10 Breakthroughs in Hydropower Technology

The East River in New York City may not be the first place you'd associate with renewable energy, but this once-polluted waterway has emerged as a key player in the green-energy revolution. In September 2012, Trey Taylor, the founder of Verdant Power, submerged a specially designed three-bladed electric turbine into the river alongside Manhattan's eastern shore. Taylor's invention, which looks like a modern fan mounted on a torpedo-shaped body, is engineered to generate electricity from the movement of the river's currents [source: McGeehan].

By 2017, up to 30 of these turbines could be placed in the river, with each one producing 35 kilowatts of electricity. If successful, this initiative could generate enough energy to power hundreds of homes. Constructed from plastic and layered with fiberglass, the East River tidal turbines represent just one of many technological advancements revolutionizing the hydroelectric industry [source: McGeehan].

Across the globe, scientists and engineers are exploring various concepts—some practical, others speculative—that aim to transform this ancient power source into an even more crucial part of modern energy. Currently, hydropower provides 6 percent of U.S. electricity (which accounts for 70 percent of renewable electricity in the U.S.) [source: U.S. DOE]. The potential is boundless, though not all locations are ideal for hydroelectric development.

10: Fish Ladders

For freshwater fish like trout, encountering a dam is the last thing they want. Dams block juvenile fish from swimming upstream to reach the waters where they will spawn and live out their adult lives. Environmentalists have long voiced concerns about the destruction dams cause. This is where fish ladders come into play.

One of the most advanced fish ladders in the U.S. can be found at the Thompson Falls hydroelectric plant on the Clark Fork River in Montana. This is the first full-length fish ladder in the continental U.S. created specifically for bull trout, a threatened species. The $8 million, 72-foot-high (22-meter) ladder features 48 steps that the fish can ascend [sources: Holyoak, PPL Montana].

Fish traveling upstream are drawn to the small opening at the bottom of the ladder by water discharge. They begin their climb up the steel and concrete fish ladder, fighting against the current with each step. The 48 steps, or pools, are approximately 5 feet (1.5 meters) wide and 6 to 10 feet (1.8 to 3 meters) long, with openings at both the top and bottom. Eventually, the fish reach a 17-foot (5-meter) gathering pool followed by a holding tank. Once in the tank, scientists examine and tag the fish before releasing them above the dam [sources: Holyoak, PPL Montana].

Fish ladders don’t always perform as expected. A study from the University of Massachusetts Amherst discovered that only a small portion of fish populations are successfully navigating the dams observed in the research [source: Adams].

9: Helicoid Penstocks

Nature often holds the answer. At the close of the 20th century, when a hydropower engineer collaborated with a medical scientist, they developed a new method to increase the output of existing hydroelectric stations by nearly 10 percent [source: Piesold and Caro]. The breakthrough involved mimicking the spiral design of human blood vessels to create a similarly shaped penstock pipe.

The helicoid penstock resembles a rifle barrel with spiral grooves etched inside. As water flows through it, the rushing current spins like a bullet through the barrel. The spiraling effect directs the water flow precisely toward the turbine, enhancing its efficiency [source: Piesold and Caro].

8: Hydrosphere

It may sound theoretical, but inventor Rick Dickson is confident that his concept will prove effective in practice. His invention, a hydroelectric generator, harnesses the enormous pressure differences found in deep water bodies like lakes or oceans. He calls it a hydrosphere and believes it could produce up to 500 megawatts of continuous renewable energy [source: Scoop].

While Dickson has yet to build a prototype or obtain a patent, his hydrosphere is essentially an enclosed cylindrical hydroelectric dam that operates based on the pressure variations in ocean or lake water [source: Scoop].

7: Air-Water-Gravity Generator

The invention of the hydrosphere inspired Dickson to develop yet another concept, the Air-Water-Gravity generator, which he envisions as the future of hydropower. The AWG is a large, hollow cylinder filled with air and anchored to the ocean floor at different depths. Inside this cylinder, an electrical generator is housed. To generate energy, water is allowed to flow into the cylinder under immense pressure via a valve. The incoming water fills a vacuum chamber and forces a piston upwards along a stator, the static part of the generator, causing a rotor to spin. As the piston rises, it generates electricity [source: Free Press Release].

Once the piston reaches a metal stop at the top of the stator, it activates a valve that connects to a hollow snorkel pipe at the base of the cylinder. This pipe opens, letting air decompress, which forces the rotor to descend along the stator, generating electricity once more. Simultaneously, water is expelled forcefully from the cylinder through the snorkel pipe, shooting up to the surface like a geyser. Afterward, the release valve closes, the water intake opens again, and the cycle restarts. Depending on its size and its placement depth in the ocean, the AWG has the potential to generate up to half a gigawatt of continuous power [sources: Free Press Release, Beyond Fossil Fuels]. At the time of publication, the device had not been prototyped or patented.

6: Wave Power

The sound of waves crashing against rocky cliffs or a sandy shore can be quite calming, but did you know it's also a sound full of energy? Waves carry kinetic energy, which is the energy associated with motion. The power behind this motion comes from the wind and the ocean's natural forces [source: Union of Concerned Scientists].

Scientists and engineers have developed numerous technologies to capture the hydrokinetic energy produced by ocean waves. In fact, experts believe that if we were to harness just 15 percent of the energy along the U.S. West Coast, it could generate enough electricity to match the output of all the hydroelectric dams in the country [source: Union of Concerned Scientists].

5: Tidal Power

Have you ever swum in the ocean and felt the outgoing tide pull you away from the shore? The force of tides is immense, and there's potential to use this natural power to generate electricity.

In 2012, one of the United States' pioneering tidal power projects began supplying electricity to the electrical grid. Located off the coast of Maine, the project featured an underwater turbine built by Ocean Renewable Power Co. This turbine, which looks like a vintage lawn mower, is essentially an underwater windmill. Its foils rotate as the tide flows in and out of Cobscook Bay near Eastport, where the tides reach impressive heights of 20 feet (6 meters). This $21 million generator can power up to 30 homes [sources: Sharp, Woodard].

4: River Power

Building dams to generate electricity is becoming a thing of the past. Dams not only change the landscape but can also harm wildlife (remember the fish ladders?). What if we could tap into a river's power without the need for dams and reservoirs? A company in California, Bourne Energy, believes they have found a solution [source: Bourne Energy].

Bourne Energy's RiverStar system captures kinetic energy along the length of a river, rather than relying on a single dam location. Here's how it works: Engineers place multiple "modules" across the river, each consisting of a turbine, stabilizer, mooring system, and energy converter. These modules are held in place with high-tension steel cables, connected to each other in a grid. As the water flows through the turbines, they spin, harnessing the river's energy to power a generator. According to Bourne Energy, RiverStar can generate 50 kilowatts in a river with a water speed of 4 knots, without impacting fish migration or obstructing river traffic.

3: Vortex Power

In 2007, Michael Bernitsas, a professor at the University of Michigan, discovered how to tap into the kinetic energy of a flowing river by studying the movement of fish in water. This led him to create VIVACE, which stands for Vortex Induced Vibration for Aquatic Clean Energy [sources: Vortex Energy, Lafay].

Trout fishermen know that when fish swim together, they curve their bodies, creating small whirlpools in the water. The fish use these vortices to push themselves forward. VIVACE operates on the same principle. A series of cylinders are placed on the river or ocean floor, and as the current moves over them, it generates vortices that cause the cylinders to move up and down. Inside each cylinder is a magnet that passes over a metal coil, generating a DC current. VIVACE then converts this DC current into AC. Unlike other hydrokinetic systems, Bernitsas' design can harness energy from slower-moving rivers [sources: Vortex Energy, Lafay].

2: Pipe Power

Almost every town has its own system of water pipes, whether they're for sewer lines, freshwater, or wastewater. But what if we could harness the power of water flowing through these municipal pipes? A new invention has done just that.

An Israeli company called Leviathan has developed a water turbine that fits inside pipes. When water flows past the turbine, it generates electricity. The device, known as the Benkatina Turbine, works with water moving through closed pipes, including sewer lines, freshwater pipes, canals, and wastewater pipes from factories [source: Leviathan Energy].

1: Making a Splash

Imagine transforming your home into a small hydropower station. That's the vision of Fulton Innovation. The Michigan-based company has developed tiny hydroelectric technologies capable of powering electric radios, speakers, clocks, and TVs, all by harnessing the water flowing from your bathroom faucet.

The core of Fulton's Splashpower technology is a device called the Miniature Hydroelectric Generator. These generators generate electricity by utilizing the water flow in a house or building. Each time you run water through a Splashpower mini-generator, you can power sprinkler systems, emergency lighting, water softeners, and even camp lighting. These mini-hydroelectric devices can also charge batteries [source: Splashpower].