Algae fuel

The growing concern of depletion of the ozone layer should be no more with the increasing discovery of green fuel sources. At the moment algae is touted to be able to both reduce the green house gas and produce fuel .There by reducing global warming. My question is why are we not planting algae on on ocean surfaces. The beauty is, it does not present the competition with food plants like other bio-fuels do.
Algaculture is thus the way to go- the planting of algae. Algae are tiny biological factories that use photosynthesis to transform carbon dioxide and sunlight into energy so efficiently that they can double their weight several times a day.
As part of the photosynthesis process algae produce oil and can generate 15 times more oil per acre than other plants used for biofuels, such as corn and switchgrass. Algae can grow in salt water, freshwater or even contaminated water, at sea or in ponds, and on land not suitable for food production.
On top of those advantages, algae — at least in theory — should grow even better when fed extra carbon dioxide (the main greenhouse gas) and organic material like sewage. If so, algae could produce biofuel while cleaning up other problems.
The more oil we produce the more carbon we consume -how beautiful