IOT POLY ENGINEERING 3-7 Power Plants – Power Stations Background

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Power Plants – Power Stations

Background

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POLY ENGINEERING3-7

Power Plants – Power Stations

Background1. What electricity is used for:

Heating, cooking, cooling, light, sound, computers, communication, entertainment…

2. Distribution grid: Our focus

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Power Plants – Power StationsTypical Operation

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1. Fuel is used to produce heat energy2. Water is heated and boiled to steam3. High pressure steam enters and spins turbines

(Turbines convert steam into mechanical energy)4. Turbines turn electrical generator (electricity is created)5. Electricity is transmitted via cables through power grid

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Power Plants – Power Stations

Alternative Operation

1. Alternative energy source (e.g. water, wind) spins turbines

2. Turbines turn electrical generator3. Electricity is transmitted via cables through power grid

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Power Plants – Power Stations

Types of Power Stations – Non-renewable

1. Fossil Fuel Power Plant – Coal a. Prime mover is steam turbine b. Flue gas exhausted to atmospherec. Waste heat released to atmosphere – cooling towers

2nd law of thermodynamics – not all heat can be converted into mechanical form to do work, some heat will be wasted

A power plant cannot be 100% efficient

Power Plants – Power Stations

1. Fossil Fuel Power Plant – Coal (cont.)

Waste Heat

Flue

Types of Power Stations – Non-renewable

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Power Plants – Power Stations

2. Fossil Fuel Power Plant – Petroleum and Natural Gas Prime mover is gas turbine

Types of Power Stations – Non-renewable

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Power Plants – Power Stations

Waste heat (options):

a. Cooling Towers: Released to atmosphere

b. Combined Cycle: Recycled in secondary boiler

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Power Plants – Power Stations

PRIMARY LOOP3. Nuclear Power Plant

4. Steam spins turbine

5. Electricity generated to grid

6. Cooling water from outside source; gets hot as it condenses steam

7. Released in cooling tower1. Closed-loop reactor

2. Control rods inserted to decrease chain reaction (control rods absorb neutrons, which slows reaction)

3. Heated reactor water boils secondary loop of water in boiler (steam generator)

SECONDARY LOOPTERTIARY LOOP

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Containment StructureReactorBoiler

3. Nuclear Power Plant (continued)

Steam TurbineGeneratorCondenser

Cooling Tower

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Power Plants – Power StationsTypes of Power Stations – Renewable Energy

1. Solar Power Planta. Total solar energy absorbed by earth in 1 hour is more

than world uses in a yearb. 1 year of solar energy is as much as twice the amount of

energy derived from all non-renewables on Earthc. All renewables (except geothermal) derive energy from the

Sun (e.g., wind, biomass, hydro, wave…)d. Sun’s warmth and light

a. Passive collection – capturing warmth and light through design

b. Active collection – using technology to transform solar energy into electricity

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Power Plants – Power StationsTypes of Power Stations – Renewable Energy

1. Solar Power Plant – PASSIVE COLLECTIONa. Architecture – designing structures

1) Face buildings south2) Solar water heating

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Power Plants – Power StationsTypes of Power Stations – Renewable Energy

1. Solar Power Plant – PASSIVE COLLECTION (cont.) b. Agriculture – growing food

1) Fruit walls (trap heat and accelerate ripening)2) Timed planting cycles3) Drying chicken manure4) Greenhouses

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Power Plants – Power StationsTypes of Power Stations – Renewable Energy

1. Solar Power Plant – PASSIVE COLLECTION (cont.) c. Other Uses

1) Water treatment – UV filter2) Cooking – focuses heat directly or creates steam

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Power Plants – Power StationsTypes of Power Stations – Renewable Energy

1. Solar Power Plant – ACTIVE COLLECTION a. Photovoltaics (PV)

Photovoltaic Effect – converts light into electric current• 1880s – first solar cell• 1958 – first significant application – Vanguard I satellite• 1960s – PV established power source for satellites

Hamau Solar Park, Germany

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Power Plants – Power StationsTypes of Power Stations – Renewable Energy

1. Solar Power Plant – ACTIVE COLLECTION (cont.) b. Concentrating Solar Power (CSP)

Use lenses, mirrors, trackers to focus large area of sunlight into small beam

• Solar troughs – most cost-effective• Parabolic reflector – most efficient

Power Plants – Power StationsTypes of Power Stations – Renewable Energy

1. Solar Power Plant – ACTIVE COLLECTION (cont.)c. Concentrating Solar Power (CSP)

• Solar tower – traps heat, creates steam for turbines• Solar updraft tower – combines chimney, greenhouse,

wind turbine

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Power Plants – Power StationsTypes of Power Stations – Renewable Energy

2. Wind Power Planta. Sun influences weather processes that create windb. Converts wind energy into electricity using turbinesc. History

1) >5,500 yrs ago – sailboats and natural ventilation2) 600s, Afghanistan – vertical shaft mills grind grain3) 1100s, Europe – horizontal shaft mills grind wheat4) U.S. – used for irrigation

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Power Plants – Power StationsTypes of Power Stations – Renewable Energy

2. Wind Power Plant (cont.)1) Blades – propellers mounted on masts are pitched (angled) 2) Gear Box – connects low-speed shaft to high-speed shaft

to increase rpm from ~50 to ~12003) Generator – converts mechanical energy of high-speed

shaft to electrical energy

Sketch and label this diagram

Mast

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Power Plants – Power StationsTypes of Power Stations – Renewable Energy

3. Hydroelectric Power Planta. Gravitational force of falling water converted into

electricity using turbinesb. History

1) >2000 yrs ago, Rome and Greece – grinding wheat into flour

2) 1700/1800s – powered textile and industrial mills3) 1882, Wisconsin – first hydroelectric plant

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Power Plants – Power StationsTypes of Power Stations – Renewable Energy

3. Hydroelectric Power Plant (cont.)1) Dam stores water in reservoir

Energy generation depends on head – height difference from top of reservoir to top of river – and volume

2) Spillway releases excess water3) Gate releases dam water into penstock – screen prevents

objects from damaging turbines4) Penstock is piping – pressure of water increases

Power Plants – Power StationsTypes of Power Stations – Renewable Energy

3. Hydroelectric Power Plant (cont.)

Power Plants – Power StationsTypes of Power Stations – Renewable Energy

3. Hydroelectric Power Plant (cont.)

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Power Plants – Power StationsTypes of Power Stations – Renewable Energy

4. Geothermal Power Planta. Harnessing energy generated from heat stored in Earthb. History

1) Hot springs used for centuries for bathing and heating2) 1911, Italy – world’s first and only plant until 1958

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Power Plants – Power StationsTypes of Power Stations – Renewable Energy

4. Geothermal Power Plant (cont.)1) Steam or hot water pumped from underground to turn turbines2) Waste steam/water returned to ground or reused

Power Plants – Power StationsTypes of Power Stations – Renewable Energy

5. Tidal Power Plants

Power Plants – Power StationsTypes of Power Stations – Renewable Energy

6. Wave Power Plants – 2 types

Linear Generator