science

Sub-bituminous coal

Sub-bituminous coal is a science topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand Sub-bituminous coal rather than just read about it. In short: Sub-bituminous coal is a lower grade of coal that contains 35–45% carbon. The properties of this type are between those of lignite, the lowest grade of coal, and those of bituminous coal, the second-highest grade of coal.

Key takeaways

Sub-bituminous coal belongs to science; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect Sub-bituminous coal to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of Sub-bituminous coal from memory before moving on to harder problems.

Reference excerpt

Sub-bituminous coal is a lower grade of coal that contains 35–45% carbon. The properties of this type are between those of lignite, the lowest grade of coal, and those of bituminous coal, the second-highest grade of coal. Sub-bituminous coal is primarily used as a fuel for steam-electric power generation.

Properties Sub-bituminous coals may be dull, dark brown to black, soft and crumbly at the lower end of the range, to bright jet-black, hard, and relatively strong at the upper end. They contain 15–30% inherent moisture by weight and are non-coking (undergoing little swelling upon heating). The heat content of sub-bituminous coals ranges from 8,300 to 11,500 Btu/lb or 19.3 to 26.7 MJ/kg. Their relatively low density and high water content render some types of sub-bituminous coal susceptible to spontaneous combustion if not densely packed during storage to exclude airflow.

Reserves A major source of sub-bituminous coal in the United States is the Powder River Basin in Wyoming.

Application Sub-bituminous coals, in the United States, typically have a sulfur content less than 1% by weight, which makes them an attractive choice for power plants to reduce SO2 emissions under the Acid Rain Program. Sub-bituminous coals release large quantities of greenhouse gases when burned, compared to higher grades of coal.

See also Types of coal Greenhouse gas emissions#Carbon dioxide (CO2) Anthracite Bituminous coal Lignite Coal mining Coal mining in the United States Coal-fired power station

References

Illustrations

Worked examples

Example 1 — a first encounter with Sub-bituminous coal

Start with the simplest possible case. Write down what Sub-bituminous coal claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In science, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to Sub-bituminous coal before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about Sub-bituminous coal ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of Sub-bituminous coal

In research: Sub-bituminous coal appears in science research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses Sub-bituminous coal in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: Sub-bituminous coal is common in secondary-school and first-year university syllabi. It links to neighbouring topics Coal, so understanding it makes those chapters shorter.
In everyday life: Look for Sub-bituminous coal outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

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How to study Sub-bituminous coal in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Sub-bituminous coal means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain Sub-bituminous coal out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Sub-bituminous coal in simple terms?

Why does Sub-bituminous coal matter?

Because it connects several science ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study Sub-bituminous coal?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on Sub-bituminous coal.