California wind energy and nutrient upwelling

The West Coast of the North American continent is remarkable for a lot of reasons. Among them is what is called the California Current System. There are only a few other areas on our planet where this sort of water transport occurs, but in California, due to a number of hydrodynamic factors, this current, interacting with the onshore winds, induces a deep, cold-water upwelling, which brings a rich mix of nutrients up from the abyss off the Western Continental Shelf.

This system promotes such fecundity – with such diverse food and feeders, that the California coastal waters have been called “The Serengeti of the Pacific.” It is not just all of the species of fish that feed off of this upwelling – from sedentary rockfish to migratory tuna, along with all manner of forage fish and pelagic invertebrates, it is also the Blue, fin, minkes, and humpbacks, who are feasting on all of this biota.

And then there are all of the toothed whales – dolphins, porpoises, beaked whales, and orcas, and their respective prey; and the variety of pinnipeds – from California sealions, and fur and elephant seals, all in the trophic pyramid feeding off the nutrients brought up from the deep. And then the birds…

And to get an idea about how productive this upwelling can be, a single blue whale can consume up to 16 tons (12% of its body weight) of krill per day! So when 40 blue whales were recently feeding off the coast of San Francisco for a couple of weeks – this gives you an idea of the volume of nutrients brought up from the upwelling.

I bring this up because of a paper that came across my screen a few weeks back that evaluated how windspeed is reduced by the turbine blades pulling energy out of the wind. In this paper, they indicated that windspeed could be reduced by 42%-50%. I read this just prior to a workshop I attended by the California Energy Commission, wherein they mentioned that while they were planning on building out 10 Giga-watts of wind capacity by 2030, the projected capacity of California offshore wind harvesting could be 200GW.

Understanding that all of that power comes out of the energy of the wind, 200GW is not trivial. 10GW is not trivial. So I read up on this to find who has been modeling the energy harvesting impacts on the upwelling.

I’ve looked into four different models, and they vary significantly, but just taking the more conservative California Ocean Protection Council model “found that modest changes to wind speeds … found in the lee of wind farms (approximately 5 percent reduction), which leads to an approximately 10-15 percent decrease in upwelled volume transport and resulting nutrient supply to the coastal zone.”

Even if the transfer function between upwelling and nutrient delivery was linear, this would mean that the California Current System would support 10%-15% less life than it currently does. This is not trivial either.

So what can be done? Amory Lovins of the Rocky Mountain Institute maintains that the cheapest, most abundant, and easiest energy supply available is reduction in use.

There are all manner of ways that this could be accomplished, but the first step would be getting energy conservation into the conversation.