Energy generation today utilizes a wide variety of fuel sources. These can be classified as Combustion/Thermal, Nuclear or Renewable/Alternative. The technology employed also varies depending on the technical requirements of translating or converting the fuel source into useful work. This is usually in the form of electricity.
This list offers you a one-stop understanding of the world's major energy systems. From the well-known to the controversial, these energy types literally keep our world running.
First a little bit of clarification. We'll be using the terms power and energy in this article, but what exactly is the difference?
What is energy?
Energy, put simply, is the capacity to do work. It may exist in potential, kinetic, thermal, electrical, chemical, nuclear, or other various forms. For instance, you could say energy is what makes it possible to push things around.
Energy is measured in many different units, but common examples include joules, BTUs, newton-meters, and even calories. When referring to electrical energy the most commonly used unit is the hallowed watt-hour.
[Image Source: Pixabay]
What is power?
While energy measures the "quantity" of work done, power indicates how fast can get the work done. Power is defined as the rate of producing or consuming energy.
The standard unit of electrical power is the watt. This is defined as a current of one ampere, pushed by a voltage of one volt. (This is not so simple for AC, but we'll gloss over that for now.)
To most readers, the distinction is obvious but it is very common for energy and power to be used interchangeably. Put simply, power is energy per unit of time. Power is watts. Energy is watt-hours.
Energy Generation Evolution
Historically, energy generation was performed either by human or animal labor, biomass combustion or mechanical conversion to provide useful work for a task. Most are still used today (windmills, horses, house fires etc) but are not as efficient or upscalable as large scale energy generation systems such as power plants.
The modern world relies heavily on electricity for day to day operations and so we will restrict the article to mass electrical energy generation systems.
Most energy generation today comes from power plants of varying design depending on the fuel source used. In most cases, power plants consume fuel to produce electricity for distribution on a mass scale. Nearly all power plants will have an AC generator or alternator and transformer to generate and transport electricity, sometimes over very long distances.
Alternators are effectively a rotating machine that converts mechanical work into electricity through the relative movement of magnetic fields and conductors. The energy source harnessed to turn the generator shaft varies widely, and is chiefly dependent on the type of fuel used.
The International Energy Agency (IEA) estimate that global energy consumption in 2014 was 13,699 Mtoe or 5.74 × 1020 joules. Mtoe stands for Million Tonnes of Oil Equivalent. The following pie charts, collated by IEA shows the estimated energy use around the globe between 1973 and 2014.
Comparison between 1973 and 2014 global energy consumption [Image Source: IEA]
Types of power plants
Since power plants are designed for the bulk generation of energy with primarily three types are generally used today. The three primary and reliable sources are thermal, nuclear and hydro-electric with a fourth ever improving and growing type - renewable or alternative.
Thermal Power Station
By far the most conventional type of energy generation system, Thermal Power Plants, generate electricity to a reasonable high efficiency. These types of plants burn fossil fuels, such as coal, to boil water and make super-heated steam to generate electricity within a turbine. The steam turns the blades of the turbine, which is mechanically coupled to an alternator rotor generating useful electricity for export.
[Image Source: Pixabay]
Nuclear Power Station
Nuclear power stations are not actually that dissimilar to thermal power plants. One obvious difference is the fuel source. The primary difference being that hydrocarbons are replaced with radioactive elements such as Uranium or Thorium. The furnace and boiler are also replaced with the reactor and heat exchange tubing.
As the fuel source undergoes nuclear fission within the reactors, the heat generated is then transferred to water in the heat exchangers. As with thermal power plants, superheated steam is then used to generate and export electricity via a turbine, alternator and transformer.
Hydro-Electric Power Station
Harnessing the power of water under the influence of gravity instead of steam, Hydro-electric power stations often use a dam or river to "store" water in a reservoir. As the water is released and flows through the turbine, the turbine blades are spun and electricity is generated n much the same way as thermal or nuclear power plants.
Reservoirs are either replenished naturally through the water cycle or mechanically "loaded" by pumping water from a lower to a higher reservoir ready for future energy generation.
A small or micro-hydroelectric power system can produce enough electricity for a home, farm, or ranch.
Hydro-electric energy generation does have a much lower capacity compared to nuclear or thermal. For this reason, they are primarily used to support thermal and nuclear plants during peak load times.
In the US, hydropower accounts for around 10 percent of the country's energy generation.
Hoover Dam [Image Source: Pixabay]
Alternative or Renewables Energy Generation
As previously mentioned the bulk workload for the globe comes from Thermal, Nuclear or Hydro-Electric power plants. The last few decades has seen growth in alternative, smaller scale, generation technologies. They are often employed to service discrete demands or as part of a larger energy policy to reduce the need to consume more polluting fuel sources.
These fall into the following general categories:
1. Solar power generation. (making use of the available solar energy)
2. Geothermal power generation. (Energy available in the Earth’s crust)
3. Tidal power generation (Harnessing the power of the sea)
4. Wind power generation (energy available from the wind turbines)
As natural resources become depleted over time, the coming decades and centuries will likely see massive further growth and development in these forms of energy generation. This may be from incremental improvements in existing tech or the creation of completely new and novel methods. Great advancements are being made in other energy generation systems and we well see nuclear fusion added to our energy mix "soon."