Oil shale

Some rocks hold oil inside.

These rocks are very old. They come from tiny plants and bits of life.

We can heat these rocks to get oil. The heat turns the rock into a vapor. Then the vapor cools into liquid oil. This oil can be used for power. It can also be used for building. People have used these rocks for a long time.

It is a very special kind of rock.

Oil shale is a special kind of rock. It is made of tiny grains. These rocks hold a solid mix called kerogen. Kerogen comes from old bits of life. This includes algae and pollen.

We can get liquid oil from these rocks. First, we must heat the shale to a high temperature. This uses a way called pyrolysis. This step turns the rock into a vapor.

Then, the vapor cools down. This makes a liquid called shale oil.

This oil can be used for power or fuel.

People have used oil shale for a long time. In ancient times, people in Mesopotamia used it for roads.

Today, some countries have big oil shale industries. Estonia and China use it a lot. Brazil, Germany, and Russia use it too. Making shale oil is expensive. It can also affect the land and air. The United States has the largest amount of oil shale in the world. Most of it is in the Green River Formation. This area covers parts of Colorado, Utah, and Wyoming.

Oil shale is a special kind of sedimentary rock. It is made of very fine grains. These rocks are rich in organic matter. This means they contain a solid mixture called kerogen. Kerogen is made from the remains of old living things. These include algae, pollen, and bits of plants.

Some oil shales formed in oceans. Others formed in lakes or on land. This helps scientists understand how the rock was made. It is different from oil-bearing shales. Those rocks already contain liquid petroleum.

We can turn this rock into liquid fuel. This happens through a process called pyrolysis. First, the oil shale is heated to a very high temperature. This heat turns the kerogen into a vapor.

Next, the vapor is allowed to cool down. As it cools, it turns into a liquid called shale oil. This liquid is a substitute for regular crude oil. It can also be burned directly in furnaces. This can provide heat for homes or power for electricity.

Humans have used oil shale for thousands of years. Around 3000 BC, people in Mesopotamia used "rock oil" for roads. They also used it as an adhesive for buildings. In the 10th century, an Arab physician described how to extract oil from it. The first patent for extracting oil was granted in 1694 in Britain. Modern industrial mining began in 1837 in France. During the Industrial Revolution, Scotland produced much oil shale. They used it to make lamp oil and kerosene for lighting.

Today, different countries use oil shale in different ways. Estonia and China have well-established industries. They use it for both oil and power. Brazil, Germany, and Russia also use it to some extent. The United States has the largest amount of oil shale resources. Most of these are in the Green River Formation. This formation covers parts of Colorado, Utah, and Wyoming. About 80% of the world's oil shale resources are in the United States.

Extracting oil from shale is a hard job. It costs more money than getting regular crude oil. It can also have a large impact on the environment. Mining can affect how we use land and water. It can also cause air pollution and greenhouse-gas emissions.

Scientists must balance the need for energy with these concerns. Even so, the huge amount of oil shale in the world keeps it interesting. It remains a major part of how we study the Earth's history.

Oil shale is an organic-rich, fine-grained sedimentary rock. It is not a standard fossil fuel like petroleum, but it contains a solid mixture of organic compounds called kerogen. This kerogen can be processed into liquid hydrocarbons. While the term "shale oil" is often used for both, scientists distinguish between oil shale and oil-bearing shales. Oil-bearing shales, such as the Bakken or Eagle Ford Formations, contain tight oil already inside the rock. In contrast, oil shale requires heating to release its liquid content.

To produce fuel, the rock undergoes a chemical process called pyrolysis. This process begins by heating the oil shale to a very high temperature. This heat causes the kerogen to transform into a vapor. Once the vapor is produced, it is allowed to cool down. As it cools, the vapor separates into two distinct parts: a liquid called shale oil and a combustible shale gas. The resulting shale oil acts as a substitute for conventional crude oil.

Geologists classify oil shales based on how they were originally deposited. This classification is often based on the environment where the original organic matter settled. Marine oil shales formed on the ocean floor. Lacustrine oil shales formed at the bottom of lakes. Terrestrial oil shales were deposited on land. This system was developed by Adrian C. Hutton to help estimate the yield and composition of extracted oil. Scientists also use the van Krevelen diagram to classify kerogen types based on hydrogen, carbon, and oxygen content.

Human history with oil shale stretches back to prehistoric times. Around 3000 BC, people in Mesopotamia used "rock oil" for road construction and building adhesives. During the Iron Age, Britons used tractable oil shales for burial cists or ornaments. The first patent for extracting oil from stone was granted in Britain in 1694. Modern industrial mining began in 1837 in Autun, France.

During the Industrial Revolution, Scotland became a major producer. By 1913, Scottish operations produced about 2% of the global petroleum supply. This was driven by the demand for kerosene and lamp oil.

Global oil shale resources are massive but vary in accessibility. A 2016 estimate set the total world resources at an amount equivalent to the yield of trillions of barrels of oil. The United States holds the largest share, containing more than 80% of the world's total resources. Most of this is found in the Green River Formation, which spans Colorado, Utah, and Wyoming. Other significant deposits exist in China, Russia, and Brazil. However, there is a difference between "resources" and "reserves." Resources are all known deposits, while reserves are those that can be extracted economically with current technology.

Extraction is a complex and expensive endeavor. Producing shale oil costs more financially than producing conventional crude oil. It also carries a significant environmental footprint. Mining and processing can lead to issues with land use and waste disposal. It also requires careful water use and wastewater management. Furthermore, the process can result in air pollution and greenhouse-gas emissions.

Despite these challenges, oil shale remains a key part of the energy conversation. Estonia and China have well-established industries that use oil shale for both oil and power generation. Other countries like Germany, Brazil, and Russia also utilize it to some extent. The industry has seen many ups and downs. For example, the 1973 oil crisis led to a production peak in 1980. Later, low oil prices caused major projects, like Exxon's Colony Shale Oil Project, to be canceled. As technology evolves, the potential of these vast organic-rich rocks continues to be studied.