Solar energy 'power towers' to light up California
Utility Southern California Edison on Wednesday announced a giant solar energy contract with BrightSource Energy, which could eventually result in powering 845,000 homes with the sun's energy.
Through a series of seven projects, SCE intends to purchase up to 1,300 megawatts of electricity from BrightSource Energy's solar towers that use heat to produce electricity.
Although the companies didn't provide a price tag for the deal, it's one of the biggest solar energy contracts to date in the U.S. and a validation of solar tower technology. The project still needs to be approved by regulators and financed.
BrightSource Energy's demonstration facility in Israel's Negev Desert where an array of heliostats, or moving mirrors, concentrate light onto a tower to make steam.
(Credit: BrightSource Energy)The first project from the deal is scheduled to be a 100-megawatt installation in Ivanpah, Calif. which could be operating in early 2013, supplying 286,000 megawatt-hours of electricity per year, or enough for 65,000 homes.
Concentrating solar technology uses reflective troughs or mirrors to concentrate light onto a liquid to make steam. The steam then runs a traditional electricity turbine.
The technology, best suited for desert climates, is being revived in places like California which have a mandate to produce 33 percent of their electricity from renewable sources by 2020.
BrightSource Energy uses mirrors to reflect sunlight onto a tower to heat water which makes steam. The Google.org-backed company, which has roots with developers who did solar thermal projects in the 1980s, says that its air-cooling process preserves water, an important consideration for desert projects.
Several concentrating solar companies were founded in the past five years, but the credit crisis and economic downturn has made it very difficult to finance these expensive projects. One BrightSource Energy competitor, Ausra, has shifted its business strategy away from giant solar power plants.
California utility Pacific Gas & Electric is expected to announce a large solar deal, which will involve solar photovoltaic panels, some time this quarter.
New Jersey utility Public Service Electric and Gas Company on Tuesday announced that it has applied for a $773 Million Solar Energy program to make 120 megawatts of electricity.
Martin LaMonica is a senior writer for CNET's Green Tech blog. He started at CNET News in 2002, covering IT and Web development. Before that, he was executive editor at IT publication InfoWorld. E-mail Martin. 
1) They are VERY $$$ for the amount of energy they produce.... hopefully this will change some day.
2) They take quite a bit of energy to actually produce and create electronic waste and production chemicals,etc. (my guess is that some of these concentrated solar systems have less environmental impact in many ways).
3) They produce so little energy per surface area.
I like solar cells for many things... and I think for small applications, they probably are great. But, I think the idea of plants like this is to generate power on the utility scale and then just distribute it through the grid like we are no used to. I hope to see the day when we can produce so much energy through plants like this or linear fresnel systems that we can stop worrying about energy usage, and just focus on pollution. There really is no good reason we should have to worry about how much energy is being used when it would be so easy to generate as much as we need in relatively clean ways.
CSP (concentrated solar power - what they are talking about here) has a lower initial capital outlay. They have system efficiencies of 14% to 20% - if you look at the AC side of things and if you allow for water cooling. This brings us to the achilles heel of CSP - the use of water. Not many locations where you have a lot of direct irradiation and an abundance of water. If you recycle cooling water you will likely pay for it with efficiency losses.
The PV solutions are currently still more expensive up front but show enormous cost reduction potential with volume (and volume is coming online big time). You are right, eventually 70% of the world's energy will be generated by PV - in a 100 years time frame.
Meanwhile, certain locations will lend themselves to utilize PV over CSP and CSP will play in the very large utility scale market due to lower cost per kWh on a Gigawatt scale.
Today PV system efficiencies range from 4% for certain thin films to 25% for CPV (concentrated PV based on multi junction cells with 40% conversion efficiency). My guess, in 10 years PV solutions will reach 35% system efficeincies and grid parity with fossil fuel based energy.
Hang in there, it's all good...
1) Physics For Presidents (summary of the energy section: http://muller.lbl.gov/teaching/Physics10/PffP.html)
2) The Manhattan Project 2009
Another solution I've heard a lot about is the linear fresnel systems that heat some kind of liquid in tubes, then some kind of silicon based substance to like 800 degrees. Then this liquid can run turbines 24x7.... though I'm guessing the water usage is still going to be a problem (well, it's not exactly 'using' water.... it is more a source and supply problem.... there has been roughly the same amount of water on the planet for a long, long time.)
Solar towers concentrate all the energy very efficiently in one spot producing a very high temperature differential. That corresponds to a high maximum efficiency---that's one of the laws of thermodynamics. If you have all the energy in one hot spot, you can engineer the heck out of that one thing.
That and PV or Optics all have the shared flaw of the moment they're damaged, they lose their effectiveness and are expensive to replace - making multiple points of failure. For a mirror field and tower? Tower's the only expensive part, comparatively. Mirrors aren't expensive.
power (which this is not) and produce two to three or four times as much - and last 60 years, not the 20 years this solar plant will be in operation , and can be built in 3 years, not 11. It becomes ever more obvious why California is a financial disaster area tha the highly educated and companies are avoiding like the plague. California the brainless and now the dead broke.
- by solar_thermal February 11, 2009 4:04 PM PST
- Until very recently I operated one of the very large solar plants in the Mojave. Yes they are talking about rated capacity which is very different than actual output. The actual output will probably be closer to 25% of that. The good thing is that they will be nearer the rated capacity during the peak energy use hours in California. I will disagree with how long a solar-thermal plant can operate. Really it is just a normal steam plant and can basically operate indefinitely with proper maintenance. Some of the solar plants in the Mojave are already over 20 years old and work fine. Nuke plant also require extensive and very costly maintenance periodically too. That being said I am a very big fan of Nukes.
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(16 Comments)OK I do not know anyone, in the solar industry, who feels we are anywhere near running the world with it. I feel that PV will eventually be important but I am not a fan of building large ?solar plants? with it. For now it just requires too much land and because we have no way to store the electricity on a large scale, they are just not controllable. With a PV plant one cloud can cause major load swings on the grid. With a solar thermal plant single clouds will cause the plant slowly lose power in a much more controllable manner. Solar thermal also tends to lend itself to other technologies that may lead to cost effective energy storage. Natural gas can be added to solar thermal systems so they can ride out clouds or be used at night. The present solar thermal plants use this system.