# Welcome to Appropedia

## Sharing knowledge to build rich, sustainable lives.

 Appropedia is for collaborative solutionsin sustainability, appropriate technology and poverty reduction. You are welcome to add to and edit Appropedia - your site to find, co-create and improve the solutions we need. Our vision and mission. Contributors have made 284,554 edits and uploaded 22,423 files.Browse our categories or all 6,244 articles.

## Announcements — more

 As part of a 3-D printing class, graduate students will be designing printable open-source appropriate technology for sustainable development. If you want a technology designed to be 3-D printed, post your ideas here. Chosen designs will be made and open-sourced for the global community. Deadline Nov. 13, 2014

Aleiha's parabolic solar cooker. The paraboloid is an interesting shape with some amazing qualities. It has the power to concentrate light, electronic waves, sound, etc. to its focus at the center. To find the focal point of a paraboloid, one must use the formula, $y=p*x^2$, where p is a constant. The variable y is the depth of the dish, and x measures the distance from the center axis to the maximum circumference of the dish. You have to pretend that there is an x axis going through the center of the base of the dish and a perpendicular y-axis passing from the center of the base of the dish to the focal point. The two numbers, x and y, represent a point on the paraboloid, and from that, you are able to determine where the focus is.

Parabolic cookers have been used for centuries now. The idea to concentrate light using curved mirrors was developed by the Greeks, Aztecs, Incas, Romans and Chinese. The Incas used bronze and gold for their mirrors and they built structures that were several stories high. This technology seems to have appeared around the same time for each of the civilizations. It is thought that Archimedes harnessed the technologyW to defend Syracuse from invading Roman fleets in 212 BC.

Converting a very used gas power lawnmower into a solar charged, low emission, almost silent, lawn cutting machine.

 Permaculture is a design system for creating sustainable human environments. The word itself is a contraction not only of permanent and agriculture but also of permanent culture, as cultures cannot survive for long without a sustainable agricultural base and landuse ethic. — Bill MollisonW, Introduction to Permaculture

## Visit the Energy Portal

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.

Selected service learning Projects gallery (refresh)

Engr305 Appropriate Technology Projects: Below are selected service learning projects from Engr305 Appropriate Technology, which is a course on appropriate technology at Humboldt State University taught by instructor Lonny Grafman.

 Air Ship Air City rooftop greywater filtration A rooftop greywater filtration system
 Aleiha's parabolic solar cooker Parabolic Solar Cooker
 Amal's ethanol still A valved reflux ethanol still
 Backyard Biodigester A biodigester converting organic waste to a fuel source
 Bike Rodeo bicycle blender A kid's bike blender for Rio Dell Community Resource Center
 Bike trailer A bike trailer from a converted baby stroller
 Blue ox earthen oven Blue Ox earthen oven
 Bottoms strawbale earthen plaster Earthen plaster and natural paint recipes

## Selected categories

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## Construction zone — correct mistakes & flag spam as needed

 Newest articles more Wanted pages - click to add info more New pages being developed: Note: Appropedia's newest pages may not yet comply with our policies. Page titles in italics are "redirects," often created when moving a page. Create a new page: These red links are invitations for you to contribute your knowledge. Or create a page on the topic of your choice. Newest files - images and documents that can be added to pages more G2 Global model Earths... Js8652s 11:26, 31 October 2014 2.39 MB Excubator sketch floor... LucasG 10:31, 30 October 2014 5 KB Excubator sketch front... LucasG 10:29, 30 October 2014 12 KB Excubator sketch front... LucasG 10:23, 30 October 2014 22 KB Excubator sketch side ... LucasG 10:19, 30 October 2014 13 KB Note: Appropedia's newest files may not yet comply with our policies.