Climate change and cutting down the levels of greenhouse gas emissions have been approached in various ways through geo-engineering. One of the most commonly known technologies is the dispersion of iron salts in the oceans in order to stimulate growth of algae in infertile areas and stimulate photosynthesis.
The theory behind the process is that when algae die, the locked carbon that is required for the photosynthesis will sunk to the sea bottom.
According to a study published in the International Journal of Global Warming, however, there is a number of factors that have not been taken into consideration. Daniel Harrison of the University of Sydney Institute of Marine Science, NSW, a lead author of the publication, claims that with the current efficiency of the spreading of iron, the carbon dioxide per square kilometre of ocean is more likely to be absorbed. In his opinion, carbon sequestration should be approached in a more economical way.
The study is based on a series of calculations that include quantities of permanently sequestered carbon but the loss due to ventilation, greenhouse gas production, nutrient stealing and carbon emissions released during the process of iron salts production and transportation are subtracted.
The findings indicate that as little as 10 tonnes of carbon is sequestrated per square kilometre for a century, which means that a tonne of carbon dioxide costs around $500 US. .
Harrison states that previous estimates do not take into account the costs of iron salts distribution over large areas, which reduces the net storage of carbon. He adds that the cost could be reduced and the efficiency could be increased, but this is only given that we have the almost impossible to achieve ideal conditions.