Energy consumption is the amount ofenergy used.[1] Inphysics, energy consumption refers to thetransformation of energy from one form to another, rather than its complete disappearance. According to the law ofconservation of energy,energy cannot be created or destroyed, only converted.[2] For instance, when a light bulb "consumes" electricity, it is not destroying theelectrical energy but rather converting it intolight andheat.[3] Similarly, a car "consumes" gasoline by converting itschemical energy intokinetic energy (motion) and heat.[4] Understanding energy consumption is crucial for analyzing theefficiency of various systems and processes, as the ultimate goal is often to minimize the conversion ofuseful energy into less desirable forms, such aswaste heat.[5]
From a societal andeconomic perspective, "energy consumption" often refers to the use of energy resources by human civilization to power homes, industries,transportation, and other activities.[6] This typically involves drawing upon various primaryenergy sources, including fossil fuels (coal, oil, natural gas), nuclear power, and renewable sources (solar, wind, hydro, geothermal).[7] The scale and patterns of this consumption have significant implications for environmental sustainability, economic development, andgeopolitical stability. Analyzing trends in global and regional energy consumption helpspolicymakers and researchers understand resource availability, greenhouse gas emissions, and the potential for transitioning to moresustainable energy systems.[8]
Inelectrical engineering, "energy consumption" specifically refers to the amount ofelectrical energy utilized by a device,circuit, or system over a period of time.[8] This is distinct from "power," which is the rate at which energy is consumed or transferred. While power is measured in watts (W) or kilowatts (kW), energy consumption is typically measured in watt-hours (Wh) or kilowatt-hours (kWh).[9] The relationship is fundamental: energy (E) equals power (P) multiplied by time (t):[10]
Electrical engineers are deeply concerned with energy consumption for several critical reasons. First, it directly impactsoperational costs for consumers and industries, as electricity bills are calculated based onkWh consumed. Second, energy consumption is inextricably linked to energy efficiency.[11] An efficientelectrical system or device converts a larger proportion of inputelectrical energy into its desired output (e.g., light, motion, computation) and minimizes conversion into undesirable forms, primarily heat. Understanding and optimizing energy consumption is therefore crucial for designing systems that are not only effective but also sustainable and cost-effective, leading to advancements in areas likepower electronics,smart grids, and low-power integrated circuits.[11]
In the body, energy consumption is part ofenergy homeostasis. It derived fromfood energy. Energy consumption in the body is a product of thebasal metabolic rate and thephysical activity level. The physical activity level are defined for a non-pregnant, non-lactating adult as that person's total energy expenditure (TEE) in a 24-hour period, divided by his or herbasal metabolic rate (BMR):[12]
Topics related to energy consumption in a demographic sense are:
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