The Handy Chemistry Answer Book (2014)

ENERGY SOURCES

What is the breakdown for fuel source usage globally?

Roughly 32.4% of the world’s energy is used in the form of oil. About another 27% comes from coal sources, and another 21% from natural gas. Together, these three sources account for a total of over 80% of the energy sources used globally. The remaining 20% comes primarily from combustible renewables and waste (10%), nuclear energy (6%), and hydroelectric sources (2%). As you can see, some of the commonly discussed green energy sources, like solar energy or energy collected by wind turbines, do not yet make significant contributions to the breakdown of energy sources commonly used on a global scale.

Energy Sources Worldwide*

*According to a 2010 survey published by the International Energy Agency (http://www.iea.org/publications/freepublications/publication/kwes.pdf).

What is crude oil?

Crude oil is the oil that is found underground in natural reserves. It is formed from the natural decay of living things that were in the sea millions of years ago, which is why it’s commonly called a “fossil fuel.” The key ingredient that makes oil a valuable energy source is hydrocarbons. As we discussed briefly in “Chemical Reactions,” hydrocarbons release substantial amounts of energy when they undergo combustion reactions.

How is oil refined?

There are several processes that can be used to refine oil. The oldest way is through distillation, which involves heating up the crude oil slowly, allowing the different hydrocarbons to boil off one at a time, and then collecting them as vapors. There are also newer chemical refinement methods that can use a chemical reaction to convert one type of hydrocarbon into another.

Oil refineries like this one can either refine oil through distillation processes or through chemical methods.

What is cracking?

Fluid catalytic cracking is the name for the process that converts high-boiling hydrocarbons found in crude oil into lighter hydrocarbons that are more useful as gasoline and other products. These units operate continuously for years at a time, and there are hundreds of them around the world. In addition to the high temperature and heat that these reactors use to break down long hydrocarbons, there are catalysts used to help speed up the process. These catalysts are usually strong acids in the form of zeolites, specifically faujasite, which is a mixture of silica and alumina.

What is fracking?

Hydraulic fracturing, or “fracking,” is a technique used to break up rock deep underground in order to release the natural gas trapped inside it. The fluid injected into the rock is generally water-based, but the specific mixtures of chemicals dissolved in that water are generally a closely guarded secret. Using fluids to crack rocks is an old technique dating back over a hundred years, but modern techniques trace back to experiments in the 1940s by Floyd Farris and J.B. Clark, who worked for Stanolind Oil and Gas.

Where does coal come from?

Coal is formed from trees and plants that died hundreds of millions of years ago. The dead plant material eventually became buried deep underground, which placed a large amount of pressure on it. Over time the plant material became compressed and hardened, eventually forming coal. While this resource can be replaced over very long periods of time, we use it much, much faster than it can ever be regenerated.

If fracking is an old technique, why does it seem to be taking off now?

The second key innovation that has allowed fracking to grow so fast in recent years is the ability to drill wells horizontally. Technically any well that isn’t vertical is called directional or slant drilling. Hydraulic fracturing can release trapped natural gas from a much wider area this way, which has led to the recent surge in this technique.

How does a nuclear reactor generate energy?

Nuclear power comes from the energy released in fission processes, like the ones we discussed in “Nuclear Chemistry.” The nuclear reactors used for commercial energy production make use of controlled chain reactions of uranium-235. Upon colliding with a neutron, uranium-235 decays spontaneously into two lighter atoms, releasing energy for each atom of uranium that is split. The amount of energy released in the fission process is very large compared to that released from the combustion reactions that we use to obtain energy from fossil fuels. The result is that we can get a lot of energy from a relatively small amount of uranium. In fact, a kilogram of enriched uranium can generate about the same amount of energy as eight million liters of gasoline!

Where do we get uranium?

Uranium is mined largely in Kazakhstan, Australia, and Canada, although the U.S., South Africa, Namibia, Niger, Brazil, and Russia are also significant producers. Uranium is mined using a leaching process that allows it to be dissolved from ore deep in the mine and then pumped to the surface, where it is extracted and concentrated for use.