IB Physics – Global environmental physics Where does our electricity come from? Castle Peak, West...

IB Physics – Global environmental physics

Where does our electricity come from?

Castle Peak, West Kowloon; China Light and Power

Lamma Island, outlying islands; Hong Kong Electric

What fuel is used to generate electricity in each of these power stations?

What fuel is used to generate electricity in each of these power stations?

http://envf.ust.hk/werhk/images/CLP_Signature_bi_spot2.jpg


Thermal power generation

The Coal-fired power station in Gelsenkirchen, Germany which claims to be the cleanest in Europe.


Pollution?

Smoke stack from US power station in Pittsburgh in 1975 - The company installed wet scrubbers to minimize emissions in a $42 million environmental improvement project

1. Write down the equation for the combustion of fossil fuels

2. List any pollutants formed and explain where they come from.

3. Describe what effects may these have on (i) our health and (ii) the environment?

4. Suggest what can be done to reduce the amount of pollutants produced in fossil fuel combustion

1. Write down the equation for the combustion of fossil fuels

2. List any pollutants formed and explain where they come from.

3. Describe what effects may these have on (i) our health and (ii) the environment?

4. Suggest what can be done to reduce the amount of pollutants produced in fossil fuel combustion


Why does this happen?

1. What impression are these videos trying to give?

2. Is this fair?

1. What impression are these videos trying to give?

2. Is this fair?


World Energy demand

By the end of this lesson you should be able to;1. Outline the principal mechanisms involved in the

production of electrical power.2. Define the energy density of a fuel.3. Discuss how choice of fuel is influenced by its energy

density.4. Outline the historical and geographical reasons for the

widespread use of fossil fuels.5. Discuss the energy density of fossil fuels with respect

to the demands of power stations.6. Discuss the relative advantages and disadvantages

associated with the transportation and storage of fossil fuels.

7. Describe the environmental problems associated with the recovery of fossil fuels and their use in power stations.

By the end of this lesson you should be able to;1. Outline the principal mechanisms involved in the

production of electrical power.2. Define the energy density of a fuel.3. Discuss how choice of fuel is influenced by its energy

density.4. Outline the historical and geographical reasons for the

widespread use of fossil fuels.5. Discuss the energy density of fossil fuels with respect

to the demands of power stations.6. Discuss the relative advantages and disadvantages

associated with the transportation and storage of fossil fuels.

7. Describe the environmental problems associated with the recovery of fossil fuels and their use in power stations.


The proportions of different energy sources used to generate electrical energy in 2006

Other0.8%

Combustible renewables and waste

1.0%

Other18.0%

Hydro16.2%

Oil6.7%

Gas19.7%

Coal40.1%

Nuclear15.1%

Non renewable Waste0.3%


Thermal power energy transformations

Chemical energy in fuel

Thermal energy in steam

Kinetic energy in turbine

Electrical energy from generator

Efficiency = Useful energy out x 100 %

Total energy in

100 MJ 32 MJ

Efficiency = 32 MJ x 100 % = 32 % 100 MJ


How it works

Electromagnetic induction java applet


Block diagram of thermal power generation

Generator

Electricity to grid

Water

Boiler

High pressure steam

Fuel

Air

Turbine

Condenser

Low pressure steam

Cooling water in

Cooling water out

1. Explain why we are currently very dependent on fossil fuels for our energy security?

2. Outline how geographical features effect the location of a thermal power plant?

3. Outline some of the transport and storage issues for fossil fuels?

1. Explain why we are currently very dependent on fossil fuels for our energy security?

2. Outline how geographical features effect the location of a thermal power plant?

3. Outline some of the transport and storage issues for fossil fuels?


Energy density of selected fuels

FoodEnergy

density / MJkg-1

Fossil Fuels Energy density / MJkg-1

carbohydrates 17.2 Gas (methane) 55.5

fats 38.9 coal, anthracite 31.4

proteins 17.2 coal, bituminous > 23.9

Bio mass fuelsEnergy

density / MJkg-1

coal, sub-bituminous

17.4 - 23.8

charcoal 29.0 coal, lignite < 17.43

dung, air dry 12.0 diesel 45.3

rice husks 15.5gasoline, automotive

45.8

wood, green 10.9 kerosene 46.3

Explain why energy density is important for power generation companiesExplain why energy density is important for power generation companies


Estimating the energy density

Procedure1.Design a method to carry out your experiment to compare the energy density of a solid fuel, liquid fuel and a gaseous fuel.2.List the independent, dependent and control variables3.Record your raw data in a table, including uncertainties.4.Process any data as required to calculate the energy density of each fuel and present your results appropriately.5.Write a conclusion on your findings.

Procedure1.Design a method to carry out your experiment to compare the energy density of a solid fuel, liquid fuel and a gaseous fuel.2.List the independent, dependent and control variables3.Record your raw data in a table, including uncertainties.4.Process any data as required to calculate the energy density of each fuel and present your results appropriately.5.Write a conclusion on your findings.

If time is limited, just carry out the experiment for one fuel and share results with the rest of the class

If time is limited, just carry out the experiment for one fuel and share results with the rest of the class


Conclusions

1. Which fuel has the highest energy density?

2. What causes the largest uncertainties in your data?

3. How can you reduce these uncertainties?

4. What recommendations can you make to power generation companies?

1. Which fuel has the highest energy density?

2. What causes the largest uncertainties in your data?

3. How can you reduce these uncertainties?

4. What recommendations can you make to power generation companies?

Complete all the questions on GEP 4 and mark with the solutions sheet


Design – Fuels heating water (GEP6)

A fuel is used to heat some water.

Design an experiment to investigate one variable which affects the final temperature of the water.

A fuel is used to heat some water.

Design an experiment to investigate one variable which affects the final temperature of the water.

IB Physics – Global environmental physics Where does our electricity come from? Castle Peak, West...

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