Macrogeneration

Question 1

4 main stages of a fossil fuel power plant

Answer 1

1. Fuel - release of stored chemical energy, changed into thermal energy
2. Evaporation of water - thermal energy evaporates water, steam directed into steam turbine
3. Steam turns the turbine - steam turns the fins of a turbine
4. Condensing in the cooling tower - hot steam condenses into a liquid and is sent back to the furnace.

Question 2

Direct renewable energy source definition + example:

Answer 2

A renewable energy source that takes energy from a source and converts it into electrical energy directly
E.g. wind, hydroelectric, wave, tidal

Question 3

Indirect renewable energy definition + example

Answer 3

A renewable energy source that takes energy from a source and converts it into electrical energy indirectly via a physical characteristic of the material used
E.g. Solar PV, biomass

Question 4

4 stages of transmitting electrical energy across the national grid:

Answer 4

1. Electricity produced in power station (e.g. 22kV)
2. Step up transformer increases voltage to reduce heat losses (e.g. 22 to 275/400kV)
3. Transmission lines send electricity across the grid
4. Step down transformer - 33kV for industry - 11kV for distribution to towns - 240V to individual buildings

Question 5

Smart grid definition:

Answer 5

A computer controlled electricity network that switches input from one energy source to another as demand varies on the grid

Question 6

4 Key requirements of a smart grid:

Answer 6

1. Can predict demand
2. Can measure output from renewables
3. Can adapt to give non renewable output if needs be
4. Can export or import to/from other nations

Question 7

Benefits of a smart grid:

Answer 7

1. Maximizes renewables
2. Minimizes fossil fuels
3. Controls electricity demand - providers can alter prices to encourage consumers to use
   electricity at less demanding times
4. Offers a potential income stream to micro generators

Question 8

Efficiency difference with combined heat and power (CHP) compared to traditional power plants

Answer 8

Traditional power plants ≈ 40%
CHP power plants ≈ 80%

Question 9

Other name for CHP:

Answer 9

Co-generation

Question 10

How does CHP work

Answer 10

Steam in the cooling towers heats water in pipes which run to local homes or businesses

Question 11

Advantages of CHP:

Answer 11

1. Efficiencies can exceed 80%
2. Energy loss via transmission is reduced
3. Less fossil fuels needed
4. Energy bills can be minimised