http://www.oilgae.com/algae/oil/extract/extract.html
Here is a site that explains a few methods of extracting the oil from the algae and also a few drawbacks of the methods. There are two main types of extraction, mechanical and chemical, each with their own pros and cons. We need to way out the pros and cons of each and also consider developing a new method of extraction that will combine features of the two to create the best possible method of extraction.