UEE30811 - Certificate III Electrotechnology Electrician

TAFE NSW

Unit UEENEEE104A SOLVE PROBLEMS IN D.C. CIRCUITS Equation Sheet Sheet Equation Stage 1: This list does not contain all equations in the course and transposition may be required.

A B C D E

1 = = = = =

푄 퐼푡 퐹 푚푎 푊 푃푡 푊 퐹푠 푊 푚푔ℎ 2 = = = = ퟐ훑퐧퐓

퐕 퐕 - ퟔퟎ 퐕 퐈퐑 퐈 퐑 퐏 100 3 = = 퐑 = 퐈 η % = × from obtained Symbols 2 1 2 푉 표푢푡푝푢푡 푃 푉퐼 푃 퐼 푅 푃 푖푛푝푢푡 4 = = = (1푅+ ) 푅1퐴1푙2 휌푙 ℎ 푐 푅 푅2 퐴2푙1 푅 푅 훼∆푡 5 = + 퐴 + = + + = = = = + 푅1 푇 1 2 3 푇 1 2 3 푇 1 2 3 1 푇 푉 푉 푉 푉 1푅 푅1 푅1 푅1 퐼 퐼 퐼 퐼 푉 푉 1 2 A S1046 6 = = = = + + = + + = 푅 푅 = + + 푅1 푅1푅2

푇 1 2 3 푇 1 2 3 2 푇 푇 푉 푉 푉 푉 푇 1 2 3 퐼 퐼 퐼 퐼 퐼 퐼 1 2 1 푅 1 11 2 1 7 = 푅 =푅 푅 푅 = = +푅 +푅 = +푅 푅+ 표 푟 푄 퐴 ∈ ∈ 푇 1 2 3 퐶 퐶 휏 푅퐶 퐶 퐶 퐶 퐶 푇 1 2 3 8 = 푉 = 푑 = = 퐶 퐶= 퐶 퐶 2 ∆∅ 푁 퐿 ∆∅ ∆퐼 퐿 푁 퐿 휏 푉 푁 푉 퐿 9 = ∆퐼 = 푆 = 푅 = ∆푡 = ∆푡

푚 ∅ 푙 푒 퐵푙푣 퐹 퐵푖푙 퐹 퐼푁 퐵 푆 표 푟 10 = = = = 퐴 =휇 휇 퐴 푚 푚 푔 퐹 퐹 퐸 푘∅푛 푇 푘∅퐼푎 푇 퐹푟 퐻 ∅ 푙 푆 Equation Sheet Sheet Equation Stage 2: This list does not contain all equations in the course and transposition may be required.

Stage 1: equations are also used during stage 2

A B C D E

11 = 0.637 = 0.707 = sin = 3 = 120 푎푣푒 푚푎푥 푅푀푆 푚푎푥 푚푎푥 푛푃 푉 푉 푉 푉 푣 푉 휃 푉퐿 √ 푉푃 푓 1 12 = 0.637 = 0.707 = sin = 3 = -

푎푣푒 푚푎푥 푅푀푆 푚푎푥 푚푎푥 퐿 푃 퐼 퐼 퐼 퐼 푖 퐼 휃 퐼 √ 퐼 푡 from obtained Symbols 13 = = = 푓 푉 푉 퐼 푉 퐼푍 푍 14 = 푍+ = + ( ) = 2 퐼 = cos = 1 2 2 2 2 퐿 퐶 푅 푍 �푅 푋 푍 �푅 푋퐿 − 푋퐶 푋 휋푓퐿 푋 2휋푓퐶 휃 15 = cos = = sin = cos = 푍 2 2 푃 푃 푉퐼 휃 푆 푉퐼 푄 푉퐼 휃 푃 �푆 − 푄 휃 AS1046 16 = 3 cos = 3 = 3 sin tan = 3 = 푆 + 1 2 −1 푊 − 푊 푃 √ 푉퐿퐼퐿 휃 푆 √ 푉퐿퐼퐿 푄 √ 푉퐿퐼퐿 휃 휃 √ � � 휃 푐표푠 휆 ( 푊1 )푊2100 17 = 4. = = % = × 1 ′ 1 1 2 1 푁퐿 퐹퐿 푉 푁 퐼 푁 푟푒푔 푉 − 푉 푉 44∅120푓푁 2 % ×2 1 2 100 푉 ( 퐹퐿 ) 100 18 = 푉= 푁 % = 퐼 푁 × % = 푉 × = 100 푠푦푛 1 푁퐿 퐹퐿 1 푠푦푛 푓 푟 푆 푓 �푛 − 푛� 푟푒푔 푉 − 푉 푁 푓 푆 푠푦푛 푉 푁퐿 푇 푘∅퐼푎 19 푃 푛 푉

2 100 20 = η % = × 60 1 휋푛푇 표푢푡푝푢푡 푃 푖푛푝푢푡 Equation Sheet Sheet Equation Stage 2a: This list does not contain all equations in the course and transposition may be required.

Stage 1: equations are also used during stage 2

A B C D E

21

22 = ( ) = = = × cos η = 퐼 -

퐹 퐼 2 퐹 from obtained Symbols 푉푇 퐸퐺 − 퐼 푅푖 퐸 퐸 2 퐸 푑 휃 23 퐴 = (tan 푑 tan ) = (tan tan ) 푃

푄푐 푃 휃1 − 휃2 푋푐 푅 휃1 − 휃2 24

AS1046 Stage 3: This list does not contain all equations in the course and transposition may be required.

A B C D E % % 25 = 57.7% = 57.7% = × = × 100 100 2 푃 푃 푃 푃 푚표푡표푟 푠푡 푇퐴푃 퐷푂퐿 푇퐴푃 푉 Ү 1 푉 ∆ 퐼 Ү 1 퐼 ∆ 퐼 %� � 퐼 퐼푙푖푛푒 푠푡 � � 퐼퐷푂퐿 26 = × = × = × 3 3 100 푇퐴푃 퐼푆푇 퐼퐷푂퐿 푇푆푇 푇퐷푂퐿 푉푠푡 � � 푉퐷푂퐿 27 = × Constant = 푇=푆푇 × 푉푠푡 2 푉 퐼푆푇 � � 퐼퐷푂퐿 푉푠푡 푉 � � 푇퐷푂퐿 푓 28 푉 Unit Guide – Assessment

Required skills and knowledge

This describes the essential skills and knowledge and their level, required for this unit.

Evidence shall show that knowledge has been acquired of safe working practices, rationale and solving problems in the relevant unit. The knowledge and skills shall be contextualised to current industry standards, technologies and practices.

View the section title page in your class workbook or the complete unit guide for a full list of the fundamentals covered by each topic within this unit.

Below is a list indicating the content areas to be covered by the required skills and knowledge specification for this unit:

Note: Topics may not be delivered in the order indicated by the full unit guide.

Additional information pertinent to your learning may also be included during unit delivery.

KS01-EE104A Direct current circuits

TOPIC NUMBER AS WORKBOOK LISTED IN THE SECTION NUMBER CONTENT FULL UNIT GUIDE Section 1 BASIC ELECTRICAL CONCEPTS T1 Section 2 BASIC ELECTRICAL CIRCUITS T2 Section 3 OHM’S LAW T3 Section 4 ELECTRICAL POWER T4 Section 5 EFFECTS OF CURRENT T5 Section 6 EMF SOURCES T6 Section 7 RESISTORS T7 Section 8 SERIES CIRCUITS T8 Section 9 PARALLEL CIRCUITS T9 Section 10 SERIES - PARALLEL CIRCUITS T10 Section 11 RESISTANCE 2 and FACTORS AFFECTING RESISTANCE T11 Section 12 METERS T12, T13 Section 13 CAPACITORS AND CAPACITANCE T14 Section 14 CAPACITORS IN SERIES AND PARALLEL T15 Section 15 DC Revision Questions T1 – T15 Notes

************************ Contents

Section 1 ‐ Basic Electrical Concepts

Section 2 – Basic Electrical Circuits

Section 3 ‐ Ohm’s Law

Section 4 – Electrical Power

Section 5 – Effects of Current

Section 6 – EMF Sources

Section 7 – Resistors

THEORY EXAM 1 and PRACTIAL TEST 1

Section 8 – Series Circuits

Section 9 – Parallel circuits

Section 10 – Series ‐ Parallel Circuits

Section 11 – Factors Affecting Resistance

Section 12 ‐ Meters

Section 13 – Capacitors and Capacitance

Section 14 – Capacitors in Series and Parallel

Section 15 – Revision Questions

THEORY EXAM 2 and PRACTIAL TEST 2 Section 1

BASIC ELECTRICAL CONCEPTS

KS01-EE104A Direct Current circuits

TOPIC 1 Basic electrical concepts encompassing

 electrotechnology industry  static and current electricity  production of electricity by renewable and non-renewable energy sources  transportation of electricity from the source to the load via the transmission and distribution systems  utilisation of electricity by the various loads  basic calculations involving quantity of electricity, velocity and speed with relationship to the generation and transportation of electricity.  safely connect and test an electrical control circuit for correct operation.

NOTE:- There are 15 Topics to be covered in this course as specified in the Unit Guide UEENEEE104A Solve problems in d.c. circuits. These are covered in the following 14 sections. The front of each section has a dot point listing of the topic elements contained within that section. Some elements are covered in more than 1 section. Some sections contain material from several topics. These elements also a good guide to use when searching for further material in text books and online. 1: Basic Electrical Concepts 1 Electrical industry

The industry sector covers a wide range of electro technologies, from the installation of a simple light bulb and switch to sophisticated electrical, electronic and communications equipment and wiring installations such as a fully automated manufacturing plant with robots.

It covers a wide number of sectors such as:- domestic (homes, unit, apartments and villas), rural (hobby farms to large agricultural properties), commercial (small offices and light industrial units to large office buildings) fire protection (from a 1 room office building to large shopping centres, office towers, Defence Force and industrial sites), security (from a 1 room apartment or office to the largest buildings, Defence Force industrial and government sites), industrial (from very small factories to large sites in Port Botany), marine (jetties, marinas and boats & ships) and aviation sites (airports communications, runway lighting and navigation sites), leisure sites (caravan and camping locations), power generation (coal fired power stations, wind farms, photo- voltaic sites, natural gas fired power stations, geo-thermal power generation sites, hydroelectric generation sites etc.), power transmission and distribution companies. The list is almost endless. If it’s part of modern life, it uses electricity.

It includes the design, installation and maintenance of all types of electrical equipment from domestic appliances to sophisticated high tech machines and complex systems servicing the above sectors in permanent and temporary buildings.

Supply Industry Sector Includes many companies and Authorities such as TransGrid, , , . Electricity is generated at many locations, most are outside major cities, some are in remote areas.

Electricity in NSW is generated from a wide range of fuel sources, including black coal, natural gas, coal seam methane gas and renewable energy sources such as hydro, wind, biomass and solar.

NSW has around 18,000 MegaWatts (MW) of installed capacity. Interconnectors with Queensland and Victoria provide additional capacity of about 1100 MW and 1500 MW respectively. A MegaWatt (MW) is a very large unit of electricity, equivalent to about 150 homes running during the evening ‘peak’ hours.

ELECTRICTY and GENERATION

Electricity as we use it, 230Volts AC, has to be ‘generated’, it does not naturally occur. During generation we cause large numbers of electrons to move, we call it ‘electricity’. Electricity is transported from the generation sites, called ‘power stations’ via overhead power lines and eventually it comes into our homes, shops and business’s; it then is connected to the ‘loads’ via fixed wiring and sometimes flexible cords & plugs. The ‘loads’ are the devices and equipment we wish to operate.

A typical load is a kettle, when we plug the kettle into a power point and switch it on, we connect the load in the kettle to the electricity and as electricity flows through the load (an element inside the kettle) the load gets very hot, heat is transferred to the water and soon 1: Basic Electrical Concepts 1 after it causes the water to boil. The loads are the ‘good parts’ which electricity will run, e.g. the kettle, toaster, frypan, microwave, oven, dishwasher, refrigerator, freezer, air conditioner, television, computer, games console, room lights, charger for your mobile phone etc. etc. in fact there is not much in our lives which runs without electricity or is connected to something which is run by electricity. It is so common in our lives, few people even think about it until there is a blackout.

The tables below provide a list of major existing, under construction and proposed NSW power stations larger than 30 MW of installed capacity. A full list of current NSW generators registered with the Australian Energy Market Operator (AEMO) can be found on the AEMO website. There are over 20,000 MW of power plant proposals (including over 9000 MW from renewable sources) at various stages of development from concept to construction. Big things are happening.

To give you an idea of how big and diverse the generation sector is, we shall look at some facts, all of these sites are major infrastructure sites with values reaching into billions of dollars. Major existing NSW power stations (as at 28.11.2011) Location Owner Technology Capacity Appin Mine Illawarra EDL Group CSM 56 MW Bayswater Hunter Steam/Coal 2720 MW Blowering Snowy Hydro 80 MW Broadwater North Coast BaGasse 30 MW Capital Tarago Renewable Power Ventures Wind 141 MW Condong North Coast Delta Electricity BaGasse 30 MW Colongra Central Coast Delta Electricity OCGT 668 MW Cullerin Upper Lachlan Wind 30 MW Eraring Lower Hunter Steam/Coal 2720 MW Walwa Acciona Energy Wind 47 MW Guthega Snowy Snowy Hydro Hydro 60 MW Liddell Hunter Macquarie Generation Steam/Coal 2080 MW Mount Piper Central West Delta Electricity Steam/Coal 1400 MW Munmorah Central Coast Delta Electricity Steam/Coal 600 MW Murray* Snowy Snowy Hydro Hydro 1500 MW Redbank Hunter Redbank Project Coal Tailings 145 MW Shoalhaven Nowra Eraring Energy Hydro 240 MW Smithfield Smithfield Marubeni Gas Cogen 160 MW Tallawarra Wollongong TRUenergy CCGT**** 435 MW Tower Mine Illawarra EDL Group CSM** 41 MW Tumut Snowy Snowy Hydro Hydro 2116 MW Uranquinty Wagga Wagga Origin Energy OCGT*** 648 MW Vales Point Central Coast Delta Electricity Steam/Coal 1320 MW Wallerawang Central West Delta Electricity Steam/Coal 1000 MW Warragamba Sydney Eraring Energy Hydro 50 MW Tarago Woodlawn Wind Pty Ltd Wind 48 MW 1: Basic Electrical Concepts 1 Projects with development approval (as at 28.11.2011)

Power station Location Owner Technology Capacity Bamarang Stage 1 Nowra Infratil OCGT 400 MW Bamarang Stage 2 Nowra Infratil conversion to CCGT Base load Bayswater B Bayswater Power Macquarie Generation CCGT or Ultra- 2000 MW Station supercritical Coal BlueScope Port Kembla BlueScope Cogeneration 225 MW Plant Steelworks Boco Rock Monaro Wind Prospect CWP Wind 270 MW Buronga Mildura International Power Distillate/ OCGT 150 MW Australia Capital Solar Farm Tarago Infigen Suntech Solar 50 MW Capital II Wind Farm Tarago Capital II Wind Wind 60-80 MW Conroy's Gap Wind Farm Yass Origin Energy Wind 30 MW Crookwell II Southern Union Fenosa Wind 92 MW Highlands Eraring Upgrade Lower Hunter Eraring Energy Coal 360 MW Glen Innes Glen Innes Babcock & Brown / Wind 81 MW National Power Gloucester Gas Project Gloucester AGL Energy CSM 15 MW Gullen Range Goulburn Epuron subsidiary Wind 241 MW Kyoto Energy Park Upper Hunter Pamada Wind 102 MW Solar 10 MW Hydro 1 MW Leafs Gully Appin AGL Gas 360 MW Manildra Solar Farm Manildra Infigen Suntech Solar 50 MW Marulan Marulan TRUenergy OCGT/CCGT 450 MW Marulan Marulan TRUenergy OCGT 350 MW Moree BP Solar Farm Moree BP Solar Solar 150 MW Mount Piper Power Mount Piper TRUenergy CCGT or Ultra- 2000 MW Station Extension Power Station supercritical Coal Munmorah Power Delta Electricity Coal and/or Gas 700 MW[1] Rehabilitation Station Nyngan Solar Farm Nyngan Infigen Suntech Solar 100 MW Parkes Parkes International Power OCGT 120 MW (Australia) Richmond Valley Richmond Valley MetGasco CSM 30 MW Broken Hill Epuron Wind 1000 MW Tallawarra Stage B Wollongong TRUenergy Gas 300-450 MW Taralga RES Southern Cross Wind 183 MW Tomago Newcastle Macquarie Generation OCGT/CCGT 790 MW Wellington Wellington NewGen Power OCGT 660 MW Wilga Park Narrabri Eastern Star CSM 29-40 MW 1: Basic Electrical Concepts 1 Projects in the planning system (as at 28.5.2012)

Power station Location Owner Technology Capacity Adjungbilly Wind Farm Gundagai CBD Wind - CBD Adjungbilly Wind 39 MW Pty Ltd Bango Wind Farm Yass/Boorowa Wind Prospect CWP Wind 340 MW Bannaby Gas Fired Bannaby Snowy Hydro Ltd OCGT 600 MW Power Station Birrema Bookham Epuron Pty Ltd Wind 90-264 MW Wellington Infigen Suntech Wind 60-110 MW Broken Hill Solar Farm Broken Hill AGL Energy Ltd Photovoltaic 50 MW Collector Wind Farm Collector Transfield Services Wind 120-160 MW Crookwell 3 Southern Highlands Union Fenosa Wind 45-116 MW Dalton Energy Project Dalton AGL Energy Gas 750-1500 MW Eden Biomass Twofold Bay, Eden South East Fibre Exports Pty Biomass 5 MW Ltd Flyers Creek Orange Babcock & Brown and NP Wind 80-100 MW Power Golspie Wind Farm Crookwell Wind Prospect CWP Wind 340 MW Hanging Rock Sutton Forrest Loran Energy Products Penrose CCGT 600 MW Liverpool Range Wind New England Epuron Wind 1800 MW Farm Tablelands Narrabri West Ingelgreen Power Partners Generation Biogas 55MW Nyngan Solar Farm Nyngan AGL Solar 100 MW Paling Yards Wind Farm Arkstone Union Fenosa Wind 100-180 MW Rugby Wind Farm Yass Suzlon Energy and Wind Lab Wind 290 MW Developments Rye Park Wind Farm Yass Epuron Wind 120-374 MW Glen Innes/Inverell Wind Prospect CWP Wind 485 MW Glen Innes Epuron Wind 120-340 MW Yass Yass Epuron Wind 380 MW

About six per cent of the state's total electricity usage is provided from renewable energy sources. The NSW Government has set targets through the State Plan to achieve 20% renewable energy consumption by 2020 in light of the Federal Government's expanded Renewable Energy Target. Renewable energy in NSW is derived from the following sources: hydro (88%) biomass (5%) landfill methane (5%) wind (1%) solar (1%) 1: Basic Electrical Concepts 1 NON RENEWABLE POWER GENERATION

We shall look at some typical examples of each type.

Coal Fired Steam Power Stations

Coal fired power stations are mostly in regional areas, located close to sources of water and fuel (coal).

Liddel Coal Fired Power Station in the Hunter Valley

2000MW from 4 turbines (3rd largest plant in NSW), uses nearby open cut coal and fresh water for cooling.

Steam power stations work by harnessing a suitable raw energy source, burning it to produce steam and turning steam power into electrical energy that is then sent to homes and industry.

There are several steps involved in the creation of electricity. Note: we don’t magically create electricity, we transform a source of energy (here we’re using coal) into another form of energy (electricity) and try to make it as efficient as possible.

Most electricity used in homes and businesses in NSW comes power stations which burn coal (a non-renewable fuel), it will be some time before the balance changes in favour of renewable fuels and sources, but if the Federal and State government commitments and budgets are there, it will happen eventually.

99% of electricity generation is done by turning a ‘generator’, a machine that requires power to turn at a constant speed, the size of the generator and the power required is proportional to its’ rated output. The power to turn the shaft comes from a variety of sources as we will see, the largest being a steam turbine.

Coal is pulverised into a powder and blown into a furnace with large amounts of air, the furnace produces enormous heat. Large metal pipes are run through the flames and the water inside the pipes boils causing steam, the steam is kept under great pressure (imagine sealing the lid onto a boiling saucepan) and piped through to a turbine, which is like a giant fan. As the steam is released, it forces the blades of the turbine to spin (similar 1: Basic Electrical Concepts 1 to blowing on a piece of paper), thus turning the heat energy from burning fuel into kinetic energy, or movement.

The turbine is connected to a generator by a shaft. The generator in simple terms is a coil of wire surrounded by large magnets which create a strong magnetic field. As the coil of wire rotates inside the magnetic field, ‘electricity’ is induced in the coil of wire, it is then extracted and sent away to consumers.

The boiler water is rather special and expensive, so the boiler steam is cooled when it leaves the turbine, condensed back into water so it’s easy to pump around the power station and returned to the boiler to start the process again.

In the RHS photo above, large quantities of cooling vapour can be seen coming from the 4 cooling towers. Raw water from nearby dams and lakes are used in the cooling towers to cool (condense) the expended steam back into a liquid. As part of that cooling process, the raw water vaporises when it is sprayed onto the very hot steam pipes and the vapour given off is what we see rising from the cooling towers.

The actual chimneys that discharge the various combustion gases are the 2 tall slim towers. In operation it is very hard to see any discharge from these chimneys as the ash and some by-products are removed to minimise pollution to the environment. Many people in the past have confused the cooling tower vapour as pollution, the vapour is effectively pure water as it has been boiled off when it contacted the hot boiler steam pipes, just like distilled water.

It is important to understand there are 4 major parts to the power station 1. The creation of High Pressure Turbine steam (steam in a closed vessel has tremendous force) 2. High pressure steam is used as the driving force to turn the turbine & generator 3. The creation of electricity from the spinning generator (to be technically correct it is called an ‘alternator’ as it produces AC current, but ‘generator’ is an carry over term from the very early days of creating electricity, so let’s leave it as a generator for the time being) 4. Transporting the electricity away from the power station, and delivering it to the customers. 1: Basic Electrical Concepts 1

Steam Creation Driving force Electricity Creation & Transport

Generator Steam Turbine

400MWsteam turbine generator 1: Basic Electrical Concepts 1

1000 MW steam turbine generator

We will look at several other ways to create steam and / or turn the shaft of a generator.

GAS FIRED POWER STATIONS Natural Gas (NG) is an energy source that has been used in Australia for commercial purposes for more than 100 years. It forms naturally from decayed plant and animal matter compressed over millions of years far below the earth's surface.

Australia has huge reserves to be found all over the Australasian continent. Natural Gas is initially extracted from the ground by deep drilling before being filtered, separated, then piped directly into your home or business.

Coal Seam Gas (CSG) is natural gas found in coal deposits. The coal and gas are formed from plant matter under pressure over many millions of years. Coal seam gas is used in the same way as any other form of natural gas for cooking and heating as well as in industrial processes and electricity generation.

Liquefied Petroleum Gas (LPG) - a mixture of light hydrocarbons that are gases at normal temperatures and pressures, but liquefy at moderate pressures or reduced temperatures. LPG when used as automotive fuel is referred to as LPG Autogas.

LPG occurs naturally in crude oil and natural gas production fields and is also produced in the oil refining process. Refinery production is from seven refineries across Australia in NSW, Clyde (Shell – about to close & has 11.6 MW co-generation power) and Kurnell (Caltex) [7MW co-generation power] 1: Basic Electrical Concepts 1

Australia produces currently about 3,300 kt of LPG annually. Of these volumes, 80% is naturally occurring (i.e. extracted from oil and gas production) and 20% is extracted from crude oil during the refining process.

Gas-fired power stations in Australia mostly burn natural gas from deep within the earth or coal seam gas. Gas power stations can be either:-

1. Conventional gas-fuelled boilers and steam turbines to turn electrical generators (which replace coal with gas as the fuel) 2. Gas turbines turning generators, using jet aircraft type turbines turning generators 3. Internal combustion engines turning generators. In this type, gas replaces the fuel normally burnt in diesel motors (and on a very small scale, petrol powered motors), these internal combustion reciprocating motors then turn the generator. 4. Cogeneration plants burning LPG at oil refineries (more on cogeneration later)

Natural gas is used as the fuel to run a jet turbine, and the turbine spins the generator via a reduction gearbox. Typical sizes are 1 to 125MW . (Very efficient power plants BUT noisy) 1: Basic Electrical Concepts 1

Gas fired power stations are becoming a common type of generation in NSW.

Natural gas or coal seam gas can be used instead of diesel fuel to run a conventional internal combustion engine generator plant. This plant is approximately 1 MW. 1: Basic Electrical Concepts 1

A small generator using bottled gas as fuel (modified by licenced engineers – do not try this at home!). This particular 15 kW generator will run on petrol, bottled LPG gas or Natural gas. Cost - around $3500.

RENEWABLE SOURCES OF POWER GENERATION

Renewable energy comes from sources such as the sun, wind, waves, hydro, geothermal and organic matter. Generating energy from these sources produces minimal overall greenhouse gas emissions and reduces other impacts on the environment.

SOLAR POWER

Probably the first form of energy most people think of is – Solar. Solar electricity is generated by two main technologies: solar photovoltaic (PV) cells and high temperature solar thermal power systems. In addition, relatively low-grade heat is produced by solar water heaters for domestic & small commercial use, replacing the need to heat water via electricity or gas. 1: Basic Electrical Concepts 1

Solar Photovoltaic cells (PV Cells or PV Panels) Solar PV cells convert sunlight directly into low voltage electricity hence the name ‘Photo’ for light and ‘Voltaic’ for electricity. The output from PV panels is Direct Current (DC - like a battery), this is not suitable for general household use so it is converted into Alternating Current (AC). An inverter is used to convert the DC to an AC voltage suitable for supply into the electricity grid.

Solar PV cells are also used to supply electricity in remote areas where grid connection is not available or would be very costly to install. Remote area power systems use batteries to store some of the electricity generated during the day for use at night. Although the DC battery power can be used to supply some DC appliances and DC lights, those items are not common therefore an inverter is required as part of the system so standard household appliances can be used. The inverter runs off the batteries continuously to provide 24 hour AC supply. It goes into ‘standby’ mode when no AC power is being consumed. (inverters can also be connected to your car battery to provide a temporary 230V AC power source for running power tools or computers etc).

The average size of a household grid-connected solar PV system is about 1.5 kilowatts (0.0015MW) which has a PV panel area of about 12 square metres. A system of this size has a cost typically around $19,000 (before rebates or subsidies). This is an expensive power supply option in comparison to other renewable energy technologies.

Typical roof installation of Photovoltaic cells to produce DC electricity. 1: Basic Electrical Concepts 1

The remote NSW town of White Cliffs has an interesting history. The innovative solar collectors at White Cliffs NSW were built in 1981. They were Australia’s first solar power station and produced all the towns’ electricity.

The photo above shows the dishes running as photovoltaic cells (their 2nd configuration), the little PV box at the focal point collects a large amount of energy from the parabolic dish and converts it into electricity. This is the same concept as flat PV panels that we normally see on house roofs, but in a highly concentrated form.

At first they were configured as ‘water boilers’ then later reconfigured to PV cells; ‘water boilers’ are a totally different type of operation. (see photo below). Constructed by Australian National University, the station consisted of fourteen three-metre parabolic dishes, each covered by more than 2000 mirrors and mounted on a heliostatic mounting. The dishes each focused the sun's rays on a collector, where water was boiled. The resulting steam drove a three-cylinder steam engine & generator plant, delivering up to 25kW. So the end result was steam and a spinning generator, which is a standard form of power station generation.

Batteries were used to store power and provide 24 hour power to selected buildings in the township, and an existing diesel generator was retained to provide battery charging when either low sunlight or strong winds prevented use of the solar station for long periods.

In 1996, the town was connected to the NSW grid and the dishes were converted to photovoltaic. The dishes were resurfaced, and the ‘water boilers’ were replaced by very powerful photovoltaic cells. In its’ new form, the station delivered up to 45kW. The steam engine, batteries, and diesel generator were removed, and any excess output was fed into the grid. The grid connected power station ran for around 6 years, generating valuable data on the long-term performance and efficiency of the PV modules. The power 1: Basic Electrical Concepts 1 station ceased operation in December 2004, has become dormant and the dishes are now positioned to the South, away from the sun.

Solar Thermal Power Systems

There is a range of solar systems which concentrate the sun’s energy at a focal point and use this heat to provide high temperatures for power generation (similar to burning paper with a magnifying glass). Large-scale systems (hundreds of dishes) generally produce steam at temperatures and pressures suitable for generating electricity using standard steam turbines. Waste heat from the turbines can be used for other applications such as industrial processes, heating buildings, and water desalination.

There is a wide range of solar concentrator designs including parabolic trough, linear Fresnel reflector, parabolic dish and power tower. The solar concentrators focus sunlight onto a receiver through which a fluid is passed to transfer the heat to the generation plant. The heat transfer fluid can be hot oil, molten salts or direct steam. (Search Google: Gemasolar Power Plant in AndalucÌa, Spain). Some form of heat storage may be included to enable power generation after the sun disappears. After dark, some burn natural gas to produce heat for steam, so as to provide 24-hour power generation,.

White Cliffs dishes running as a Solar or ‘water boilers’, where the sun’s rays were focused onto the collector tube which then boiled water inside the tube. The steam was then used to drive a steam generator. 1: Basic Electrical Concepts 1 HYDROELECTRIC

Hydroelectric power in NSW is mostly generated in the Snowy Mountains, although Warragamba Dam has a small (by comparison) 50MW plant. Warragamba Dam is a little over 1 hour’s drive from Miller TAFE College. Water power has been around for thousands of years, so harnessing the energy of moving/falling water is nothing new.

The Snowy Mountains Hydro scheme diagram shows water being caught in various dams and lakes, then using gravity to trasnport the water to hydro electrci power stations before being released down rivers and streams. 1: Basic Electrical Concepts 1

With a hydro electric generation plant, we replace the steam turbine with a water turbine, to achieve the same result – providing mechanical power to turn the generator shaft. A feature of most hydroelectric plants is the vertical shaft rather than a horizontal shaft, as with most other generators. 1: Basic Electrical Concepts 1

Murray 1 Snowy Hydro Power Station near Khancoban, has 10 generators rated at 95MW each.

BIO MASS

Biomass is the name given to all plants and animals (including humans) on earth. Energy from biomass refers to ways of using plants and animals as energy sources.

Biomass can be converted to energy in two ways: directly by producing electricity, normally done by burning the biomass (e.g. wood, sugar cane or waste products) for steam generators. indirectly by converting it into a liquid or gas fuel.

People have always used plants and animals as renewable energy. Burning wood for cooking and heating is as old as fire itself. Domesticated animals, such as horses, buffalo and elephants, have long been used to provide power for transportation and manual work like farm ploughing or turning rotary equipment. Oils from plants and animals were also used to provide fuel for cooking and lighting. Oil from the blubber of giant sperm whales was used widely in lamps and candles for lighting before electric lighting was widely available. Many crops that are grown for food can also be used to make biofuels.

Cogeneration

Cogeneration (also combined heat and power, CHP) is the use of a power station to simultaneously generate both electricity and useful heat, so we have 2 useful outcomes. 1: Basic Electrical Concepts 1 Some cogeneration power stations use natural gas-powered engines to generate on-site electricity. The waste heat from the engine is captured to provide heating, or for conversion to chilled water for cooling through an absorption chiller. When an absorption chiller is used, the solution is often referred to as tri-generation.

WIND FARMS

Wind farms are now common in rural NSW. Anyone who has struggled to stay upright in a strong wind is aware of the intrinsic power of the wind. Indeed wind energy has been harnessed by people for thousands of years (sailing boats are harnessing wind energy).

The windmills with cloth sails used in many European countries are a good example too, as are the multi-bladed windmills commonly seen on farms and in rural areas of Australia. The power of the wind is also used to propel sailing ships, cool homes on balmy summer evenings, and fly kites.

Recent research and development into harnessing the wind means that we can now generate more electricity using wind energy. Machines that generate electricity from the wind work in much the same way as the more familiar European windmills of old. These machines are called wind turbines. Again we use an energy source to turn the generator shaft.

Diagram of a 1: Basic Electrical Concepts 1 A wind turbine comprises a tower, topped by an enclosure called a nacelle, and the rotor, which is the propeller-like structure connected to the nacelle. The nacelle houses an electrical generator, power control equipment and other mechanical equipment, which is connected to the rotor.

The rotor blades are often made from light composite materials such as fibreglass. They are well researched and shaped to maximise the energy harnessed. The wind strikes these blades, and due to their shape, the wind causes the rotor to spin. When the wind is strong enough, the rotational energy in the rotor is converted to electrical energy within the generator.

Towers are commonly made of steel tubes, although some earlier models used steel lattices. The height of the tower varies from turbine to turbine, and is determined by the length of the blades, size of the generator, and the need to access the smoother winds available further from the ground. Wind turbines in Australia are commonly between 50 and 80 metres tall.

Diagram showing the inside of the nacelle

Wind turbines can generate significant amounts of electricity. Wind electrical power is generally proportional to the speed of the wind cubed. This means that if the wind speed doubles, the power generated is increased eightfold.

Apart from the actual wind speed at a site, the length of the blades on the rotor also determine the amount of power produced. The longer the blade, the more wind it