Phycocapture of CO2 as an option to reduce greenhouse gases in cities: Carbon sinks in urban spaces

Climate change is a shift in the average weather patterns, which could stand for a long-term period. This phenomenon is related to greenhouse gas emissions generated by anthropogenic and non-anthropogenic activities. The most notable climate change effects are the rise of sea levels, changes in the water pH, apparition or increased transmission of diseases, changes in the water cycle, loss of marine ecosystems, and several negative impacts on human health. Due to the adverse effects occasioned by climate change, global initiatives have been taken to mitigate its impact, one of these is the reduction of greenhouse gases such as CO2. Some microorganisms such as photosynthetic bacteria and microalgae can capture CO2 and use it as a carbon source for growth. The outstanding CO2 bio-capture or CO2 phycocapture capacity shown by microalgae make them excellent candidates for reduction of atmospheric CO2 in cities. CO2 phycocapture equivalent CO2 emissions in Mexico City Metropolitan Area (MCMA) was determined as a case study, considering greenhouse gas emissions in this city. It was estimated that 94,847 tons of microalgae biomass must be produced daily to equal the amount of CO2 emissions (170,726 CO2-eq per day), thus obtaining a zero balance of emissions. For the above, CO2 phycocapture implementation can be possible in cities and also in open spaces and that even its production can work as the carbon credits nowadays implemented, the space required, and the high capture rate led us to consider that the microalgae production on a larger scale may have a faster effect on the concentration of CO2 globally, which can help with greater urgency to the aims established by 2030.