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THE Solar Thermal Energy Thread (merged)

Discussions of conventional and alternative energy production technologies.

Re: THE Solar Thermal Energy Thread (merged)

Unread postby Graeme » Tue 08 Apr 2014, 18:06:46

Cheap Solar Power—at Night

When the world’s largest solar thermal power plant—in Ivanpah, California—opened earlier this year, it was greeted with skepticism. The power plant is undeniably impressive. A collection of 300,000 mirrors, each the size of a garage door, focus sunlight on three 140-meter towers, generating high temperatures. That heat produces steam that drives the same kind of turbines used in fossil-fuel power plants. That heat can be stored (such as by heating up molten salts) and used when the sun goes down far more cheaply than it costs to store electricity in batteries (see “World’s Largest Solar Thermal Power Delivers Power for the First Time”).

But many experts—even some who invested in the plant—say it might be the last of its kind. David Crane, CEO of NRG Energy, one of three companies, including BrightSource Energy and Google, that funded the plant, says the economics looked good when the plant was first proposed six years ago. Since then, the price of conventional photovoltaic solar panels has plummeted. “Now we’re banking on solar photovoltaics,” he told a crowd of researchers and entrepreneurs at a conference earlier this year.

The allure of solar thermal technology is simple. Unlike conventional solar panels, it can generate power even when the sun isn’t shining. But in practice, it’s far more expensive than both fossil fuel power and electricity from solar panels. And that reality has sent researchers scrambling to find ways to make the technology more competitive.

One big challenge, says Philip Gleckman, chief technology officer of Areva Solar, is that the arrays of mirrors, as well as the motors and gearboxes used to aim them at the sun, are expensive. One potential fix, he says, comes from a San Francisco startup, Otherlab, which replaces the motors with pneumatics and actuators that can be made cheaply using the manufacturing equipment that’s currently used to make plastic water bottles.

The head of Otherlab’s solar efforts, Leila Madrone, says the technology could cut the cost of mirror fields for concentrating sunlight by 70 percent. But even this cost reduction, she says, won’t be enough to make the technology competitive with solar panels—even though the mirrors account for a third to a half of the overall cost of a solar thermal plant.

Getting overall costs down will require increasing the amount of power a solar thermal plant can generate, so it can sell more power for the same amount of investment. One approach to increasing power output is to increase the temperatures at which solar thermal power plants can operate, which would make them more efficient. They currently operate at 650 °C or less, but some researchers are developing ways to increase this to anywhere from 800 °C to 1,200 °C. That approach is being pursued by another startup, Halotechnics, which uses high-throughput screening processes to develop new materials—including new kinds of salt and glass—that can store heat at these high temperatures (see “Cheap Solar Power at Night”).

Another option, being funded by a new program at the U.S. Advanced Research Projects Agency for Energy, is to make power plants that add solar panels to solar thermal power plants. The basic idea is that solar panels can only efficiently convert certain wavelengths of light into electricity. Much of the energy in infrared and ultraviolet light, for example, doesn’t get converted, and is instead emitted as heat. The new projects look for ways to harness that heat.


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800 Degree Heat From Solar Mirrors Frying Birds Mid Air

Unread postby Oilguy » Thu 10 Jul 2014, 18:31:16

There is growing evidence that birds flying in the vicinity of a solar thermal power project in California’s Mojave Desert are being injured and even killed either by the solar heat that’s focused with mirrors on its three energy-collecting towers, or by colliding with the mirrors themselves.

Yet a task force set up to investigate the problem at the Ivanpah Solar Electric Generating System (ISEGS) has brushed aside several recommendations by the forensics laboratory of the U.S. Fish and Wildlife Service (FWS), according to the minutes of a meeting on the subject obtained by the Los Angeles public television station KCET.

Full article at: https://oilprice.com/Latest-Energy-News/World-News/800-Degree-Heat-From-Solar-Mirrors-Frying-Birds-Mid-Air.html
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Re: 800 Degree Heat From Solar Mirrors Frying Birds Mid Air

Unread postby efarmer » Thu 10 Jul 2014, 18:56:48

I predict the birds will eventually form an insurgency and unable to assail the mirror array / power tower installations, will instead begin pooping on all the photovoltaic panels they can find in small tactical units, most probably after they have consumed all the berries they can obtain.

On a more serious note, it shows how hard it is for us to scale even solar energy technology and avoid inadvertent damage to nature. Come on engineers, how about a steam whistle that makes a really low note and spooks them before they get cooked?
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Re: 800 Degree Heat From Solar Mirrors Frying Birds Mid Air

Unread postby AgentR11 » Fri 11 Jul 2014, 00:48:00

The question is....

do they taste good on a sesame seed bun?
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Re: 800 Degree Heat From Solar Mirrors Frying Birds Mid Air

Unread postby dinopello » Fri 11 Jul 2014, 08:24:42

I may need this bird death ray at some point. This year, I planted all sorts of blueberry, blackberry and flowers of various kinds. I've always had a lot of birds but now they are taking over and getting territorial. Birds get very protective - I even had a Cardinal male and female harassing me as I worked in the garden. Must of had a nest nearby. Anyway in future seasons I plan to cover the fruit with a bird proof netting and they may get quite upset. I don't want to kill anything but maybe a few shots across the bow, as it were.
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Re: 800 Degree Heat From Solar Mirrors Frying Birds Mid Air

Unread postby diemos » Fri 11 Jul 2014, 09:36:10

Outstanding.

We should build public housing beneath the towers. Then the poor can just sit outside and wait for the free pre-cooked chickens to fall from the sky.
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Re: 800 Degree Heat From Solar Mirrors Frying Birds Mid Air

Unread postby MD » Fri 11 Jul 2014, 10:26:52

These type solar installations are well suited for the remotest of arid desert. Not so many birds out there.

Even so it would make sense for the engineers to figure a way to repel the birds. They have to clean up the mess, after all. If it gets messy enough they will fix it.
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Re: 800 Degree Heat From Solar Mirrors Frying Birds Mid Air

Unread postby BobInget » Fri 11 Jul 2014, 13:42:08

Quick reminder, these are NOT PV panels but reflective mirrors all sunlight focused on a central tower.

Until this serious problem is solved there may not be more such power plants.
Around airports many bird scaring strategies have been attempted with limited success.
Since birds at high altitudes aren't a problem for solar steam. Loud sounds might work.

Motion sensors could set off propane or CO/2 powered noise maker cannons.
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Re: 800 Degree Heat From Solar Mirrors Frying Birds Mid Air

Unread postby MD » Fri 11 Jul 2014, 14:06:07

BobInget wrote:Quick reminder, these are NOT PV panels but reflective mirrors all sunlight focused on a central tower.

Until this serious problem is solved there may not be more such power plants.
Around airports many bird scaring strategies have been attempted with limited success.
Since birds at high altitudes aren't a problem for solar steam. Loud sounds might work.

Motion sensors could set off propane or CO/2 powered noise maker cannons.


Just how serious is it? Please be specific.

thanks
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Re: 800 Degree Heat From Solar Mirrors Frying Birds Mid Air

Unread postby AgentR11 » Fri 11 Jul 2014, 14:16:48

I'm tellin ya...

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Re: 800 Degree Heat From Solar Mirrors Frying Birds Mid Air

Unread postby Surf » Fri 11 Jul 2014, 22:04:17

According to this article:
http://www.kcet.org/news/rewire/solar/concentrating-solar/bird-deaths-continue-through-may-at-ivanpah-solar.html
Of the 80 bird carcasses recorded in May, 55 were found during carcass surveys while the remaining 25 were "incidental" finds made by plant workers during normal work operations. As only about 20 percent of the facility is covered by the carcass surveys, it's reasonable to assume the actual month's death toll is upward of 300 or so.


This is strange. Ivanpah is not the only solar power tower facility in the world. it is the biggest. BrightSource did look into this and from this article 2 years ago:
http://social.csptoday.com/markets/california%E2%80%99s-newest-nimby-issue-solar-flux

BrightSource supplied evidence at the workshop from the real-world experiences of smaller solar power towers in operation, including the Department of Energy’s 10 MW Solar One pilot, their own demonstration facility in Israel; a 6 MW Solar Energy Development Center, and Torresol’s 20 MW Gemasolar power tower operating commercially since last summer in Andalusia, Spain. None of these operating plants have experienced significant issues with avian species, BrightSource says. Its Ivanpah project has broken ground, and will track bird deaths.


So it appears the problem at Ivanpah is much larger than anticipated. I wounder is the tower construction could be the cause. The Gemasolar tower is a circular concert tower with no places for birds to land. Ivanpah is a steel structure with a lot of places for birds to land. Birds like high places where land predators (snakes, coyotes, etc) cannot reach then. Perhaps they should surround the towers with sheet metal to encourage the birds to go elsewhere.
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Re: 800 Degree Heat From Solar Mirrors Frying Birds Mid Air

Unread postby Pops » Fri 11 Jul 2014, 22:18:34

wow, 300 birds. I wonder how many salmon they killed damming the Columbia?
If destruction be our lot, we must ourselves be its author and finisher. As a nation of freemen we must live through all time or die by suicide.
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Re: 800 Degree Heat From Solar Mirrors Frying Birds Mid Air

Unread postby Logic » Sat 12 Jul 2014, 07:29:59

Cats kill tons of birds as do glass covered office buildings.
It is not possible to build anything and not have any impact on nature.

These studies need to provide context. In isolation those numbers are meaningless.
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Re: 800 Degree Heat From Solar Mirrors Frying Birds Mid Air

Unread postby Surf » Sat 12 Jul 2014, 15:36:45

Cats kill tons of birds as do glass covered office buildings.
It is not possible to build anything and not have any impact on nature.

These studies need to provide context. In isolation those numbers are meaningless.


A single utility scale wind turbine might kill one bird a year . Solar PV probably zero. yes cats and building kill a lot more. however it is still strange that this one plant is killing about 80 a month while other solar thermal plants are apparently no worse than wind turbines.

It will be interesting to see how Tonopah Nevada 110 MW solar tower does (it should be online now or very soon). This plant has storage molten salt storage so its overall thermal rating is probably very close to one Ivanpah tower. Unlike the steel Ivanpah towers, Tonopah uses Concrete.
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Re: THE Solar Thermal Energy Thread (merged)

Unread postby Graeme » Wed 10 Jun 2015, 17:50:40

Why You Should Be Paying Attention To The ‘Other’ Form Of Solar Power

olar photovoltaic (PV) systems have seen explosive growth because of their stunning 99 percent price drop in the past quarter century. As a result, the other form of solar power — concentrating solar thermal power (CSP) — is a small fraction of the solar market.

But the International Energy Agency (IEA) says CSP has a very bright future too because it enables cheap, efficient storage, which allows CSP plants to provide electricity long after the sun has set. According to the IEA’s 2014 CSP Technology Roadmap, 11 percent of global electricity will be generated by concentrating solar thermal power in 2050. In this post, I review the basics of CSP and look at how its recent resurgence portends a big future.

CSP is the use of mirrors to focus sunlight to heat a fluid that runs an engine to make electricity. One of the basic CSP designs used today is the power tower (above photo of the Crescent Dunes Solar Energy Project), which uses many mirrors moving in two dimensions to focus sunlight on a central tower that holds the engine. Another key design is the parabolic trough, which uses mirrors to focus the light on a long tube filled with a heat-storing fluid (right).
The key attribute of CSP is that it generates primary energy in the form of heat, which can be stored 20 to 100 times more cheaply than electricity — and with far greater efficiency. Commercial projects have already demonstrated that CSP systems can store energy by heating oil or molten salt, which can retain the heat for hours.


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Re: THE Solar Thermal Energy Thread (merged)

Unread postby vox_mundi » Mon 22 Aug 2016, 14:36:26

Sponge creates steam using ambient sunlight

Image

How do you boil water? Eschewing the traditional kettle and flame, MIT engineers have invented a bubble-wrapped, sponge-like device that soaks up natural sunlight and heats water to boiling temperatures, generating steam through its pores.

The design, which the researchers call a “solar vapor generator,” requires no expensive mirrors or lenses to concentrate the sunlight, but instead relies on a combination of relatively low-tech materials to capture ambient sunlight and concentrate it as heat. The heat is then directed toward the pores of the sponge, which draw water up and release it as steam.

From their experiments — including one in which they simply placed the solar sponge on the roof of MIT’s Building 3 — the researchers found the structure heated water to its boiling temperature of 100 degrees Celsius, even on relatively cool, overcast days. The sponge also converted 20 percent of the incoming sunlight to steam.

In their new design, the researchers settled on a spectrally-selective absorber — a thin, blue, metallic-like film that is commonly used in solar water heaters and possesses unique absorptive properties. The material absorbs radiation in the visible range of the electromagnetic spectrum, but it does not radiate in the infrared range, meaning that it both absorbs sunlight and traps heat, minimizing heat loss.

The researchers obtained a thin sheet of copper, chosen for its heat-conducting abilities and coated with the spectrally-selective absorber. They then mounted the structure on a thermally-insulating piece of floating foam. However, they found that even though the structure did not radiate much heat back out to the environment, heat was still escaping through convection, in which moving air molecules such as wind would naturally cool the surface.

A solution to this problem came from an unlikely source: Chen’s 16-year-old daughter, who at the time was working on a science fair project in which she constructed a makeshift greenhouse from simple materials, including bubble wrap.

“She was able to heat it to 160 degrees Fahrenheit, in winter!” Chen says. “It was very effective.”
Chen proposed the packing material to Ni, as a cost-effective way to prevent heat loss by convection. This approach would let sunlight in through the material’s transparent wrapping, while trapping air in its insulating bubbles.

The bubble wrap, combined with the selective absorber, kept heat from escaping the surface of the sponge. Once the heat was trapped, the copper layer conducted the heat toward a single hole, or channel, that the researchers had drilled through the structure. When they placed the sponge in water, they found that water crept up the channel, where it was heated to 100 C, then turned to steam.

Steam generation under one sun enabled by a floating structure with thermal concentration, Nature Energy http://www.nature.com/articles/nenergy2016126 (2016)
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