Avian Mortality in Perspective

There are a lot of forces arrayed against renewable energy.  Some are well meaning and many are not.  Clearly there is an enormous fossil fuel industry effort to discredit any threats to their dominance.  As data emerges, renewables are looking better and better.  Two numbers offer a good starting point for perspective.

  1. Human death’s by autos in the US exceeds 32,000 annually.
  2. According to this 2005 study, human caused avian mortality (not including habitat destruction) was about 1 billion (10^9  birds per year.)

One project that has received a lot of attention is the 377 MW Ivanpah “power tower” in California.  This project is relatively unique as a solar energy source due to its ability to store energy for night time use.  However concerns have arisen due to the high operating temperatures of the system and early avian mortality.  In its first year of operation the upper bound for total avian mortality from known and unknown causes was just under 3,500 or about 1/10 th the number of human fatalities in auto accidents and 1 / 285,714 the total human caused avian mortality.  This post offers considerable information on Avian mortality at Ivanpah.  While it is put out by the Brightsource (the company running the facility) it should be noted that it references independent sources extensively.

Recent developments in power tower operations are encouraging in terms of dramatically reducing avian mortality.  This article about the Crescent Dunes project reports on operational changes that dramatically reduce avian mortality at power tower sites.  Initial reports are that avian mortality was eliminated.  While useful conclusions await independent verification this is encouraging news.  Further,  while avian mortality is an important issue, when put in perspective and compared to other sources of human caused bird death, it would appear that the cost benefit trade-offs are not show stoppers.

There is enough data to come up with an upper bound.  If we were to get all of our electricity (about 650 GW) from power towers we would need about 6500 Ivanpah sized facilities.  If they all killed birds at a rate of 3,500 per year then that would amount to roughly a 22% increase in avian mortality.  However, a more careful read of the literature shows that fewer than 1500 deaths definitively attributable to burning.  Which suggests less than a 10 increase in bird deaths.  And the industry is aggressively pursuing means to reduce avian deaths.  Early Crescent Dune data suggests that it may be a solved problem.

Recall that the power tower technology includes storage so it will dramatically reduce the need for natural gas generation.  An optimist would anticipate that mitigation measures could substantially decrease avian mortality, possibly eliminating it.  But in a worst case scenario we would see a 22% increase in anthropogenic avian death’s traded for elimination of CO2 production in electricity generation.  If climate change goes unchecked, human caused avian mortality will be dwarfed by rapid environmental shifts so this would appear to be a good trade even in the worst case scenario.

This is a nice graphic on avian mortality.



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