SUSTAINABILITY AND RENEWABLE ENERGY Lecture 1

A Review of The Electric Power Industry

whats sustainability

improving the quality of human life while living within the carrying capacity of supporting ecosystems

What is a Power System?

A power system is a complex interconnected network of power components that provide the means by which we produce, transmit and receive the electrical power

what are the three major parts of electrical power systems

generation, transmission, distribution

what is generation

the production of electricity.

what is transmission

the lines that transport the electricity from the generation centers

to the loads.

what is distribution

the lines that connect the individual customer to the electric power

system

where are generation plants located

The tradition has been that generation plants are located away from heavily populated areas when possible and closer to the available fuel resources. The reason being that land around such areas is less expensive and cost of transporting the fuel is not a consideration.

what are methods of generation

thermal, nuclear, renewable

what are the 3 major types of fossil fuels

coal, oil, natural gas

what are fossil fuels formed of

made up of decomposed plant and animal matter.

what are fossil fuels used for

These fuels are used to supply heat by means of chemical reactions to support electrical power generation plants.

how is oil (from fossil fuels) stored and used

Oil is stored in large tanks and is made into different products such as fertilisers for farming, plastic compounds, etc. The oil refineries split the crude oil into various types of products which include gasoline, diesel, home heating oil, oil for power plants to generate electricity, oil for ships, kerosene and aviation fuel.

what is natural gas primarily composed off

Natural gas is mostly made up of a gas called methane (CH4 ), a simple chemical compound that is made up of carbon and hydrogen atoms.

where is natural gas found

near patroleum underground

how is natural gas processed

The natural gas is pumped from below ground and sent to plants for processing in large pipelines. It usually has no odour, but before it is sent through the grid of the pipelines, it is mixed with a chemical to give it a strong odour which makes it easy to smell if there is a leak.

how is oil and gas transported

by rail, ships, and through pipelines as liquefied gas.

how is coal transported

by rail, and ships if the plant is close to a river or sea

how is oil and gas stored

Oil and gas are stored in large metal tanks

how is coal stored

coal is kept in open yards. The temperature of the coal layer must be monitored to avoid self ignition.

how is oil processed

Oil is pumped and gas is fed to the burners of the boiler

how is coal processed

Coal is pulverised in large mills, and the powder is mixed with air and transported by air pressure, through pipes to the burners. The coal transport from the yard to the mills requires automated transporter belts, hoppers, and sometimes manually operated bulldozers

what is the steam cycle part 1

Air and fuel enter the furnace, combustion occurs, and hot gases heat the boiler tubes.

what is the steam cycle part 2

Feedwater is preheated through feedwater heaters and an economizer, then enters the boiler.

what is the steam cycle part 3

Water becomes saturated steam, then is superheated and sent to the HP turbine.

what is the steam cycle part 4

After HP expansion, the steam is reheated and sent to the IP turbine, then finally the LP turbine.

what is the steam cycle part 5

Spent steam enters the condenser, becomes water, and is pumped back through feedwater heaters to complete the loop.

what is the steam cycle part 6

Some make-up water is added to compensate for small losses due to leaks.

what are the key components of the air handling and combustion system

forced draft fan, air preheater, furnace, induced draft fan, electrostatic precipitators

role of forced draft fans

Pushes preheated air into the furnace to enhance combustion efficiency.

role of air preheaters

Recovers heat from the exhaust gases to preheat the incoming combustion air—this saves energy and boosts overall efficiency.

role of a furnace

Burns fuel to produce heat that turns feedwater into steam.

role of induced draft fan

Pulls flue gases through environmental equipment (like precipitators) and out of the stack

role of ekectrostatic precipitators

Remove particulates/pollutants from the exhaust gases before release.

what are the components of water treatment system

deaerator, de-mineralizer

role of a deaerator

removes dissolved oxygen and gases from feedwater to prevent corrosion

role of de-mineralizer

filters out minerals to avoid scaling in boiler tubes

components of boiler and steam generation

economizer, boiler, superheater

role of economizer

Recovers heat from flue gases after boiler use to further preheat feedwater.

role of boiler

Converts preheated water into high-pressure saturated steam (~2400 psi, 340°C).

role of superheater

Increases steam temperature (~565°C) at constant pressure, improving efficiency and preventing turbine blade erosion.

components of turbine system

high pressure turbines, reheater, intermediate-pressure turbine, low pressure turbine, multistage turbine arrangement.

role of a high pressure turbine

First stage where superheated steam expands and does work.

role of a reheater

Reheats partially expanded steam (~535°C) to maintain energy levels before further expansion.

role of intermediate pressure turbine

Second expansion stage using reheated steam.

role of low pressure turbine

Final stage for steam expansion, extracting remaining energy before condensation.

role of multistage turbine arrangement

Most modern systems use HP, IP, and LP turbines with two reheat cycles.

components of condensation and cooling

condensor and cooling water system

role of condenser

Converts steam into liquid water using cooling water. This creates a vacuum, lowering turbine exhaust pressure, increasing the turbine’s energy extraction capability.

role of cooling water system

Essential for removing heat from the condenser.

componments of a feedwater system

condensation pump, feedwater heaters, boiler feed pump

role of condensate pumps

Move condensed water from the condenser to feedwater heaters.

role of feedwater heaters

Use extracted steam from the turbine (typically near exhaust) to preheat feedwater before entering the economizer and boiler.

role of boiler feed pump

Pressurizes feedwater to boiler operating pressure (~2400 psi).

what is the steam turbine principle of operation

The turbine converts the heat energy of the steam into mechanical energy.

what part of a steam turbine have blades

Both the rotor and stationary part of the turbine have blades.

how dose the length of the blades increase

The length of the blades increases from the steam entrance to the exhaust

what is the use of blades in a steam turbine

Steam enters through nozzles and flows through the first set of moving rotor blades. The stationary blades that follow change the direction of the flow and direct the steam into the next set of moving blades.

what dose a nozzle do in steam turbines

The nozzles increase the steam speed and reduce pressure.

what drives a steam turbine

The impact of the high speed steam, generated by the change of direction and speed in the moving blades, drives the turbine.

how dose steam turbine generate electricity

The steam turbine used to generate electricity must rotate at a constant speed.

what happens when the rotating speed of a steam turbine changes

the frequency of the AC voltage system generated will also change

how is the speed of a steam turbine regulated

A system of governors is used to regulate the speed of a steam turbine, therefore maintaining the system’s frequency constant. The governor system adjusts the speed of the turbine by compensating for any changes in load demand

what happens when a larger load is demanded

As more load is demanded from the turbine, it starts to have higher resistance to rotation. In this case, the input to the turbine must be increased accordingly to maintain the constant speed requirement. The governor system automatically adjusts the steam supply to the turbine blades

what side affect dose coal fired power plant generate

significant amount of ash and its disposition causes environmental problems that need to be dealt with

What are the environmental controls in coal plants?

Electrostatic precipitators, scrubbers, ash handling systems.

what dose electrostatic precipitators do

These are air cleaning devices that electrically charge foreign particles in the air and then collect them on positively charged plates

what do scrubbers eliminate

Harmful sulphur dioxide is eliminated by scrubbers based on lime/limestone scrubbing process.

what is the design purpose of a power plant stack

The stack is designed to disperse gases into the atmosphere with minimum environmental damage imposed.

what are the requirements for an effective power plant stack

This requires sufficient stack height which assists the fans in removing gases from the boiler though natural convection.

What is the efficiency of combined cycle gas turbines?

56–58%.

What are the advantages of gas turbines?

Quick startup, modular installation, lower CO₂ emissions, automation.

how do basic gas power plants work

More than half of the rotational energy created by the spinning turbine is used to power the compressor.

how can an induced voltage be changed

Modification of the strength of the magnetic field. Change of the speed of the conductor movement within the magnetic field

What is electromagnetic induction?

Movement of a conductor in a magnetic field induces voltage and current.

What are the two generator construction methods?

Rotating armature (less common, high maintenance). Rotating field (more common, efficient)

whats the use of generators

Generators are used to convert mechanical energy into electrical one.

whats the use of mechanical energy

The mechanical energy is used to move electrical conductors within a magnetic field.

what do generators consist of

a stationary (stator) and a rotating (rotor) part. magnetic field poles of north and south polarities. a method of producing a rotary motion, or a prime mover connected to the generator shaft. rotating conductors must also be connected to an external circuit and special slip rings

what is the rotating armature method

In this method, the AC voltage is induced into the conductors of the rotating part of the machine

in the rotating armature method how is the electomagnetic field generated

generated by a set of stationary pole pieces.

in the rotating armature method how is the required relative motion provided

prime movers such as steam turbines, gas turbines, hydro turbines, gas engines, diesel engines and others

limitations of the rotating amrnmature method

Only a small power rating can be used. the AC is extracted from a slip ring/brush assembly. A high voltage could produce sparking or arc over the brushes and the slip rings. expensive and time consuming maintanance

What are the advantages of three-phase AC power?

Less pulsation, uniform torque, economical distribution, smaller equipment.

how can AC generators be classified

AC generators can be classified into High speed and Low speed

what is the type of generator used dependent on

depends upon the prime mover available to rotate the generator

properties of high-speed generators

usually driven by steam turbines. smaller in diameter and longer in length (in comparisoin to LS generators)

properties of low-speed generators

Large in diameter (larger than high-speed counterparts). Not as long as high speed ones. The number of stator poles could be eight or even twelve.

What voltage levels are used in transmission in Australia?

132 kV to 500 kV.

What are the advantages of DC transmission over AC?

Lower losses, no stability issues, interconnection of different frequencies.

What are typical pole and tower structures used for?

Economic distribution and transmission at various voltage levels.

What are the types of electrical loads?

Residential (80%). Commercial (15%). Industrial (5%, but 30% of energy use)

What is load diversity?

Variation in load over time due to user behavior and seasonal changes.

What is spinning reserve?

Extra capacity ready to be used within seconds to minutes.

What is economic dispatch?

Serving load with minimal excess capacity using the most efficient units.

What factors affect economic dispatch?

Generator efficiency. Line losses. Fuel cost. Capacity availability. Interconnection costs

how is the bulk of electricity produced

The bulk of electricity is produced by 3-phase synchronous generators.

what are the 2 basic parts of synchronous machines

rotor and armature

what is the rotor and its use

The iron rotor is equipped with a DC-excited winding which acts as an electromagnet. When the rotor is rotating and excited, a time-varying electromagnetic field is produced in the air gap.

what is the armatures composition and use

The armature has 3-phase winding in which time-varying EMF is generated

what are the two types of rotors synchronous machines are built with

cylindrical and salient-pole