Fossil Fuels

Where Fossil Fuels Come From

There are three major forms of fossil fuels: coal, oil(petroleum) and natural gas. All three were formed many hundreds of millions of years ago before the time of the dinosaurs - hence the name fossil fuels. The age they were formed is called the Carboniferous (石炭層)Period. It was part of the Paleozoic Era. "Carboniferous" gets its name from carbon, the basic element in coal and other fossil fuels.

Coal is a hard, black colored rock-like substance. It is made up of carbon, hydrogen, oxygen, nitrogen and varying(change--verb) amounts of sulphur. There are three main types of coal - anthracite (無煙煤),bituminous (瀝青的) and lignite(褐煤). Anthracite coal is the hardest and has more carbon, which gives it a higher energy content(含量). Lignite is the softest and is low in carbon but high in hydrogen and oxygen content.Bituminous is in between. Today, the precursor(前兆) to coal - peat(泥煤) - is still found in many countries and is also used as an energy source(begining).

Oil is another fossil fuel. It was also formed more than 300 million years ago. Some scientists say that tiny diatoms(矽藻) are the source of oil. Diatoms are sea creatures(生物) the size of a pin head. They do one thing just like plants; they can convert (change/transform)sunlight directly （直接地）into stored energy.

Natural gas is lighter than air. Natural gas is mostly made up of a gas called methane（甲烷/沼氣）. Methane is a simple chemical compound that is made up of carbon and hydrogen atoms. It's chemical formula is CH4 - one atom of carbon along with four atoms hydrogen. This gas is highly flammable. Natural gas is usually found near petroleum(oil) underground. It is pumped from below ground and travels in pipelines(輸油管) to storage (貯藏--n)areas. Natural gas usually has no odor(smell) and you can't see it. Before it is sent to the pipelines and storage tanks, it is mixed with a chemical that gives a strong odor. The odor smells almost like rotten eggs. The odor makes it easy to smell if there is a leak.