This could have promise. The key to renewable fuels is to produce the feedstock cheaply, with low overhead and input costs, and on some resource that’s not already being used to produce something more valuable.
In this case the land, water, and sunshine are vast and free for the taking. This opens up 70% of Earth's surface/70% of the Earth's available solar energy which we are not currently using for much. Sun blocking cloud cover is greatly reduced over the open oceans away from land. Even if growing efficiency is very low, all we need is a low cost harvesting technology to make this work. For thousands of years we used whales to do this harvesting but we're going to need something more scalable. We could replace the entire petroleum industry using less than 2 percent of the ocean surface, and it's carbon neutral on a large scale.