1. 3.1 Energy demands: (a) Generating electricity
LO’s:
Describe how most of our energy demands are met
Describe how steam is used in a power station to generate electricity.
3 Describe how biofuels may be used to generate electricity
4 Explain why biomass is considered to be carbon neutral
4-6
4-6
4-6
6-8
Keywords
Global demand
Steam turbine
Biomass
Biofuel
uncertainties
Starter
Show clip ‘generating electricity using fossil fuels’
Label schematic diagram of a thermal power station
Main Activity
Work through PPT to explain LO’s .
Class Expt to find the best fuel
Plenary
Analyse results and discuss uncertainties.
Show clip ‘generating electricity from chicken litter’
Homework task: kerboodle
P3.1 Using fuels for energy

2. (a) Generating electricity
P3.1 Energy demands
(a) Generating electricity
Explain that, in some power stations, fuel is used to heat water to produce steam
Describe how steam drives a turbine connected to a generator
Explain the advantages and disadvantages
of using biofuels.

3. Thermal power stations
A thermal power station generates electricity by using the heat produced by the burning a fossil fuel such as coal, gas, oil or by the fission of uranium.
Over 80% of our electricity is produced by these type of power stations.

4. Fuel is burnt to turn water into high pressure steam.
Thermal power stations.
BOILER
TURBINES
GENERATOR
BOILER
Fuel is burnt to turn water into high pressure steam.
chemical energy thermal energy
TURBINE
High pressure steam turns a turbine (like a windmill)
GENERATOR
The turbine rotates the coils of a generator to produce electricity.
kinetic energy electrical energy

5. Fuel is burnt to turn water into high pressure steam.
Thermal power stations.
BOILER
TURBINES
GENERATOR
BOILER
Fuel is burnt to turn water into high pressure steam.
chemical potential energy thermal energy of steam
TURBINE
High pressure steam turns a turbine (like a windmill)
GENERATOR
The turbine rotates the coils of a generator to produce electricity.
kinetic energy electrical energy

6. Fuel is burnt to turn water into high pressure steam.
Thermal power stations.
BOILER
TURBINES
GENERATOR
BOILER
Fuel is burnt to turn water into high pressure steam.
chemical potential energy thermal energy of steam
TURBINE
High pressure steam turns a turbine (like a windmill)
GENERATOR
The turbine rotates the coils of a generator to produce electricity.
kinetic energy electrical energy

7. Fuel is burnt to turn water into high pressure steam.
Thermal power stations.
BOILER
TURBINES
GENERATOR
BOILER
Fuel is burnt to turn water into high pressure steam.
chemical potential energy thermal energy of steam
TURBINE
High pressure steam turns a turbine (like a windmill)
GENERATOR
The turbine rotates the coils of a generator to produce electricity.
kinetic energy electrical energy

11. A thermal power station

12. A thermal power station
Steam
Turbine
Generator
Electricity to
national grid
Steam condensed
back to water
Boiler

13. World energy demand and sources of energy ( 2013 )
Most of the world’s energy resources ( % ) originate
from burning
% is nuclear .
% is renewable
86%
fossil fuels
4 %
10 %
10% 4%
fossil fuels
86%

14. 5. Boiler pipes to turn water into steam
1. Generators
2. Steam turbine
3. Condenser
4. Pump
5. Boiler pipes to turn water into steam
in hot gas exhaust
The clever bit !
6. Gas turbine
CCGT A combined-cycle power plant uses both a gas and a steam turbine together to produce up to 50 percent more electricity from the same fuel than a traditional simple-cycle plant. The waste heat from the gas turbine is routed to the nearby steam turbine, which generates extra power  

15. Experiment to compare the energy in different fuels
thermometer
30cm3
water
3g Fuel burning
in a lid
HEAT

16. Wooden splint Conclusion:
The fuel which contained the most chemical energy was …………
I know this because …………………………………………………………………....
………………………………………………………………………………………………………………
It might not have been a valid test because ……………………….
…………………………………………………………………………………………………………

17. Burning approximately 3g of alcohol increased the water temperature 19 42 23 19 62 43
Wooden splint
Conclusion:
The fuel which contained the most chemical energy was …………
I know this because …………………………………………………………………....
………………………………………………………………………………………………………………
alcohol
Burning approximately 3g of alcohol increased the water temperature
by the largest amount
It might not have been a valid test because ……………………….
…………………………………………………………………………………………………………
The same mass of each fuel should have been carefully weighed out before combustion
The distance from the flame could vary, There could be draughts.
A lot of the thermal energy does not get transferred to the water. ( Possibly up to 50% !)
Uncertainties in i) the water temperature = C, ii) mass of fuel g !!

18. Biomass and biofuels
Explain the meaning of the terms biomass and biofuel
Describe how biofuels may be used to generate electricity
Explain why biomass is considered to be carbon neutral

26. Vegetable oils as fuels
Rape seed
Soya bean?
Sun flower

28. Biodiesel is CO2 neutral because:
Biofuels
Biodiesel is CO2 neutral because:
the amount of CO2 given off when used as a fuel
equals the amount absorbed while growing.
Over 40% of the electricity from renewable sources comes from biomass energy.

29. Using ethanol as a Biofuel
Ethanol can be made by
fermenting sugar from sugar cane
in warm climates.
10 % can be added to petrol
to save on petrol supplies>

33. Biodiesel is CO2 neutral because:
the amount of ……………………………………….………………………
equals the amount ……………………………………………………………

34. Q1a. i) Power stations using fossil fuels release carbon dioxide into the
atmosphere.
ii) Nuclear power stations do not release carbon dioxide into the
b. Nuclear power stations produce a small quantity of highly radioactive
waste which needs to be stored safely for thousands of years.

35. Q2a. i) Oil fired power stations + no radioactive waste .
- releases carbon dioxide to atmosphere
Nuclear power station no release of carbon dioxide to atmosphere
- radioactive waste stored safely for
thousands of years .
a. ii) gas powered stations have a rapid start up time and release less CO2
b. 10,000 kg of fossil fuel gives the same amount of energy
as 1 Kg uranium

36. Q3a. A biofuel is any fuel taken from living or recently living organisms.
Ethanol is made from fermenting sugar cane
b. A carbon neutral fuel releases the same amount of carbon dioxide when
burnt, as it took in during photosynthesis.
(Transporting the fuel across the planet is not included !)

37. This is the number of seconds in a year
Q4a Energy use each year = x Joules per year
Energy use each second = x Joules per second
(60 x 60 x 24 x 365)
= x W
Energy use each second per person = x W
6 x 10 9
= W
= 2.6 kW
This is the number of seconds in a year