Accession Number:



Frictionless Linear Electrical Generator for Harvesting Motion Energy

Descriptive Note:

Final rept. 11 Feb 2003-11 Nov 2004

Corporate Author:


Personal Author(s):

Report Date:


Pagination or Media Count:



A key limitation in a buoy-based oceanographic monitoring systems is the lack of a reliable power source with long operational lifetime. Battery packs suffer from the replacement cost and inconvenience. Traditional renewable energy devices do not fully address the need due to their poor performance in the hostile marine environment e.g. solar cells or size and cost e.g. OWEC systems To fill this important niche, we have developed a new technology that combines the uses of an ultra low friction surface treatment with an efficient linear generator. The small device can be deployed anywhere on the ocean surface without anchoring to the seabed. The friction between the sliding magnetic stacks and the inner wall of the generator is negligibly low. This not only reduces the frictional loss but also increases the system sensitivity to capture energy from the slightest movement. As magnets slide across induction coils in a tube, random AC outputs are produced. They are then rectified and regulated into stable DC output to charge a battery with an overall net efficiency of over 50 over a wide temperature range. Small prototype devices have been field-tested at near shore under mild wave conditions to produce close to 1 Watt of power and it can be scaled up to higher power capacity. The completely sealed structure makes the system corrosion resistant. The ultra low friction surface and simple design make the device mechanically robust without any sign of mechanical degradation after months of continuous operation.

Subject Categories:

  • Electric Power Production and Distribution
  • Physical and Dynamic Oceanography

Distribution Statement: