As an alternative to liquid fossil fuels, biodiesel extracted from microalgae is an increasingly important part of the bioenergy field. While it releases a similar amount of CO2 as petroleum when burned, the CO2 released from biodiesel is that which has recently been removed from the atmosphere via photosynthesis meaning that it does not contribute to an increase of the greenhouse gas. Furthermore, research has shown that microalgae produces a much higher percentage of their biomass to usable oil in a significantly smaller land mass than terrestrial crops. Currently, one of the largest obstacles in replacing diesel with biodiesel is the cost of production. Fossil fuels are still cheaper than biofuels so improvements in production efficiency are highly sought-after.