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Solar greenhouses shelter vegies from the cold

Technology

A local harvesting fresh, greenhouse-grown produce

A Ladakh local harvesting fresh, greenhouse-grown produce

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Solar greenhouses that nurture vegetables despite outside temperatures as low as minus 25 degrees Celsius are among the innovations recently recognised by international energy awards.

The greenhouses, developed by the French non-governmental organisation GERES, are used in the Indian Himalayan region of Ladakh.

The region's high altitude of 3,500 metres and low rainfall result in an outdoor growing season of just 90 days a year - making fresh vegetables imported from the plains a rare treat. But there is abundant sunshine 300 days a year.

Farmers grow food ranging from spinach to strawberries in the winter and seedlings in the spring using the greenhouses, which in autumn also extend the growing season of crops such as tomatoes, cucumbers and grapes.

Nearly 600 family-owned greenhouses were installed by the end of 2008, which also increased incomes by almost a third. Farmers sell or exchange surplus vegetables and seedlings locally - an estimated 50,000 people are thought to have benefited from the fresh produce.

And because the locals transport in fewer vegetables, 460 tonnes of carbon dioxide emissions are estimated to be avoided every year.

The greenhouses are built largely out of local materials. Each has a long, south-facing side of heavy-duty polythene; thick mud-brick walls to absorb heat during the day and release it at night; and insulated walls and roof.

Some of the walls are painted black to absorb heat. Natural ventilation prevents over-heating and excessive humidity.

Each greenhouse costs around US$600 to make. GERES provides the polythene, door and ventilation - about a quarter of the cost - while prospective owners either buy or collect the remaining materials and employ the labour or do the work themselves.

"In a lot of places this is the first time that fresh vegetables have been available in winter," said Vincent Stauffer, Indian country director for GERES.

The health of people in the region has also improved. While it is difficult to do a scientific assessment of health, there is anecdotal evidence for this from both local doctors and the community, Stauffer said.

GERES has provided free access to the building plans, and people in Afghanistan, China, Nepal and Tajikistan have now also built the greenhouses.

Other projects winning awards include a biomass project in India, an efficient woodstove made in China, solar power for homes in Ethiopia, and a Ugandan scheme making fuel from agricultural waste.

International Development Enterprises India, which supplies water pumps to farmers for irrigation, won this year's Ashden Outstanding Achievement Award.