Wednesday, January 30, 2013

How Electricity, Water And Food Could Be Produced In Desert Areas With Minimal Ecological Footprint

1) Concentrated Solar Power 2) Saltwater greenhouses 3) Outside vegetation and evaporative hedges 4) Photovoltaic Solar Power 5) Salt production 6) Halophytes 7) Algae production

The first pilot plant in a program of installations that can sustainably produce crops, electricity, biofuels, and even plants for re-vegetation efforts in a desert environment is now up and running in the Middle Eastern nation of Qatar.

The Sahara Forest Project, which brings outfits from both Qatar and Norway together, uses desert air, sunlight, and saltwater as inputs for a system that aims to be environmentally sustainable, beneficial for local human development, and financially viable over the long term. As the project's CEO, Joakim Hauge, puts it: "The Sahara Forest Project is all about taking what we have enough of, like saltwater, CO2, sunlight, and deserts, to produce what we need more of: sustainably produced food, water, and energy." The hope is that the pilot project can be scaled up to installations in drier and desert climates around the world.

Essentially, the plant takes multiple sustainable technologies and integrates their inputs and outputs into a single multistage system, thus minimizing both waste and ecological footprint:

  • Standard solar power and concentrated solar power: Arrays of mirrors create concentrated solar power by aiming sunlight to superheat seawater into steam. That steam can then drive turbines to create electricity, and the heated seawater is then used throughout the greenhouse system. Additional sustainable electricity is generated from arrays of standard solar photovoltaic panels.
  • Saltwater for fresh water and cool air for greenhouses: Hot desert air is pulled through a flow of seawater as it enters the greenhouses. This both cools and humidifies the air, creating optimal growing conditions for the agricultural crops within. At the far end of the greenhouse, the air is heated by flows of sun-heated seawater and then encounters pipes of cooled seawater, which causes the humidity to condense into fresh water that is then used for crop irrigation.
  • Outdoor vegetation: Outside the greenhouses, the seawater passes through further evaporators to create humidity for vegetation sheltered outdoors. These include trees for desert reforestation, local vegetation, various forms of crops and livestock feed, and specific forms of plants naturally adapted to salt water which serve as feedstocks for bioenergy production and other uses. At the end, remaining seawater is collected into evaporation pools for the production of salt.
  • Algae biofuel production: Lab-grown algae, which have been shown to generate up to 30 times more biofuel per acre than other plants, are grown in saltwater pools to create biofuels without taking up agricultural land or crops that double as food for humans.

The basic advantage of the Sahara Forest Project is that it doesn't use any fundamentally new or experimental technology - it merely recombines established technologies in creative ways.

At the same time, at least one of its goals - growing plants for reforestation - may be overly ambitious. "Trying to grow trees in the Sahara desert is not the most appropriate approach," Patrick Gonzalez, a forest ecologist at the University of California, Berkeley, told National Geographic back in 2010. "I can imagine that this scheme and type of technology in limited cases might work in certain areas like Dubai, where they're used to making palm-shaped islands and 160-story-tall buildings."

But for the more modest goal of returning a desert to its natural former ecosystem, "it would be more effective, but less flashy, to work with local people on community-based natural-resource management."


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