Why Algae for CO2 Capture

Algae, ranging from single-celled microalgae to large seaweeds, are the simplest and most abundant form of plant life, responsible for more than half of the world's primary production of oxygen.

Algae are an extremely important species. For one, they produce more oxygen than all the plants in the world combined! For another, they form an important food source for many animals such as little shrimps and huge whales. Thus, they are at the bottom of the food chain with many living things depending upon them

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Apart from their ability to produce biofuels, they are  also capable of fixing CO2 in the atmosphere, thus facilitating the reduction of increasing atmospheric CO2 levels, which is now considered a global problem.

Conventional capture methods are highly power -intensive and as a result, the cost will run into several billions. Hence, many scientists and environmentalists think that algal farming, will give the most promising results in this context.  Most importantly, algae-based CO2 abatement enables monetizing carbon credit + nutrient credit + biomass.

A comparision between algae-based CO2   capture and geological sequestration has been highlighted in the table below:
 

Algae-based  Technology Geological Sequestration Technology
Sustainable Social problems arises
Safe Untested on large scale
No need to transport CO2 Need to transport CO2 to sequestration site
Generates biomass No additional revenue
Coupled with wastewater treatment Coupled with oil recovery
$ = carbon credit + nutrient credit + biomass $ = carbon credit
Algae-based  Capture vs Geological Sequestration

Bio-fixation of CO2 using microalgae has emerged as a potential technology  for carbon- dioxide fixation.  Algae have the advantages of a more efficient photosynthesis superior to C4 plants (those green plants that form four carbon stable intermediates during the photosynthetic process). 

Peer reviewed research articles

  • Biological approach using solar energy to capture CO2 while; producing H2 and high value products from algae (Skjånes et al., 2007) - Read More
  • Perspectives  on microalgal CO2-emission mitigation systems — A review (Ho et al., 2010) - Read More
  • Evaluation  of strategies for the subsequent use of CO2 (Schaefer et al., 2009) - Read More

    Moreclick here


Algae’s ability to sequester CO2 and produce massive amounts of CO2 has prompted scientists to theorize that propagating algae in large ocean dead zones may be a way of sequestering millions of tons of CO2 and adding to atmospheric oxygen.

Algae are also a sensible choice with regard to their fast proliferation rates, extensive tolerance to wild, extreme environments, and their potential for comprehensive cultures. These advantages promise high performance in the reduction of carbon dioxide. After harvesting, microalgae can further be used as a product to offset some of the costs that have been incurred in the sequestration process.
 

  
Flow Diagram of Algae-based Carbon-Capture
  

Image Source: http://www.bmu.de/files/english/pdf/application/pdf/reccs_ii_en.pdf

 

 Note:  Monoethanolamine (MEA) extraction is a commonly used method for the extraction of CO2 from flue gas

  

   The algae production facilities can thus be fed with the exhaust gases from coal-fired power plants to significantly increase the algal productivity and clean up the air.  A key benefit from this technology is that the oil found in algae can be processed into a biodiesel. Remaining components of the algae can be used to make other products, including ethanol and livestock feed.