The theoretical limit of algae fuel production

Based on physical laws and assumptions of perfect efficiencies, the team calculated the theoretical limit to be 38,000 gal·ac-1·yr-1 (354,000 L·ha-1·yr-1) of unrefined oil with an uncertainty of roughly 10% and with 50% cell oil content. Limits for the practical cases examined in their report ranged from 4,900 to 6,500 gal·ac-1·yr-1 (46,300-60,500 L·ha-1·yr-1) of unrefined oil.Green Car Congress

My maximum of 100,000 to 200,000 gal was high.
But:

Only a portion of the solar spectrum is utilizable for photosynthesis; PAR (photosynthetically active radiation) is commonly defined as 400-700 nm.

So the genetic engineering here is to expand the spectrum to include shorter wavelengths.
To get a sense of the limit, the Sun illuminated the earth at a a horsepower per square meter. It takes about 75 horsepower to run a small car fueling some 50 cars per acre.