Solar greenhouses bring vegetables in from the cold
[LONDON] Solar greenhouses that nurture vegetables despite outside temperatures as low as minus 25 degrees Celsius are among the innovations recognised by international energy awards this week.
The greenhouses, developed by the French nongovernmental 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. In autumn, the greenhouses extend the growing season of crops such as tomatoes, cucumbers and grapes.
GERES will receive an Ashden Award for Sustainable Energy at a ceremony in London, United Kingdom, today (11 June).
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 fewer vegetables, 460 tonnes of carbon dioxide emissions are avoided every year.
The greenhouses consist largely 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," says Vincent Stauffer, Indian country director for GERES.
Stauffer told SciDev.Net that the health of people in the region has also improved — it is difficult to do a scientific assessment of health but there is anecdotal evidence for this from both local doctors and the community, he says.
GERES has provided free access to the plans and people in Afghanistan, China, Nepal and Tajikistan have now built the greenhouses. A community of practice to exchange ideas about their use will appear on the Solar Greenhouse website.
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.