Full steam ahead for Nevada solar project

BOULDER CITY, Nev.--The Nevada Solar One power plant is essentially a tea kettle, just one that happens to take up 300 acres and can provide enough power for 15,000 homes.

The plant, which will start to generate electricity for nearby Las Vegas in April, consists of approximately 184,000 mirrors arranged in long, parabolic arrays that focus the sun's energy on a receiver--a metal tube filled with oil that's encased in specialized glass--from German conglomerate Schott.

Sunlight heats the oil to 400 degrees Celsius (about 750 degrees Fahrenheit). The oil gets transferred to a heat exchanger where it makes steam, which then cranks a turbine to produce electricity. If the heat can't be used right away, it gets transferred to vats of molten salt which retain the heat for later use.

"The steam side, it is not rocket science. It has existed for more than 100 years. The solar side, we know it is going to work," said Gilbert Cohen, senior vice president of Acciona Solar Power, which owns the plant and will sell it to local utilities. "The potential is huge here."

The project underscores the resurgence that's taking place for a technology called solar thermal for generating electricity. Solar thermal power plants began popping up in Israel and the American Southwest in the '80s, but construction of new plants largely ground to a halt in the early '90s.

Now, solar thermal projects are under way--or at least on the white board--in Spain, Greece, Mexico, Iran, Algeria and parts of the U.S., among other places. When it goes live, Solar One will be the third largest solar thermal plant in the world with a 64 megawatt capacity. Potentially, the site could crank out 2,000 megawatts, or enough power for about a half-million people, Cohen said. The U.S. Southwest could ultimately produce 4,000 to 40,000 megawatts of solar thermal power, he speculated, enough for 1 million to 10 million consumers.

In California's Mojave Desert, already home to 354 megawatts of solar thermal facilities, Stirling Energy Systems in conjunction with utility company Southern California Edison is erecting a 500 megawatt plant to open in 2009.

Video: Thousands of mirrors
One of the biggest solar projects in recent U.S. history is almost complete.

The driving force behind the demand for solar thermal power, besides global warming and fears about rising electrical prices, are state and federal laws aimed at curbing fossil fuels and coal. In Nevada, regulations require that utilities get 15 percent of their power from renewable resources and a total of 5 percent from solar power by 2015. Other southwestern states have passed similar laws.

Solar thermal plants aren't cheap. The construction tab for building Solar One will likely run about $250 million, said Cohen. The power generated by the plant, minus any subsidies, may not get to parity with electricity generated from conventional plants until around 2020, added Nikolaus Benz, a development manager for Schott. Solar thermal electricity, according to statistics from Schott's publications, will cost around 15 to 17 cents a kilowatt hour in the U.S. Residents of Las Vegas now pay around 7 cents a kilowatt hour.

Solar thermal fans, however, say the technology represents the most economical way to harness the sun's power on a large scale. The solar plants will last for decades, so by 2030, solar thermal will be a better buy than coal-fired electricity, which is expected to go up in price. To eliminate risks to its customers--namely large utilities--Acciona sets long-term fixed prices for electricity generated by its plant.

"The return is pretty good, but you have to take the first step," Cohen said.

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The technology also has an advantage in age, added Cohen. During the 15-year lull when utilities weren't commissioning new plants, engineers had time to enhance the performance of their products and wring out operational inefficiencies. Schott, for example, has come up with a new coating for the glass tube on the receiver that lets 96 percent of the solar radiation through to the oil-filled metal tube sealed inside the glass. The coating also withstands abrasion better than earlier versions.

Solar One also makes for a pretty cool field trip. You're zipping along on an empty desert highway, and suddenly a field of kilometer-long rows of what look like white antenna dishes come into view. The fences and isolation immediately make you think: CIA. The mirrors are mounted on the arrays in four rows that form a near perfect parabola to reflect as much sunlight as possible onto the purple receiver, about the diameter of a can of pasta sauce.

Contrary to expectations, the mirrors won't sizzle birds or bugs: they only get as hot as the outside temperature, said site manager Bob Cable. When operational, the arrays will rotate with the sun--software and microcontroller adjusting the pace of their movements depending on the day of the year and the position of the sun.

Work on the massive plant is slightly ahead of schedule. Construction on Solar One--which includes over 7 million aluminum parts in the frame and 76 kilometers' worth of oil-filled receivers as well as a nearby electrical plant--began in February 2006. The field is now 90 percent done while the companion buildings are 70 percent there.

[gatornuke]

That's note how PV panels work

You stated that photovoltaics "split photons from the sun into electrons and positive charges from the sun." What you're describing here is a Pair-Production event, which only occurs with gamma rays above a 1.022 MeV threshold. This interaction produces a positron-electron pair, each with a rest mass of 0.511 MeV plus a combined kinetic energy equal to the energy of the incident photon in excess of the threshold energy.

Photovoltaic panels work by means of the photoelectric effect. In this interaction photons simply knock electrons off a metal surface when the incident photon energy is greater than the work function of the metal. The photoelectric effect is most prevalent in high-Z materials and low-energy photons with frequencies above the threshold value. Thus, ultraviolet radiation from the sun is ideally suited for this application.

[gatornuke]

meant to say "not"

... and it doesn't appear that cnet allows you to revise comments.

[LuvThatCO2]

Wouldnt solar energy heat the planet?

If you're trapping on Earth solar energy that largely would have been reflected back into space... wouldnt large scale use of this technology warm the planet as the energy balance gets out of whack?

We'd probably have to offset that change to planetary albedo somewhere else.

[gatornuke]

No

This is no different than a conventional Rankine cycle power plant. It's the same stuff you'll find in a Nuclear, Coal, or oil-fired plant, the only difference is that the heat to make steam comes from the sun... at the outrageously expensive price of 15 c/kWhr, but that's besides the point.

[baike]

nope

The heat energy that is trapped is converted to mechanical energy in the steam turbine which is then converted to electrical energy. The heat energy is not dissipated into the atmosphere. The enrgy converted to electricity would most likely be equal to or greater than the energy that would have been reflected back into space had the sunlight hit the surface of the Earth. So it would NOT heat up the Earth. Also this type of power plant would displace a need for a fossil fuel burning plant that releases large quantities of greenhouse gases. The only difference between a solar thermal plant and a coal, gas or a nuclear one is where the heat comes from.

[Hardrada]

Yeah, the same way that...

opening the refrigerator door cools off the room.

[iwarp62]

Prolly not

It's true that you would be storing energy that would have been otherwise reflected, However it's probably way less energy being added to our surroundings then say nuclear energy or burning fossil fuels would release.

[HandGlad2]

Power for Los Vegas?

You mean the city next to the Boulder dam that gets loads of inexpensive hydro-electrical energy?

What kind of numbskull decided that was a place needing more electricity?

[qwiji]

Las Vegas, yes.

Vegas is indeed one of the fastest growing cities in the nation. (Gambling aside, even.) Pretty much the whole country is on the same grid. The juice doesn't have to be consumed in Vegas, it can be used to alleviate the load of power plants that normally supply LA or Phoenix, or anywhere else in the region.

Remember the blackout of the north east in about 2003? The grid is huge.

[Hoser McMoose]

Probably...

Probably the same "numbskull" that looked at the power needs of Las Vegas and realized that they were SEVERELY under supplied already with an expectation of power demand to go up 40% in the next 10 years.

The Hoover Dam has a peak power generation of ~2,000MW. Las Vegas has a current peak demand of ~5,600MW, and that demand is expected to hit ~8,000MW by 2015. Even if demand stays constant and Las Vegas were to get 100% of the energy production from the dam it would still be supplying less then half of what they need.

[adlyb1]

Uhhh

Numbskulls that know that only about 24% of the electricity generated at Boulder/Hoover dam is slated for Nevada and the other 76% is distributed all over the Southwest. In fact, Southern California receives more power from the dam than Nevada.

[GMonR]

The drawback of renewable energy...

Well, I don't think the designers picked Las Vegas because of where the demand for electricity is... I don't think this "solar power plant" would be very effective if it were located near, let's say, Seattle.

The drawback of generating electricity from the sun is that you need, well, the SUN to be shining...

The only way renewable energy production can ever be practical is for locations "rich" in natural renewable energy (sun, wind, or water) to produce and share their extra energy with other locations, which, thankfully, is accomplish thanks to the power grid...

The size of the modern power grid is such that variations in weather patterns are evened out, and it will always be sunny, windy, and rainy in at least some parts of the area covered by the grid...

[westrajc]

Las Vegas Is A Waste

Las Vegas, a city in the desert that greedily consumes all available water, energy and lives. The desert IS the right place to put a solar energy production facility. It's definately the wrong place for large populations of humans.

The whole South West is a problem. If Global Warming is truly accelerating, the SW will dry up completely. As a resident of MI, I will fight to the death to keep the same money-grabbing multinationals who have lived fat on oil from building pipelines to shunt our Great Lakes South, just so a bunch of STUPID, Gluttenous, Gamblers/Retirees can have their "paradise" in the sun!

Let's face it people. If we truly had the will to put all the resources we now pour into NASA, the D.O.D. and Entertainment into developing a self-supporting green society, we could be completely free of our dependence on non-renewable energy within 10 years or less! Heck, if we pulled our collective heads out of our @$$, we could wipe out hunger, poverty and crime while we were at it!

As long as greed is the primary motivator for human echievement, all we will ultimately achieve is our own destruction. JCW 2007

[weeze345]

Numbskull?

If you look at time lapse pictures of said dam, I believe the level of water in Lake Mead behind the dam has dropped significantly since it went on line as a hydro plant. I don't know the time frame, but I believe experts are afraid that in the very near future there will not be enough water to create the necessary head pressure to spin the turbines. The need to replace this power supply will need to be addressed very soon. The transmission lines are already near by (because of the hydro plant) so it's a logical place to start. Cuts down the cost of running new lines from another site to Las Vegas. Just a thought.

[willtr2]

solar power

is the way to go but you are not thinking outside the box

thirty volt power for houses will be easer to produce with solar

or it the electric company is afraid of electricity theft 60 or 90 volts with a drop down in power to the home to thirty volts

there are benefits to this including safety
with technology to catch up and each house may be able to produce own energy

taboo for electric companies

[Llib Setag]

LV Hydro-power?

Doesn't Las Vegas get all of it's electricity from the nearby Hoover
Dam Hydro-Power & Colorado River?

Hydro-power is GREEN renewable energy source too.

Green is GREAT & I am all for it, but I am missing something here?

Good idea with vast amount of solar energy in Las Vegas Nevada.

[juno_sun]

Just becasue they build a power plant some place does not mean the power it genertaes is for that place. California gets a lot of its power from Nevada

[fastolfe00]

Photons, electrons, and square feet

"PV panels ... split photons from the sun into electrons and positive charges from the sun."

The photons actually liberate electrons from the material and set them in motion, creating negative and positive charges that then ripple through the material. In other words, electrons are simply pushed along the electrical circuit using the energy provided by the photons. Electrons aren't created.

"One hundred thousand square feet of molten salt holds enough heat to provide electricity for four hours."

I don't understand how much molten salt this is. Should this be cubic feet? Or is there some amount of depth to this 100k square feet to give us an actual volume?

[rolyb]

I think the solar panel connected to water pump to produce electricity was already outdated. Have anyone see a Japanese version of solar power eledtricity? The solar panels was conected to rechargeable battery cell, then connected to the transformer, then to the meter then to the switch panel, strong enough to power the electricity for the house, a commercial complex. The same sesign can be use to power electric cars.