The first cucumbers grown in the desert – using seawater and solar power – were harvested in December 2012 at The Sahara Forest Project’s 10,000 sq metre pilot project facility in Qatar.
In the first phase of the project, researchers will be gathering extensive data on the various environmental technologies to produce food, energy and fresh water so that their integration can be optimised. During the second phase (likely to be in 2014), a test and demonstration centre will work as a multipurpose innovation hub, in order to prove the financial viability of the project. Once this has been achieved, commercialisation and large-scale implementation can go ahead in a variety of desert regions.
The pilot facility uses four main technological components:
1. Concentrated solar power (CSP)
to generate heat and electricity, using mirrors to concentrate the sun’s energy to produce heat. This then makes steam to drive a turbine, which in turn drives a generator to produce electricity. The heat from the mirrors also drives a multistage evaporative desalination system to produce distilled water for the plants in the greenhouse and outside.
The waste heat – which is dissipated across the greenhouse rooves via the saltwater cooling system – is used to warm the greenhouses in the winter and to regenerate the desiccant used for dehumidifying the air.
The pilot project is providing the first testing ground to examine the impacts of co-locating CSP collectors with revegetated areas, in which plants and humidifying hedges can reduce the dust levels in the air. This can in turn increase the performance of solar energy systems, and partially protect the CSP mirrors from the harsh desert winds.
2. Saltwater-cooled greenhouses
provide suitable growing conditions for year-round cultivation of highvalue vegetable crops. The greenhouse structure consists of three bays to allow for comparisons of performances between ETFE and polythene roof coverings on the horticultural yield. By using seawater to provide evaporative cooling and humidification, the crops’ water requirements are minimised and yields maximised, reducing their carbon footprint.
The cooling system consists of an evaporative cooler at one end of the greenhouse – the cool air is supplied under the plants via polythene ducts to ensure that it is evenly distributed at a low level. As the air heats up it rises and is expelled via high-level openings in the end wall.
The middle bay has a twin skin ETFE membrane roof that forms a void over the greenhouse. This is linked to an evaporator pad and fan, which can use the waste heat from the CSP to evaporate seawater or regenerate the desiccant and produce hot moist air. When the air is passed through the void at night it cools. The moisture in the air then condenses out to give fresh water, which can be used to irrigate the plants.
3. Outside vegetation and halophytes
The water coming from the greenhouse is at a concentration of about 15% salinity. To reduce the salt content further, the brine is passed over external vertical evaporators set out in an array to create sheltered and humid environments. These areas are planted to take advantage of the beneficial growing conditions for food
and fodder crops and for a wide range of desert species.
New candidate species for use as harvested and grazing fodder for livestock, and as bioenergy feedstock, will be identified and characterised from among native desert plants. The carbon sequestration benefits of various planting and cropping approaches will then be measured and compared.
Beyond traditional horticulture and agriculture, halophytes – salt-loving plant species – are being cultivated in saltwater. These hardy plants, often already well adapted to desert conditions, are highly promising sources of fodder and bioenergy feedstocks that can thrive in highly-saline environments. However, irrigating with saltwater directly into the soil can cause significant environmental harm. The pilot facility is therefore implementing and testing a variety of novel cultivation techniques to allow low cost halophyte cultivation, while ensuring no saltwater enters surrounding soil or groundwater aquifers.
4. Algae production
A state-of-the-art 50 cubic metre algae test facility enables commercial-scale research on the cultivation of marine algae species native to the Gulf and RedSea for use as nutriceuticals, biofuels, and as animal and fish fodder.
New synergies with the saltwatergreenhouse infrastructure, mariculture operations, and soil remediation methods will be optimised. In addition, staff and a team of international collaborators plan to carry out cutting-edge research in cultivation and harvesting methods.
• This project is a co-operative venture between The Sahara Forest Project AS, Yara ASA, the world’s largest supplier of fertilizer, and Qafco, the world’s largest single-site producer of urea and ammonia. It also includes research by a large international network of scientific collaborators. Visit www.saharaforestproject.com for more detailed information.