Christopher Olson was surfing with his son at Surfside, Texas the evening before Hurricane Katrina hit the Gulf Coast. As the waves increased to heights of 12 feet, he started thinking about the possibilities that harvesting ocean energy could bring to generating electricity.
Several years and several tens of prototypes later, Olson and his collaborators have formed a company called SwellFuel, and created a few models of ocean energy converters. Two of the latest prototypes are known as "the duck diver" and "the stinger."
Duck DiverThe duck diver is designed for use in fairly shallow water, and consists of yellow plastic tubing connected in a square shape with a hollow center. The plastic square is attached by a rod to the sea floor, with a lever that allows the device to adjust its height between low and high tides (see figure below). The ability to endure different water levels, Olson explains, has been a challenge for many ocean energy converters in the past. This flexibility, coupled with the device's robustness, also enables the duck diver to withstand large waves by submerging itself vertically under the water--hence its name. And, like a duck or other floating object, the device moves toward a wave as it approaches, and then is pushed back by the wave as it passes. The device captures the horizontal push and vertical lift of the waves, as the waves pass by again and again.
This energy can then be transferred to a generator and converted to electricity. In one of SwellFuel's videos, Olson demonstrates a single device supplying enough energy to power 100 1.6-volt LEDs, in relatively calm water. Better yet, each device costs just $65 to make, is designed to survive for 10 years without maintenance, and can be constructed by someone with "general mechanical knowledge." This is because SwellFuel plans on selling its products to many coastal cities that don't have a great deal of high-level technology available. Watch a YouTube video of the duck diver .
StingerAt 44 x 44 inches, the stinger is a bit larger than the duck diver, and has a similar appearance, with a square-shaped yellow tube as its floating device. The stinger has a lever on top of the tubing, and when pulled down by the force of a wave, it can turn a generator up to 90 revolutions. SwellFuel's plan is to connect a multitude of stingers in a grid, and the company's goal is to generate 350,000 kW per year with the full-scale ocean energy converter.
Because the energy generated by the waves is not usually consistent, Olson also suggests the stinger can be used to compress air. You don't need consistent energy to compress air, he explains, and the energy from the air compressor could then be used to power a generator. And, he adds, even an inconsistent flow of DC current can be used to produce hydrogen. Watch a YouTube video of the stinger.
Olson and SwellFuel have demonstrated the device to positive reception in El Salvador, and have recently received licensing for their products in El Salvador, Guatemala, Honduras, Nicaragua and Belize. They explain that the devices would be located far from public areas, and preferably in parts of the ocean that are inaccessible by people, in order to not interfere with nature's scenery. According to their Web site, the company so far has one patent and several applications, and is possibly interested in working with a company to produce and sell their products.
An amateur engineer, Olson admits that the devices are simple--and, as he says, that's exactly why they work so well.