Capturing energy from ocean waves converts the motion of the ocean into electrical energy using a new pump mechanism called the dynamic adaptive piston pump.

Dynamic adaptive piston pump insights

• Harnessing wave energy is made possible by a new type of pump mechanism dubbed the Dynamic Adaptive Piston Pump (DAPP).
• For this pump to work in the ocean, it can be installed in a buoy that takes wave power and turns it into electricity.
• Ocean waves have characteristics that make them ideal for power generation: reliable forecasts of high seas, predictable currents and dependable waves.

Anyone who has been on a windy beach or on the stormy seas has experienced the power of the ocean. That power has been a largely untapped energy resource—until now. New pump mechanisms will soon allow wave power to be converted into electricity, offering a new clean energy option.

How does a wave energy converter work?

Harnessing wave energy is made possible by a new type of pump mechanism dubbed the dynamic adaptive piston pump (DAPP), depicted in the graphic.

The DAPP system consists of an upper cylinder (a) and a larger lower cylinder (b) stacked vertically with a smaller movable cylinder (c) between them (Figure 1). When the movable cylinder shifts downwards, the pressure of the fluid inside forces the outflow valve (e) at the bottom of the lower cylinder to open, and the contents are expelled (Figure 2). With the lower cylinder empty, the pressure from the liquid beneath the unit pushes the outflow valve closed (Figure 3). Then, with the movable cylinder at its lowest position, more fluid flows into the upper cylinder. The pressure of the incoming fluid forces the valve (d) at the bottom of the movable cylinder to open (Figure 3). The internal redistribution of the contents causes the movable cylinder to automatically move back to its upper position and creates pressure to close the valve at the bottom of the movable cylinder (Figure 4).

For this pump to work in the ocean, it can be installed in a buoy that takes wave power and turns it into electricity. The device would need to be anchored to the seabed and feature a pre-tension system to pull the buoy downwards. Ideally, the buoy would be around 18 meters tall and 9 meters in diameter. Wave swells carry the buoy upwards. The buoy is forced back downwards by the stored pressure inside a pneumatic cylinder. The buoy’s up and down motion would then be converted into energy using a mechanical drivetrain, with gears that rotate relative to the bobbing movements.

The key components enabling wave energy harvesting include two medium-voltage motors (one to drive the test rig and a second to handle energy storage), as well as medium-voltage switchgears in the buoy that deal with the generated energy and powers the motors.

Although harnessing wave energy may sound futuristic, a ½ scale prototype has already had one successful test off the coast of Scotland. The next phase of testing is currently underway, which involves building a full-scale rig. The plan for later this year is to build a full-scale fleet of buoys and start generating wave energy in an electric power grid.

Advantages of wave power vs. other methods

Wave energy offers an attractive option for increasing clean energy production. Ocean waves have characteristics that make them ideal for power generation: reliable forecasts of high seas, predictable currents and dependable waves. This energy can be combined with wind and solar to yield a stable mix of clean power. While fossil fuels have had the advantage of being able to deliver power daily, wave power could give renewable energy the same reliability.

It’s essential to diversify clean energy sources. Although solar panels and wind turbines are making great gains, the International Energy Agency (IEA) reveals that more than 80% of the world’s energy is still derived from fossil fuels, a level that has been constant for decades. According to the NRDC, fossil fuels are responsible for land degradation, water and air pollution and other environmental harm.

Wave energy is a global solution. Conditions suitable for power generation can be found around the world, from Portugal to Polynesia, in regions where swells are created from multiple weather systems over a long period of time. These regions have the largest potential for generating wave energy, with little or no correlation to wind or solar conditions.

Ocean energy also eliminates the need for large structures on land, one of the main critiques of solar farms and wind turbine fields. Wave power creates stable electricity that is predicted to be one of the cheaper energy options in the long run.

Harnessing the power of the oceans

Advancements in renewable energy technologies have enabled fossil fuel energy alternatives. Yet clean energy sources such as wind and solar power are still heavily dependent on atmospheric conditions. The ocean’s currents are much more predictable and harnessing the movements of waves could soon become a reliable way to generate power. In addition to wind and solar, the new dynamic adaptive piston pump could allow the ocean’s currents to help reduce the world’s dependence on fossil fuels and create a cleaner future.

Randall Scasny is senior community content specialist, Newark. Edited by David Miller, Content Manager, Control Engineering, CFE Media and Technology, dmiller@cfemedia.com.

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Keywords: industrial pump design, sustainability

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