In less than five years, 20% of Australia’s tomatoes will probably be grown in a completely sustainable, energy self-sufficient way. They will be irrigated by seawater and require no energy other than sunlight. By the same time – and with the same technology – Somali farmers may have created fertile oases on their arid land to grow their crops: The Seawater Greenhouse enables them to irrigate the desert without harming the environment.

Have you ever wondered how some coastal areas can be too arid for anything to grow? British scholar Charlie Paton did. As an 18-year-old, he hitchhiked through the Middle East and North Africa. In Morocco in particular he found it perplexing that one of the most arid parts of the world – the Sahara – could exist next to an infinite ocean – the Atlantic.

The question took hold of him and left him no peace. Charlie studied engineering, specialised in solar energy and started experimenting with methods of solar desalination in the mid 80’s. He built different solar-powered stills, discarded many of his initial ideas, and developed new ones. The result was the Seawater Greenhouse: a self-sufficient greenhouse that uses nothing but seawater and solar energy to grow crops in desert areas.

Desalinating seawater is nothing new. But it usually requires huge amounts of energy, which is difficult to provide by solar energy alone. In conventional mechanical desalination, for instance, water is pushed through a very fine filter membrane, which requires very high pressure and constant power. Furthermore, plants in desert areas need a lot of water due to high evaporation rates. Neither holds true for the Seawater Greenhouse, which takes four to eight times less water than conventional greenhouses and is so energy-efficient that solar energy is enough to power both desalination and irrigation of the crops. Farmers even have some purified drinking water left over along with some table salt and nutrients extracted for the plants.

Charlie is convinced that this technology can help mankind tackle some of the most pressing global challenges. He talked to us about his innovative technology, about international agricultural policy and about his struggles with EU bureaucracy.

Charlie, you’re from the UK, the country of eternal rain and cloudiness. How did you decide to develop an idea for desert areas in particular? 

It was a combination of curiosity, some knowledge about sunlight and some experience of travelling around the Middle East and North Africa. I had developed a reasonably effective solar still that could produce six litres a day by collecting one square meter of sunlight. But then I did some calculations and realised to irrigate Morocco using this technology, you would have to cover half the country with solar stills – which isn’t such a good idea. So I dug further into alternative methods of desalination and irrigation and finally developed the Seawater Greenhouse in 1994.

What is the best size for a greenhouse? You spoke of family farms, but you’ve also already produced much bigger compounds.

You can make it any size you like. In Australia, we’ve built a greenhouse for a company of 0.2 hectares in size, but they made it 100 times bigger – it now covers 20 hectares, engages 300 employees, and will be growing 15,000 tons of tomatoes annually by the end of this year. But in Somalia, for instance, employing people raises a number of problems for farmers because of tribal or family traditions. So it seemed better to enable them to grow stuff themselves. In fact, this is also the way most greenhouse horticulture around the world works: About 80% of all food is produced on farms of four hectares or less. 

How has your experience in these very diverse countries differed?

The climate varies from place to place and we spend a lot of time studying the conditions. But the social and economic factors also differ a lot. On the Canary Islands, for example, agriculture is almost not economically viable anymore, as you can get cheaper bananas and tomatoes from Morocco or Latin America. People would rather invest in tourism than in agriculture. It is completely different in Australia: Importing food as well as transporting food across this huge country is expensive. So local self-sufficiency is highly desirable. But as the cost of labour is high, the main challenge here is to reduce labour. It is the opposite in Somalia. About 85% of the population are rural farmers or pastoralists, but they are not very efficient owing to a lack of fresh water and still need to import 40% of their food. Because of all these considerations, it is much easier for us to work with local organizations when developing a new project. When we start a new project, it’s usually because a local organisation has contacted us beforehand. 

There’s no end of environmental problems and they’re almost all related to water. 

You once said that the Seawater Greenhouse could reverse the damage done by conventional greenhouses i.e. in Spain. Why?

The greenhouses in Spain – and in many other parts of the world – take water out of the ground five times faster than it comes in. As a consequence, the water table drops, many plants no longer have their roots in water and the water itself becomes more saline. Loss of vegetation causes desertification, which again causes less rainfall. I think there’s a potential for a complete game change with the Seawater Greenhouse.