The United States Navy has been researching the most effective method of separating hydrogen and oxygen in order to make hydrocarbons, a key ingredient in jet fuel. The U.S. Navy estimates the cost per gallon at $3.00 to $6.00, which is roughly the same as non-ocean water jet fuel.
After the 2011 Fukushima nuclear power incident, various countries have begun looking into the possibility of replacing nuclear power with wind power.
Currently, some countries are looking into developing floating windmills that aren't directly attached to the ocean floor—instead, they'll float with a buoyancy mechanism and will be anchored with lines to the sea floor.
We can currently produce biodiesel, jet fuel, biogasoline and plastic with algae. The first phase of a 300-acre algae farm has just been completed in New Mexico. It is set to produce 1.5 million gallons of biofuel annually.
Geothermal power is not new to us, but enhanced geothermal systems are a new combination of fracking—hydraulic fracturing—and geothermal energy. You frack into a not-so-active volcano and inject water, which comes back out in the form of steam.
As the steam rises it turns turbines, creating energy. According to Wired magazine, by 2050, this method will be able to generate 100,000 electric megawatts, which is currently the capacity of the entire European Union wind power network.