Triglycerides can be converted into biodiesel or other liquid fuels such as diesel by well-established and effective chemical technologies using the existing oil refinery infrastructure. Importantly, biodiesel has a high energy density and furthermore, it is an excellent fuel for combustion engines. Today, the biodiesel in the market place is produced from palm oil, rape seed and animal fat. However, it is unlikely that the size of this production will ever cover more than a few percentages of our needs for liquid fuels due to environmental considerations and the adverse influence of such production on the global food supply.
Some micro-algae contain large amounts of triglycerides, in particular when they are subjected to stress. As a consequence, production of micro-algae might contribute to the future supply of liquid biofuels. During the ‘80ties and ‘90ties attempts were made to cultivate promising species of algae in open ponds, but problems with contamination, insufficient productivity and lack of inexpensive ways to harvest the algae led to the closure of the project. Since then, new knowledge on the cultivation of algae has been obtained. In particular, the beneficial effects of the carbon dioxide concentration and the effects of stress has been described with the result that the productivity in closed reactor systems has been increased dramatically. On this background several companies aiming to produce biodiesel from algae have been founded. Some predictions suggest that the production price of biodiesel can be kept below $ 100 per barrel but such figures are in the eyes of others unrealistic due to the manufacturing costs of such reactors and the costs harvesting of the algae. However, only a small part of the potential of this area has been explored. As an example, the oil production capacity has only been studied for a small part of the vast number of algae available and only under conditions that do not fully seek to explore the physiological diversity of this group of organisms.
Internal as well as external resources.
Biodiesel is a perfect fuel for combustion engines. Production of fat for biodiesel is a true bottle neck since existing sources (palm oil, rape seed and animal fat) are insufficient and cannot be scaled up significantly without compromising the global food supply. Algae reactors need not compete with food production since they can be located in desserts, in lakes or in the ocean.