Friday, May 8, 2009

Turbines in the Water

In 2006, I saw a documentary at the Telluride Mountain Film Festival called “building the future – energy” which highlighted four innovative individuals making a difference to meet increased energy efficiency through technology. Or more pointedly, meeting new energy frontiers and advancements. I was struck by one person in particular whose class lecture the other day reminded me of:  Trey Taylor. He is capturing hydroelectric power that does not require a dam. He and his team are putting windmills, if you will, in rivers to capture the large amount of constant energy created by tidal movements. Even Dr. Webber mentioned the other day in class that the best “wave” energy is not caught on the wave’s surface. Well maybe these guys have it right. After two failed attempts to lower their devices into the east river (each previous attempt resulted in the loss of either a blade or other malfunction due to strong currents), they successfully placed these turbines in the East River in NYC. Currently, they generate enough power for a small convenient store/market in Manhattan.

To me, this is quite a feat. It might take many trails and years for it to be mainstream, but it works! And when I think about all of our cities in the US that are built on rivers – Pittsburgh, Boston, NYC, Cleveland, Portland OR, all the ones along the Mississippi, Denver, Newark, Boise, Atlanta, Cincinnati, others– the potential for this technology grows. And lots of our (US) rivers are dirty – too dirty to swim or recreate in so we may as well put them to other productive uses. And while not all river flows are created equal, any technological application (or “fix”) is best applied when done so contextually – that is, with a full understanding and respect for the local climate and context. But…the East River is more productive and efficient than the other rivers alluded to in the above list of cities since it flows both ways, meaning, it’s a tidal straight with fluctuating currents.

But this cannot be the silver bullet to urban energy issues. They’re expensive – the NYC project cost $7MM, and I wonder if people will say that fish get caught in them the same way people say windmills kill birds. (They are 16 feet in diameter). And though dams are often objectionable to environmentalist – for good reason, primarily the downstream impacts such as siltation changes and community displacement – these seemingly less intrusive turbines might not be so objectionable. Often when things are ‘invisible to us, they really are out of mind. For example, we don’t always think about our water pipes coming in and wastewater pipes going out of our houses until one of them breaks and becomes visible to us. 

The initial attempt that saw in 2007 in that movie failed, as did the second. But this past fall, NYC invested in a third attempt and now has 6 turbines rotate enough to generate electricity only about 77 percent of the time. But At full capacity, the 10 MW project could power an estimated 10,000 homes. Hmmmm…..not much of a dent for NYC, but every small step helps. Due to the so-far success of this third attempt (still by the same company, Verdant), NYC wants to eventually put in 300 of these turbines (which will also help Verdant get back the millions of dollars they lost in the first few attempts.  Part of NYC’s reason for this project is that they want to have 80% of their energy generated within the city – through any way possible: wind, solar, tidal. ). Perhaps we can catch up to Nova Scotia, Australia or France. Apparently in 2000, the idea of turbines in the east river was way too far-fetched as it was rejected by NY state senate; but times have changed and our culture is more aware and accepting of, and more ready for, alternatives – perhaps especially ones that are not visible to us. Once underwater, it’s not a noise, sight, or other nuisance to consumers. This invisibility (along with the other positive factors) could enhance the success of the project and make the East River pilot study the benchmark for implementing other projects in other cities. 


koh said...

That's and interesting place to harness power. I can't see rivers providing enough power to be a significant contribution to our energy consumption, but like you said, every small step helps.

What I do worry about is how these turbines would affect transportation; although they are out of sight and out of mind, they may interfere with shipping routes along the Mississippi River or other boats. If they decide to make them bigger, the turbine blades may very well stick out of the water when water level drops.

contango said...

Interesting post and neat technology.

In response to the comment above, current tends to flow strongest in the portion of a river/estuary that is deepest when you examine a cross section that is perpendicular to the direction of flow. This is partially a function of the way these rivers were "carved out" and a partially a function of fluid mechanics and the greater significance of boundary effects in shallow spots. I would think that this would mean that most of these turbines would be ideally placed in deeper portion of the river where navigational constraints would be less of an issue. In addition, I am sure that the naval architects in charge of these projects are smart enough to install these turbines in deep enough water so that no surface bourn craft (i.e. not a submarine) would interfere with the blades in the lowest conceivable water level scenario. Unless, of course, they got their Naval Architecture degree from A&M-Galveston.