An innovative wave-energy generator (cheap, easy, and reliable)

[krispos42]

I caught this article in Machine Design magazine. I wanted to share it because previously I had only heard of wave-driven power generation as scaled up, buoyant versions of those shake-powered flashlights.

This design uses a float attached to two water pumps. A field of floats woud pump massive amounts of seawater at moderate pressures through PVC piping to an on-shore generating station and through a turbine before being returned back to the ocean.

All the wiring would be located on land, with the hardware underwater being make of corrision-resistant materials such as PVC, stainless steel, concrete, bronze, and titatium.

Electricity From Ocean Waves

March 3, 2009
A novel design puts a spin on conventional hydroelectrics to harvest energy from the sea.

In recent years, there has been an increasing emphasis on sustainable-energy sources as part of ongoing efforts to combat climate change. The greatest success in the history of sustainable energy is hydroelectric power, which has been performing reliably for over 100 years. And more-recent technology effectively harnesses wind power, both on land and offshore. In fact, the use of wind power is now so widespread, it is easy to forget how recently the technology became acceptable for generating electric power. The question arises as to why a similar exploitation of the energy of ocean waves has not happened, a principal focus of this article. Also emphasized are the similarities between hydroelectric power and wave power, the principal connection being that water can be stored. A new wave-power device illustrates these similarities.

<snip>

The Glenbower Wave Pump uses the heaving action of ocean waves to pump seawater to shore, where it is passed through conventional turbines to generate electric power before being returned to the ocean. The system may include onshore water storage to provide continuous operation, particularly where topographical conditions are favorable. The equipment consists of a series of wave-pump assemblies and pipework to deliver the water to shore under a pressure suitable for power generation on dry land.

A single wave-pump assembly consists of the following components: one float; four horizontal anchors connected to the float by mooring lines; two vertical anchors located directly under the float, two reciprocating pumps connected between the float and the vertical anchors; two surge tanks, one sitting on each of the two vertical anchors; a discharge pipe to carry the water to shore, and a small air pipe to supply pressurizing air from shore to the pump assembly (See “Wave-pump assembly” illustration).

The float is fabricated from mild steel, or from a light, corrosion-resistant material such as fiberglass. Since the float is also used to increase the surge-tank volume, it is designed as a pressure vessel and hence is depicted as a cylindrical vessel with spherical ends. The four mooring lines permit vertical movement of the float, as well as limited horizontal movement — the upwind lines being typically taut and the downwind lines being slack.

The pumps are a reciprocating type, not unlike a traditional hand-cranked pump. The connection at each end of the pump permits rotation about both horizontal axes. This lets the float respond to the random action of the waves, and also ensures that the pumps remain in pure tension or compression under the loading imposed by the rising and falling of the wave. The configuration of the pumps is generally similar to that of conventional air or hydraulic cylinders, except the rod is hollow and is used as the discharge pipe to convey the pumped water into the surge tanks.

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http://machinedesign.com/article/electricity-from-ocean-waves-0303

According to the article, the floats would be 10' in diameter and 138' long, or 3 meters by 42 meters. The pump pistons would be almost 8 feet in diameter. They have calculations in the article for a couple of different scenarios that have a single float pump making over 360 horsepower. Of course after friction losses and turbine-conversion losses and such you'd probably only get maybe 100 HP out of the process but that's 100 free horsepower. About 75 kilowatts. No pollution, no carbon dioxide, just cheap energy.

[poverlay]

1. Wonderful! I don't see much reason why the ocean can't provide the majority of the world's

electricity with a negligible amount of ecological impact. Plus that whole "what do we do at night for solar and what to do when the wind doesn't blow?" question is a terrific non-issue.
I love wave power!

[krispos42]

2. Until I read this, I thought it was impractical

Putting all the electrics in the seawater, then all the other components to turn very-low-frequency (0.15 hertz) and probably low-voltage AC power into standard 60-hertz, high-voltage AC seems very expensive and prone to continuous maintenence. I think you'd have to convert the ocean-created AC to DC, then back to line AC.

This is just a wave-powered water pump, and you use the water power like you'd use regular hydroelectric from a dam!