The North American energy infrastructure is dependent upon a variety of resources including fossil fuels, nuclear and renewable energy sources. Fossil fuels contribute the largest percentage to energy production in the United States.
According to data released by the U.S. Department of Energy in 2014, fossil fuels account for 69.03 percent of the nation’s energy while 8.33 percent comes from nuclear power. All renewable energy sources combined generated 9.68 percent. Each of these resources requires complex processes and machinery to convert them into accessible energy.
Continuing technological advancements play a large role in the efficiency, safety and viability of available energy resources.
Part 1: Fossil fuels
Fossil fuels include petroleum, coal and natural gas, petroleum, of course, being the primary fuel used in electricity production in the United States.
On a basic level, petroleum is obtained through the following process:
1. Drilling a hole approximately 1 meter in diameter and inserting a steel pipe.
2. A drill bit with a pipe, or drill collar, is used to cut through the rock.
3. A drill string is attached to the bit and is extended as the well becomes deeper.
4. Once the hole is drilled, steel pipe, or casing, is inserted.
5. A drilling rig is typically employed for this process since it is equipped with all of the implements required to carry out these operations.
6. Perforations are made in the casing to allow oil to flow into the pipe from the rock.
7. The reservoir is then sealed and a smaller tube provides a pathway for the oil to the surface. If the pressure is not high enough to push the oil to the surface, a gas lift or pump jack may be used.
8. After the well is completed, an assembly of valves is affixed to the mouth to control pressure and flow.
The petroleum is then distilled at a refinery to produce gasoline, kerosene and other chemicals used in consumer products.
Coal represents about 20 percent of the energy resources used in the production of electricity in the U.S. After it is mined, coal must undergo processing prior to combustion:
1. First, it is crushed in a feeder breaker.
2. Large lumps travel on a conveyor and are broken up by a toothed drum.
3. Next, the coal is crushed by a sizer that ensures the largest particle size is less than 75 millimeters.
4. The coal is then screened to separate fine particles from coarser ones. Uniform particle size produces even combustion that is desired for kilns whereas coarser particles are used for grated applications.
5. The next step, beneficiation, is the process whereby impurities are removed from the coal.
6. The subsequent cleaning process helps separate out particles of stone since the coal is lighter.
7. The final step is charring, which removes hydrogen and oxygen, resulting in a product that consists primarily of carbon.
The demand for natural gas has increased significantly in recent years as it offers an abundant, low cost energy source with comparatively low greenhouse gas emissions. However, its use in electric power generation may be limited by the availability of natural gas pipeline transport systems.
Natural gas is most often discovered in subterranean rock formations, usually near or in conjunction with coal beds or petroleum reservoirs. After a well is drilled and the gas is extracted, it is processed to remove impurities.
Hydrocarbons and fluids must be removed to produce dry natural gas before it can be transported through major pipelines.
A variety of equipment is usually installed at the well to carry out these purification processes. For example, a low temperature separator is used to remove oil and condensates from natural gas and flash tank separator-condensers aid in recovering methane from the glycol dehydration process that would otherwise be released into the atmosphere.
Note: This article first appeared in the May 2015 edition of Energy Digital