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Energy consumption in the body is a product of the basal metabolic rate and the physical 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 her basal metabolic rate (BMR): [ 2 ]
Energy has been harnessed by human beings for millennia. Initially it was with the use of fire for light, heat, cooking and for safety, and its use can be traced back at least 1.9 million years. [4] In recent years there has been a trend towards the increased commercialization of various renewable energy sources.
The first known use of fuel was the combustion of firewood by Homo erectus nearly two million years ago. [citation needed] Throughout most of human history only fuels derived from plants or animal fat were used by humans. Charcoal, a wood derivative, has been used since at least 6,000 BCE for melting metals.
Electricity is a very convenient way to transfer energy, and it has been adapted to a huge, and growing, number of uses. [75] The invention of a practical incandescent light bulb in the 1870s led to lighting becoming one of the first publicly available applications of electrical power.
In comparison, the refined forms of energy include for example refined oil that becomes fuel and electricity. Energy resources may be used in various different ways, depending on the specific resource (e.g. coal), and intended end use (industrial, residential, etc.). Energy production and consumption play a significant role in the global economy.
[4] [5] The rate of heating from this human-caused event is without precedent. [6]: 54 The main origin of changes in the Earth's energy is from human-induced changes in the composition of the atmosphere. [1] During 2005 to 2019 the Earth's energy imbalance (EEI) averaged about 460 TW or globally 0.90 ± 0.15 W/m 2. [1]
The unidirectional flow of energy and the successive loss of energy as it travels up the food web are patterns in energy flow that are governed by thermodynamics, which is the theory of energy exchange between systems. [4] [5] Trophic dynamics relates to thermodynamics because it deals with the transfer and transformation of energy (originating ...
From hot springs, geothermal energy has been used for bathing since Paleolithic times and for space heating since ancient Roman times. [280] Moving into the time of recorded history, the primary sources of traditional renewable energy were human labor, animal power, water power, wind, in grain crushing windmills, and firewood, a traditional ...