.1 Comparison of Ethylene Glycol, Propylene Glycol and Corn Glycol [16]
51
7.3 Simulation Results Using Glycol
In this part, we will discuss about some results using Glycol and will compare
them with the normal condition. Moreover, the graphs in this section explain the
advantages of glycol. Graphs are as follows:
Different Climates
Winter and Rainy (Average)
Winter and Rainy (Maximum)
Summer (Average)
Summer (Maximum)
Generated Power
Temp.
(KW)
(F)
0.021
38.5
0.217
68
0.367
110.33
0.512
117
Table 7.2 Temperature vs. Power (Without using Glycol)
52
Different Climates
Winter and Rainy (Average)
Winter and Rainy (Maximum)
Summer (Average)
Summer (Maximum)
Generated Power with
Glycol(KW)
0.025
0.255
0.43
0.603
Temp.
(F)
46
80
129
138
Table 7.3 Temperature vs. Power (Using Glycol)
53
Power in different climates (KW/Day/Panel)
Winter and Rainy (Average)
Winter and Rainy (Maximum)
Summer (Average)
Summer (Maximum)
Normal With Glycol
0.021
0.025
0.217
0.255
0.367
0.43
0.512
0.603
Table 7.4 Comparison of generated Power
Therefore, from these results we can see that usage of glycol is better than using
normal water as a coolant.
54
Chapter 8
CONCLUSION
The purpose of this project is to reduce the costs of petroleum by using solar energy.
It is impressive that new methods of power generation are invented and being used as
well. With these sources, we can generate lots of power and with very low cost.
Moreover, they are free (especially solar energy) too and easy to get. In fact, we do not
need to do anything to get this source (solar). In addition to these reasons, solar energy
source has a long life and it is renewable.
We can conclude that from the simulation and calculations shown in the previous
chapters that we can generate tremendous amount of energy by using just one solar panel.
So, in the future if we want to increase the amount of generated power then we can just
increase the number of panels and can generate more power or we can just increase the
area of one panel and can increase the power generated.
55
REFERENCES
[1] http://gov.ca.gov/press-release/11073/
[2] http://papundits.files.wordpress.com/2009/05/april-09-power-chart.jpg
[3] http://www.econbrowser.com/archives/2009/06/gas_price2_jun_09.gif
[4] http://204.64.105.28/specialrpt/energy/renewable/solar.php
[5] http://stalix.com/isolation.pdf
[6] http://www.solarseller.com/solar_insolation_maps_and_chart_.htm
[7] http://www.gaisma.com/en/location/redding-california.html
[8] http://www.ci.redding.ca.us/demographics.html
[9] http://www.svwmp.water.ca.gov/pdf_documents/Redding/Project15A.pdf
[10] http://www.apricus.com/html/solar_collector_insolation.htm
[11] http://en.wikipedia.org/wiki/Fresnel_mirror
[12] http://ieeexplore.ieee.org/stamp/stamp.jsp?arnumber=04789472
[13] http://en.wikipedia.org/wiki/Sopogy
[14] http://www.sopogy.com/microcsp/
[15] http://www.sopogy.com/pdf/contentmgmt/App_Sheet_Power_Print.pdf
[16] http://www.solarpanelsplus.com/corn-glycol/