Nang-luong-tai-tao_Nguyen-huu-phuc_chapter-1_intro_renewable-energy.pdf

Green Energy Course Syllabus
CHAPTER 1: Introduction to Green Energy (1 lecture)
CHAPTER 2: Electric Power Industry - Distributed Generation Technologies (1 lecture)
CHAPTER 3: Wind Power Systems (2 lectures)
CHAPTER 4: Solar Resource- Photovoltaic Materials (1 lecture)
CHAPTER 5: Photovoltaic Systems (3 lectures)
CHAPTER 6: Energy Storage - Electric Vehicles (1 lecture)
CHAPTER 7: Other Renewable Energy Resources (0.3 lecture)
CHAPTER 8: Smart Grid (0.7 lecture)
TUTORIALS: DC-DC Converters; MPPT; Roof Top Solar Home; HOMER Sofware; PV+ Wind
Power Problems; Papers on RE
LABS: on RE topics
CuuDuongThanCong.com https://fb.com/tailieudientucntt

Renewable Energy and Energy Storage for
A Sustainable Development: What Alternatives?
A look on energy, renewable energies, energy storage and
synthetic fuels, hybrid architecture, fuel cells, hydrogen as
a vector of energy of the future.
2/18/2012 2
CHAPTER 1: Introduction to
Green Energy Technology
Biên sọan: Nguyễn Hữu Phúc
Khoa Điện- Điện Tử- Đại Học Bách Khoa TPHCM

The Earth resources are quite limited in quantity
Many challenges to mankind in 21st century: development,
health, water, food, demography, education, energy
Energy…
for a sustainable development
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Energy
is an abstract concept for different concrete manifestations
• In physics, energy (Ancient Greek: ἐνέργεια energeia "activity, operation"[1]) is a quantity that is
often understood as the ability a physical system has to produce changes on another physical
system.[2][3] The changes are produced when the energy is transferred from a system to another. A
system can transfer energy by means of three ways, namely: physical or thermodynamical work,
heat transfer, or mass transfer.
• Energy is a scalar physical quantity. In the International System of Units (SI), energy is measured in
joules, but in many fields other units, such as kilowatt-hours and kilocalories, are customary.
• Energy is by nature of conservation: Energy may not be created nor destroyed.
• Any form of energy can be transformed into another form. When energy is in a form other than
thermal energy, it may be transformed with good or even perfect efficiency, to any other type of
energy.
• With thermal energy, however, there are often limits to the efficiency of the conversion to other
forms of energy, as described by the second law of thermodynamics. Depending on circumstances,
some fraction of thermal energy exists in a form unavailable for further transformation; the
remainder may be used to produce any other type of energy, such as electricity.
-cooking, heating
- lighting
- mechanical work: machines
-Industrial processing
- information processing
-transports

Primary sources of energy
Fire from burning wood or oil
Animal force (horses, dogs, buffalos,…)
Water of rivers and tides (mills, …)
Wind (pumps, mills,…)
And other forms of renewable energies
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Energy sources of 21st century
• Fossil fuels: coal, oil, natural gas
• Nuclear Energy
• Electricity: secondary form of energy as of modern energy type of high
quality, synonym of development.
• During 20 th century, there are great concerns for our green planet:
- natural resources are quite limited, especially in terms of energy
- mankind is destroying the earth environment in the process of his
development
• What is the future: towards a development with renewable resources?...
• And which new energy vectors will be adapted?
2/18/2012 6
=> Primary Energy and Energy Storage Vectors

Electrification of the world
Vision
Sustainable energy production
Photos: NASA,
NREL

Trustworthy energy systems
Vision
Best use of resources
Photos: Philips Lumileds,
OSHA, I. Dobson

Flexible, intelligent autonomy
Vision
Photos: ajou.ac.kr, EPRI, LBL

World Energy Situation
World consumption of energy, as of 2004
140.106 GWh or 12 G TOE (G= Giga= 109;
TOE= Ton of Oil Equivalent)
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Renewables
Fossil Fuel
Nuclear
PRIMARY SOURCES

2/18/2012 11
Average Energy Consumption/ day
A man consumes 65 kWh/day on the
average

• Fossil Fuels are widely and directly used as
primary sources and serve as convenient
energy vector with low efficiency.
2/18/2012 12
Sectors consumming primary energy
Industry
Residences and offices
Transports
Electricity
production
Output
electricity
produced
of 12%

2/18/2012 13
Joules, BTUs, Quads
A quad is a unit of energy equal to 1015 (a
short-scale quadrillion) BTU,[1] or 1.055 × 1018
joules (1.055 exajoules or EJ) in SI units.
The unit is used by the U.S. Department of
Energy in discussing world and national
energy budgets. The global primary energy
production in 2004 was 446 quad, equivalent
to 471 EJ. [2]
Some common types of an energy carrier
approximately equal 1 quad are:
8,007,000,000 Gallons (US) of gasoline
293,083,000,000 Kilowatt-hours (kWh)
36,000,000 Tonnes of coal
970,434,000,000 Cubic feet of natural gas
5,996,000,000 UK gallons of diesel oil
25,200,000 Tonnes of oil
252,000,000 tonnes of TNT or five times the
energy of the Tsar Bomba nuclear test.

Development, Oh, Development !
… of economy
…. of consumption
… of population
….and of polution
And degeneration of natural
resources !!
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Pollution, gas emission: global warming, urban polution

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Green House Effect: a beneficiary and fragile equilibrium
Deforestation: 1 GTons/ year
Fossil emission: 6 Gtons/year
Absorption Capacity of the Earth: 3 Gtons/year
Annual emission of CO2 (in 10
12
mol C/year),
since the beginning of industrial era

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Population growth: towards a figure of 10 billions of
people in 2100

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Population growth and development: growth of energy consumption
2000: 12 G TOE
2020: 20 G TOE
2040: 28 G TOE

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2000: 12 G TOE
2020: 20 G TOE
2040: 28 G TOE

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A “soft” scenario of
development
A Great Effort !

Which renewable energies?
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Fossil Hydrocarbons = Solar Energy Storage

Energy received from the Sun: 1600.10
9
GWh/year
-reflected: 480 109 GWh (30%) Wind: 32.109 GWh (8%)
-converted: 400 109 GWh (25%)=>↕ Hydrology : 352.109 GWh (88%)
-heat: 720 109 GWh (45%) Others: 4%, of which Photosynthesis: 0.96.109 GWh (0.24%)
Exploitation estimated in Millions of GWh/year:
• Solar Radiation: 1000.106 GWh
• Photosynthesis: 1000.106 GWh
• Biomass: 58.106 GWh
• Wind: 50.106 GWh
• Thermal-Sea: 80.106 GWh
• Hydraulic Sources: 20.106 GWh
• Tide: 0.5.106 GWh
• Geothermal Sources: 0.04.106 GWh
• Human Consumption: 140.106 GWh
2/18/2012 27

Electricity
clean, easy to control, highly efficient= development
an ideal secondary vector, but…
distributed through a network which is bulky and costly
(2 billions of human population have no access to electricity)
Renewable Energy => Electric Energy
Which primary sources is electricity
produced from?
World production: 40.106 GWh
(3200 GW installed)
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38%
18%
40%
4%
Hydropower
Coal filled Thermal Power
Gas ThermalPower
Diezen and others
EVN,
9278
MW,
79%
External
EVN,
2439
MW, 21%
Vietnam- Power Installed : 11,717MW ( in 2006)

Electricity production is nowadays imperfect
with a majority of electricity produced from thermal power plants (from
fossil fuels: coal, gas, oil)
a mediocre efficiency of lower than 40%
which means 60% of energy lost in heat rarely recuperated
=> a big energetic waste of non- renewable resources
Heat recovery => Cogeneration
An action of conscience already taken…even in timidity
• Wind power: 30 % growth per year/ 35 000 MW installed
• 0.5% of world electricity production
• 145 000 MW expected in 2010
• which means 2.5 % of world electricity production
• Photovoltaic Energy: 2000 MW installed/ 30-40 % growth/year
• 0.02%, but so promising beyond 2050
• In Europe:
• 1 MW of Wind Power= 2.4 GWh/year
• 1 MW of PV Energy= 1.2 GWh/year
• 1 MW of Nuclear Energy= 7 GWh/year
ENERGY STORAGE?
29

The World is Now Going Green with Wind Power….
2/18/2012 30

Vietnam is Really Going Green?
• First windmills of 2, 0
MW/unit already installed
along Natonal Highway 1
A in Tuy Phong District-
Binh Thuan Province
=> Demand for Green
Power is a must in
Vietnam in the near
future.
=> Training and
Researches in the field of
Green Energy related to
electric power really
attract undergraduate and
graduate students.

Going Green with PV Systems Applications: Stand Alone or…
2/18/2012 32

off-grid or grid-connected
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Renewable energy= Flux Energy
Which energy vectors are well suitable for the future?
At present:
• Fossil fuels= energy storage and energy vector
• Electricity= energy of flux , enrgy vector (20% in final usage)
In the future:
• Electricity, flux energy from renewables and nuclear energy.
• Other vectors : capable of being stored and transported
• Hydrocarbon from CO2 of atmosphere: biofuels
• Hydrogen
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Energy Storage using Hydro Reservoirs of Different Altitudes
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Storage in the form of Mechanical Energy= Compressed Air Energy Storage
(CAES)
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Kinetic Energy Storage Using Flywheels
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Electrochemical Conversion and Energy Storage- Batteries
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Lead Acid Batteries
of oldest technology and so far find widespread applications
- Advantages: low cost, robust, wide applications in vehicles, UPS, recycled up to 98%
- Disadvantages: low charge/discharge cycles: 500 cycles; low ratio of energy stored/mass:
35 Wh/kg and low power/mass: 100 W/kg
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2/18/2012 40

Super Capacitors
An electric double-layer capacitor (EDLC), also known as supercapacitor, supercondenser,
pseudocapacitor, electrochemical double layer capacitor, or ultracapacitor, is an electrochemical
capacitor with relatively high energy density.
Compared to conventional electrolytic capacitors the energy density is typically on the order of
thousands of times greater. In comparison with conventional batteries or fuel cells, EDLCs also have
a much higher power density.
A typical D-cell sized electrolytic capacitor displays capacitance in the range of tens of millifarads.
The same size EDLC might reach several farads, an improvement of two orders of magnitude. EDLCs
usually yield a lower working voltage; as of 2010 larger double-layer capacitors have capacities up
to 5,000 farads.[1] Also in 2010, the highest available EDLC energy density is 30 Wh/kg[2] (although
85 Wh/kg has been achieved at room temperature in the lab[3]), lower than rapid-charging lithium-
titanate batteries.[4]
EDLCs have a variety of commercial applications, notably in "energy smoothing" and momentary-
load devices. They have applications as energy-storage devices used in vehicles, and for smaller
applications like home solar energy systems where extremely fast charging is a valuable feature.
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Maxwell Technologies "MC" and "BC" series supercapacitors (up to 3000 farad capacitance)
Maxwell Technologies "MC" and "BC" series supercapacitors
(up to 3000 farad capacitance)

2/18/2012 42
7] Supercapacitors have several disadvantages and advantages relative to batteries, as described below.[
Disadvantages
The amount of energy stored per unit weight is generally lower than that of an electrochemical battery (3–5 W·h/kg for an standard ultracapacitor, although 85
W.h/kg has been achieved in the lab[10] as of 2010[update] compared to 30-40 W·h/kg for a lead acid battery), and about 1/1,000th the volumetric energy density of
gasoline.
Typical of any capacitor, the voltage varies with the energy stored. Effective storage and recovery of energy requires complex electronic control and switching
equipment, with consequent energy loss
Has the highest dielectric absorption of any type of capacitor.
High self-discharge - the rate is considerably higher than that of an electrochemical battery.
Cells hold low voltages - serial connections are needed to obtain higher voltages. Voltage balancing is required if more than three capacitors are connected in
series.
Linear discharge voltage prevents use of the full energy spectrum.
Due to rapid and large release of energy (albeit over short times), EDLC's have the potential to be deadly to humans.
Advantages
Long life, with little degradation over hundreds of thousands of charge cycles. Due to the capacitor's high number of charge-discharge cycles (millions or more
compared to 200 to 1000 for most commercially available rechargeable batteries) it will last for the entire lifetime of most devices, which makes the device
environmentally friendly. Rechargeable batteries wear out typically over a few years, and their highly reactive chemical electrolytes present a disposal and safety
hazard. Battery lifetime can be optimised by charging only under favorable conditions, at an ideal rate and, for some chemistries, as infrequently as possible.
EDLCs can help in conjunction with batteries by acting as a charge conditioner, storing energy from other sources for load balancing purposes and then using
any excess energy to charge the batteries at a suitable time.
Low cost per cycle
Good reversibility
Very high rates of charge and discharge.
Extremely low internal resistance (ESR) and consequent high cycle efficiency (95% or more) and extremely low heating levels
High output power
High specific power. According to ITS (Institute of Transportation Studies, Davis, California) test results, the specific power of electric double-layer capacitors
can exceed 6 kW/kg at 95% efficiency[11]
Improved safety, no corrosive electrolyte and low toxicity of materials.
Simple charge methods—no full-charge detection is needed; no danger of overcharging.

Energy
…and…
transport
2/18/2012 43

CO2 Emission
2/18/2012 44

Transport
• Road Traffic: 98% of vehicles
petrolium consuming
• 2005: 0.8.109 vehicles
• 2010: 1.5.109 vehicles
• 5000 km in car = 1 Ton of CO2
emission
• The same figure applied for
traveling by
airplane/passenger
2/18/2012 45
World Road Traffic

Biofuels: biogas, biodiesel, alcohol
2/18/2012 46

Evolution of transport systems:
always with more comfort and less pollution
• Amelioration of existing heat engines
• Design of thermal motors with higher efficiency and less
poluting: new combustibles introduced and better combustion
process control
2/18/2012 47
-Ever increasing penetration of electric energy into transport in
every car types, individual and public.
-More electrical car now is a trend: air-bags, GPS, radars,
electronically controlled ignition, brakes, …
-And now hybrid car, electric vehicles is a fact.
Autonomy: energy Power: some 10 kW
Introduction of Electric Drive

Electric Vehicles: Embedded Energy
Existing issues to be solved:
-Autonomy of 200 km
-Long charge rate: many hours
2/18/2012 48
Example of solar energy
recharge station

Energy Storage by Battery
2/18/2012 49
the best existing battery technology: Li-Ion: 150 Wh/kg !

2/18/2012 50
Solar Car: SunRacers

2998 km traveled with an average speed of 59.3 km/h (stop time not
taken into account) with 46 974 Wh (equivalent to 6 litters of gas)
2/18/2012 51

Japanese car wins World Solar Challenge in Australia (w/ Video)- October 28,
2009 -Tokai Challenger
A Japanese sun-powered car won the World Solar Challenge on Wednesday
after averaging speeds of more than 100 kilometres (62 miles) per hour in a
four-day race through Australia's desert Outback.
Organisers said the Tokai Challenger crossed the finish line in Adelaide, South
Australia, at 3:39 pm local time, after 29 hours and 49 minutes' racing
following Sunday's departure from the northern city of Darwin.
The futuristic Tokai put in a near-flawless run with only one flat tyre on the
3,000 kilometre race. Its nearest rivals were more than two hours behind and
were due to battle it out for second place on Thursday.
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Hybrid Cars- Electric Cars-
Fuel Cell Solution with Zero Emission

Daimler Chrysler FC 86 kW “ Ballard”- H2, 350 bars, hybrid- 60 units
manufactured, of which ~ 30 units in operation as of Sept 2005 (15 in the US)
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2/18/2012 56
- Where does hydrogen come from?
- What devices are used for hydrogen storage?
- What is hydrogen specific energy?
Hydrogen as An Energy Vector
Hydrogen is a promising candidate for energy storage, in terms of being stored in
reservoirs as petroleum.
Specific Energy of Various Combustibles
2/18/2012

Hydrogen Sources
• Hydrogen does not exist in natural form
Hydrogen can be get from:
• Fossil: from oil, natural gas, coal
• Electricity: nuclear, photovoltaic, wind, hydraulic, geothermal
+ electrolysis
• Heat: Thermochemical process
• Photons: photo-electrolysis, photobiology, photosynthesis +
biomass transformation and fermentation
2/18/2012 57

2/18/2012 58
A sample showing a possible energy chain of the
future: Solar Energy- Hydrogen- Electricity Hydrogen (Energy Storage) and
Electricity (Energy Flux) :
two complementary energy vectors

2/18/2012 59
Hydrogen (Gas) Storage in Tanks under
High Pressure

H2 Applications
2/18/2012 60

Introduction
Renewable Energy Systems

Electric Systems in Energy Context
• Class focuses on renewable electric systems, but we first need
to put them in the context of the total energy delivery system
• Electricity is used primarily as a means for energy
transportation
• Use other sources of energy to create it, and it is usually
converted into another form of energy when used
• About 40% of US energy is transported in electric form, a
percentage that is gradually increasing
• Concerns about need to reduce CO2 emissions and fossil fuel
depletion are becoming main drivers for change in world
energy infrastructure

The World
• The total world-wide energy consumption was 472 quad
(2006), a growth of about 19% from 2000 values
• A breakdown of this value by fuel source is 171.7 quad
(36.3%) from petroleum, 127.5 (27.0%) from coal, 108.0
(22.9%) from natural gas, 29.7 (6.3%) from hydroelectric, 27.8
(5.9%) from nuclear, 4.7 (1.0%) other used as electric power,
2.8 (0.6%) other not used as electric power
• World-wide total is 86.2% fossil-fuel, and (currently) less than
1.0% in the focus area of this class

Per Capita Energy Consumption in MBtu per Year
(2006 data)
• Iceland: 568.6 Norway: 410.8
• Kuwait: 469.8 Canada: 427.2
• USA: 334.6 Australia: 276.9
• Russia: 213.9 France: 180.7
• Japan: 178.7 Germany: 177.5
• UK: 161.7 S. Africa:117.2
• China: 56.2 Brazil: 51.2
• Indonesia: 17.9 India: 15.9
• Pakistan: 14.2 Nigeria: 7.8
• Malawi: 1.9 Afghanistan: 0.6
Source http://www.eia.doe.gov/pub/international/iealf/tablee1c.xls

Global Warming: What is Known is CO2 in Air is Rising
Source: http://www.esrl.noaa.gov/gmd/ccgg/trends/
Value
was about
280 ppm
in 1800,
387 in 2009
Rate of
increase
is about
2 ppm
per year

As is Worldwide Temperature
(at Least Over Last 150 Years
Source: http://www.cru.uea.ac.uk/cru/info/warming /
Baseline is 1961 to 1990 mean

Monthly Worldwide Temperature
Data, Last 30 Years (Celsius, 1961-1990 Deviation)
-0.4
-0.2
0
0.2
0.4
0.6
0.8
1
1979/08
1981/02
1982/08
1984/02
1985/08
1987/02
1988/08
1990/02
1991/08
1993/02
1994/08
1996/02
1997/08
1999/02
2000/08
2002/02
2003/08
2005/02
2006/08
2008/02
http://hadobs.metoffice.com/hadcrut3/diagnostics/global/nh+sh/monthly

68
Eventual Atmospheric CO2 Stabilization Level Depends
Upon CO2 Emissions
Regardless of what we do in the short-
term the CO2
levels in the atmosphere willcontinue to
increase.
The eventual stabilization levels depend
upon how
quickly CO2 emissions are curtailed.
Emissions from electricity production are
currently about 40% of the total

How Information is Presented is Also Important
The actual area of Greenland and Mexico is about the same
Source: http://data.giss.nasa.gov/gistemp/2008/Fig1.gif

World Population Trends
Country 2005 2015 2025 %
Japan 127.5 124.7 117.8 -7.6
Germany 82.4 81.9 80.6 -2.1
Russia 142.8 136.0 128.1 -10.3
USA 295.7 322.6 349.7 18.2
China 1306 1393 1453 11.2
India 1094 1274 1449 32.4
World 6449 7226 7959 23.4
Source: www.census.gov/ipc/www/idb/summaries.html; values in
millions; percent change from 2005 to 2025

Energy Economics
• Electric generating technologies involve a tradeoff between
fixed costs (costs to build them) and operating costs
• Nuclear and solar high fixed costs, but low operating costs
• Natural gas/oil have low fixed costs but high operating
costs (dependent upon fuel prices)
• Coal, wind, hydro are in between
• Also the units capacity factor is important to determining
ultimate cost of electricity
• Potential carbon “tax” major uncertainty

Natural Gas Prices 1990’s to 2009
Marginal cost for natural gas fired electricity price
in $/MWh is about 7-10 times gas price

Coal Prices have Fallen Substantially from Last Year
Source: http://www.eia.doe.gov/cneaf/coal/page/coalnews/coalmar.html#spot

Vertical Monopolies
• Within a particular geographic market, the
electric utility had an exclusive franchise
Generation
Transmission
Distribution
Customer Service
In return for this exclusive
franchise, the utility had the
obligation to serve all
existing and future customers
at rates determined jointly
by utility and regulators
It was a “cost plus” business

Vertical Monopolies
• Within its service territory each utility was the only game in
town
• Neighboring utilities functioned more as colleagues than
competitors
• Utilities gradually interconnected their systems so by 1970
transmission lines crisscrossed North America, with voltages
up to 765 kV
• Economies of scale keep resulted in decreasing rates, so most
every one was happy

Current Midwest Electric Grid

Abandoned Wind Farm Need South Point in Hawaii
Source: Prof. Sanders

Power System Structure
• All power systems have three major components: Load,
Generation, and Transmission/Distribution.
• Load: Consumes electric power
• Generation: Creates electric power.
• Transmission/Distribution: Transmits electric power from
generation to load.
• A key constraint is since electricity can’t be effectively stored,
at any moment in time the net generation must equal the
net load plus losses

LOADS
• Can range in size from less than one watt to
10’s of MW
• Loads are usually aggregated for system
analysis
• The aggregate load changes with time, with
strong daily, weekly and seasonal cycles
– Load variation is very location dependent

GENERATION
• Large plants predominate, with sizes up to
about 1500 MW.
• Coal is most common source (56%), followed
by nuclear (21%), hydro (10%) and gas (10%).
• New construction is mostly natural gas, with
economics highly dependent upon the gas
price
• Generated at about 20 kV for large plants

New Generation by Fuel Type
(USA 1990 to 2030, GW)
Source: EIA Annual Energy Outlook 2007

Basic Steam Power Plant
Rankine Cycle: Working fluid (water) changes
between gas and liquid

Modern Coal Power Plant

$4 Billion, 1600 MW Prairie State Energy
Campus Under Construction
Located in
Southern
Illinois near
St. Louis,
construction
started in
October 2007
with
completion
expected is
2011/2
Largest Coal-Fired Plant
under construction
in the United States; now
25% complete
http://www.prairiestateenergycampus.com/default.asp

Basic Gas Turbine
Compressor
Fuel
100%
Fresh
air
Combustion
chamber
Turbine
Exhaust
gases 67%
Generator
AC
Power
33%
1150 o
C
550 o
C
Brayton Cycle: Working fluid is
always a gas
Most common fuel is natural gas
Maximum Efficiency
550 273
1 42%
1150 273

  

Typical efficiency is around 30 to 35%

Gas Turbine
Source: Masters

Combined Heat and Power
Compressor
Fuel
100%
Fresh
air
Combustion
chamber
Turbine
Exhaust gases
Generator
AC
Power
33%
Heat recovery steam
generator (HRSG)
Water
pump
Feedwater
Exhaust 14%
Steam 53%
Process heat
Absorption cooling
Space & water heating
Overall Thermal Efficiency = 33% (Electricity) + 53% (Heat) = 86%

Combined Cycle Power Plants
Efficiencies of up to 60% can be achieved, with even higher
values when the steam is used for heating

Determining operating costs
• In determining whether to build a plant, both the fixed costs and
the operating (variable) costs need to be considered.
• Once a plant is build, then the decision of whether or not to
operate the plant depends only upon the variable costs
• Variable costs are often broken down into the fuel costs and the
O&M costs (operations and maintenance)
• Fuel costs are usually specified as a fuel cost, in $/Mbtu, times
the heat rate, in MBtu/MWh
– Heat rate = 3.412 MBtu/MWh/efficiency
– Example, a 33% efficient plant has a heat rate of 10.24

Heat Rate
• Fuel costs are usually specified as a fuel cost,
in $/Mbtu, times the heat rate, in MBtu/MWh
– Heat rate = 3.412 MBtu/MWh/efficiency
– Example, a 33% efficient plant has a heat rate of
10.24 Mbtu/MWh
– About 1055 Joules = 1 Btu
– 3600 kJ in a kWh
• The heat rate is an average value that can
change as the output of a power plant varies.

Fixed Charge Rate (FCR)
• The capital costs for a power plant can be
annualized by multiplying the total amount by a
value known as the fixed charge rate (FCR)
• The FCR accounts for fixed costs such as interest
on loans, returns to investors, fixed operation
and maintenance costs, and taxes.
• The FCR varies with interest rates, and is now
below 10%.
• For comparison this value is often expressed as
$/yr-kW

Annualized Operating Costs
• The operating costs can also be annualized
by including the number of hours a plant is
actually operated
• Assuming full output the value is
Variable ($/yr-kW) =
[Fuel($/Btu) * Heat rate (Btu/kWh) +
O&M($/Kwh)]*(operating hours/hours in year)

Coal Plant Example
• Assume capital costs of $4 billion for a 1600 MW coal plant with a
FCR of 10% and operation time of 8000 hours per year. Assume a
heat rate of 10 Mbtu/MWh, fuel costs of 1.5 $/Mbtu, and variable
O&M of $4.3/MWh. What is annualized cost per kWh?
Fixed Cost($/kW) = $4 billion/1.6 million kW=2500 $/kW
Annualized capital cost = $250/kW-yr
Annualized operating cost = (1.5*10+4.3)*8000/1000
= $154.4/kW-yr
Cost = $(250 + 154.4)/kW-yr/(8000h/yr) = $0.051/kWh

Capacity Factor (CF)
• The term capacity factor (CF) is used to provide a
measure of how much energy an plant actually
produces compared to the amount assuming it
ran at rated capacity for the entire year
CF = Actual yearly energy output/(Rated Power *
8760)
• The CF varies widely between generation
technologies,

Generator Capacity Factors
Source: EIA Electric Power Annual, 2007
The capacity factor for solar is usually less than 25%
(sometimes substantially less), while for wind it is usually
between 20 to 40%). A lower capacity factor means a
higher cost per kWh

One-line Diagrams
• Most power systems are balanced three phase
systems.
• A balanced three phase system can be
modeled as a single (or one) line.
• One-lines show the major power system
components, such as generators, loads,
transmission lines.
• Components join together at a bus.

Substation Bus

Midwest Portion of Transmission Grid

PowerWorld Simulator Three Bus System
Bus 2 Bus 1
Bus 3
Home Area
204 MW
102 MVR
150 MW
150 MW
37 MVR
116 MVR
102 MW
51 MVR
1.00 PU
-20 MW
4 MVR
20 MW
-4 MVR
-34 MW
10 MVR
34 MW
-10 MVR
14 MW
-4 MVR
-14 MW
4 MVR
1.00 PU
1.00 PU
106 MW
0 MVR
100 MW
AGC ON
AVR ON
AGC ON
AVR ON
Load with
green
arrows
indicating
amount
of MW
flow
Used
to control
output of
generator Direction of arrow is used to indicate
direction of real power (MW) flow
Note the
power
balance at
each bus

Metro Chicago Electric Network

Power Balance Constraints
• Power flow refers to how the power is moving
through the system.
• At all times in the simulation the total power
flowing into any bus MUST be zero!
• This is know as Kirchhoff’s law. And it can not
be repealed or modified.
• Power is lost in the transmission system.

Basic Power Flow Control
• Opening a circuit breaker causes the power
flow to instantaneously (nearly) change.
• No other way to directly control power flow in
a transmission line.
• By changing generation we can indirectly
change this flow.

Transmission Line Limits
• Power flow in transmission line is limited by
heating considerations.
• Losses (I2 R) can heat up the line, causing it to
sag.
• Each line has a limit; Simulator does not allow
you to continually exceed this limit. Many
utilities use winter/summer limits.

Overloaded Transmission Line

Interconnected Operation
• Power systems are interconnected.
• Interconnections are divided into smaller
portions, called balancing authority areas
(previously called control areas)

Balancing Authority (BA) Areas
• Transmission lines that join two areas are
known as tie-lines.
• The net power out of an area is the sum of the
flow on its tie-lines.
• The flow out of an area is equal to
total gen - total load - total losses = tie-flow

Area Control Error (ACE)
• The area control error is the difference between
the actual flow out of an area, and the scheduled
flow.
• Ideally the ACE should always be zero.
• Because the load is constantly changing, each
utility must constantly change its generation to
“chase” the ACE.

Automatic Generation Control
• BAs use automatic generation control (AGC) to
automatically change their generation to keep
their ACE close to zero.
• Usually the BA control center calculates ACE based
upon tie-line flows; then the AGC module sends
control signals out to the generators every couple
seconds.

Three Bus Case on AGC
Bus 2 Bus 1
Bus 3
Home Area
266 MW
133 MVR
150 MW
250 MW
34 MVR
166 MVR
133 MW
67 MVR
1.00 PU
-40 MW
8 MVR
40 MW
-8 MVR
-77 MW
25 MVR
78 MW
-21 MVR
39 MW
-11 MVR
-39 MW
12 MVR
1.00 PU
1.00 PU
101 MW
5 MVR
100 MW
AGC ON
AVR ON
AGC ON
AVR ON

Generator Costs
• There are many fixed and variable costs associated
with power system operation.
• The major variable cost is associated with
generation.
• Cost to generate a MWh can vary widely.
• For some types of units (such as hydro and
nuclear) it is difficult to quantify.
• Many markets have moved from cost-based to
price-based generator costs

Economic Dispatch
• Economic dispatch (ED) determines the least cost
dispatch of generation for an area.
• For a lossless system, the ED occurs when all the
generators have equal marginal costs.
IC1(PG,1) = IC2(PG,2) = … = ICm(PG,m)

Power Transactions
• Power transactions are contracts between
areas to do power transactions.
• Contracts can be for any amount of time at
any price for any amount of power.
• Scheduled power transactions are
implemented by modifying the area ACE:
ACE = Pactual, tie-flow - Psched

100 MW Transaction
Bus 2 Bus 1
Bus 3
Home Area
Scheduled Transactions
225 MW
113 MVR
150 MW
291 MW
8 MVR
138 MVR
113 MW
56 MVR
1.00 PU
8 MW
-2 MVR
-8 MW
2 MVR
-84 MW
27 MVR
85 MW
-23 MVR
93 MW
-25 MVR
-92 MW
30 MVR
1.00 PU
1.00 PU
0 MW
32 MVR
100 MW
AGC ON
AVR ON
AGC ON
AVR ON
100.0 MW
Scheduled 100 MW
Transaction from Left to Right
Net tie-line flow is
now
100 MW

Distributed Generation (DG)
• Small-scale, up to about 50 MW
• Includes renewable and non-renewable
sources
• May be isolated from the grid or grid-
connected
• Near the end user

Integrated Generation, Transmission, Buildings, Vehicles
kWh
PHEV
N. Gas
Heat kWh
kWh
Smart
meters
Vehicle-to-Grid
Combined
Heat and
Power (CHP)
Renewables
Grid
Source: Masters

Pluggable Hybrid Electric Vehicles (PHEVs) as
Distributed Generation
Source: www.calcars.org
• Can provide services back to
the grid
Source:
http://www.popularmechanics.com/automotive/new_cars/4215489.html
• Can charge at night when electricity is
cheap

DG Technologies
• Microturbines
• Reciprocating Internal Combustion Engines
• Stirling-Cycle Engine
• Concentrating Solar Power (CSP)
– Solar Dish/Sterling
– Parabolic Troughs
– Solar Central Receiver
• Biomass
• Micro-Hydro
• Fuel Cells

Reasons for Distributed Generation
• Good for remote locations
• Renewable resources
• Reduced emissions
• Can use the waste heat
• Can sell power back to the grid

Terminology
• Cogeneration and Combined Heat and Power (CHP)
– capturing and using waste heat while generating electricity
• When fuel is burned one product is water; if water vapor exits
stack then its energy is lost (about 1060 Btu per pound of water
vapor)
• Heat of Combustion for fuels
– Higher Heating Value (HHV) – gross heat, accounts for latent
heat in water vapor
– Lower Heating Value (LHV) – net heat, assumes latent heat in
water vapor is not recovered
– Both are used - Conversion factors (LHV/HHV)

HHV and LHV Efficiency
• Find LHV efficiency or HHV efficiency from the heat
rate:
• Convert to get the other efficiency:
HHV( )
HHV( )
3412 Btu/kWh
(3.16)
Heat Rate (Btu/kWh)
LHV
LHV
 
HHV LHV
LHV
(4.1)
HHV
 
 
  
 
Note the LHV is less than the HHV

Microturbines
• Small gas turbines, 500 W to 100s kW
• Only one moving part
• Combined heat and power
• High overall efficiency
Source:
http://www.capstoneturbine.com
Capstone 65 kW Microturbine
230 kW fuel
80% CHP
Efficiency
120 kW hot
water output
65 kW electrical
output
45 kW waste heat

Microturbines
1. Incoming air is
compressed
2. Moves into cool side
of recuperator & is
heated
3. Mixes with fuel in
combustion chamber
4. Expansion of hot
gases spins shaft
5. Exhaust leaves
Figure 4.1

Reciprocating Internal Combustion Engines (ICEs)
• Piston-driven
• Make up a large fraction of the DGs and CHP today
• From 0.5 kW to 6.5 MW
• Electrical efficiencies ~37-40%
• Can run on gasoline, natural gas, kerosene, propane, fuel oil,
alcohol, and more
• Relatively clean for burning natural gas
• Most are four-stroke engines
• Waste heat for cogeneration

Four-Stroke Engines
1. Intake
2. Compression
3. Power
4. Exhaust
Figure 4.3

Two-Stroke Engines
• A compression stroke and a power stroke
• Intake and exhaust open at end of power
stroke, close at start of compression stroke
• Greater power for their size
• Less efficient
• Produce higher emissions

Spark-Ignition (Otto-cycle)
• Easily ignitable fuels like gasoline and propane
• Air-fuel mixture enters cylinder during intake
• Combustion initiated by externally-timed
spark

Compression-Ignition (Diesel-cycle)
• Diesel or fuel oil
• Fuels not premixed with air
• Fuel injected under high pressure into cylinder
towards end of compression cycle
• Increase in pressure causes temperature to
rise until spontaneous combustion occurs,
initiates power stroke

Diesel Engines
• More sudden, explosive ignition – must be
built stronger and heavier
• Higher efficiencies
• Require more maintenance
• Higher emissions

Charged Aspiration
• Increases efficiency of ICEs
• Pressurize air before it enters the cylinder
• Turbocharger or supercharger
• Able to lower combustion temperature and
lower emissions

Advanced Reciprocating Engines Systems (ARES) Project
• US Department of Energy
• Goals
– 50% (LHV) electrical efficiency by 2010
– Available, reliable, and maintainable
– Reduce NOX emissions
– Fuel flexibility
– Lower cost
Check it out online:
http://www.eere.energy.gov/de/gas_fired/
Source:
http://www.ornl.gov/sci/de_materials/documents/posters/ARESOverview.pdf

Stirling Engines
• An external combustion engine
• Energy is supplied to working fluid from a
source outside the engine
• Poor-quality steam engines used to explode,
and Stirling engines operate at low pressures
• Used extensively until early 1900s
• Now – can convert concentrated sunlight into
electricity

Stirling Engines
• Two pistons in same cylinder- left side hot,
right side cold
• Regenerator – short term energy storage
device between the pistons
• Working fluid permanently contained in the
cylinder
• Four states, four transitions

Stirling Engines
• Efficiency ~ less than 30%
• Less than 1 kW to ~25 kW
• Inherently quiet
• Cogeneration possible with cooling water for
the cold sink

Concentrating Solar Power Technologies (CSP)
• Basic idea: Convert sunlight into thermal energy, use that
energy to get electricity
• Concentration is needed to get a hot enough temperature
• Three successfully demonstrated technologies:
– Parabolic Trough
– Solar Central Receiver
– Solar Dish/ Sterling
• This is a different topic than photovoltaic (PV) cells which we’ll
cover later

Solar Dish/ Sterling
• Multiple mirrors that
approximate a parabolic dish
• Receiver – absorbs solar
energy & converts to heat
• Heat is delivered to Stirling
engine
• Average efficiencies >20%
Source: http://www.eere.energy.gov/de/csp.html

Solar Dish/ Stirling
• 25 kW system in Phoenix, AZ
• Developed by SAIC and STM Corp
Source:http://commons.wikimedia.org
Stirling engine,
generator, and cooling
fan

Parabolic Troughs
• Receivers are tubes - Heat
collection elements (HCE)
• Heat transfer fluid circulates
in the tubes
• Delivers collected energy to
steam turbine/generator
• Parabolic mirrors rotate east
to west to track the sun
Source: http://www.eere.energy.gov/de/csp.html
Source:
http://www.nrel.gov/csp/troughnet/solar_field.html

Parabolic Troughs - SEGS
• Mojave Desert, California
• Aerial view of the five 30MW
parabolic trough plants
• Solar Electric Generation System
(SEGS)
Source: http://www.flagsol.com/SEGS_tech.htm
Source: http://www.flagsol.com/SEGS_tech.htm

Solar Central Receiver
• Also called Power Towers
• Heliostats – computer
controlled mirrors
• Reflect sunlight onto
receiver
Source:
http://www.eere.energy.gov/de/csp.html

Solar Central Receiver – Solar Two
• 10 MW
• Two-tank, molten-
salt thermal storage
system
• Barstow, CA
Source: http://www.trec-uk.org.uk/csp.htm

Supplementing CSP
• Hybrid Systems
– Conventional generation as a backup
• Thermal Energy Storage
– Effectively makes solar power dispatchable
– Storage is still a largely unsolved issue

CSP Thermal Energy Storage
• SEGS I (operated 1985-1999)
– two tank energy storage system
– mineral oil heat transfer fluid to store energy
• German Aerospace Center
– High-temperature concrete or ceramics
– Pipes are embedded, transfer energy to media
• Solar Two
– Molten-Salt Heat Transfer Fluid

CSP Comparisons
• All use mirrored surfaces to concentrate
sunlight onto a receiver to run a heat engine
• All can be hybridized with auxiliary fuel
sources
• Higher temperature -> higher efficiency
Annual Measured
Efficiency
Required
Acres/MW
“Suns” of
concentration
Dish Stirling 21% 4 3000
Parabolic
Troughs
14% 5 100
Solar Central
Receiver
16% 8 1000

Biomass
• Use energy stored in plant material
• 14 GW around the world, half in US
• 2/3 of biomass in US is cogeneration
• Little to no fuel cost
• High transportation costs
• Low efficiencies, <20%
• Leads to expensive electricity

Gas Turbines and Biomass
• Cannot run directly on biomass without
causing damage
• Gassify the fuel first and clean the gas before
combustion
• Coal-integrated gasifier/gas turbine (CIG/GT)
systems
• Biomass-integrated gasifier/gas turbine
(BIG/GT) systems

Cofiring
• Burn biomass and coal
• Modified conventional steam-cycle plants
• Allows use of biomass in plants with higher
efficiencies
• Reduces overall emissions

Biomass plant in Robbins, IL
• GE is converting the plant to generate power from 3’’ wood
chips made from scrap lumber
• Photos from PES field trip last year

Biomass plant in Robbins, IL

Fuel Cells
• Convert chemical energy contained in a fuel directly into
electrical power
• Skip conversion to mechanical energy, not constrained by
Carnot limits
Chemical energy
Heat
Mechanical energy
Electrical energy
Chemical energy
Electrical energy
Conventional
Combustion
Fuel Cells

Fuel Cells
• Up to ~65% efficiencies
• No combustion products (SOX,CO) although
there may be NOX at high temperatures
• Vibration free, almost silent – can be located
close to the load
• Waste heat can be used for cogeneration
• Byproduct is water
• Modular in nature

Fuel Cells - History
• Developed more than 150 years ago
• Used in NASA’s Gemini earth-orbiting
missions, 1960s
http://scienceservice.si.edu/pages/059017.htm
For more information on the
history of fuel cells, see the
Smithsonian project-
http://americanhistory.si.ed
u/fuelcells/
http://americanhistory.si.edu/fuelcells/pem/pem3.htm

Fuel Cells - History
• Residential use – Plug Power’s 7 kW residential fuel cell power plant
• Use at landfills– generate power from methane
• The list goes on…
http://americanhistory.si.edu/fuelcells/pem/pem5.htm
http://www.fuelcells.org/basics/apps.html

Fuel Cells- Basic Operation
Protons diffuse though electrolyte so cathode is positive
with respect to anode
Anode Cathode
Electrolyte
2 2 2
H H e
 
 
2 2
1
2 2
2
O H e H O
 
  
2H 
I
Electrical Load
Catalyst

Fuel Cells- Basic Operation
• Combined anode and cathode reactions:
• This reaction is exothermic- it releases heat
• A single cell only produces ~0.5V under normal operating
conditions, so multiple cells are stacked to build up the
voltage
2 2 2
H H e
 
 
2 2
1
2 2
2
O H e H O
 
  
2 2 2
1
(4.20)
2
H O H O
 

Pluggable Hybrid Electric Vehicles (PHEVs)
• The real driver for widespread implementation of controllable
electric load could well be
PHEVs.
• Recharging PHEVs when
their drives return home
at 5pm would be a really
bad idea, so some type of
load control is a must.
• Quick adoption of PHEVs depends on
gas prices, but will take many years at least

Smart Grid and the Distribution System
• Distribution system automation has been making steady
advances for many years, a trend that should accelerate with
smart grid funding
• Self-healing is often
used to refer to
automatic distribution
system reconfiguration
• Some EMSs already
monitor portions of the
distribution system
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