Supported by the German Federal Ministry of Education and Research Silicon sheets harvest electricity from ocean waves EPoSil consortium presents first demonstrator model

  • Climate-friendly technology for renewable energy
  • Huge economic potential
  • Four companies and two universities join forces
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  • July 29, 2013
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press release

Stuttgart – Eco-friendly electricity from wave energy: in a Bosch laboratory, a first demonstrator model shows how wave energy can be converted into electricity. A research network made up of four companies and two universities aims to establish sustainable power generation along the world’s coastlines. Until January 2015, the German Federal Ministry of Education and Research is supporting this project, known as EPoSil (electroactive polymers based on silicon for power generation), to the tune of nearly two million euros. This grant is part of the “smart materials for innovative products” program.

Huge potential
Waves are a huge potential source of energy – 29,500 terawatt-hours a year, according to calculations by the United Nations. By comparison, the International Energy Agency reports that some 21,500 terawatt-hours of electrical power were generated worldwide in 2010. EPoSil hopes to unlock this reserve of renewable energy. To quote a report on ocean energy by the UN Intergovernmental Panel on Climate Change: “Ocean energy has the potential to deliver long-term carbon emissions reductions.” This is a view shared by the German Federal Transportation Ministry is its “ocean development plan.”

The consortium members
A number of expert partners have come together to exploit wave energy: Wacker Chemie AG supplies a silicon-based material. This is an essential part of the electroactive polymer that converts mechanical energy into electrical power. The project is coordinated by Bosch, together with its subcontractor Compliant Transducer Systems. The Technical University of Darmstadt is developing a method for testing the electroactive polymers. A scale model is to be tried out in the wave canal of the Technical University of Hamburg-Harburg. The systems for testing the generator units are being developed by Ingenieurbüro Brinkmeyer & Partner in Winnenden, near Stuttgart. Bosch Rexroth is supporting the consortium by constructing the models.

Converting wave energy
The energy converter is basically a three-ply sheet. The top and bottom layers are conductive to electricity, i.e. they are electrodes. The middle layer is made of extremely elastic silicon, which has pronounced isolating properties. Even under industrial conditions, this can be manufactured at a constant thickness. The movement of the waves exerts a mechanical force on the converter (sheet). Initially, the upward movement of the wave compresses the silicon. As a result of this compression of the middle layer, the distance between the two electrodes is reduced. A tiny electrical current is applied from an external source, positively charging one of the electrodes, and negatively charging the other. As the wave begins to fall, the force acting on the converter decreases. The silicon relaxes and returns to its original thickness. The distance between the negatively and positively charged electrodes increases. This effect leads to an increase in electrical power in the converter. The result is that the mechanical energy of the wave has been converted into electrical power. This power is harvested, and the cycle begins again.

A stack of sheeting
Technically, there are several ways in which the three-ply sheets can be compressed by ocean waves. To give a simple example: imagine a buoy made up of two parts. The upper half floats on the ocean surface, the bottom half is firmly anchored to the ocean floor. The two halves are connected to each other by a stack made up of thousands of sheets. Every 3 to 10 seconds, these sheets are deformed by the movement of the waves. “The electrical current from one individual layer is minimal, but when it is multiplied by a thousand or more, it soon adds up,” says Dr. Istvan Denes, who works for Bosch corporate research and advance engineering in Waiblingen near Stuttgart. In a next stage, an array of several converters will generate electricity. Denes uses a demonstrator model, developed by the TU Darmstadt, to show that this works in dry runs in the laboratory.

Test in the wave channel
The first true-to-scale model of a wave-power generator is slated to be launched in the wave channel of the Technical University of Hamburg-Harburg in 2014. Looking further ahead, the plan is to have commercial wave-power generators compressing and relaxing again tens of millions of times. The target efficiency for converting mechanical energy into electrical power is 50 percent.

Background information on the internet
- UN IPCC on the potential of ocean energy:, see pdf page 504
- IEA report on power generation:, see pdf page 27
- “Ocean development plan” of the German Federal Transportation Ministry:, see pdf page 29

The parties involved
German Federal Ministry of Education and Research:
Robert Bosch GmbH:
Wacker Chemie AG:
Ingenieurbüro Brinkmeyer & Partner:
TU Hamburg-Harburg:
TU Darmstadt:
Compliant Transducer Systems:
Bosch Rexroth:

The Bosch Group is a leading global supplier of technology and services. It employs roughly 375,000 associates worldwide (as of December 31, 2015). The company generated sales of 70.6 billion euros in 2015. Its operations are divided into four business sectors: Mobility Solutions, Industrial Technology, Consumer Goods, and Energy and Building Technology. The Bosch Group comprises Robert Bosch GmbH and its roughly 440 subsidiaries and regional companies in some 60 countries. Including sales and service partners, Bosch’s global manufacturing and sales network covers some 150 countries. The basis for the company’s future growth is its innovative strength. Bosch employs 55,800 associates in research and development at 118 locations across the globe. The Bosch Group’s strategic objective is to deliver innovations for a connected life. Bosch improves quality of life worldwide with products and services that are innovative and spark enthusiasm. In short, Bosch creates technology that is “Invented for life.”

The company was set up in Stuttgart in 1886 by Robert Bosch (1861-1942) as “Workshop for Precision Mechanics and Electrical Engineering.” The special ownership structure of Robert Bosch GmbH guarantees the entrepreneurial freedom of the Bosch Group, making it possible for the company to plan over the long term and to undertake significant up-front investments in the safeguarding of its future. Ninety-two percent of the share capital of Robert Bosch GmbH is held by Robert Bosch Stiftung GmbH, a charitable foundation. The majority of voting rights are held by Robert Bosch Industrietreuhand KG, an industrial trust. The entrepreneurial ownership functions are carried out by the trust. The remaining shares are held by the Bosch family and by Robert Bosch GmbH.

Additional information is available online at and,

PI8222 - July 29, 2013

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