Portal:Energy

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The Energy Portal

Aleiha's parabolic solar cooker
In physics, energy is an indirectly observed quantity. It is often understood as the ability a physical system has to do work on other physical systems. Since work is defined as a force acting through a distance (a length of space), energy is always equivalent to the ability to exert pulls or pushes against the basic forces of nature, along a path of a certain length.

Sustainable energy is the provision of energy that meets the needs of the present without compromising the ability of future generations to meet their needs. Sustainable energy sources are most often regarded as including all renewable energy sources, such as hydroelectricity, solar energy and power, wind power, wave power, geothermal energy and power, biomass fuel and energy, and tidal power. It usually also includes technologies that improve energy efficiency.

While many renewable energy projects are large-scale, renewable technologies are also suited to rural and remote areas, where energy is often crucial in human development. As of 2011, small solar photovoltaic (PV) systems provide electricity to a few million households, and micro-hydro configured into mini-grids serves many more. Over 44 million households use biogas made in household-scale digesters for lighting and/or cooking, and more than 166 million households rely on a new generation of more-efficient biomass cookstoves.

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Earth bound radiation losses
The solar resource. Solar energy is the source of all energy on earth, available to us in a number of derivatives. Plant matter for example, which relies on solar energy for nutrition, experiences natural compression and decomposition over millions of years to form the the fossil fuels we use today for electrical generation and transportation. Other examples of this can be seen in use of biomass for fuel or the harvesting of wind energy which is reliant on solar heated air for the formation of currents.

We are also able to utilize the solar resource directly. Solar thermal technologies take advantage of this resource to heat a working fluid that can transfer energy to an air stream or water for domestic or commercial use. Solar Photovoltaic or PV devices exploit various materials (principally Silicon) that experience sub-atomic variations when exposed to solar energy in order to induce an electric current. Both solar PV and thermal technologies provide a useful source of energy with little to no moving parts, no pollution and very little embodied energy.

In order to effectively design a solar energy system, an understanding of the available solar resource at the location of interest is required. All of the energy available on Earth is derived from the sun. We can model the sun's surface as blackbody. At a specific temperature, approximately 5777K for the sun, a blackbody emits energy with a unique radiation spectrum. The spectrum is divided into three broad ranges classified as ultraviolet, visible and infrared which transmit radiation at varying intensities. The highest intensities are found within the visible spectrum, peaking at a wavelength close to 0.5um. Averaged over the entire surface, the power density of the sun is found to be approximately 63 x 10 W/m2.

Photovoltaic vaccine refrigeration at Centro De Salud

Building a solar powered (photovoltaic) vaccine refrigerator with a community hospital in Northern Mexico. Now the sun helps keep the vaccines consistently cold.

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Biofuels: Anaerobic digestion · Alcohol fuels · Algae fuel · Biodiesel · Biogas · Biogasoline · Wood


Energy crops: Barley · Cassava · Hemp · Potato · Rice · Soybean · Wheat


Energy use: Heating and cooling ·


Energy storage: Alkaline versus rechargeable batteries · Animal-based · Electrochemical cell · Fuel cells · How to - Battery charger · Mass-based · Solar panel · Spring based


Geothermal power:


Greenhouses: Construction of an Affordable Greenhouse · Humboldt greenhouse gallery


Passive solar design: Parras passive solar design gallery · Thermal mass · Thermosiphon


Photovoltaics: Energy · System energy · Grid connection · Holographic solar · Humbolt gallery · Maintenance · Panels · Parras gallery · Refrigeration · Vaccine refrigeration · Test field · Troubleshooting · Rural lighting · Water pumping


Solar cooking: Analysis of a solar cooker  · and development · and health


Solar dehydrating: Food Drying with Superheated Steam · Solar drying in Uganda


Solar distillation: Compound parabolic concentrator · Effect of water on light transmission of glass · Improving Basin Solar Stills · Solar distillation TB · Solar fuel alcohol distillation


Solar energy: Open Solar Outdoors Test Field · Smart windows · The solar resource


Solar hot water: DIY solar thermal collectors · Installation and Design Principles · System types


Solar power: Heliostats · Solar thermal energy


Water: Hydraulic ram pumps · Hydroelectricity · Microhydro power · Rope pump


Wind power: Types of wind turbines (Small) · Windmill · Windpumps

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