Before oil drilling technology was developed whale oil was the thing. It was a biofuel that delivered itself to the coastal villages where it was needed most. We are coming full circle. We probably won't use whales to harvest the energy but we could. Many people don't know this but whales are dumber than cows. They have few natural predators so their brains had no reason to evolve much. If we can farm cattle we can grow and farm whales if we need to.
The oceans are extremely large. A great thing is that 200 miles out is international waters. There are few environmentalists and lawyers floating by to cause trouble. Algae has so many things going for it that it seems obvious to me it should be on the short list. Soon the towel heads will have nothing to do but pound sand.