Energy industry is a sector of human economic activity, comprising a complex network of natural and engineered subsystems dedicated to the conversion, distribution and utilization of diverse energy resources.
The primary objective of this sector is to generate usable energy by converting natural, primary energy sources into secondary energy carriers – mainly electricity and heat.
This process typically involves several stages:
• The acquisition and concentration of energy resources, exemplified by the extraction, processing, and enrichment of nuclear fuel.
• Transportation and supply of energy carriers to conversion facilities, such as delivering natural gas, coal, or fuel oil to thermal power plants.
• Conversion of primary energy into secondary energy at power plants – for example, transforming the chemical energy of coal into electrical and thermal energy.
• The transmission and distribution of secondary energy to customers, for example, through power lines and electrical grids.
The electric power industry is a subsystem of the broader energy sector, encompassing the generation of electricity at power plants and its delivery to consumers via transmission lines. Its central components are power plants, which are commonly classified by the type of primary energy used and the type of conversion technologies applied.
The predominance of certain types of power plants in a specific country or region is largely determined by the availability of local energy resources. The electric power industry is generally divided into two main categories: conventional (traditional) power generation and non-conventional (alternative or renewable) power generation.
A key characteristic of traditional power generation is its long-standing development and widespread adoption. It has been thoroughly tested under a wide range of operating conditions over many decades.
The majority of the world's electricity is produced at traditional power plants. This sector is divided into several main categories.
• Thermal power
In thermal power generation, electricity is produced at thermal power plants (TPPs), which use the chemical energy of fossil fuels for this purpose. Thermal power plants are classified into the following types:
• Steam turbine power plants, where energy is converted using steam turbine system.
• Gas turbine power plants, where energy is converted using a gas turbine system.
• Combined-cycle power plants, where energy is converted using combined gas and steam turbine systems.
Globally, thermal power dominates among conventional energy sources. Approximately 46% of the world's electricity is generated from coal, 18% from natural gas, and around 3% from the combustion of biomass. Oil accounts for about 0.2%. In total, thermal power plants provide around two-thirds of global electricity production.
• Hydropower
In this sector, hydroelectric power plants (HPPs) generate electricity by harnessing the energy of flowing water.
• Nuclear power
This sector involves the generation of electricity at nuclear power plants (NPPs), which use the energy released from a controlled nuclear fission chain reaction, most commonly involving uranium or plutonium.
Alternative energy refers to a range of emerging methods for the generation, storage, transmission, and use of energy from sources that, while not yet as widely adopted as traditional ones, are gaining attention due to their economic advantages and typically low environmental impact. These sources are primarily renewable and, in most cases, are more geographically localized, which enhances energy security — especially when integrated with conventional energy systems.
Alternative energy is characterized by its environmental friendliness, very high capital construction costs, and relatively low unit capacity.
Main areas of alternative energy include:
• Wind power
• Solar energy
• Small-scale hydropower
• Geothermal energy
• Bioenergy
• Fuel cell systems
• Hydrogen energy
• Fusion energy industry
In a general sense, an energy system is the aggregate of all types of energy resources, as well as the methods and means for their production, conversion, distribution, and utilization, which together ensure the supply of various forms of energy to consumers. An energy system includes the electric power sector, oil and gas supply, the coal industry, nuclear energy, and other subsystems. At the national level, these components are typically integrated into a unified energy system. On a regional scale, they form interconnected or regional energy systems. The integration of individual energy supply systems into a unified structure is also referred to as the inter-sectoral fuel and energy complex (FEC). This integration is primarily driven by the interchangeability of different forms of energy and energy resources.
In a narrower sense, the term energy system often refers specifically to the set of power plants and electric and thermal networks that are interconnected and operate under a common regime. These systems support continuous processes of energy conversion, transmission, and distribution, enabling centralized control and efficient system management. In modern conditions, electricity is supplied to consumers from power plants, which may be located either near or far from the point of consumption. When consumers are situated at significant distances, electricity is transmitted over long distances using high-voltage transmission lines. In both cases, electricity is transmitted via power lines. However, when consumers are located far from a power plant, electricity must be transmitted at high voltage, requiring the construction of step-up and step-down substations along the way. These substations allow power plants to be interconnected via power lines for parallel operation under a common load. Similarly, combined thermal power plants (TPPs) and boiler facilities are connected to each other via heat distribution points and heat pipelines, though only over much shorter distances. The combination of all these elements is referred to as an energy system.
Such integration provides significant technical and economic advantages, including:
• Significant reduction in the cost of electricity and thermal energy;
• Substantial improvement in the reliability of electricity and heat supply to consumers;
• Enhanced operational efficiency across various types of power plants;
• Decreased requirement for reserve generation capacity.
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