- Craig Embleton
- United Kingdom
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The potential for reducing atmospheric CO2 levels through solar-desalinated irrigated vegetation of the Sahara and Arabian deserts.
I have recently completed a thesis in which I investigated the potential of using solar-desalinated water to irrigate the Sahara and Arabian deserts in order to grow vegetation and lower atmospheric CO2 by creating a net carbon sink. I chose Eucalyptus grandis x urophylla to model this proposal, due to its relatively well-researched growth rate and water requirement and high transpiration ratio. A monoculture is not ideal of course, but served as a model for a proof-of-concept.
I calculated how much carbon could be sequestered in the vegetation and soil of a E. grandis x urophylla forest, the water required to irrigate the trees and the electricity needed to provide the water through desalination of seawater, and to supply the water to the trees by pumping it across the desert in pipes.
I reviewed how much electricity could be generated using concentrating solar power in the MENA region from studies undertaken by the DLR (German Aerospace Centre) for Desertec and related this to the electricity requirements of region in 2050 and the electricity requirements to desalinate the seawater to irrigate the trees. I then calculated the area of land required for the parallel troughs or linear Fresnels used to provide the electricity from the land use efficiency of the CSP. I also looked at the costs, benefits and possible sources of income from the project.
Results suggest that a forest of E. grandis x urophylla occupying 8.4million km2 of MENA deserts could be capable of sequestering 8 – 14.3GtCyr-1 in the vegetation and upper-soil profile. Non-land-use-change anthropogenic carbon emissions are currently 8.7Gtyr-1. The forest would require 7,560 – 8,400km3 water yr-1 for irrigation, which would require 56,144 – 62,553TWh electricity yr-1 to desalinate. Electricity could be supplied by CSP units covering 324,532 – 579,194km2.
I am now looking to take this research into practical studies and would welcome advice. My thesis is available here: http://www.greenfrontier.org/blog/