An Alternate Current Spinning in the Electronic Media Stream

New ideas and technologies are by their very natures controversial.  Some, like pharmaceuticals, undergo years of testing before their approval for human use, and even then may have unanticipated side effects that only emerge with time.  Others - such as the present sub-prime mortgage debacle - may be widely adopted in a wave of what Allen Greenspan famously termed "irrational exuberance", despite their fatal flaws.  Our tolerance for risk and uncertainty plays a huge part in determining who will be an early adopter and what negative impacts society is willing to absorb; see the renewed interest in nuclear power pitched as a means of offsetting greenhouse gas emissions for an example of this phenomenon.

To take but one example, it may well be that producing clean, renewable energy is of greater global value than preventing the localized environmental impacts such installations may entail.  On the other hand, those impacts may be deemed unacceptable by those who experience those impacts or when what is sacrificed for the greater good is also perceived as a great loss. In addition to your own proximity, where you fall out in this debate has a great deal to do with what you value, the importance you place on specific outcomes, and the information available to you that mitigates or exposes negative impacts.  For most of us, that data comes from the electronic media stream, and what we conclude from it depends on how well we can critically navigate its prevailing currents.

Consider Marine Current Turbines, an emerging alternative energy technology and also name of a company producing experimental electrical generators powered by tides and strong underwater currents.  The idea is initially attractive to me, a conservationist concerned about our dependence on old, polluting energy technologies.  It has the potential to produce renewable energy in commercially viable quantities, has a lower visual profile than wind power installations and the turbines do not impact waterfowl flyways.  So what's not for me to like?

If you search for "marine current turbines" on-line, you quickly find the company's website and a Wikipedia entry that on closer inspection proves to be nothing more than an advertisement written by the company itself.  As a story on NPR's Morning Edition highlights this morning, manipulation and even outright sabotage of Wikipedia entries by interested parties is not only widespread, it can often be tracked directly to the computers of those putting their own spin on the article.  There was no attempt to hide the origin of the Marine Current Turbines entry, making reference as it does to "our belief that the technology does not offer any serious threat to fish or marine mammals (emphasis added)."  In a way, I appreciated the unsophisticated approach taken to get the company's message out in a manner that becomes transparent to a critical consumer of these data.  A lot depends on the skepticism of the reader, however.  If you were searching, as I was, for information on the environmental impacts of this experimental technology, this entry raises a red flag. If you are favorably predisposed toward this technology, perhaps the Wikipedia entry makes it easier for you to support.

I was interested in the potential impacts because spinning turbines do indeed impact marine life and I wanted to know how that was addressed with this new technology and whether the benefits of such renewable energy generation clearly outweighed any negative consequences for the near-shore marine environment.  Here is what I learned and where I had to go to learn it.

The Wikipedia entry, clearly posted by the Marine Current Turbines company about itself and its technology, has this to say about environmental impacts:

"Environmental Impact Analyses completed by independent consultants have confirmed our belief that the technology does not offer any serious threat to fish or marine mammals. The rotors turn slowly (10 to 20 rpm) (a ship's propeller, by comparison, typically runs 10 times as fast and moreover our rotors stay in one place whereas some ships move much faster than sea creatures can swim). The risk of impact from our rotor blades is extremely small bearing in mind that virtually all marine creatures that choose to swim in areas with strong currents have excellent perceptive powers and agility, giving them the ability to successfully avoid collisions with static or slow-moving underwater obstructions."

Further down the page, it notes:

"It is expected that MCT's turbines will generally be installed in batches of about 10 to 20 machines. Many of the potential sites so far investigated are large enough to accommodate many hundreds of turbines. It is worth noting that as a site is developed, the marginal cost of adding more turbines and of maintaining them will decrease, so considerable economies of scale can be gained as the project grows."

Let's pause a moment and test some of these assumptions.  These statements indicate that the impacts on marine life from fixed turbine installations compare favorably to ship propellers, the implication being that society tolerates these impacts and they are much worse.  This is a spurious comparison.  Ship rotors and outboard motors do take a toll on large marine mammals near the surface.  On the other hand, "marine creatures that choose to swim in areas with strong currents" do so out of a strong instinctual preference for these conditions.  Running a gauntlet of turbines, installed in batches of 10-20 at sites able to accommodate many hundreds of rotors, may be unavoidable for a wide array of marine life that utilize these underwater corridors.  I would certainly want to see studies of population dynamics and simulations of the response of a shoal of fish to a bank of large rotors turning once every 3-6 seconds before I made such claims of negligible impact.

There are relatively few sites that have both strong currents and appropriate depths to erect the steel columns for marine turbines.  There are many more places where the rising and falling tide would provide the power for power generation.  Marine Energy advocates stress the positives, but full environmental impact studies have yet to be done.  The University of Strathclyde in an assessment of the benefits and constraints of Marine Current Turbines or MCTs, makes a rather contradictory statement when it concludes on the one hand that risk to marine creatures "is unlikely because small and medium sized creatures would tend to be pushed out of the way by the blades (due to fluid dynamics) and larger mammals, such as seals, whales and dolphins, are known to avoid ships and ships propellers and could be expected to exhibit that same behaviour with MCTs", and then goes on to say that a ship's propeller "is a far greater hazard as it rotates at far greater speeds, e.g. up to 10 times faster, and it is attached to a moving vessel that may travel faster than the fauna."   So then marine creatures don't avoid propellers as was previously asserted?  This is why the comparison to ship rotors doesn't wash.

The report does offer a number of other potential impacts of marine current turbines, including seismic surveys and blasting prior to installation; localized disturbance of the seabed; sediment displacement for cable installation (including any contaminants present); scouring around the base of the pile affecting seabed morphology; possible discharge of oil from the gearbox or pollution from the anti-fouling paint used to prevent bio-fouling, co-occurring marine resources, rare species, etc at the generation site;  and impacts on current flow and coastal processes because an oversized scheme could act as a barrier to the oncoming current.  It goes on to say:

"The exact environmental impact of a Marine Current Turbine has not yet been assessed therefore it is not possible to quantify the exact impact an array of turbines may have on the ecology, environment and existing users. However, installing a monopile-mounted 16-metre diameter turbine in water up to 50 metres deep, would inevitably have some impact, possibly negative or positive on the surrounding environment. The level of impact would be determined by the quantity of units installed and the packing density.

The second strategy, which selected the maximum number of units that could be installed thus maximising the storage required, would result in maximum environmental impact. The first strategy, which compromised the number of installed units with the aim of reducing the storage required to an acceptable level, would have a less impact."

The take away message here is that there are a number of things which might or might not happen as a result of building and operating a marine current turbine array at any given site and more study is needed.  I can live with that, as far as it goes.  But how far are we willing to go to determine that the predicted impacts are within acceptable levels?  There is tremendous economic pressure to develop viable alternative energy technologies and the field is getting hotter all the time.  Too much delay and you will be scooped by a competitor and climate change won't wait for technology to catch up.  Not enough thoughtful study and there may be impacts that we come to regret down the road.

I remain intrigued by the technology and what I have read about it in the prevailing electronic media stream.  But I am wary of its source, and continue to look for independent verification of untested claims stated as fact.  The US Marines have a leadership principle that states; "Aim for the 70% solution."  In this case, we are not quite there yet.

Comments

[charlie crystle]

well said, Tim.

[GreenmanTim]

Thanks for your kind words, James, and for the link to your work that I look forward to reading. I would much prefer we make informed choices, and this is particularly critical with new energy technology. I find that many of my fellow conservationists struggle with wanting to support clean renewable energy in theory but unable to accept its localized impacts. Those sites that could impact migration corridors are even more difficult to endorse. I have previously written about marine wind turbines and conservation values here: http://greensleeves.typepad.com/berkshires/2007/05/blowing_in_the_.html

[James Aach]

As an engineer who works in the power field (nuclear) I'd have to say your blog's account of marine turbines was rather a breath of fresh air - asking good questions while not dismissing the possibility they might have some value.

If you'd like a unique look at the good and bad of nuclear power from the inside (it's much different than what most proponents or opponents portray) see my novel "Rad Decision", which is posted free at my website http://RadDecision.blogspot.com and is also in paperback. Stewart Brand, founder of The Whole Earth Catalog, has been kind enough to endorse it. One area I tried to explore echoes your comments on how people make decisions on risk vs. reward. Nature's checkbook is hard to balance, and there are never perfect answers in the energy biz - -just choices.