5) Macro generation

Question 1

The UK power production mix:

Answer 1

42% Natural Gas
18% Nuclear
5% Coal
(18% wind, 6% biomas)

Question 2

Stages of a fossil fuel power plant

Answer 2

Learn the in-book diagram

Question 3

Stage 1: Combustion of the fossil fuel

Answer 3

The fossil fuel is combusted in a furnace to release the chemical energy that it contains (Thermal).

Question 4

Stage 2: Evaporation of water

Answer 4

Thermal energy produced is used to increase temperature of the water in the furnace, water enters the furnace in liquid form. The high temperature evaporates water to steam which is ejected from the furnace towards the steam turbine.

Question 5

Stage 3: Steam used to turn a turbine

Answer 5

The steam turns the steam turbine as it is pumped in at high temperatures. Steam collides with the fins of the turbine causing it to turn. Steam enters extremely hot and still leaves hot.

Question 6

Direct renewable energy sources: Definition and four types

Answer 6

These renewable energies take energy from a renewable source such as the wind or waves in the ocean and can convert this into electrical energy directly.
Wind, Hydroelectric, Wave & Tidal

Question 7

Indirect renewable energy sources: Definition and three types

Answer 7

These take energies from a renewable source such as the Sun using a physical characteristic of the material being used, and convert this energy into electrical energy.
Solar PV, Biomass

Question 8

Wind

Answer 8

Wind: KE of wind —>
Hub: Ke of blades, hub & shaft —>
Gearbox: KE of high speed shaft —>
Generator: Electrical Energy.

( Thermal/ Sound loss at hub, gearbox and generator stage)

Question 9

Solar

Answer 9

Sun: Radiant Energy —>
PV Panel: Electrical Energy.

( Thermal loss at PV Panel )

Question 10

Hydroelectric

Answer 10

Dam: GPE—>
Moving Water: KE—>
Turbine: KE as it rotates—>
Generator—> Electrical Energy

(Thermal/ sound loss at Moving Water, Turbine & generator stage )

Question 11

Tidal

Answer 11

Behind Tidal Barrier: GPE —>
Moving Water: KE —>
Turbine: KE as rotates —>
Generator: Electrical Energy.

(Thermal/ sound loss at Moving Water, Turbine & generator )

Question 12

Wave

Answer 12

Sun: Radiant Energy from sun produces
wind with KE —>
Waves: The KE of wind causes KE of the
waves —>
Wave Generator: KE of waves causes tubes
on surface of ocean to gain KE —>
Generator: KE from tubes turns a generator
forming electrical energy.

(Thermal/ sound loss at Wave generator and Generator )

Question 13

Biomass

Answer 13

Biomass Fuel: Chemical Energy —>
Burning Fuel: Thermal Energy —>
Steam: Thermal Energy —>
Turbine: KE —>
Generator: Electrical Energy.

(Thermal loss at steam, Thermal and sound loss at turbine and generator)

Question 14

Transmission of Electrical Energy across The Grid: Stage 1

Answer 14

Producing electricity in the power station, electricity produced in the station is 22KV (22,000V)

Question 15

Transmission of Electrical Energy across The Grid: Stage 2

Answer 15

The step-up transformer, 22KV cannot be sent across the grid constantly as the cables would be heated, due to high currents. Transformer sets voltage very high so that current is very low, for efficiency.

Question 15

Transmission of Electrical Energy across The Grid: Stage 3

Answer 15

Transmission lines, materials with low resistances are selected to minimise energy losses, cost must also be considered. Transmission lines take electricity from the step up transformer to the step down transformer.

Question 16

Transmission of Electrical Energy across The Grid: Stage 4

Answer 16

Step down transformer, when electricity reaches consumer, voltage is too high and dangerous. Step down transformer is used to reduce voltage down to levels required by the consumer. 33,000V for industry and 11,000V for distribution to towns and villages. 240V for houses, schools, shops and businesses.

Question 17

The conventional electricity distribution method.

Answer 17

Over the past years, electricity flowed from the power plant to the consumer in one direction which meant managers in electricity firms needed to predict demands for electricity very accurately and so the system was inefficient.

Question 18

Problems with incorporating renewables to the National Grid:

Answer 18

The problem is the nature of these renewables; One day that there is no wind, windmills will not work and on days where there is no sun, solar PV systems will have minimal output.

Question 19

Why do we need to incorporate renewables into the national grid?

Answer 19

This is because the one direction flow from plant to consumer is no longer satisfactory as any consumer has the power to produce electricity.

Question 20

How does the National Grid need to change?

Answer 20

1) Incorporating intermittent renewable electricity into the distribution network
2) Facilitate power production from all consumers which would require two- way flow of electricity
3) Accurate real-time data is required to establish the renewable electricity production and overall demand for electricity for all consumers at any time

Question 21

What is a SMART Grid and what will it do?

Answer 21

A SMART Grid will incorporate renewable energies into the Grid and will Predict demands, Measure output from Renewables, Adapt non- renewable power outputs and Export/ Import energy to other nations.

Question 22

What are the benefits of a SMART Grid?

Answer 22

Maximise renewable energy use,
Minimise fossil fuel imports,
Control electricity demands.

Question 23

What are interconnectors?

Answer 23

An electrical cable joining two nations together on land or sea. It facilitates the exportation of energy from one nation to another.

Question 24

What are the current interconnectors from Ireland to the UK?

Answer 24

The electricity markets of NI and ROI are joined and called the Single Electricity Market (SEM) and came into operation in 2007, and it is also connected to GB. The Moyle interconnector connects NI to Scotland, Eirgrid connects Meath to England and Greenlink connects ROI to Wales.

Question 25

What are the benefits of interconnectors? (Environmental)

Answer 25

Electrical energy from one nation can be exported to another nation when production exceeds demands and so there is less fossil fuels used. Connections to nations like Norway facilitates storage of renewable energy by means of pumped hydro, which can then be used in times of need, reducing the use of fossil fuels needed.

Question 26

What are the benefits of interconnectors? (Economic)

Answer 26

An interconnected grid enables nations to sell renewables. More competition = lower consumer costs.

Question 27

Problems with traditional power plants:

Answer 27

Thermal energy leaves at the top of the cooling towers to the cooler air in the form of steam, this usually means a traditional power plant will have around 40% efficiency.

Question 28

Another name for Combined Heat and Power:

Answer 28

Cogeneration

Question 29

Combined Heat and Power

Answer 29

Seeks to increase effectiveness of the overall electricity production process by making use of the thermal energy wasted. The steam is condensed into hot water which is sent to homes. CHP Plants are located close to homes to reduce energy loss.

Question 30

Advantages of CHP:

Answer 30

-Efficiency can exceed 80%, -Transmission is short, energy losses reduced, -Carbon emissions reduced and less fossil fuels are used, -Energy bills are minimised.