Elementary power
Image: Seawater Greenhouse Ltd
British engineer Charlie Paton has come up with Seawater Greenhouses that are powered by the elements. Could these greenhouses be the answer to food production in inhospitable environments?
Technology in pictures
Engineer's story
Charlie Paton with some of the first tomatoes produced by his invention.
Image: Seawater Greenhouse Ltd
Out of Africa
Engineer Charlie Paton is on a mission to turn the most arid regions on Earth into lush environments for growing food. His dream began with a trip across north Africa.
‘It all started as the skies cleared after a sudden downpour in Morocco,’ recalls Charlie.
‘The sun was intense and as we dried, steam rose off us. The idea for the Seawater Greenhouse came to me. Use the same natural process to evaporate sea water, capture the fresh water and use it to grow food.’
In Australia the evaporator can produce up to 2000 litres of water a day.
Image: Seawater Greenhouse Ltd
Trial and error
It’s taken 20 years of trials and tests to get the Seawater Greenhouse ready to grow food on a commercial scale. Prototype greenhouses can now be found around the world.
‘We had to work out how best to control the natural processes of evaporation and condensation,’ explains Charlie. ‘To do this we ran experiments under different temperatures and wind speeds. This let us fine-tune the greenhouse design and maximise the amount of fresh water produced before building the first commercial one in Australia.’
Return to green? Thousands of years ago, the Sahara region was thick with vegetation.
Image: Flickr/kahunapulaj
Tropical haven
Thanks to the evaporators, the inside of the Seawater Greenhouse becomes very humid and much cooler, perfect for growing fruit and vegetables.
‘Plants that live in a mild climate with lots of light grow fantastically well,’ says Charlie. ‘And the Seawater Greenhouse evaporates ten times more water than needed to irrigate the plants inside, so moisture spreads out of the greenhouse and encourages plant growth around it. These plants in turn pump moisture into the atmosphere and more vegetation flourishes, greening the desert!’
The hot sea water evaporator (left) and condensation pipes containing cold sea water (right).
Image: Seawater Greenhouse Ltd
Rain-making
Back inside the greenhouse, the water vapour in the air must be condensed into a liquid, collected and fed to the plants.
‘After the air has moved over the area with crops it passes through a second evaporator. This has hot sea water, which has been heated by the sun, flowing over it,’ Charlie explains. ‘This warms the air and allows it to hold even more water. The water condenses on cold pipes right at the back of the greenhouse and trickles down, just like condensation on the side of a cold drink.’
What the experts think
This artwork includes solar panels which could power fans to draw more air over the evaporators. Image: Bellona Foundation
Saharan supermarket
Could Seawater Greenhouses transform the barren Sahara Desert into the largest food-growing region in the world?
The Sahara Forest Project aims to cover vast areas of northern Africa in Seawater Greenhouses.
‘The project is critical to enable developing countries in the Saharan region to feed their growing populations,’ says Frederic Hauge, President of Bellona, a charity involved in the Sahara Forest Project. ‘The best way to guarantee prosperity is to give people a reliable means of food production.’
Expanding Cairo. Seawater Greenhouses could provide work and food for Egypt’s soaring population.
Image: Flickr/Digital Globe-Imagery
Rocky road
The Sahara Desert spans many different countries. David Molden, Deputy Director General at the International Water Management Institute thinks the plan may face some political challenges.
‘The Sahara Forest Project has promise, but the biggest hurdle will be to get the finance to realise large-scale projects like this. You also need to bring together a skilled workforce, ensure access to markets to sell the produce and a supportive government.’
In harsh conditions every drop of water is vital. Image: Flickr/rbairdpccam
Simply does it
The Sahara Forest Project could help supply the region with food and create export income. But who will really benefit?
‘Sharing simple techniques like “no-till farming”, which keeps moisture in the soil, could boost crop yields for small farmers,’ explains Monique Mikhail of Oxfam. ‘Basic skills and good water management need to come first for people in Saharan countries to escape poverty. The Seawater Greenhouse can make an impact, but only if they are low-cost and easy to manage.’