Deserts aren't exactly known for their agriculture. However, the designers behind the Sahara Forest Project believe they can use greenhouses to change sandy desert dunes into lush, life-giving forests.
The Sahara Forest Project works by combining two existing technologies: Seawater Greenhouses, which irrigate crops with evaporated, desalinated ocean water, and Concentrated Solar Power (CSP), which uses sunlight and mirrors to convert water into steam that powers turbines. The two technologies work well together because the greenhouses produce 500 percent more water than the plants need [source: Oppenheim]. Some of the extra water can be used to provide the CSP turbines with fuel and to clean the mirrors, making the Sahara Forest Project a closed system that produces food, energy and fresh water.
Additional, unused water generated by the greenhouses will initially be used to grow plants like jatropha for biofuel. However, the excess water, influx of new plants and local cooling effect of the greenhouses will eventually transform portions of the desert into forested land.