Wind Farms Can Be Made 10 Times Smaller

July 14, 2011 by kris de decker Filed Under: Wind Power, Wind turbines

Size of wind farms “Modern wind farms comprised of horizontal-axis wind turbines (HAWTs) require significant land resources to separate each wind turbine from the adjacent turbine wakes. This aerodynamic constraint limits the amount of power that can be extracted from a given wind farm footprint. The resulting inefficiency of HAWT farms is currently compensated by using taller wind turbines to access greater wind resources at high altitudes, but this solution comes at the expense of higher engineering costs and greater visual, acoustic, radar and environmental impacts.”

“We investigated the use of counter-rotating vertical-axis wind turbines (VAWTs) in order to achieve higher power output per unit land area than existing wind farms consisting of HAWTs. Full-scale field tests of 10-m tall VAWTs in various counter-rotating configurations were conducted under natural wind conditions during summer 2010. Whereas modern wind farms consisting of HAWTs produce 2 to 3 watts of power per square meter of land area, these field tests indicate that power densities an order of magnitude greater [21 to 47 watts] can potentially be achieved by arranging VAWTs in layouts that enable them to extract energy from adjacent wakes and from above the wind farm.”

Small wind farm “The results suggest an alternative approach to wind farming that has the potential to concurrently reduce the cost, size, and environmental impacts of wind farms.”

Read more: ‘Potential order-of-magnitude enhancement of wind farm power density via counterrotating vertical-axis wind turbine arrays’, John O. Dabiri. Introduction. Research paper (pdf). Via Ecogeek. 

Illustrated Inventory of Antique Farm Tools (1600 – 1940)

July 11, 2011 by kris de decker Filed Under: Farming, Hand tools, Obsolete technology

Rotary seed drill Peter Charles Dorrington collected and restored over 750 antique farm tools between 1985 and 2001. Most of these tools were agricultural hand implements and fenland tools that were used in England, Wales and Scotland, dating from about 1600 to 1940, for example: “chaff cutters”, “flails”, scythes”, “dibbers” and “breast ploughs”. Antique Farm Tools. On the picture: a rotary seed drill. Related: the museum of old techniques.

The Flying Men of Yungas Valley

July 10, 2011 by kris de decker Filed Under: Aviation, Bridges, Mountains, Public transport, Random, Ropeways, South America, Travel, Trees

Wire cables “In Bolivia’s jungles and steep cliffs the Yungas people do not walk. They fly. On ropes. Like birds. Faster than astronauts. These ‘birds’ are known as cocaleros, or coca harvesters. They use ropes to swing across the narrow valleys, suspended from ancient rusting pulleys.” Watch the video. Jerry, thanks for the link. Previously: Aerial ropeways: automatic cargo transport for a bargain.

Covered Bridges: How to Build and Rebuild Them

July 3, 2011 by kris de decker Filed Under: Bridges, Civil engineering, Obsolete technology, Random, Wood

covered bridges how to build and rebuild them

“This manual is intended to provide comprehensive support to those involved with maintaining, assessing, strengthening, or rehabilitating covered bridges, especially heavy timber truss bridges. At one time, the United States reportedly had 14,000 of these unique bridges dotting the countryside over a surprisingly large area. Now, fewer than 900 of the historic structures survive.

Timber bridges initially were built without coverings and failed in just a few years because of rot and deterioration, because chemical wood preservatives were not available or used. Builders familiar with the construction of houses, barns, and large community structures naturally added siding and roofs to help protect the bridge. They understood that the covering would soon pay for itself.

They believed that regular maintenance and occasional replacement of the light covering was far easier and cheaper than building an entirely new bridge. North American covered bridges still serve after nearly 200 years, due in part to the continued soundness of the trusses, which was possible only with these protective coverings.”

“Covered Bridge Manual“, 327 pages, US Department of Transportation, 2005. Via Arquitectura y madera. Previously: wooden bridges / wooden pipelines. Picture by Rainer Ebert.

Social Conflict and the Age of Scarcity

June 30, 2011 by kris de decker Filed Under: Social unrest

Riots in greece “In an age of abundance, the easiest way to deal with social conflict is to buy off the disaffected. That’s how industrial societies over the last century came to provide welfare for the poor, mortgage guarantees and college grants for the middle class, subsidies for farmers, tax breaks for businesses – name a group that’s had enough political savvy to organize and raise a ruckus, and you can just as quickly name the arrangements by which they were paid off to minimize the risk of disruptions to the system. That was politically feasible in an expanding economy; even when the shares of the existing pie were grossly unequal, the fact that everyone could have at least a little more each year made those with smaller slices willing to work with the system in order to get their cut.

In an age of scarcity, that easy option no longer exists, and social conflicts heat up rapidly. That’s the unmentioned subtext for much of what’s going on in politics on both sides of the Atlantic just now. The middle class, who shrugged and turned its collective back when the working classes of Europe and America were thrown to the sharks thirty years ago, are now discovering to their horror that they’re next on the list, as the rentier class – the relatively privileged fraction of industrial society that makes its living from investments rather than salaries – struggles to maintain its prosperity at everyone else’s expense. The gutting of social safety nets, the slashing of salaries and benefits, and the impoverishment of millions of previously affluent people are part of that process, and lead to a rising spiral of social conflict that may well push a good many nations into crisis or collapse.”

Read more: How not to play the game. Picture: Oneiros.

Portraits of Farm Animals

June 30, 2011 by kris de decker Filed Under: Animal power

Portrets of farm animals

Portraits of farm animals by Rob MacInnis. Via The Brook (“We are an international animal welfare organisation dedicated to improving the lives of working horses, donkeys and mules in some of the world’s poorest communities”).