We model the economics of afforesting deserts by desalinating and distributing sufficient water for trees to grow. This could increase the global land available for new forest growth by a factor of 5x.
The best case economics are achievable in the Permian, where 10% IRRs are achievable at $30/ton CO2 prices, total costs are 60% lower than current produced water disposal costs, and the CO2 savings could be sufficient to make entire upstream operations to ‘Net Zero’.
Economics are more challenging for desalinating sea-water and distributing it inland. If 50T of water are required by T of CO2 capture in forests, equivalent to adding 100mm of annual rainall, then costs may be passable. But to grow forests in the Sahara would likely require well over 300T of water per T of CO2 and the energy economics become impossible.
The data-file also contains useful workings from our recent research report, Green deserts: a final frontier for forest carbon?