Trace useful energy from fossil fuels
Connect chemical energy, a boiler, turbine and generator while evaluating fuel supply and environmental effects.
Exam scope and assessment notes
Core and Extended · Physics 0625, 2026–2028, section 1.7.3. Resource mechanisms, five comparison factors and qualitative efficiency are Core. Solar origins and exceptions, fusion in the Sun and electricity research, and numerical energy and power efficiencies are Supplement. Written practice is self-checked. Human subject-teacher review, supervised practical experience and cumulative assessment remain pending. Resource comparisons need the supplied site and task evidence; these are teaching models, not a project recommendation or a claim of measured output.
Before you begin
- Identify source stores and transfer pathways.
- Distinguish a rotating turbine from a generator that transfers energy electrically.
Work on paper. Try each question before revealing help, and explain why your method works.
Quick readiness check
Which store is the initial source in unburned coal?
What you will learn
- Describe direct heating and thermal electricity generation from fossil fuels.
- Compare renewability, availability, reliability, scale and environmental effects.
Chemical energy supplies a heating chain
Coal, oil and natural gas contain chemical energy. Combustion can transfer energy directly by heating, for example to a boiler that heats water. In a stated steam power station, steam turns a turbine and the turbine drives a generator, transferring energy electrically. The boiler supplies steam, the turbine rotates and the generator supplies electrical output; these are different roles.
Not every fuel use includes all three components. A gas heater supplies useful heating without a turbine and generator, and some electricity plants use hot combustion gases or combined stages. Explain the stated plant rather than adding an imaginary steam boiler to every fossil-fuel process. Other energy also reaches internal stores and surroundings.
Supply can be controlled, but the resource is finite
Fossil fuels are non-renewable on human timescales: formation takes far longer than their use. They can be stored and transported, so an available fuel-burning plant can adjust generation independently of current sunshine or wind within its operating limits. Reliability still depends on fuel deliveries, equipment, maintenance and cooling. Large stations need suitable infrastructure; fuel availability and transport differ between locations.
Combustion releases carbon dioxide and may release air pollutants, with amounts depending on fuel and controls. Extraction and transport can damage environments, and cooling and waste heat can also affect surroundings. Availability is not proof of an unlimited supply or no environmental cost. Compare the whole stated task and lifecycle rather than describing a large controllable output as automatically the best option.
Pause and explain
Does storing a year's coal supply make coal a renewable resource?
Worked example
A stated coal station burns fuel in a boiler, produces steam, turns a turbine and supplies a generator. Give each component's role.
Show the worked solution
- Combustion transfers energy from the fuel's chemical store to heat water in the boiler.
- Steam turns the turbine.
- The rotating turbine drives the generator, which supplies electrical transfer.
Answer Boiler heats water; steam turns turbine; turbine drives generator.
Try a topic test
Choose Easy, Normal or Difficult. Save your answers and open worked review after finishing.
Test this topic →From guided practice to a new situation
Write your answer and reasoning first. Use a hint only if you are stuck. The model solution is for self-checking; your written work is not automatically marked.
Trace the specified coal-to-electricity steam station through boiler, turbine and generator.
Give me a hint
Follow the chemical source, heated fluid and rotation in order.
Compare my reasoning
- Combustion supplies energy to heat water in the boiler.
- Steam drives the turbine.
- The turbine drives the generator supplying electrical energy.
Chemical store → boiler heating → steam and turbine → generator electrical output.
Look for these in your work
- Name the three component roles.
- Include other transfers rather than assuming perfect conversion.
Contrast a gas water heater with the specified coal steam station: which has the boiler/turbine/generator electricity chain, and what useful output does the heater supply?
Give me a hint
Identify the desired transfer rather than forcing every device into one chain.
Compare my reasoning
- The stated coal station supplies electrical output through turbine and generator.
- The heater supplies useful heating to water.
- A turbine and generator are not required for that direct heating task.
The station uses the stated electricity chain; the heater supplies direct water heating.
Look for these in your work
- Distinguish useful tasks.
- Do not invent unnecessary components.
A remote site has delivered fuel and a working plant but uncertain future deliveries. Assess a claim that fossil electricity is always reliable, renewable and environmentally harmless.
Give me a hint
Separate current stock, replenishment timescale and whole-process impacts.
Compare my reasoning
- A delivered stock can support operation now, but future supply and maintenance remain relevant.
- Fossil fuel is non-renewable on human timescales.
- Extraction, transport and combustion can have environmental impacts even when output is controllable.
Current stock can help reliability; it does not establish renewable or harmless supply or future deliveries.
Look for these in your work
- Use the supplied availability evidence.
- Address reliability, renewability and environmental impact separately.
Common mistakes
- A turbine and generator are different components.
- Stored fuel is not renewable merely because it is currently available.
- Do not add a turbine to direct domestic heating.
What can you explain now?
Does a fuel-burning heater need a turbine to deliver useful heating?
Compare with the explanation
No.
It can transfer energy directly by heating without converting it into electrical output.
After trying it yourself, choose your next review. This is your self-assessment.
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Make it stick
Trace a fossil steam station and distinguish five comparison factors from a claim that one controllable fuel solves every task.
If you needed the solution, close it and solve the problem again from a blank page. A correct answer is stronger when you can explain the reason for each step.