---
title: "Classification of traditional fuels with examples"
subject: "Energy Resources"
chapter: 1
key: "semester_6/energy_resources:classification-of-traditional-fuels"
source: https://www.bctengineer.com/q/semester_6/energy_resources/classification-of-traditional-fuels
site: BCT Engineering
---

# Classification of traditional fuels with examples

Energy Resources · Chapter 1: Fossil fuels and their characteristics

- Asked in: year not given, 5 marks
- Video: [Classification of Fuel |On the basis of occurrence and physical state](https://www.youtube.com/watch?v=1a6K8DxUW4A) — C for Chemistry
- Answer checked by Claude Opus 5.5 (high effort) on 2026-10-14
- Page: https://www.bctengineer.com/q/semester_6/energy_resources/classification-of-traditional-fuels
- Whole chapter: https://www.bctengineer.com/md/semester_6/energy_resources/chapter-1

## Question

Classify traditional fuels according to their physical state and the way they are obtained. Give two examples in each class and state the main advantages and disadvantages of solid, liquid and gaseous fuels.

## Short answer

Traditional fuels are classified by physical state and source: solid (wood, coal; cheap, easy to store but smoky, low calorific value); liquid (petrol, diesel; high calorific value, clean, easy control but costly, fire hazard); gaseous (natural gas, LPG; high efficiency, no ash, but storage risk of explosion).

## Answer

A **fuel** is a substance that releases heat energy on combustion. Traditional (conventional) fuels are the carbon-based fuels used for centuries: wood, coal, petroleum products and natural gas.

#### Classification

| Physical state | Natural (primary) | Prepared (secondary) |
|---|---|---|
| Solid | Wood, peat, lignite, coal | Charcoal, coke, briquettes |
| Liquid | Crude petroleum | Petrol, diesel, kerosene, furnace oil, alcohol |
| Gaseous | Natural gas | LPG, producer gas, water gas, coal gas, biogas |

Fossil fuels (coal, crude oil, natural gas) were formed over millions of years from buried plant and animal remains. Wood and charcoal are non-fossil but are also traditional fuels.

#### Solid fuels
- Advantages: cheap, easy to store and transport, no explosion risk in storage.
- Disadvantages: low calorific value, ash and smoke, difficult to control the flame, low thermal efficiency, labour needed for handling.

#### Liquid fuels
- Advantages: high calorific value (about 42–46 MJ/kg), clean burning with little ash, easy to transport by pipe, easy to control flow and flame, no ash handling.
- Disadvantages: costly, fire hazard, need closed storage tanks, many are imported, give CO and unburnt hydrocarbons if burnt badly.

#### Gaseous fuels
- Advantages: highest efficiency, complete combustion with little excess air, no ash or smoke, easy control, can be preheated, transported by pipeline.
- Disadvantages: need large storage volume or pressure cylinders, high risk of leakage and explosion, costly equipment.

## Check yourself

The answer's key points as multiple-choice questions, with the correct option and why.

1. Which pair are prepared (secondary) solid fuels?
   A. Peat and lignite
   B. Charcoal and coke
   C. Wood and coal
   D. LPG and producer gas
   Answer: B. Charcoal, coke and briquettes are made from natural solid fuels; wood, peat, lignite and coal are natural. (Key point: Prepared solid fuels)

2. What is the main disadvantage of gaseous fuels?
   A. Large storage volume or pressure cylinders and high risk of leakage and explosion
   B. Low thermal efficiency and large ash production
   C. Very low calorific value and heavy smoke
   D. Difficult flame control and handling labour
   Answer: A. Gases need big storage or cylinders and leak or explode easily; their strengths are high efficiency, no ash and easy control. (Key point: Gaseous fuel disadvantages)

3. Why are liquid fuels preferred over solid fuels for many uses?
   A. They are cheaper and carry no fire hazard
   B. They are all produced locally with no import
   C. They burn completely with no CO under any conditions
   D. Higher calorific value, little ash, and easy pipe transport and flame control
   Answer: D. Liquids have about 42-46 MJ/kg, leave no ash and are easy to control, though they are costly and a fire hazard. (Key point: Advantages of liquid fuels)

## Related in Energy Resources

- [Micro hydro scheme components and classification](https://www.bctengineer.com/question.md?key=semester_6%2Fenergy_resources%3Amicro-hydro-scheme-components-classification) — Energy Resources, chapter 5

## Related in other subjects

- [Monitoring gaseous and liquid dielectrics for impurities](https://www.bctengineer.com/question.md?key=semester_8%2Fhigh_voltage_engineering%3Adielectric-impurity-monitoring) — High Voltage Engineering, chapter 7
- [Physical and chemical characteristics of solid waste](https://www.bctengineer.com/question.md?key=semester_7%2Fenvironment_and_pollution_control%3Asolid-waste-characteristics) — Environment and Pollution Control, chapter 5
- [Liquid lubricants and their classification](https://www.bctengineer.com/question.md?key=semester_2%2Fengineering_chemistry%3Aliquid-lubricants-classification) — Engineering Chemistry, chapter 8
- [USCS classification from PSD curves](https://www.bctengineer.com/question.md?key=semester_4%2Fsoil_mechanics%3Auscs-classify-psd-curves-a-b) — Soil Mechanics, chapter 3