Seasonal Variations in the Chemical Composition of the Macroalgae Laminaria digitata

Macroalgae are multicellular organisms that are capable of generating higher dry biomass at a faster rate, compared to terrestrial plants. These features have made macroalgae a potential biofuel feedstock. Among the macroalgae, the largest growing species are reportedly those belonging to the Class Phaeophyceae and are termed as "kelp". However, previous studies on kelp cultivation harvested the macroalgae at only one period of the year, and the effects of seasonal variations, which can drastically change the macroalgae's chemical composition, were not considered.

In order to fill these knowledge gaps, researchers from the Institute of Biological, Environmental and Rural Sciences (IBERS), Aberystwyth University and Energy and Resources Research Institute, School of Process, Environmental and Materials Engineering, University of Leeds (United Kingdom), recently investigated the effect of changing seasons in the chemical composition of the macroalgae, Laminaria digitata. In their study, the researchers harvested the kelps at different months during a one-year period. After which, they measured the chemical composition of macroalgae. Finally, they determined the ideal month for harvesting the kelps. From the results of their study, the researchers found that for the production of biofuel, July would be the best month for Laminaria harvesting, since the metal concentrations were low, carbohydrate concentrations were high, and the high heating values (as determined from the proximate and ultimate analysis) were also the highest. The macroalgal harvest seems suited for biofuel production by biological conversion. Thermochemical conversion of the macroalgae to biofuels (for example, by combustion or pyrolysis), may not be recommended, due to the high water and metal contents. The full paper is published in the journal, Bioresource Technology (URL above).