Offshore Persistent Monitoring

OPT LEAP PowerBuoy

This week, in one of the numerous Twitter feeds I follow was a story about Ocean power Technologies, a company in the USA, deploying  an Autonomous Power Buoy with US Coastguard support.

The buoy was deployed 35 miles off the coast and in 43m of water.

OPT LEAP PowerBuoy
OPT LEAP PowerBuoy

One of the problems with powered buoys, for those with payloads that need energy of course, is the means to generate that power. Those sufficiently close inshore can be powered by underwater cables with battery or small generators for backup. For lower power application solar panels are now well established in the market, the UK manufacturer Hydrosphere has an interesting web site with lots of information

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The largest data buoy, the 2 tonnes 3m DB 8000 in the Hydrosphere range has enough solar panels to supply 400W of peak power, similar to the Ocean Technologies system.

The US research is aimed at harnessing wave energy to eliminate the need for umbilical’s and costly to maintain batteries and generators whilst providing an alternative power source to solar panels that provides more space ‘topside’ for sensors.

Both wave and solar still need batteries and a power management system to ensure power is available when it is needed, rather than when it can be provided by either waves or the sun.

The buoy itself was an APB-350 Autonomous PowerBuoy which uses the same technology as the much larger Mk 3 and Mk 4 utility scale Power Buoys capable of generating power for export to the shore.

It might not surprise but one of the sponsors for this research programme is the Department of Homeland Security (Operative Research and Development Agreement ) with previous research funding supplied by the US Navy.

The previous research programme from the US Navy was equally interesting and the results showed greater than expected power generation and prolonged survivability in the highest sea states, including a full on encounter with Hurricane Irene.

This technology has two broad uses applications, self sufficiency and power generation. Scaling up produces a renewable energy wave energy harvesting system that is understandably getting most attention including trials off Scotland with a 150kw model and plans for the Cornwall Wave Hub

The US Navy has an interest in this technology for their Total Ocean Monitoring Enterprise programme, linking in with the deployable system mentioned above.

The simple idea is to use self sufficient buoys for detection of threats and provision of early warning using a string of buoys as a tripwire at a distance from areas that need protection, chokepoints, base areas, approach lanes etc.

RF Tripwire
RF Tripwire

Communicating via iridium satellite or 3G/4G mobile technology at for point to point communicating mesh networks the buoys can contain a number of sensors. All the usual suspects of ELINT, electro optical and sonar could be used but the main thrust of research has been to integrate transponder detection (AIS) with low power HF Radar, correlating the two together and with other sources to allow total surface situational awareness.

HF Radar is traditionally used for surface current and wave height monitoring, ice berg tracking and oil spill detection.

CODAR and Rutgers University are engaged with the research to use their radar systems for ship detection, identification and tracking. Trials are also underway using bistatic and multistatic sensors, separating the transmitter and receiver.

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The MoD currently has 220 aids to navigation and 110 heavy moorings that are maintained by Briggs Marine under a 15 year agreement contracted through Serco.

There are some interesting possibilities with this kind of system, persistent term monitoring and surveillance on a semi permanent basis is the obvious one, the Falkland Islands, mainland UK, Cyprus and of course Gibraltar. :)

As a deployable system, park one a handful of these offshore, mesh network them together and add in a combination of ELINT, AIS, HF Radar, acoustic and other sensors and you can monitor choke points, pirate activity and coastal shipping movements.

The US TOME project seems to characterise the potential very well in calling it an RF Tripswire.

Best thing about the Ocean Power Technology buoy, it fits into a 40ft ISO container, back of the bloody net!

OPT Autonomous Power Buoy
OPT Autonomous Power Buoy

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