If you have driven down I-15 from Las Vegas to Los Angeles recently, you may have seen one of these.  There are actually three of them on the west side of the Interstate.  They are quite bright and hard to miss.  They tower at the edge of the Mojave like lighthouses on the edge of a sea long since dried up.  These towers make up the Ivanpah 1, Ivanpah 2, and Ivanpah 3 solar thermal power stations.  I couldn’t help but stop and gawk at them as I was driving through with my family.

Solar Thermal Electric Generating System

The Ivanpah Solar Electric towers, hereafter called “death rays,” operate on the  simple principle that the sun is hot.  The sun is so hot, in fact, that it boils water into steam and turns a turbine to generate electricity.  This method is similar to any other coal, natural gas, or nuclear facility that heats water.  The only difference in the Ivanpah death rays from a nuclear plant, is that the nuclear reaction is 93 million miles away.

How Big Are They?

Between the three towers, each with their field of mirrors (or heliostats), the facility covers about 3500 acres.  There are a total of 173,500 of these heliostats with two mirrors each.  Heliostat is a fancy word that means “rack that follows the sun.”  Each Heliostat holds two mirrors that are about 75sq. ft.  Each tower is approximately 459ft. high.  This facility cost about $2.2 Billion to build of which $1.6 Billion came from a federally guaranteed loan.  Ground was broken in October of 2010, and the towers first began producing in January of 2014.  The steam turbines in use give the facility a maximum output of 392 megawatts.

How Hot Are The Towers?

In contrast to the white hot tower at the top of the article.  Here is a picture that I took of the Ivanpah 3 tower that was shut down for maintenance.  It was amazing to me that the tower goes from black to white when it is lit.  I was probably standing about a half mile away from the Ivanpah 1 and 2 towers, and the heat was noticeable.  The documentation online says that these towers run at about 1000 degrees Fahrenheit.  The steam in the lines enters the heat exchange at 480F and comes out at 1050F.

Performance Enhancing Gas

One interesting feature of the Ivanpah death ray towers is that they use supplements.  These towers run at their highest efficiency only when they are hot.  When the sun goes down at night, the towers cool down quite a bit.  This means that you waste a lot of time heating them the next day.  The chosen solution for this problem is to burn natural gas.  Burning natural gas heats the towers to bring them up to temperature.  Once they are running, the natural gas shuts off.  This also means that natural gas can add heat on days that aren’t quite as sunny.  On average, the natural gas adds about 5-10% capacity to the output of the towers.

Are The Solar Death Rays Dangerous?

In a few words, yes and no.  While the reflected light off of the towers was bright, it wasn’t quite like staring at the sun.  If you put on sunglasses, you could look at the operating towers fairly comfortably.  Most of the Danger from these towers comes from the heat.  Staff at the plant refers to birds that fly through the concentrated sunlight as streamers.  The heat is so intense from the tower that it will burn a birds feathers and kill it in flight.  Some people estimate that around 28,000 birds have been killed by Ivanpah towers.

You Said Two Solar Farms

Looking at the above satellite image of this area, you can see the three Ivanpah death rays to the West.  Just east of the Ivanpah towers is the Stateline Solar facility, still in California.  Then in the far East of the picture, you can also see the Silver State Solar Power South facility in Nevada.  From the ground, these two photovoltaic farms seem much larger than the Ivanpah tower arrays.  Interestingly enough, the photovoltaic farms aren’t actually that much larger than any one of the Ivanpah Heliostat arrays.

Silver State Solar Power South Facility

The Nevada solar facility has an estimated capacity of 250 megawatts.  It covers 2900 acres, and cost only about $1 Billion to set up.  It started construction in September 2014 and began electrical production in November 2015.  The photovoltaic panels are fixed in place and do not track the sun, so they are much simpler.  For optimum placement, the terrain had to be graded.  This facility is also located on public land, just in Nevada instead of California.

Stateline Solar Facility

This California-side photovoltaic facility covers 1685 acres.  It has a capacity of 300 megawatts.  Construction of this facility began in October 2014 and production began in December 2015.  This facility was estimated to require 400 jobs during construction and 12 ongoing jobs to maintain the facility.  This facility is also on public land.  The Stateline Solar Facility has around 3.2 Million of First Solar’s photovoltaic panels placed at a fixed angle.

How Do Death Rays Compare To Solar Panels?

Placing photovoltaic solar farms immediately next to what was the largest solar power facility in the world gives us an interesting study.  With these facilities so close to one another, they should get similar exposure.  The Ivanpah solar facility is larger and more expensive than either of the photovoltaic farms, but it also has a larger theoretical capacity.  If only someone could tell us what their power output was so we could compare.

Megawatts Generated Per Month

Thanks to the electricity data browser on the U.S. Energy Information Administration website (eia.gov), I was able to put together the above chart.  The Ivanpah 1, Ivanpah 2, and Ivanpah 3 facilities are represented by the yellow, red, and purple lines respectively.  The blue and the green lines show Stateline Solar and Silver State Solar Power South respectively.  This makes it look like the Ivanpah towers aren’t producing as much as the photovoltaic panels.  What if we wanted to know which technology was a more efficient use of land?

The blue line in the above graph is the sum of the production of all three Ivanpah towers divided by the 3500 acres that they occupy.  The green and the orange lines represent Stateline Solar and Silver State Solar respectively.  This makes the Stateline Solar facility look almost twice as efficient at certain times.

Which Technology Generates The Most Power?

Within the confines of the map I included earlier, there is a lot of electricity generated.  The largest single facility on the map belongs to the three Ivanpah death ray towers.  Next after that, comes either of the two photovoltaic farms. The third type of electricity generation on the map is dwarfed by any of these.  If you look in the middle o the Silver State Solar Facility, you will see a small group of buildings that aren’t solar panels.  This is the Higgins Generating Station, which burns natural gas.  This small plant alone generates the yellow line in the above graph.  As far as Solar Power has come, it still has a long way to go.