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Building an Oasis in the Sahara

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SFP signature visionSFP signature vision

For a few short millennia after the last Ice Age, the Sahara Desert - until then as arid as it is today - bloomed. Between 8000 B.C.E. to 6000 B.C.E., possibly a result of a dramatic drop in atmospheric pressure fostered by collapsing northern ice sheets, rainfalls were plentiful and vegetation lush.

Populations used to hugging the catchments of the Nile Valley ventured out across the landscape as frequent downpours transformed the bulk of the area's 3.8 million square miles into savannah.

The monsoonal rains and resulting lush soils fostered new human settlements where domesticated livestock were farmed and crops flourished. Forests of cedar and cypress thrived and giraffe, elephant, buffalo, antelopes, rhinoceros, and warthog roamed the land, quenching their thirst at lakes and swamps flush with fish, crocodiles and hippopotami. Then sometime between 7,300 and 5,500 years ago the good times were over. The monsoon retreated south and the Sahara again became what it was and is today: a baking desert with one of the world's harshest climates, where survival is a touch and go affair.

Seawater greenhouse south of Port Augusta, along the Spencer Gulf.Seawater greenhouse south of Port Augusta, along the Spencer Gulf.Now an ambitious project marrying science, forward-thinking and natural design principles is underway that could ultimately see parts of the Sahara restored to this earlier luxuriance. If it proves its worth, desert areas of Australia which likewise once supported vegetation might one day enjoy a similar transformation.  

Under an audacious and visionary plan to turn parts of the Sahara into a verdant oasis, The Sahara Forest Project (SFP) is to test the viability of deploying two proven technologies - the Seawater Greenhouse and both concentrated and photovoltaic solar power – to achieve hugely beneficial synergies. Applied in combination with traditional and energy crop production, they will be used to revegetate arid areas, turn seawater into fresh and create food, electricity and biomass for energy purposes.

Better still, restoring areas of desert to biological activity comes with another bonus: allowing sequestration of significant amounts of carbon in plants and soil. The intention is to develop and deploy an integrated, large-scale system for reforestation while creating green jobs via profitable production of food, biofuels and electricity from sunlight, nutrients and seawater.

A co-operation between Seawater Greenhouse, Exploration Architecture, Max Fordham Consulting Engineers and the Bellona Foundation, the SFP reached a major milestone in January 2011 with an agreement signed with regional Jordanian authorities. Under the agreement SFP will conduct three detailed studies in Jordan, paving the way for a Test and Demonstration Centre. Regional authorities in Jordan will secure the necessary land for the centre and latter stage expansion, while Norwegian authorities will finance the studies.

"The project has gained considerable political support and is designed to address a cluster of intertwined problems posing a historic threat to the stability of our ecosystems and human development," says Sahara Forest Project CEO Joakim Hauge. "It involves combining several methods to solve, in one fell swoop, a whole range of major environmental problems of our time.”

Supplying sufficient water, clean energy and food for the world's ever expanding population is arguably modern man's greatest challenge. The SFP envisages addressing these needs holistically. The intent is to use nature’s own processes to convert abundant resources like sunshine, salt water and CO2 into food, water, clean electricity and biomass in a major leap towards achieving the so-far illusory goal of restorative growth.

“We will use what we have enough of, to produce what we need more of,” Hauge says.

“As a nice side benefit, the barren desert outside will be supplied with enough moisture to become, over time, a green valley blooming with vegetation. Even better: algae, vegetables, and other plants will play an additional role, absorbing carbon dioxide from the air.”

Natural Synergies

The strength of the audacious project lies in the way it combines proven technologies in new ways to optimise generation of energy, water and biomass as the technologies work in synergy, supporting and enriching each other.

Thus saltwater greenhouses grow algae for fuel and vegetables for food whilst converting seawater into fresh. Concentrated solar energy provides electricity to drive pumps and fans and creates steam to add moisture to the mix. Condensation combined with excess steam adds to the moist damp conditions outside the greenhouse, to further promote green growth downwind. Furthermore, the theory goes, the cultivation of algae will ensure a health supply of biomass, which can then be used to produce energy or food.

Normal greenhouses are a poor choice for arid areas because they can promote desertification, potentially soaking up five times more water to irrigate crops than local annual rainfalls. The Seawater Greenhouse overcomes this limitation by evaporating seawater and condensing it into fresh.

The technology involves pumping seawater (or better still allowing it to gravitate to an area below sea level) to create a cool, humid growing environment where the water is evaporated from cardboard grilles at the front and condensed as distilled water at the back. Humid, cool air in the greenhouses promotes plant growth and creates external condensation. A 1000 m2 Seawater Greenhouse already erected in Oman is proving the concept by evaporating round 5 m3 of water a day per hectare of land. Unlike conventional greenhouses and desalination plants it uses little electricity, with the thermodynamic work of cooling and distillation powered by solar and wind.

In a Seawater Greenhouse water “lost” to evaporation (an amount much higher than that condensed back into freshwater) delivers humidity to the outside environment, allowing for cultivation of crops or revegetation of areas downwind. Cool and humid conditions in the greenhouse, meanwhile, enable crops to grow with very little water. Since the crops are not stressed by excessive transpiration, their quality and yields are both high

In this way the simple process mimics the natural hydrological cycle, where water heated by the sun evaporates, cools down to form clouds, then returns to the earth as fog, rain or dew.

Growing tomatoes in a desertGrowing tomatoes in a desertThe other major prong of the SFP is the application of Concentrated Solar Power (CSP), currently rated as one of the most innovative and effective ways of creating power from the sun. It also does best in hot arid areas where the sun is at its most powerful. The technology uses reflecting mirrors to turn water into steam to power turbines.

“Aqaba is a dry desert area with plenty of sunshine, as well as a coastline. It is a perfect fit for this project,” Hauge says.

CSP is increasingly seen as one of the most promising forms of renewable energy, producing electricity from sunlight at a fraction of the cost of photovoltaics.

“The process uses mirrors to concentrate sunlight to create heat which is used to drive conventional steam turbines to generate electricity,” says Charlie Paton, Seawater Greenhouse CEO and creator of the Seawater Greenhouse concept. Paton estimates less than one per cent of the world’s deserts, covered with concentrating solar power plants, could produce as much electricity as the world now uses. He sees huge commercial potential to restore forests and create a sustainable source of fresh water, food and energy.

The technology has proved its worth in a number of sites, including at Nevada Solar 1 near Las Vegas, and the solar tower in Barstow California. In time the energy created by CSP in the Sahara might prove transportable to Europe via high voltage DC power lines.
And that is not the only windfall envisaged by the project’s proponents: eventually they believe the new vegetation will be sufficient to play a role in driving down CO2 concentrations in the earth’s atmosphere, to play its part in addressing climate change.

Once sufficient data has been collected from the Demonstration Centre the partners will work towards large-scale commercial rollout, aiming to ensure restorative growth on multiple locations within a few years.

“The SFP is a fiercely ambitious effort ... but ambitious is exactly what we must be,” Hauge says. “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, instead of importing oil from us.”

Further reading:

Fourth World Conference on the Future of Science “Food and Water for Life” – Venice, September 24-27, 2008 - The Sahara Forest Project – a new source of fresh water, food and energy - A proposal for ameliorating the effects and causes of climate change, Paton C. (2008).

Sahara Forest Project

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