by Mary and Vince Palermo

A group gathers under one of Tessera’s Sun Catchers.

A group gathers under one of Tessera’s Sun Catchers.

Monday, December 6, at the Saguache County Courthouse the final public hearing on the Tessera proposal to build a solar plant will be conducted.  It will begin at 2pm with a presentation by Tessera followed by public comments.   The Commissioners plan to be there until 7pm to hear from County residents.  Be aware, you won’t get to vote—only speak.  There will be only three votes at a later date cast by the Commissioners, but you will be heard and this is your opportunity to let them know where you stand on this issue.  And this issue is a big deal with lots of controversy.

The proposed Tessera solar electric plant would be on County Road T, west of State Highway 17.  It is planned to consist of 5,728 SunCatchers, each generating 25 kilowatts with a total generating capacity of 145 megawatts.  To those not familiar with the SunCatcher, it is made of a 35-foot-diameter curved mirrored disk, which focuses the heat of the sun on a Sterling engine.  Each 4-cylinder engine turns an electric generator to make electricity from the heat.  And this is the cause of our principal controversy.  Those 22,912 cylinders each have a piston going up and down making what has been described, be those who have seen them in action, as an harsh, irritating, mechanical noise.

There is only one Tessera plant in existence, which consists in

of 60 SunCatchers and it is located Maricopa County in an industrial zone near Phoenix, Arizona.  We visited that plant in September and got lots of information, listened to the SunCatchers, and also measured the noise of the SunCatchers.  We measured the noise levels outside the fence line because we were not allowed to take sound level measurements within the SunCatcher field.  How loud is it?  Pretty loud—75 decibels outside the fence is equivalent to noise from a busy, 4-lane highway.

A little understanding of decibels will help to grasp the noise numbers.  Decibel is the technical measure of the energy in the vibration of air we call sound.  A sound meter acts like the ear and gives numbers to the loudness of sound.  Decibels don’t add up; the numbers actually multiply sound energy the same as the ear responds to sound.  Example:  25 dB (decibels) plus 25dB equals 28dB, not 50dB.  25 decibels is very quiet, like the wonderful experience we have out here in a meadow or in the forest.  55dB is  average city noise and is 1,000 times the sound energy of  25dB.  75 decibels is 100,000 times the sound energy of 25dB, and is loud and uncomfortable.

We measured ambient sound in the Baca/Crestone area in 2008, and found our ambient sound to be 20 to 25 decibels when a car is not nearby nor a plane overhead.  That is very quiet. We recently measured ambient sound at the proposed Tessera project site on Road T.  We found it to be at least as low as 27dB—equally quiet.  We live in a county blessed with a soundscape that promotes wellbeing as well as enjoyable experiences.

Several Saguache County residents, including us, recently visited the Tessera Maricopa plant.  To repeat as we stated above: at noon with the sun shining we measured a noise level of 75dB outside the fence line.  This sound was not only loud, but it was also an unpleasant noise.

Tessera published two noise studies:  the first in June, 2010, proposed 8000 SunCatchers.  They stated in the study that 8000 SunCatchers would produce 41 to 52dB at the fence line here in Colorado.  That is 133 times the number of 60 SunCatchers in Arizona.  They also stated it would produce 20dB less noise!  Question:  Will 133 drums, all beating at the same time make less or more noise than one drum beating?  The answer is so obvious, but their sound expert states that 8000 Suncatchers make less noise than 60.

When Tessera realized there were people in  Saguache County who understood their language, they came back in September with a proposal for 5,728 SunCatchers.  This moved the SunCatchers back 500 to 600 feet from the fence, using scrubland as a sound buffer and noise mitigation.  Now, they said the noise at the fence would be 55dB—not meeting the Saguache County Guidelines, but complying with the Colorado State ordinance for residential.  Careful study of their sound graph reveals that they believe 5,728 SunCatchers produce a noise level of 65dB at the edge of the SunCatcher field (the outside row, equivalent to the fence line in the previous proposal).  Same question: does 5,728 SunCatchers here produce less or more noise than 60 SunCatchers in Maricopa?  Same answer.  I, Vince, estimate the noise level at the outside row of  SunCatchers to be between 80 to 85dB.  Allowing 15 to 20dB of sound decay due to the setback, it looks like noise level at the fence will be at least 60 to 65dB—which does not meet the Colorado State residential ordinance, or the Saguache County Solar Guidelines.

We feel that Tessera technology is not appropriate for Saguache County.  It will destroy our long-valued quietude, the SunCatchers would be heard for miles on a calm clear day, and there will be unhappy residents.    This is not the last opportunity for renewable solar energy in Saguache.  There is already another proposal utilizing a different technology, and there will be many more solar developers wanting to harvest our sun.  Our premium sun will continue to shine for a long time, attracting lots of attention.

Show up on December 6!  Also contact our Commissioners:  Sam Pace; Linda Joseph; Mike  Spearman  Your voice counts.  Remember, it takes two votes up or down to pass or reject this controversial project.  See you there.