Biodiesel can be produced by extracting the oil from the algae cell.

BBC: Bath's Roman Baths algae could fuel cars

The research team are therefore also looking for a species of algae with a weaker cell wall and high oil content.

BBC: Bath's Roman Baths algae could fuel cars

Another restraint on producing large quantities of algae is that its cell walls are difficult to break, making extraction of the oil inside an energy intensive process.

BBC: Bath's Roman Baths algae could fuel cars

The fat was stored outside the cell walls, making it easier to extract without first killing the algae.

FORBES: Biofuel From Algae Could Compete With Oil, Report Says