Secondary Fuels: Electricity And Hydrogen Flashcards
Why are secondary fuels used?
Primary fuels that come directly from the environment rent always in forms that are easy to use
Name 2 secondary fuels
Electricity
Hydrogen
How is electricity generated?
It involves to conversion of energy from a range of original primary fuels
What forms of energy can be directly converted to electricity?
Kinetic energy,chemical energy and light
Kinetic energy, chemical energy and light, are the forms of energy that can be directly converted t electricity. What happens with primary fuels that aren’t in these energy forms?
Several energy conversions may be needed to convert energy in a primary fuel to an energy store that an be converted to electricity
How can electricity be gained from kinetic energy?
Kinetic energy can spin an electrical conductor with a magnetic field in a generator
This is used directly in wind and wave power
In a conventional power station, how is electricity produced from heat energy?
Heat energy boils water, converting it to kinetic energy in high pressure expanding steam which is used to spin turbines which are used to spin generators.
What is used to get electricity from light energy?
Photovoltaic cells
How is electricity gained from light energy using photovoltaic cells?
Photons of light strike PV cell surface and displace electrons which makes the surface layer negatively charged.
The free electrons can flow along a conductor to the positively charged layer
The moving electrons can be used in electrical appliances
How can chemical energy be converted to electricity?
In reactions where one chemical accepts electrons at an electrode, and another releases at another electrode
The electrons flowing between the electrodes can be used to power electrical equipment
How are electrochemical cells used in batteries to store energy?
They store chemical energy which can be converted to electricity
What is the disadvantage of electrochemical cells in normal batteries?
Once the chemical reactions have taken place to produce the electricity, the battery loses its ability to make more
How do rechargeable batteries solve the problems of normal batteries?
They use electricity to reform the chemicals that produce electricity
Electrochemical cells are also used in fuel cells. How do fuel cells work?
They use electrochemical cells to store energy in chemicals like hydrogen and alcohols
They wont lose their ability to produce electricity, as long as a supply of fuel is available
How do fuel cells containing hydrogen and oxygen work?
Hydrogen releases electrons whilst oxygen accepts them
The resulting ions combine to create water
What are the advantages of using electricity?
No pollution is caused when used
It is easy to convert to other energy forms
Transport is easy
How is electricity transported?
Conducting cables
What are the disadvantages of using electricity?
Converting primary fuel to it isn’t very efficient
It is difficult to store, there are no large scale options currently available
Initial production of it might be polluting
Why may it be necessary to transport electricity using a grid of electrical cables?
The location where it is generated might be geographically limiting
What are the issues with underground cables for electricity?
Laying them is expensive
The cables need to be cooled, which requires energy to pump the coolant fluid
What are the issues with overhead cables for the transport of electricity?
They can cause aesthetic problems in scenic areas
Birds might be killed if they collide with them
How is hydrogen an important secondary fuel?
It enables the energy from unreliable and intermittent supplies to be efficiently used because they can be converted to a form that can be stored
how is hydrogen as a secondary fuel produced?
By the electrolysis of water using electricity from surplus primary energy sources
What are the 2 main methods used to release chemical energy from stored hydrogen?
Combustion to produce heat
Fuel cells
