Climate change, together with rising world populations and unsustainable farming practices, are causing the exhaustion of fresh water and food resources. The necessity for both is expected to exceed availability in the foreseeable future. It is the simple reality of this situation which gave rise to the idea for the Seawater Greenhouse. The Seawater Greenhouse (developed by Seawater Greenhouse Ltd, London) provides a low-cost solution by enabling year-round crop production in some of the world’s hottest and driest regions. It does this using seawater and sunlight. The technology imitates natural processes, helping to restore the environment while significantly reducing the operating costs of greenhouse horticulture.
As of 2015, the Seawater Greenhouse company has developed projects in Gran Canaria, Tenerife, Oman, Abu Dhabi, Australia. A project in Somalia is currently under development.
In Somalia, only 1.5% of the 6000 square kilometres are cultivated, and average yields are just 0.5 tons per hectare per annum.
The Seawater Greenhouse company has developed simple and cost-effective tent structures that transform hostile elements – saltwater, extreme climate, solar radiation and arid land – into micro oases. Using low-tech elements – cardboard, netting, humidity and air circulation – in specific configurations, the tent structures can increase production of salads, herbs, spices and fruit to 300 tons per hectare per annum. The windbreak design creates an adjacent microclimate forthe cultivation of less intensive crops, which multiplied over many interconnected units forms a substantial and sustainable agricultural asset. Smart phone and app technology is well established across the region. Growers will be able to use a ‘Cloud’ based monitoring service to get expert advice, meteorological data, and share knowledge with each other.
Objectives and beneficiaries
Water shortage and the incapacity to grow food due to environmental conditions are two basic causes of worldwide poverty. Over 1.2 billion people do not have access to safe water supplies and the number is growing. Seawater Greenhouses can help to redress these inequalities. Rainfall remains fairly constant but the need for water has doubled over the last 20 years and continues to grow. Rising population levels are causing the use of fresh water to exceed renewable supply. The depletion of ground water is accelerated as a consequence. Agriculture uses the most fresh water, approximately 70% worldwide. This percentage is often higher in regions that suffer from chronic water shortages. In North Africa, up to 90% of available water is used in agriculture. These unsustainable, yet widespread activities have accelerated land degradation on a large scale. The effects are largely irreversible, as it takes roughly 500 years for one inch of top soil to form. The Seawater Greenhouse makes efficient use of abundant resources – seawater, sun, and degraded land – to produce fresh water, high-quality crops and a restored landscape.
Cultivation inside greenhouses is water efficient and reliable, but existing greenhouses are too expensive for some regions. The challenge is to design an affordable solution accessible to the rural poor. It will make use of sustainable energy, nutrient and water resources to provide optimised conditions for cultivation. The design will target family units. A hub-and-outgrower business structure will enable the project to become self-financing within 5 years.
Strong points of the practice
The technology developed by Seawater Greenhouse has many advantages. Even in the most hostile, arid regions, the Seawater Greenhouse can create ideal growing conditions for crops inside the greenhouse and produce fresh water for irrigation, using only seawater and sunlight. The system does not rely on scarce fresh water, costly desalination equipment or fossil-fuel driven greenhouse climate control systems. Seawater Greenhouse growers can therefore enjoy these advantages from both an economic and environmental perspective.
Expected results and benefits for climate change adaptation and mitigation
• Freshwater production: The fresh water produced is pure and distilled from seawater, with no need for chemical treatment.
• No fossil-fuel requirements: Unlike traditional greenhouses, which often rely on gas or other fossil fuels for temperature control and CO2 enrichment, Seawater Greenhouse systems use only seawater and sunlight to control the growing environments, with equal effectiveness.
• Pesticide free: the seawater evaporators have a biocidal and scrubbing effect on the ventilation airflow. This greatly reduces or eliminates the need for pesticides.
• Land: Seawater Greenhouse technology enables the development of land normally considered unsuitable for agriculture.
• Cost-effective: Commercial grade crops yields, coupled with significantly lower capital and operating costs result in enhanced operator economics.
• Salt and mineral production: Salt gained in the process can be sold and other minerals used as crop nutrients.
• Import Substitution and Jobs: On a country or regional level, there may be advantages linked to import substitution. Most arid regions of the world are net importers of horticultural produce.
• Air Flow: Use low-cost net-structures to contain the cool air and control internal conditions even though external wind patterns may change. This requires careful modelling and prediction of air flow using of state-of-the-art mathematical techniques.
• Brine Waste: Brine left over from the Reverse Osmosis (RO) desalination process is used for cooling, so pollution from the brine is avoided.
• Downstream of the greenhouse the seawater gets turned into salt – so that nothing is wasted and further value is added. This helps to support a sustainable business model.
By employing Seawater Greenhouse systems on a large scale these regions could see rises in local green employment as well as reductions in costs by substituting expensive imports with high-quality, locally produced Seawater Greenhouse crops.
A key feature that women can provide much of the semi-skilled labour, providing units are kept to family size. Aside from increasing domestic market demand for horticultural produce (with significant benefits for nutrition and health), the MENA market alone has a trade deficit in fresh produce of $1.1bn. Five hundred hectares of seawater greenhouse would supply just 2% of that market and generate greenhouse equipment sales of ≥£75m.
Replicability potential of the practice
Through extensive modeling, testing and experimentation, an integration of proprietary technologies have been developed. The concept was first researched in 1991 and developed by Light Works Ltd in the United Kingdom. The initial pilot research project commenced in 1992 on the Canary Island of Tenerife, and the positive results confirmed its viability and the potential for other arid regions.
Since the Tenerife greenhouse, two further research centres were established in order to test the technology in more extreme climates, increase water production rates, research crop yields and improve climate control. The second Seawater Greenhouse was constructed on Al-Aryam Island, Abu Dhabi, United Arab Emirates in 2000 and the third system and joint research facility was completed in 2004 near Muscat, Oman in collaboration with Sultan Qaboos University.
Informed by the success of the latest Seawater Greenhouse project in Australia (which has recently secured $100m venture capital for a 100-fold expansion and thus proven economic viability), in 2015 the team is developing a lower cost and more rugged solution for the arid regions of Africa – a continent where 58% of the land is classified as desert.
Aston University has teamed up with Seawater Greenhouse Ltd and with Gollis University (Somaliland) to develop a solution for improved food security in this region, with support from Innovate UK and the Department for International Development.
Aston University will carry out modelling of airflow, temperatures and evaporation to guide the design. The Aston team will also design desalination systems, using solar energy, to make the system independent of freshwater and conventional energy resources.
The project has been awarded a £0.5m shared cost ‘Agritech Catalyst’ grant by Innovate UK.
The Somaliland project will enhance food security and create employment in arid, coastal regions. It contrasts with conventional agricultural intensification that relies on abstraction of groundwater, high use of fertiliser and intensive energy inputs. Traditional farming in Somalia is based on pastoralism and open-field farming. Yields are low, averaging 0.5 t/ha/yr, and crops are constrained by erratic rainful and a harsh climate. By overcoming these constraints we will enable a horticultural sector to develop at scale. Productivity in a greenhouse is very high − in the range 300-700 t/ha/yr. Protected cultivation is also resilient, and less affected by variations in weather and changes in climate. With over 3,000 km of coastline and vast areas of flat coastal plains, Somalia has the potential to become a major producer of horticultural crops.
[Editor's Note: Information selected by ICCG and integrated with materials provided by the authors of the practices]