With a growing population raising the need for food, water and energy efficiency of spatial utilization is paramount. Our cities should be denser and farmland managed with greater care. But what if we could take some of the harshest land on the planet and use it to supplement these needs at a low cost? Three firms have proposed a method to use the Sahara Desert as the next prime ground for creating fresh food, fresh water and clean energy. Despite the fact that the project has been around for over a year, it exemplifies the kind of coordination and synergy that Intercon promotes and the direction our society should be moving towards.
The center of the project begins in collaboration. I find it no coincidence that innovative thinking is the result of numerous minds from different, but interconnected, fields working together. Shaping the vision are the firms Exploration Architecture, Seawater Greenhouse Limited and Max Fordham & Partners—architects, water specialists and environmental engineers respectively. Like all areas of study, each of these three offer a vintage of expertise that bears opportunities for interconnection with others.
This triumvirate based their innovative offensive in the face of a slow-moving but devastating dilemma: the growing of the world’s deserts. With all of the issues that the planet has on its plate right now (war, recession, healthcare, global warming) the issue of desertification is not on the radar screen of many, but its existence is very real. The miles of flat, arid landscapes with their unyielding temperatures and unforgiving sandy soils expand their borders every year, swallowing more fertile land and stripping it of its moisture. Up until now we have accepted this occurrence as a problem beyond our ability to address.
But then again, maybe we can. Using an interconnected combination of Concentrated Solar Power fields and Seawater Greenhouses the system can theoretically function indefinitely with nearly no influx of new energy or resources.
How it Works:
To begin, seawater is drawn into each greenhouse complex and dripped over evaporators to be turned into vapor, creating a warm, humid environment poised for growing plants. More water suspended in the air reduces the amount of fresh water needed for direct irrigation. When the air is cycled through the greenhouse to bring more carbon dioxide to the plants, the humid air is released back into the atmosphere and adds moisture to the local environment. The design team proposes that with enough acreage, it may contribute enough added moisture to induce local rainfall.
The evaporators find their necessary power from Concentrated Solar Power (CSP) arrays stretched out across the landscape. Using mirrors to focus sunlight and heat liquid for steam production, CSP is viewed by many as the most viable source of renewable energy in the near term. It can be twice as efficient as photovoltaic panels in energy production as it uses the sun’s energy to create power. The system also produces a great deal of waste heat.
By themselves, these two systems are impressive technologies with a great deal of potential, but linked and integrated together, their possibilities rise exponentially. The excess heat of the CSP facilities can be captured through cogeneration and used for the desalination of more saltwater. The project team estimates that onsite power can desalinate 40 million cubic meters of water for terawatt-hour of harvested solar power—that is over 10.5 billion gallons. Strips of greenhouses can be arranged to shield the CSP mirror arrays and reduce dust and sand collection that lowers their efficiency. Three new export streams can emerge from each project location, all of which are in extreme demand around the globe: clean power, fresh water, fresh food.
As with any good system built on ecological underpinnings, its function begets its own continued success. Theoretically, as the installations grow in size and number more sand is replaced with greenhouses or planted fields. Moisture content in the air will continue to rise while the ground temperature of more acres will continue to fall. The expansion of deserts could be reversed to eventually re-vegetate some of the world’s harshest climates turning them into net producers of vital resources.
While the project is an impressive map for a regenerative, progressive model, I think that the possibilities go even further.
- Plant waste from greenhouses is rich in nutrients and can be composted to produce a base for naturally fertilizing future crops or spread over surrounding area to instigate new native plant growth.
- Another possibility is taking a page from the city of Kalundborg’s playbook and using the wealth of heated salt water for fish farming. This could produce yet another food crop and another organic waste stream that can be used to create organic fertilizers.
- So much desalination will also produce a great deal of salt, which draws us back to CSP. One of the reasons CSP seems so promising is the opportunity for power storage with heated salt solutions being one of the frontrunners. Eventually, excess power could be sold day and night to surrounding townships.
So what’s the catch? Well how much it costs to build solar greenhouses, CSP arrays and the labor to manage them all has to factor in somehow and chart a realistic time frame for expansion. There is also the fact that the Sahara is the world’s largest desert (3.3 million square miles) and constitutes nearly a quarter of Africa. Such statistics begs the question of how many facilities would have to be created before the stated goal of local climate alteration was actually achieved. The number could be staggering.
While I give the project a great deal of respect, we always have to remember that all of our operations and endeavors are subordinate to a much larger system. Even if the project does succeed, I have to ask what affect would a green Sahara have on the rest of the world’s ecosystems? Would rainfall in the Sahara prompt drier spells somewhere else? Could wind patterns or coastal currents change as a result of cooler regional temperatures? As interested as I am about the finer details that all seem to point towards success, I would also be curious about an analysis of the possibilities for global weather repercussions. Even the best of intentions do not occur in a vacuum.
Photo Credit: www.exploration-architecture.com