Algae prove promising candidates for biodiesel production via 'survival of the fattest'
Smart methods for cultivating algae bring the efficient production of biodiesel using algae in sight. On Tuesday 19 January, Peter Mooij will obtain his doctorate at TU Delft for his work on this subject.
There is huge scientific interest in the use of microalgae to produce carbohydrates and in particular lipids (fats), as lipids from microalgae can be converted into biodiesel. The amount of CO2 released by the combustion of this biodiesel is equal to the amount of CO2 that was previously extracted from the atmosphere by the microalgae. Thus the use of biodiesel does not lead to an increase in CO2 in the atmosphere.
'Microalgae offer two huge advantages over other biological oil production platforms', says doctoral candidate Peter Mooij from TU Delft. 'Firstly, after cultivation, microalgae can be made up relatively largely of lipids. And secondly, relatively little fresh water and agricultural land is required to cultivate microalgae.'
Survival of the fattest
Mooij uses a smart method to cultivate suitable algae that is economically viable for large-scale algae production: survival of the fattest. The fattest algae survive. 'In the reactor we give a competitive advantage to the algae with the required characteristics, in this case the production of carbohydrates and fats. We start with a collection of 'ordinary' algae. During the day we provide them with light and CO2. This is enough for them to produce oil, however they are unable to divide.
They need nutrients for cell division and they are only given these in the dark. To absorb these nutrients, the algae need energy and carbon. This means that only the fattest algae can divide, as they have stored these during the day. By removing some of the algae every day, the culture will eventually exist of only the fattest algae.'
'All of our experiments led to systems in which carbohydrates (starch) formed the primary energy storage compounds', continues Mooij. 'So we have found a suitable environment in which carbohydrate production by algae is rewarded.'
Unfortunately this environment is not yet selective for the storage of fats. The culture environment needs to be made even more specific to achieve this. 'But a greater understanding of the ecological role of lipids and carbohydrates in microalgae clears the way for the creation of lipid-specific selective environments. Rewarding a microalga for showing the desired behaviour by using a selective environment, one of the central concepts in my research, will be shown to be a valuable approach once there is a better understanding of the ecological role of lipids.'