2006 Environment Award Laureate
Seawater Greenhouse, Ltd
| Laureate Country: United Kingdom |
| Project Country: Oman |
| Website: www.seawatergreenhouse.com |
| Video: 2006Videos/seawater greenhouse.mov |
Project Overview:
Seawater Greenhouse recreates the hydrological cycle to provide one of the world's greatest needs: fresh water. It distills fresh water from seawater and cools the growing environment to create optimum conditions for cultivation. This enables crops to grow in places where it would otherwise be difficult or impossible. As the process is driven by solar energy, it represents a sustainable opportunity for cultivating and creating food, employment and economic activity in arid coastal regions.
Problem Addressed:
A shortage of water and the inability to grow food is the root cause of much suffering and poverty. Over one billion people do not have access to a safe supply of water, and the number is growing. Large areas of the world already suffer from drought while deserts and populations increase in size. In coastal regions saline intrusion reduces the ability to grow crops and is a major problem in many parts of the world.
Technology Solution:
The Seawater Greenhouse uses seawater within a greenhouse to produce fresh water and cool air. The front wall of the greenhouse is a seawater evaporator consisting of a cardboard honeycomb lattice facing the prevailing wind. Fans assist in air flow. Seawater trickles down the evaporator, cooling and humidifying the air as it passes through into the planting area. About 30 percent of the sunlight is intercepted by an array of tubes in the greenhouse roof area which remove heat and provide some shade. Combined with the evaporator, this creates optimum temperature and humidity yet sufficiently high light intensity. Cool air passing through the planting area and then at the back of the greenhouse, combines with hot dry air from the roof area. The mixture then passes through a second evaporator over which hotter seawater, collected from the tubes in the roof, creates hot, saturated air which flows through the condenser and is cooled by the seawater that has been cooled by the front evaporator. The temperature difference causes fresh water to condense out of the airflow. The volume of fresh water is determined by air temperature, relative humidity, solar radiation, and the airflow rate. The key element of Seawater Greenhouse is the condenser that actually makes the fresh water. The amount of water produced is relative to the surface area of the condenser, the larger this is, the more fresh water produced. Modular all-plastic condensers consisting of a series of thin wall polyethylene tubes assembled on-site have significantly reduced costs by almost half, eliminated corrosion, and produce more fresh water.
