Algal biofuel: Yang et al. (2011)

I would now like to add to the information from my previous post by reviewing the article by Yang et al. (2011), which focuses on algal biofuel cultivation under the different climates across the US, to examine the spatial differences in the viability of these biofuels. The results have shown the microalgae biofuels to be competitive in terms of how much energy they produce, but they were also found to be highly water-intensive. This can be a problem in arid and water-scarce areas, meaning that they are only viable under certain climates. A technological fix for the high water requirement also exists, which is the use of an enclosed photobioreactor instead of open ponds for cultivation. This would allow the biofuels to be grown in water-scarce regions. However, this also increase the operational cost, meaning trade-offs have to be made.

Another problem is that algal biofuels need nutrient to grow; as mentioned by in a comment left by one of my followers, this may prove to be detrimental in the future due to the problem of phosphorus depletion. The phosphorus is used in fertilizers and is thus vital to support the increasing global consumption of food, but it is running out (see Dan Dan’s blog for more detailed information on this). The biofuels will therefore put extra pressure on this resource, which is finite at the moment. However, this problem may be eliminated by the time the phosphorus starts running out, as research has been directed towards the development of technology that may allow us to recycle the chemical (Dan Dan’s blog). Additionally, Yang et al. (2011) have shown that using sea water, recycling the water in which the algae are grown and using wastewater as an algae growth medium, reduces the water requirement by ~90% and the fertilizer requirement by ~50%. Species of algae which grow under low phosphorus conditions can also be chosen to further reduce the fertilizer requirement. This means that these spatial and temporal variations in the problems of algal biofuels will potentially most likely be overcome, making algal biofuels viable in the different situations.

A high growth rate of algal biofuel makes it more economic to implement. The growth rate was found to be highest where a balance between temperature and evaporation rate exists; out of the 28 states examined in the US, the climates of Florida, Hawaii and Arizona were found to be the most suitable. This shows that algal biofuels are economically viable in climates other than that of Australia.