Clean Power

Published on March 15th, 2017 | by Tina Casey

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US Navy Wades In With Another Pitch For Low Cost Renewable Energy

March 15th, 2017 by  

The Trump Administration is no friend to renewable energy, but it seems that the US Department of Defense has other ideas. The Air Force is forging ahead with solar projects in California and New Jersey, and now the Navy is giving itself a big pat on the back for helping to develop a new device for harvesting ambient energy from rivers, tides, and ocean currents.

The Navy seems particularly excited about the potential for providing remote villages in Alaska with relief from the high cost of diesel fuel for heating and power generation.

The Challenge Of Hydrokinetic Energy

The new device is in the category of hydrokinetic energy systems. Like hydro dams, hydrokinetic systems use the flow of water to power turbines that generate electricity (wave power devices are in a related but slightly different slot).

The big difference is that conventional hydropower requires a lot of infrastructure to amp up water pressure. Hydrokinetic devices require no such thing. They simply use an ambient current to spin a turbine, so they could be anchored to a riverbed or tethered to a barge.

That’s not quite as simple as it sounds. Without the benefit of high pressure, hydrokinetic turbines spin relatively slowly. Combined with the need for durability and corrosion resistance, that adds up to an engineering challenge.

The Oceana Energy Company Spots An Opportunity In Alaska

The new device was developed by Oceana Energy, which describes itself as a “hardcore” technology company.

In a press release issued last week, the Navy described the role of its Naval Surface Warfare Center, Carderock Division in the renewable power project:

In a CRADA [Cooperative Research and Development Agreement] effort started July 2006, Carderock teamed with Oceana Energy Company to develop and test an in-stream hydrokinetic device to be used in coastal communities to harvest ocean currents, tides, or river flows.

Their effort led them to concentrate on this technology’s usefulness in remote communities in Alaska. According to a report released by Oceana, the remote nature of many of the communities in Alaska make energy a critical challenge with costs that can be 5-10 percent higher than grid-connected locations.

That thing about energy challenges facing communities in Alaska is somewhat ironic, considering the state’s robust fossil sector:

…The North Slope contains half a dozen of the 100 largest oil fields in the United States and one of the 100 largest natural gas fields. Alaska’s Prudhoe Bay field remains among the 10 largest oil fields in the nation…

All that abundance is counterbalanced, though, by transportation issues and other externalities.

According to the Navy, diesel and heating fuel goes for up to $10 per gallon in some remote communities.

Why Is This Hydrokinetic Device Different From Other Hydrokinetic Devices?

Oceana has high hopes for the new device and the Navy is not shy about taking partial credit for the innovation.

That’s because Caderock is home to the David Taylor Model Basin tow tank:

The basin is among the largest of its kind in the world, containing a shallow-water basin, a deep-water basin, and a high-speed basin. Using its sophisticated combination of towing carriages, wave-makers and measuring equipment, engineers are able to determine the sea-keeping qualities and propulsion characteristics of ship and craft models up to 40 feet in length.

The basin served as a test bed for the initial design of the new device. It sports a kind of double-decker blade design to boost efficiency:

…by including blades on both the inside and outside, the reaction loads on the ring tend to be balanced and generate more power. The device can then leverage the force exerted on it by the natural water flow in a river, thus allowing the turbine to generate energy.

The deployment of magnets to generate electricity also propels the new device into next-generation territory. Here’s the explainer from Carderock:

The rim itself is actually moving around so there’s a series of magnets in the rim that’s moving and coils in the stationary section, and that’s what creates the electrical power…It is simple magnetics — simple electrical generations technologies.

You can find more details on the Oceana website. As for the focus on the market potential in Alaska, Oceana produced a report that picks out all the juicy bits:

…the size and location of Alaska makes it the leading potential of hydrokinetic energy in the U.S. It is estimated Alaska has approximately 40 percent of the total river energy, 90 percent of the total tidal energy and approximately 60 percent of the total wave energy in the U.S.

Another factor is the location of remote communities that Oceana anticipates serving — they are primarily situated by rivers.

Err…Paging Scott Pruitt!

Another sign that the Department of Defense will not let up on the renewable energy course it charted under the Obama Administration comes from newly tapped Defense Secretary James Mattis.

The organization Pro Publica has just unearthed previously unpublished, written testimony submitted by Mattis to the Senate Armed Services Committee after his confirmation hearing, and he had plenty to say about the urgency of responding to climate change:

“Climate change is impacting stability in areas of the world where our troops are operating today…It is appropriate for the Combatant Commands to incorporate drivers of instability that impact the security environment in their areas into their planning.”

Here’s Pro Publica’s take on the subject:

Mattis’ statements on climate change, for instance, recognize the same body of science that Scott Pruitt, the new Environmental Protection Agency administrator, seems dead-set on rejecting. In a CNBC interview last Thursday, Pruitt rejected established science pointing to carbon dioxide as the main driver of recent global warming.

Hmmm…not sure who wins if EPA and DoD start brawling about climate change, so stay tuned.

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Photo (cropped) courtesy of Oceana Energy via US Navy.


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About the Author

specializes in military and corporate sustainability, advanced technology, emerging materials, biofuels, and water and wastewater issues. Tina’s articles are reposted frequently on Reuters, Scientific American, and many other sites. Views expressed are her own. Follow her on Twitter @TinaMCasey and Google+.



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