Seawater Greenhouses Produce Tomatoes in the Desert

by | 2.18.2011 at 10:58am | 50 Comments
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According to the World Health Organization, about 20 percent of the world’s people live in regions that don’t have enough water for their needs. With the global population increasing by 80 million each year, a third of the planet will likely face water shortages by 2025. This looming water crisis is inextricably linked to food production because agriculture accounts for 70 percent of all fresh water used, and obtaining irrigation water in arid regions has serious environmental impacts. Drilling wells can deplete groundwater, and desalination is energy-intensive and leaves behind concentrated brine.

The Seawater Greenhouse, however, provides what may be an economical and sustainable way of producing fresh water and crops in hot, dry regions near the ocean. Marco Goldschmied, President of the Royal Institute of British Architects, said in 2000,“The Seawater Greenhouse is a truly original idea which has the potential to impact on the lives of millions of people living in water-starved areas around the world.”

Photo credit: World Bank Photo Collection

A seawater greenhouse produces crops year-round in hot dry areas using only seawater and sunlight. Tomatoes, cucumbers, peppers, lettuce, strawberries, herbs—anything that can be grown in traditional greenhouses—can be grown in seawater greenhouses. The award-winning technology, invented by Seawater Greenhouse Ltd. founder Charlie Paton, was inspired by the natural water cycle where seawater heated by the sun evaporates, cools to form clouds, and returns to earth as precipitation.

The humidification and de-humidification that result from differences in temperature between surfaces heated by the sun and cold water from the sea are the keys to the seawater greenhouse system.

Photo credit: Seawater Greenhouse Ltd.

Seawater is pumped into pipes in the greenhouse and is trickled down over the first evaporator, a large spongy honeycomb-like surface. As air is drawn through the honeycomb and into the greenhouse by fans, it is cooled by the seawater and becomes more humid. The cool humid air creates favorable growing conditions for the greenhouse crops. At the back of the greenhouse, the cool air is drawn through a second evaporator containing seawater that has been heated by the sun in the ceiling pipes. The air then becomes hot and humid to the saturation point. When the hot humid air meets an array of vertical pipes containing cold seawater, fresh water condenses (just like hot steamy air in your shower condenses on the cooler mirror and tile surfaces). The fresh pure water is then piped to a storage container and used to irrigate the crops.

The sustainable system is clean, efficient, and elegant in its design. The greenhouse control system, pumps and fans are powered by electricity produced completely by solar power. The honeycomb evaporator filters out pollen and pests that are killed by the saline water so the greenhouse doesn’t need much pesticide. Nutrients harvested from the brine are pumped back into the irrigation system to fertilize the crops, and the rest of the salt is made into gourmet salt crystals that Seawater Greenhouse Ltd. sells.

Because the greenhouse produces its own fresh water, and uses no fossil fuels or pesticides, its operating costs are 10 to 25 percent less than those of a traditional greenhouse. Its fixed costs are 10 to 15 percent less because it doesn’t need to purchase cooling, heating, or desalination equipment, and because it is usually built on cheap land where little can grow.

Seawater greenhouse technology works best in arid regions by the sea, and near consumer markets so crops can be easily transported.  Areas of Europe such as Crete, France, Greece, Italy, Portugal and Spain; California and Mexico in North America; large parts of China, India, Pakistan and Turkey in Asia; and much of Australia, the Middle East and northern Africa, are good candidates for seawater greenhouse projects.

The seawater greenhouse concept was first developed in 1991 by Light Works Ltd. in the UK. A successful pilot project on Tenerife in the Canary Islands in 1992 led to research projects on Al-Aryam Island in Abu Dhabi and Muscat, Oman. In 2005 Seawater Greenhouse began collaborating with the architects Nicholas Grimshaw & Partners on the harbor redevelopment of Las Palmas de Gran Canaria, exploring the use of its technology to cool a more urban environment. They are designing the 1.9-mile promenade, botanic garden, and Water Theatre using some of the same principles to produce fresh water and cooling.

Photo credit: Port Augusta greenhouse, Seawater Greenhouse Ltd.

In 2009, private investors backed the first commercial Seawater Greenhouse in Port Augusta, South Australia. The 2,000-square-meter structure, which draws seawater from the Spencer Gulf, is capable of producing 100,000 kilos of tomatoes each year. The excess fresh water it produces will be used to grow citrus plants outdoors. The Port Augusta greenhouse, which cost $2 million, produced its first crop of tomatoes in December.

This January, water-scarce Jordan and Norway joined forces on the Sahara Forest Project, a 200,000-square-meter demonstration center near Aqaba on the Red Sea that will produce fresh water, food, energy, and sustainable biomass. The project is being developed by London-based Seawater Greenhouse, Max Fordham Consulting Engineers, and Exploration Architecture, and the Bellona Foundation, a Norwegian environmental NGO.

The Sahara Forest Project will use water from the Red Sea in seawater greenhouses to produce fresh water for the crops and grow algae in open ponds for fuel and food. The project will also grow halophytes, plants tolerant of salty conditions, that have potential to be an energy crop. Because each 10,000 square meters of seawater greenhouse evaporates 50 tons of water daily, the greenhouse will help restore vegetation on the surrounding arid land through ventilating the “lost” humidity to create a cooler and more humid micro-climate downwind of the greenhouse. The “lost” humidity will also increase the chance for precipitation in the area. The algae, crops and other plants will sequester carbon dioxide from the air. Extra fresh water produced by the seawater greenhouse will be heated by a concentrated solar power plant (CSP), generating steam that will turn a turbine to produce electricity. The CSP’s excess heat will be used to desalinate seawater for drinking water. A single Sahara Forest Project facility with 50 MW of concentrated solar power and 50 hectares of seawater greenhouses would produce 34,000 tons of produce, employ over 800 people, export 155 GWh of electricity and sequester more than 1,500 tons of CO2 each year. If the demonstration project is successful, Aqaba will provide 200 hectares for a larger scale facility.

Photo credit: The Sahara Forest Project Foundation / Screenergy

Construction on the demonstration center will start in 2012, with the commercial scale development scheduled to begin in 2015.  The creators are planning a large-scale commercial facility comprised of a 10-million-square-meter area of seawater greenhouses, CSP towers, orchards, native species such as Jatropha for biofuel, and a desalination facility.

“The Sahara Forest Project is a fiercely ambitious effort…but ambitious is exactly what we must be,” said Bellona’s president, Frederic Hauge. “A critical prerequisite for solving both the climate crisis and the world’s food problem is to enable developing countries to produce their own food, their own water, and their own clean energy…”

Columbia Water Center demonstrates research-based solutions to global freshwater scarcity.  Follow Columbia Water Center on Facebook and Twitter

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50 Responses to “Seawater Greenhouses Produce Tomatoes in the Desert”

  1. Zaka Imam says:

    Excellent development.Shall follow development as these are very important for countries having long coastline, and rain fed agriculture
    Zaka Imam, Ph.D

  2. Matthew Stewart says:

    So I have some questions.

    How often do they need to change out the honeycomb cardboard evaporators due to salt build up?

    Is the salt retrievable in a manner that is economical and possibly would allow the re-use of the evaporator?

    I am hoping that the salt and used evaporators are not merely discarded as waste.

  3. Renee Cho Renee Cho says:

    Hi Matthew, I will try to find out the answers to your questions.

  4. Renee Cho Renee Cho says:

    Matthew, This information is from the Science and Development Manager of the Sahara Forest Project.

    The cardboard evaporative pads will need to be changed out eventually, but not often. In the early Seawater Greenhouse built in Oman, the original pads were still working after more than two years. When they do require replacement, the retired pads will be re-used — potentially as building materials.

    As for the salt :
    One of the great advantages of the Sahara Forest Project is that it can derive benefits from the brine left over from desalination — which is typically treated as a waste and returned to the original seawater source, where it can eventually cause significant environmental damage. Instead, in the Sahara Forest Project, brine is repeatedly recycled for evaporative cooling and humidification — both inside and outside of the greenhouses — to facilitate more plant growth. When it finally reaches a very concentrated state, the brine is then placed in evaporative ponds, where it remains until it becomes dry salt. The contents of this salt has a range of uses, whether as traditional road salt, or — at large scales — as a potential resource from which valuable minerals can be extracted.

  5. Glennert Riedel says:

    I’m from Curacao in the Caribbean. In the past I tried to promote the Seawater Greenhouse here on the island but the interest was low. Now with the rising vegetable prices and import from the mainland becoming less available the government is looking for alternatives. I have an appointment the day after tomorrow with people from the government. My questions: What is the minimum economical viable size for a Seawater Greenhouse?
    How much labor (man hours) does it cost to produce the above mentioned 100.000 kilo’s of tomatoes?

  6. Renee Cho Renee says:

    Glennert,
    Seawater Greenhouses says on their website that their systems can fit a wide range of scales, and can start on a smaller scale then expand gradually. However, I’m trying to get a more specific answer for you and also find out about man hours.

  7. Glennert Riedel says:

    Thank you Renee

  8. Tai Mesches and Kat Klett says:

    Hello Renee,

    Excellent article thanks for all your caring responses and help to those interested in pursing this technology in their own country! Keep up the good work.

  9. Renee Cho Renee says:

    Glennert,
    To answer your questions, your best bet would probably be to contact the Seawater Greenhouse company (www.seawatergreenhouse.com) directly, and Charlie Paton, the inventor of the greenhouse — They would know the key economic data for the greenhouse as a standalone entity.

  10. Glennert Riedel says:

    Thanks Renee,
    I will do that. Keep up the good work.

  11. Glennert, I have worked with Charlie Paton at Seawater Greenhouse for some time, looking at the economic parameters and investment alternatives for the Seawater Greenhouse. I visited the Australian installation in January. There are a lot of variables you need to look at to understand what is a minimum economically viable installation. Costs of vegetables (imports), including transport costs, wastage, storage, duty etc. Costs of local land, labour, and many different operational components. Is there a market for premium products? For example you could start selling products which are hard or impossible to import.

    I generally say that a minimum installation should be 1-2 hectares, but it depends on the answers to the above questions. If you are on a very small island, maybe you need to export to other islands in your local area to reach a viable size. We have an economic model we use to calculate this, when we have all the data we need to come up with a more precise answer.

    Hope that helps.

    Thomas Bjelkeman

  12. Glennert Riedel says:

    Hi Thomas, We have met back in 2008 in Curacao.
    There is a growing market for premium products. There are more than 5000 hotel rooms at the moment and the number is growing.

    In order to be compeitive you must be able to sell for example tomatoes for less than $2.11 per kilo and make a profit.

    I’ve been asked to give some input to the government on how to increase local agriculture production and am preparing a presentation for the minister of economic afairs. This is a one shot opportuity in the sense that if he is not convinced he will continue shopping elsewhere.
    Do you have a list of all the data needed for the economic model?
    Are there costs invoved to have this clculation made?
    Thanks and best regards,

    Glennert

  13. Jessica Janes says:

    This is a brilliant way to capture and utilize this natural resource. Since it is hard to control population growth, we have to develop alternative agricultural supplies, such as this.

  14. [...] responses do exist to conserve agricultural water in parched areas—from seawater greenhouses that grow tomatoes in the desert to permaculture projects on the Dead Sea that use 80 percent less water than [...]

  15. Jeannie says:

    The left over salt can also be used for the plants themselves. Is there a chance that this Seawater project be started in north america? Though it’d be hard to find the perfect spot for the system.

  16. Renee Cho Renee says:

    I haven’t heard of any projects being started in North America, but certainly the coast of California and Mexico and Baja would be good candidates.

  17. joan says:

    Excellent article…extremely well written!!

  18. [...] – from the utopian vertical farms of Dickson Despomier to more practical but still revolutionary greenhouses that grow tomatoes in the desert using only seawater and [...]

  19. Max turunen says:

    This is good… but is this water distilled water ? are tomatoes ok with it ? does some pinch of salt be added back to it for nutrient balancing ? What about fish… the fish tank keeping with the greenhouse sounds very working… would fish be ok with that water ? if not, what would need to be done to that water before fish grant their approval and dung for the plant fertilization ?

  20. Renee says:

    Max – The fresh water is condensation of water vapor from humid air. It is essentially distilled water and has no nutrient content. A small amount of seawater can be added back to provide some nutrients, but Seawater Greenhouse Ltd. uses a form of seaweed extract as a general fertilizer. It is a more concentrated nutrient formula but with less sodium than straight seawater.
     
    Charlie Paton, inventor of the seawater greenhouse, said that he is sure that aquaculture would also work but thinks getting the nutrient balance would be tricky.

  21. Genius concept! With the growing fresh water crisis and the polar ice caps melting at an ever-increasing rate, finding ingenious ways to put salt water to use for sustainable agriculture will likely become increasingly crucial.

  22. Steve says:

    The water is condensation of water vapor from humid air. It is essentially drinking water and has no nutrient content. A bit of sea water can be added back to provide some nutrients, but Seawater Greenhouse Ltd. uses a form of seaweed extract as a general fertilizer. Excellent sharing and appreciate for nice blogging.

  23. We need to start implementing smart ideas like this all over the world ASAP! I’m glad that their are smart people out there that are part of the solution.

  24. Frank Kern says:

    When I heard about this I initially thought there had been a breakthrough in some kind of reverse osmosis plant system but of course evaporation and condensate recovery is the best and least resource-hungry method. I have used it myself whilst driving down Western Morocco to obtain drinking water from seawater using a plastic rain poncho.

    The true genius part is taking the waste salt and selling it on as gourmet cooking salt!

  25. Danny says:

    This sounds interesting and very well thought out. I am presently involved in the development of high tech irrigation that requires, on average, 40% less water and fertilizer when compared to conventional agriculture with drip irrigation. I believe it will complement projects like this, and result in lower operating cost and more water left for additional agriculture. Who could I contact to share this information?

  26. This is a great concept and would make use out of otherwise unusable land. More projects like this need to be implemented. And having the ability to remove the salt and then resell makes the whole project practically zero waste which is the best!

  27. This is absolutely awesome.
    Isnt it funny how nature herself has given everything required to enable us to harness the power.
    As a builder, i too wondered about the salt build up in the filters, but selling it on as “Gourmet Salt” is brilliant.
    Mind you it is in direct competition with the salt farm located in South Australia.

    Brilliant article

  28. Rav says:

    YES….down in Mexico the tomato growers have just about used up the last available water growing tomato’s and have seriously lowered the water tables.

    This is an obvious solution to that dilemma especially considering that mexico is having the worst drought in history.

  29. Back in the early 70′s I worked on desalinization plants for the government….there were 6 of them if I recall correctly. We mostly looked at material viability due to the highly corrosive nature of salt water. At the time we found no sustainable way to use salt water due to the costs. I’ll bet there are far more economical ways to do desalinization now and utilize the remaining salts. I’ll be doing a new blog on http://www.tomato411.com shortly and I’ll mention the “Desert Tomato Growth” and see if there are others that frequent my site that have any experience with all of this….great article!

  30. It’s a fantastic concept. As climate continues to amplify the world’s water crisis it’s increasingly important to utilize technology (like desalinization) to help sustain the world’s need for clean drinking water. Although costly, I’d love to see more countries in drought prone regions finance desalinization plants – ultimately, it can be a significant, life saving investment.

  31. Hello there! Would you mind if I share your blog with my myspace group?
    There’s a lot of people that I think would really enjoy your content. Please let me know. Thank you

  32. Renee Cho Renee Cho says:

    Not at all. Please do. Thanks.

  33. Very interesting concept, its ideas like this that we need to keep the world sustainable and healthy, lets hope others follow suite!

  34. Nazila says:

    Hello dear i am a Ph.D student in water resources i just want to start my thesis about sea water using for irrigation the method that you use is so interesting for me would you mind giving me a text or document in which i can study more about the details of your work ?
    with best regards

  35. Renee Cho Renee Cho says:

    HI Nazila,
    If you click on the second link in my blog, you can access a paper Charles Paton wrote about the technology he used. If you click on the first link, you can go to the Seawater Greenhouse website – I would recommend contacting them directly for more information.

  36. Rudresh says:

    I really appreciate the concept of using seawater as an alternative to fresh water in water scarce areas. My only doubt is on the characteristic of soil in the coastal areas. I have visited a coastal area in Gujarat, India and found that the salt content is very high in the soil and growing plants is impossible.

    What kind of steps have been taken to grow tomatoes in these areas? Are these crops genetically modified to grow under such conditions?

    Your inputs would be appreciable.

  37. Renee Cho Renee says:

    Hi Rudesh,
    I would suggest that you contact Seawater Greenhouse directly and they will be able to answer your questions. The website is http://www.seawatergreenhouse.com

  38. Alfredo Alvarez says:

    Excelent concept, for taking care of our environment while we take advantage of it. I wonder there is technical information to build one of this greenhouses available somewhere.
    Danny, I would be glad if you could share that information with me aealvare@gmail.com
    Regards.

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  40. J Macallister says:

    Hi Dalmar,

    It seems you are thinking about the dry season sunlight being too intense for food production. I am just guessing that some form of shading would be easy enough to construct, or perhaps some treatment to the greenhouse material such as polarization or surface treatment to reduce the incoming light intensity. It appears that in some cases there is surplus water, so that another possibility maybe to have evaporative coolers act as air conditioners to avoid runaway high temperatures.

  41. Jacqueline says:

    Amazing innovation and technology that hopefully will bring help where it is needed most. Imagine if that was coupled with the wealthy giving to help the poor on a regular, sustained basis instead of spending thousands on yet another luxury.

  42. Fatma says:

    Dear Renee Cho,

    I live in Oman. Can you please let me know where is this salt water green house? because I am interested in Hydroponics.Thanks.

  43. Renee Cho Renee Cho says:

    Hi Fatma,
    You should contact The Seawater Greenhouse directly for the information:
    http://www.seawatergreenhouse.com/contact.html

  44. DANIEL says:

    Sorry, but I don’t see the thermodynamics logic in this design. As everyone knows, containing anything in plastic in a desert (or anywhere else for that matter) results in the greenhouse effect, hence HIGHER heat, not lower.

  45. Dr.A.Jagadeesh says:

    Great achievement in desert regions with sea water. Amazing.
    I was in Israel and could see the innovative way they produce fruits in the desert type of conditions.
    Dr.A.Jagadeesh Nellore(AP),India

  46. Lisa says:

    This is such a great concept. Hopefully human ingenuity can solve our problems as a planet. Great work scientists!

  47. ali says:

    hi Renee
    I’m trying to gather information about Paton’s innovation and try to construct a little one in framwork of Charlie’s details are provided in his Articles and etc. so i have a questions about details of Greenhouses materials.
    what type of Evaporative pad is used in This Greenhouses?
    What is gender of That?

  48. Renee Cho Renee says:

    For that kind of technical information, I think it would be best for you to contact Seawater Greenhouse directly:

    http://www.seawatergreenhouse.com/

  49. Mohammed junaid says:

    How does Evaporative cooling work ? where high humidity climate available at coastal areas in gulf region ,and how can it gives certain temperature to crop like tomato which require average 24-28 degree C with relative humidity up to 75 % inside . Most of the coastal areas having max humidity.
    my question is how they control humidity inside. humidity play a important role in plants growth .

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