Which will have the most impact?

Wave- and tidal-energy systems harness natural oceanic flows—among the most powerful and constant dynamics on earth—to generate electricity. A variety of companies, utilities, universities, and governments are working to realize the promise of consistent and predictable ocean energy, which currently accounts for a fraction of global electricity generation.

While the ocean’s perpetual power makes wave and tidal energy possible, it also creates obstacles. Operating in harsh and complex marine environments is a challenge—from designing systems to building installations to maintaining them over time. It is more expensive than producing electricity on solid ground.

Despite decades of work, marine technologies are still in early development and lag well behind solar and wind. Tidal energy is more established than wave, with more projects in operation today. Across the world, a variety of wave-energy technologies are being tested and honed, in pursuit of the ideal design for converting waves’ kinetic energy into electricity.

Wave and tidal energy is currently the most expensive of all renewables. Still, the opportunity of marine-based energy is massive. Proponents believe wave power could provide 25 percent of U.S. electricity, for example. Realizing it will require substantial investment and expanded research.

There is an energy transition under way. The world is shifting away from carbon-based fuels to renewable energy. With distributed renewables, such as rooftop solar, a utility’s customers become producers and can sell power to the grid. Another part of the transition is distributed energy storage—the ability to retain small or large amounts of energy produced where you live or work and use it to meet your own needs.

The wind and sun have their own timetables, making generation variable. Storage can ensure electricity is available, even when sunshine or breezes are not. There are two basic sources of small-scale storage: stand-alone batteries and electric vehicles. If they are used to enable more reliance on renewables, there will be substantial climate benefits.

Creating a distributed energy storage system, or grid independence, requires affordable storage, and until now, prices for batteries have been prohibitively expensive. That is changing. From $1,200 per kilowatt-hour in 2009, the cost dropped to roughly $200 in 2016. Companies are predicting $50 per kilowatt-hour in a few years. For $1,200 per kilowatt-hour, you can purchase a 24-kilowatt-hour energy storage system and get a car thrown in for free—the all-electric Nissan LEAF.