ENERGY SOURCES & RESOURCES
Energy - power derived from physical or chemical sources
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This definition of energy is not to be confused with the definition that applies in mechanical physics.
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Energy sources can be divided into two primary categories:
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Renewable sources - resources that can be restored, or from which energy can be reaped immediately or almost immediately after energy has already been obtained; unlimited energy sources, e.g. solar power, wind power
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Non-renewable sources - sources of energy which are limited in quantity and will effectively run out over time, e.g. fossil fuels, natural gas.
- although these resources will eventually be produced again by natural processes, they will take millions of years to do so
NON-RENEWABLE ENERGY
COAL
Coal - a sedimentary black or brown rock composed predominantly of organic carbon
There are two main types of coal:
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thermal coal - coal with a significant moisture count, thus burned for steam and used in energy production
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metallurgical coal - coal that can be mined to produce the carbon necessary for steel-making
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Biomass - the biological raw material that an energy resource/fuel is made of
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Coal is formed from the energy stored in plants hundreds of millions of years ago. As time passes, layers of rock form over dead organic matter, allowing for pressure and heat to be exerted on the biomass. This initiates chemical and physical change within the biomass to form coal as we see it now. Coal is typically found in layers of vein-resembling 'seams' underground.
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The process of generating electricity with coal is:
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Coal rocks are pulverized in powder then exposed to hot air, allowing for combustion to take place
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Water pumped through the system is exposed to the heat and turns to steam
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This steam, due to the high pressure, has the strength to turn a turbine
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The turbine is attached to a generator, which converts kinetic energy to electric energy
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The team returns to a liquid state once more (water) and the process continues
NATURAL GAS
Natural gas - flammable gas, composed predominantly of hydrocarbons
A large percent of natural gas is methane. Natural gas occurs underground; similar to coal, over the process of millions of years, organic matter was pressurized to incident physical and chemical changes, causing the biomass to become partly coal, partly petroleum (crude oil), and partly natural gas.
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By drilling holes underground where geologists believe there to be a significant reserve of natural gas, this gas can be captured and used to produce energy. The gas obtained is usually mixed in with other hydrocarbons and substances, those of which are not useful. Because of this, the gas must be filtered and separated at a plant.
Natural gas is versatile and can be utilized in various power production plants including:
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Steam engines
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Industrial natural gas-fired turbines
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Microturbines
PETROLEUM
Petroleum - a naturally occurring liquid found under the Earth's surface that can be refined into fuel
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As mentioned above, petroleum is formed the way coal and natural gas is formed; biomass is pressurized over millions of years to form coal, petroleum and natural gas
There are three technologies that convert petroleum to fuel:
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Petroleum oil is combusted to produce steam. This steam turns a turbine, allowing a generator to convert kinetic energy to electrical energy
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Petroleum oil is burned, the heat allowed the water pumped through the column to heat as well as turn to steam. This steam turns a turbine, allowing a generator to convert kinetic energy to electrical energy
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Oil is first combusted to turn a turbine. Once the exhaust gasses are recovered, they are used to heat water in a boiler, which once more emits steam and turns a turbine.
RENEWABLE ENERGY
URANIUM
Uranium - a heavy metal commonly used in nuclear reactors to produce nuclear energy via fission
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Enriched uranium - a type of uranium in which the percentage composition of uranium-235 has been increased via the process of isotope separation
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Uranium is thought to be formed in cosmic events like supernovae or the merger of two neutron stars. Naturally occurring uranium in the Earth is found in ores; these ores are composed of three major isotopes of uranium: uranium-238, uranium-235, uranium-234. Uranium-235 is most commonly used for nuclear power generation, as it can sustain a fission chain reaction, and weaponry. Low-enriched uranium is preferred for nuclear power.
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Nuclear fission - the the process in which the nucleus of an unstable atom is split into two or more smaller nuclei, which are referred to as fission products
Fission chain reactions are commonly used in nuclear power plants as a source of clean and renewable energy. Nuclear fission energy requires the presence of a moderating substance to sustain the reaction for as long as possible so that the maximum amount of energy is produced. Moreover, the rate of the reaction must also be controlled in order to ensure efficiency and safety of the reaction – this is done using control rods made of elements that can absorb neutrons (most often boron).
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Nuclear fusion has not been used as an energy source on Earth because we do not currently possess the technology to cause fusion reactions (extremely high amounts of energy are required).
WIND
Wind energy is produced mainly using wind turbines. Typically, wind turbines are located in rural areas as they take up a large amount of space. Wind turbines require high-speed winds to spin the blades of the turbine, and then a generator is used to convert that kinetic energy into electrical energy
The wind turbine blades are designed in two different ways:
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Drag type blades - this blade design uses the force of wind to rotate the blades; they have a higher torque than lift designs but rotate at a slower speed, making them less efficient for large-scale energy production
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Lift type blades - this design allows wind to remain within the blade's grasp for a longer period of time, resulting in a pressure being built on the tail edge; the pressure difference forces the blade to move at a higher speed
SOLAR POWER
Solar power - electric or thermal energy generated by harnessing the energy of the sun via photovoltaic cells in solar panels (other technologies are also used)
Solar power is generated by solar panels, which are comprised of PV cells. These cells are made of silicon combined with other materials that ensure that there are extra electrons on one side of the cell and less electrons on the opposing side. When the sunlight hits the cell, photons remove electrons from the silicon; the electrons then travel to the side with missing electrons. This causes an electrical current, which eventually reaches a converter that turns it into electrical energy.
HYDRO-ELECTRIC POWER
Hydro-electric power - electric energy produced through the force and power of moving water; this energy is harnessed via HEP plants
The most common type of hydroelectric power plant stores water in a reservoir and allows it to move through a turbine. This rotates the turbine and a generator converts this kinetic energy to electrical energy. Such power plants can even be downsized, so as to provide energy domestically.
BIOMASS
Biomass - any matter that is living, be it flora or fauna, is considered biomass; the term is typically used to describe plant matter and animal and human waste
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Biomass can be converted to electrical power through many methods, the most common being the burning/combustion of biomass to heat water, the steam of which will rotate turbines attached to a generator. Typically wood-based material (wood chips, trunks, logs, etc.) are used for the production of electrical energy. Corn and wheat are typically combusted to produce steam.
