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Renewable energy (or green energy) is energy from renewable natural resources that are replenished on a human timescale. The most widely used renewable energy types are solar energy, wind power, and hydropower. Bioenergy and geothermal power are also significant in some countries. Some also consider nuclear power a renewable power source ...
e. Energy is sustainable if it "meets the needs of the present without compromising the ability of future generations to meet their own needs." [1][2] Definitions of sustainable energy usually look at its effects on the environment, the economy, and society. These impacts range from greenhouse gas emissions and air pollution to energy poverty ...
The free energy is the portion of any first-law energy that is available to perform thermodynamic work at constant temperature, i.e., work mediated by thermal energy. Free energy is subject to irreversible loss in the course of such work. [1] Since first-law energy is always conserved, it is evident that free energy is an expendable, second-law ...
= Gibbs free energy = enthalpy passed into a thermodynamic system = absolute temperature of the system = entropy. and exergy and Gibbs free energy are equivalent if the environment and system temperature are equivalent. Otherwise, Gibbs free energy will be less than the exergy (for systems with temperatures above ambient).
Oceans often act as renewable resources. Sawmill near Fügen, Zillertal, Austria Global vegetation. A renewable resource (also known as a flow resource [note 1] [1]) is a natural resource which will replenish to replace the portion depleted by usage and consumption, either through natural reproduction or other recurring processes in a finite amount of time in a human time scale.
For a similar process at constant temperature and volume, the change in Helmholtz free energy must be negative, <. Thus, a negative value of the change in free energy (G or A) is a necessary condition for a process to be spontaneous. This is the most useful form of the second law of thermodynamics in chemistry, where free-energy changes can be ...
An energy system is a system primarily designed to supply energy-services to end-users. [1]: 941 The intent behind energy systems is to minimise energy losses to a negligible level, as well as to ensure the efficient use of energy. [2] The IPCC Fifth Assessment Report defines an energy system as "all components related to the production ...
Energy flow is the flow of energy through living things within an ecosystem. [1] All living organisms can be organized into producers and consumers, and those producers and consumers can further be organized into a food chain. [2][3] Each of the levels within the food chain is a trophic level. [1] In order to more efficiently show the quantity ...