Energy

Simpler, cheaper renewable energy system uses waves to inflate rubber

A prototype DEG (left), at the University of Edinburgh's FloWave Facility
A prototype DEG (left), at the University of Edinburgh's FloWave Facility
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A prototype DEG (left), at the University of Edinburgh's FloWave Facility
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A prototype DEG (left), at the University of Edinburgh's FloWave Facility
An illustration depicting a shore-based full-size DEG
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An illustration depicting a shore-based full-size DEG

Although we've seen a number of experimental wave-power systems in recent years, a new one is claimed to be less expensive and to incorporate fewer moving parts, while still remaining durable in rough seas. It's known as a Dielectric Elastomer Generator, or DEG for short.

The prototype system was developed by scientists at Scotland's University of Edinburgh, and at Italy's Universities of Trento, Bologna and Scuola Superiore Sant'Anna Pisa. It basically consists of an anchored vertical cylinder which a column of air is trapped inside of. The top of the cylinder is sealed with a rubber membrane, while the bottom is open to the surrounding ocean.

As the crest of a wave passes around the device, it forces water up inside of the cylinder. This pushes the trapped air up, causing the membrane to expand. Once the device is in the trough of the wave, the water level inside the cylinder drops – this causes the membrane to be sucked down, as negative pressure is created inside the DEG.

Because the rubber incorporates layers of dielectric material, it generates voltage both as it puffs out and as it's pulled down. "The membrane is charged at its maximum inflation or deflation, it is discharged at the rest position," U Edinburgh's Prof. David Ingram tells us. "So energy is generated both from the wave crest and the wave trough passing the generator."

An illustration depicting a shore-based full-size DEG
An illustration depicting a shore-based full-size DEG

In a commercial version of the system (illustrated above), the resulting electricity could be relayed to shoreside communities via underwater cables. A small-scale prototype has already been successfully tested in a wave tank at the university – based on its performance, it is estimated that a full-size device could generate the equivalent of 500 kilowatts of electricity, which would be enough to power about 100 homes.

It is hoped that within a matter of decades, "fleets" of the DEGs could be deployed in areas such as the Scottish coastline, where powerful waves are plentiful.

A paper on the research was recently published in the journal Proceedings of the Royal Society A.

Source: University of Edinburgh

13 comments
paul314
If these membranes are durable, that would simplify wave generators enormously. The ones in development now have lots of moving parts.
Andreas Buechel
https://www.ed.ac.uk/news/2019/device-could-deliver-wave-energy-to-thousands "(...)Engineers say that their design could be used in fleets of low-cost, easily maintained structures at sea within decades, to take advantage of powerful waves in Scottish waters.(...)" --------- as i understand this .... the "within decades" is meant to express the durability of the structures with me is the hope that in times where .... emission-free till 2030 ... is a goal worth to aim for, that in such times with great wishes of the people for effective change and also at the same time many a invention ready at this very moment to be upscaled and installed in massive dimensions .... that it surely will not need decades to replace toxic nuclear fisssion plants with such beautifull and elegant devices
Deres
The issue is that wave energy is mainly linked to the Wind power. Thus such a device would globally have the same intermittency as a Wind generator ... As the renewable énergies are intermittent, the safest way to use them is to have completing énergies to always have minimal power. This device does not provide this advantage it seems.
watersworm
"Afullsize device = power 100 homes (heating and colling includes ?)" OK, what is the size of the "full size device ? What about countries without shorelines (sorry for the stupid question) ? Except these "tiny" points, good idea (in decades?)
PAV
Less moving parts is good. Durability of rubber is questionable. Rubber elasticity changes with temperature, humidity and age (fatigue). I wonder what the life span of this giant membrane is, and the cost to replace it. What's the carbon footprint for the manufacturing of a membrane that size?
RangerJones
I can imitate wave technology with a blower and a pump and do it as many times a day as I choose for 1/10th the money as i operate them off the electricity I'm producing.
Neil Farbstein
500 kilowatts is a ridiculously small amount of power. 5 100 watt lightbulbs. Might be misprint.
AlBerard
And WHAT is the cost of a full size unit all installed and how long is the payback period .
Expanded Viewpoint
Yes, methinks that someone needs to do a cost/benefit ratio analysis on this device, and please don't forget to factor in the cost of manufacturing and maintaining it too! A much simpler and durable iteration would be a metal buoy that bobs up and down and use that motion to spin a generator directly, then use the power to charge up a battery. The degradation of the rubber membrane due to UV light could make it less than attractive as a replacement for what we have now. Randy
ljaques
I really like that quiet concept. Existing wave and tidal generators are extremely noisy and rile (or even damage @ 118-152dB) the lives/bodies of nearby sea creatures. Quiet generators are a godsend to the sea. I'll bet these things could be added to most seagoing ships to power lighting, accessories, etc.
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