FOR years, marine energy has been dominated by massive tidal barrages and underwater turbines anchored to the seabed. Now, a different technology is attracting attention by generating electricity from machines that fly beneath the ocean's surface.

Known as energy kites, these underwater systems are emerging as one of the most innovative approaches to harnessing tidal power. And with new financing support in Europe and expansion plans in Asia announced this year, the technology is moving beyond experimental trials and closer to commercial deployment.