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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Solar heater
Solar hot water describes active and passive solar technologies that utilize the sun’s freely abundant solar thermal energy in order to heat water for a desired application. It is one of the most efficient ways to heat water (in terms of energy/waste), as it requires no energy conversion, unlike electric-resistance heating or fuel burning. It is a simple transfer and concentration of heat energy from one place to another. Another interpretation of the efficiency of the practice is that the solar energy is free, and only dependent on the extent of the technology used, and its cost and efficiency. In other words, the energy is free, only the collection, conversion, and storage devices cost.

If you have ever felt hot water trickle out of a garden hose that’s been sitting in the sun, you’ve experienced solar hot water in action. Essentially, a solar hot water system is made up of a solar thermal collector, a well-insulated storage container, and a system for transferring the heat from the collector to the container vis-à-vis a fluid medium, which in some circumstances is the water to be used itself.

Being as there are, on a global scale, near countless applications using domestic, commercial and industrial hot water, there are also nearly as many opportunities to apply solar thermal technologies to heat this water. But today the market is changing, and both the economic and environmental costs associated with using gas and electricity to heat water are being challenged by more efficient, less costly systems.

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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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