4.Macrogeneration

Question 1

Define the Law of Conservation of energy.

Answer 1

Energy cannot be created of destroyed {1} But it can be transferred or transformed from one form to another {1}

Question 2

Demonstrate how a simple wind generator works;

Answer 2

Look at a diagram

Question 3

Identify the main energy transformations that take place in the wind turbine.

Answer 3

Kinetic energy transferred from the shaft (connected from the rotor, through gearbox, to the generator), to relative rotational motion (kinetic energy) between a metal coil and a magnetic field in the generator. {1}
This results in electromagnetic induction. On other words kinetic energy of relative motion is transferred into inducted electrical energy. {1}

Question 4

Explain the concept of a smart grid and outline how it can facilitate the incorporation of electricity generated from renewable energy sources;

Answer 4

The energy produced from renewable sources varies over time. {1}
A ‘SMART’ grid systems computer measures the amount of electricity that is being produced at any point in time and then increases of decreases the amount of non-renewable that needs to be generated to meet the requirements.
{1}
In doing so the ‘SMART grid’ enables the amount of pollutant / carbon dioxide produced to be minimised.

Question 5

Identify another name by which Combined Heat and Power (CHP) is also known. {1}

Answer 5

Cogeneration

Question 6

Discuss the role of Combined Heat and Power in improving energy efficiencies inn traditional power plants. {4}

Answer 6

Combined Heat and Power (CHP) integrates the production of usable heat and power (electricity) {1}
In one single, highly efficient process {1}
CHP generates electricity whilst also capturing usable heat that is produced in this process {1}
This contrasts with traditional ways of generating electricity where vast amounts of heat are wasted. {1}

Question 7

State the law of conservation of energy.

Answer 7

Energy can neither be created nor destroyed [1]; it can only be converted
from one form to another.

Question 8

Renewable energy sources can be used to generate electricity either
directly or indirectly. Give one example of their use to generate
electricity directly and one example of their use to generate electricity
indirectly.
Direct use:
Indirect use:

Answer 8

Direct: One example from:
Wind [1] or Hydroelectric [1] or Wave/Tidal. [1]
Indirect: One example from:
Solar Photovoltaic [1] or Biomass. [1]

Question 9

Fig. 1 below shows a typical power generation and distribution system
such as the National Grid.With reference to Fig. 1 describe how electricity is distributed through
the National Grid.

Answer 9

Power stations generate electricity at 22kV [1]; this is stepped up to high
voltage (275kV or 400kV) by transformers [1]; electricity is transmitted at
high voltage to reduce energy losses in wires [1]; voltage is stepped down
by transformers close to consumers [1]; electricity is distributed to homes
at 240V. [1]

Question 10

Explain the concept of a smart grid.

Answer 10

A computer controlled electricity network that switches input from one
energy source to another [1]; as demand for energy varies on the
grid. [1]

Question 11

Outline one way in which a smart grid can facilitate the efficient
supply and distribution of electricity.

Answer 11

• By using a network of intelligent meters located throughout the
grid to accurately predict demand. [1]
• By incorporating electricity generated by a wide range of energy
sources, including renewables, in order to meet demand. [1]
• By incorporatin