Jet Stream Wind Power as a Renewable Energy Resource

December 13, 2011 by kris de decker Filed Under: Renewables

“Jet streams are regions of sustained high wind speeds in the upper atmosphere and are seen by some as a substantial renewable energy resource. However, jet stream motion is associated with very small generation rates of kinetic energy to maintain the high wind velocities, and it is this generation rate that will ultimately limit the potential use of jet streams as a renewable energy resource. We have calculated that the maximum sustainable extraction from jet streams of the global atmosphere is about 7.5 TW. This estimate is about 200-times less than previous estimates and is due to the fact that the common expression for instantaneous wind power merely characterizes the transport of kinetic energy by the flow, but not the generation rate of kinetic energy.”

Climate change

“We also find that when maximum wind power is extracted from the jet streams, it results in significant climatic impacts due to a substantial increase of heat transport across the jet streams in the upper atmosphere. This results in upper atmospheric temperature differences of >20 °C, greater atmospheric stability, substantial reduction in synoptic activity, and substantial differences in surface climate. We conclude that jet stream wind power does not have the potential to become a significant source of renewable energy.”

Jet stream wind power as a renewable energy resource: little power, big impacts. Earth System Dynamics, November 2011.

The Lost Art of Lashing

December 4, 2011 by kris de decker Filed Under: DIY, Knots, Random

the lost art of lashing

“Stable and strong – you can almost make anything with lashing.”

Illustrated manual at makeprojects.

Previously:

Solar Powered Sun Tracker

November 28, 2011 by kris de decker Filed Under: Solar

Instead of installing an expensive motor, former Princeton student Eden Full is making a simple part that expands with heat, automatically moving a panel to its most electricty-generating position: The SunSalutor.

Celebrating the Luddite Uprisings

November 28, 2011 by kris de decker Filed Under: Low-tech living, Luddites, Random, Technology

celebrating the luddite uprisings

“November 2011 – January 2013 marks the 200th anniversary of the Luddite uprisings, in which artisan cloth workers smashed machines which were destroying their trades, undercutting wages and forcing them into unemployment and destitution. Today, the industrial system that the Luddites were rebelling against has led to climate change and huge losses of biodiversity, and its new technologies, such as information technology, genetic engineering and nanotechnology raise equally profound issues. Yet anyone who raises concern about the price and side-effects of new technologies is harshly condemned as a ‘luddite’, someone supposedly irrationally opposed to technology and progress.”

“In fact, the Luddites were not ‘luddites’ in that sense: the idea that they were opposed to all technology is a history written by the victors. In fact the Luddites opposed only technology ‘hurtful to Commonality’, ie. to the common good, rather than the narrow interests of the few. They destroyed some machines whilst leaving alone others in the same workshop. So being a luddite today means being a sceptic about the dogma of technology as progress, not about denying the real benefits of some technologies. It means insisting that the crucial decisions about which technologies are developed are made democratically, not just imposed by corporations and technocratic elites. And it means standing up for our own ideas of what progress really is.”

Help celebrate 200th anniversary of the Luddite uprising: Luddites at 200 website. See also: “Lessons of the Luddites“.

Lifting Tool for Carrying Plant Containers

November 16, 2011 by kris de decker Filed Under: DIY, Ergonomics, Farming, Hand tools, Trees

lifting tool for plant containersThe tool shown here was designed for use in outdoor nurseries specializing in ornamental and bedding plants. At nurseries in California where it was tested, it reduced workers’ forward bending angle by as much as 47%.

The time spent working at a forward-bent angle of more than 20 degrees was reduced by nearly half. Hand gripping effort was reduced by more than half. Lifting strain was reduced by 40%.

Workers reported less work-related pain when using the handles, and those who had the most severe symptoms at the start reported the most improvement.

[Read more…]

When Low-Tech Goes IKEA

November 13, 2011 by kris de decker Filed Under: Access to information, DIY, Human power, Language, Pedal power, Pedal powered machines, Random

when lowtech goes ikea

What happens when two industrial design students from Sweden end up in Kenya creating a pedal powered machine for small-scale farmers who are often illiterate and speak more than 60 languages? You get a do-it-yourself design that seems to have come out of the IKEA factories – pictoral manuals included.

“Made in Kenya”, the bachelor project of Niklas Kull and Gabriella Rubin, is a textbook example of low-tech made accessible to everybody, regardless of their native tongue and language skills.

[Read more…]