Researchers are assessing innovative methods for natural carbon removal that could add tremendously to the fight to curb climate change. Scientists from LUT University in Finland have analyzed the CO2 sequestration potential of afforestation in the desert and arid lands if desalinated seawater is used to water the forests.
They published their research in Natura Sustainability under the title: “Afforesting arid land with renewable electricity and desalination to mitigate climate change”.
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The desalination of seawater is seen as a sustainable water supply and renewable energy (solar + batteries and wind) is used to power the desalination plants. The solution of employing low-cost renewable electricity to power the desalination process is called seawater reverse osmosis. Water transportation infrastructure and a high-efficiency drip irrigation system are also required.
The results show that over the period 2030–2100, the cumulative CO2 sequestration potential of such forests is 730 gigatons of CO2. The need for an additional PV demand is about 10.7 TW and 19,700 TWh of PV electricity, according to researcher Christian Breyer. The average cost of the proposed afforestation systems is estimated to be about 200 €/tCO2 ($214/ ton of CO2) for that period and will differ in different parts of the world.
In 2030, the annual global cost of irrigating and maintaining these restored forests with desalinated water is estimated at €457 ($490) per ton of CO2 while by 2100 it falls to €99 ($106) per ton of CO2. The proposed system is more expensive in Afghanistan, Iran, Chad, and Niger, mainly due to water transportation costs that are higher than the global average.
According to the paper, the team used the LUT Energy System Transition Model (LUT-ESTM) to analyze the energy requirements of afforestation and to estimate the electricity, water, and global CO2 sequestration costs over the 70-year period.
Additionally, the world’s areas with the greatest potential for sequestration are the Middle East and North Africa (MENA), followed by sub-Saharan Africa. They have a cumulative CO2 storage potential of 131 gigatons and 87 gigatons by 2070, respectively. Europe and Eurasia have the least potential by 2070 of 3.4 gigatons and 1.2 gigatons of CO2 sequestration respectively, due to the shortage of suitable land.
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The problems that the proposed systems also solves are the limit of land in other parts of the world for reforestation, the limit of water resources in arid lands, and electricity shortage.
The research offers valuable findings that afforestation in unused and arid areas is feasible and could contribute considerably to climate change mitigation. Currently, many engineered carbon removal pathways are under development towards a global scale but afforestation remains one of the most preferable and natural carbon removal solutions.
