Can cnidarians teach us how to harvest algae energy?

It is an old idea to use the ability of algae and photosynthetic bacteria to efficiently use the sun energy to produce sugars and oil, to our needs.
The problem is how to do it well enough, so it will be both cheap and easy. most of the attempts to use these creature in the field have failed, mainly because harvesting them, by actually killing them in the process makes the growing procedure to expensive.
I suggest that in order to solve this problem we need to further investigate how some organisms can make a symbiotic connection with algae in nature.
An example for that is the beautiful cnidarian (The family of jellyfish and sea anemones) Green Hydra, that can grow symbiotic green unicellular organisms, and to use their sugar as fuel. in return the Hydra provide protection and good growing environment to the fragile algae.
I think that we should make some effort researching this symbiosis, and learn how the Hydra, and other members of its family can harvest these algae, and copy this technique.