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THE Solar Thermal Energy Thread (merged)

Discussions of conventional and alternative energy production technologies.

Springerville Solar Array Instrumentation

Unread postby BabyPeanut » Fri 25 Feb 2005, 22:15:19

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Unread postby savethehumans » Sat 26 Feb 2005, 00:27:08

Good, solid, LOCALIZED alternative fuel stats--copied into my files! Thanks, babypeanut! :)
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Unread postby MarkR » Sat 26 Feb 2005, 19:57:19

Wow. That's an impressive project that I'd not come across before.

Any idea how much it cost? I've not been able to find any information on that.

However, it's nice to see actual measurements of load factor - although, I was surprised to see their target is less than 20%. I'd expected it to be a bit higher, given the location in the desert.
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Overlooked Solar Technology

Unread postby geronimo » Thu 02 Jun 2005, 08:30:48

Hello folks, first post here after a fair time lurking, read Heinberg at end of last year.

Alot of posts i have seen regarding potential alternative technologies only consider photovoltaic power generation, which imo face serious problems wrt scalability, longevity & industrial byproducts. Consider that a thermal solar facility such as Solar Two has around 20% efficiency (or more if in configuration similar to This). The design of the plant means it can provide effective thermal storage of solar energy after the sun sets to provide electricity for more hours of the day than a PV array.

The heliostats can also create a source of high temperature heat in the central collector which can be used for promising technologies such as thermochemical hydrogen production via the sulfur-iodine cycle. Hydrogen may have its problems as an energy carrier but it should be considered our end-goal fuel for its versitility. For some applications such as aircraft & large ocean transport it has no real non-fossil equivalent. I consider future use to centre around its distribution in liquid form despite the energy required to reach this state, due to such a low energy denstiy in any other form. Liquid hydrogen can also do dual-use as a cryogen & energy storage in advanced power delivery designs such as This.

As another benefit of solar thermal techniques, the waste heat can be used to desalinate water, which in arid areas would be a valuable byproduct and forms the basis of this ambitious scheme. In fact i see the real value of photovaltaics as a source of electricity for remote or mobile locations and less benefit for large-scale power production.

Comments welcome!
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Unread postby pilferage » Thu 02 Jun 2005, 11:15:25

Kind of a shame they closed down the plant in Mojave. Although right next to the 395/58 there's something that looks like solar power generation, I'm not sure what type though. Maybe they just moved it because of the winds?
This technology seems to hold a lot of promise. It's more efficient, scalable, relatively cheap, (I believe) provides off-peak generation, and the components seem relatively cheap and easy to fix.
Good post!
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Unread postby SidneyTawl » Thu 02 Jun 2005, 18:10:39

was the one in the mojave the one that used the single foucus reflecter. Sorta like a big "radar dish" focusing the sun into a small tower full of molten salt.

Places along and near the equator could really make this work.
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Unread postby Cyrus » Thu 02 Jun 2005, 22:31:10

Well, although this is great technology, I don't think it is feisable for mass energy production. I think we are a little too far down the line to make this scalable. Trust me, we will run to coal way before this, which will destroy the environment, and...well you get the picture.
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Unread postby cube » Fri 03 Jun 2005, 04:17:22

I think it's too expensive to build individual reflectors like what's shown in the picture. I'm highly skeptical of solar energy...but a possible cheaper methode would be to use highly reflective fabric. The fabric can be suspended from towers forming a giant circle. As the fabric sags under it's own weight it will make a parabola like shape.

if that makes any sense
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Unread postby geronimo » Fri 03 Jun 2005, 06:58:22

Yes currently it does not compare favourably costwise with existing fossil power gneration, i am interested in it more from the technically feasible viewpoint. At the scale of the demonstration plant incidental type costs are high but here is an idea of the cost structure once it is scaled up. Fabric hung between towers would form a catenary curve rather than a parabola btw, and i have doubts about its durability - one of the benefits of this technology is that a field of heliostats would last for decades with cleaning & the occasional replacement of drive mechanisms.
Matters of scalibility do pose some interest, a typical 200 MW solar tower plant would need about 2.6 sq km of mirrors & would take up 14 sq km of land area. Consider that world float glass production is about 3 billion sq m (ref) so if we took 10% of prodction and aluminized it we could build over a hundred of these plants per year adding 20 GW annually to world capacity.
Location is vital for this kind of solar since it relies on direct solar radiation, for the continental US anywhere in the dark red areas would be good.
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Unread postby geronimo » Tue 19 Jul 2005, 09:11:08

Wow my post on overlooked solar technology has been.....overlooked :P I was hoping for some feedback from people on why they think this could/could not be implemented (technical reasons please, i am aware of the political and economic hurdles). The solar resource is there to be used, and the main drawback to its use is its dilute nature as apposed to the concentrated source we get out of the ground. Creating this kind of infrastructure is the means to concentrate and harness it for use in a way that is much more efficient than any biological process using areas of the earth's surface that cost us much less to give up than good agricultural land for example. This technology would compete financially with nuclear without the associated burdens of waste storage and proliferation. It would be a lasting legacy for future generations and would help secure a stable climate for our planet.
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Unread postby Andy » Tue 19 Jul 2005, 10:15:25

Agreed Geronimo. The alternatives are begging to be given their day in the sun (PUN INTENDED). The problem is our cultural, economic inertia that is going/maybe already has turned the situation into an impossible one. We waited too long and it may now be too late.

There is no theoretical reason why solar in its various forms coupled with a cessation of exponential growth should not be able to meet our needs. Certainly not from a materials perspective. PV for instance is silicon, the 2nd most abundant element on earth (albeit needs to highly refined thus large energy input) Solar thermal is principally glass and plastic. Wind is steel and carbon fibre. Wave is principally steel; OTEC principally steel with titanium/aluminum (again large energy input but not materials limiting) etc. etc. And these materials can be recycled at end of life.

I have read a statement, can't remember source now that states that 1 kg of silicon will provide more useful electricity than the same amount of uranium even when used for nuclear breeders. The advantage accelerates when thin film materials are used like CSG (Crystalline Silicon on Glass) that uses 1 micron width silicon layers.
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Unread postby Aaron » Tue 19 Jul 2005, 10:29:10

Solar Two has around 20% efficiency


It's not that these techniques are bad per se...

But comparing them to conventional hydrocarbons is like pissin in the Grand Canyon.

1:1.2

vs

1:50

Not hard to understand now huh?

It's also worth noting that cheap hydrocarbon power is part of the efficiency calculation for this technology. As oil becomes more expensive, this will degrade the efficiency lower than it's anemic 20% projection.
The problem is, of course, that not only is economics bankrupt, but it has always been nothing more than politics in disguise... economics is a form of brain damage.

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Unread postby Devil » Tue 19 Jul 2005, 10:31:23

Don't forget solar water heating: this is available, works and has a payback time of ~2 yr at frost-free latitudes and ~5 yr up to about 55-60°. I have 8 years personal experience and 95% of the hot water in our household is heated, courtesy of Mr Sol Helios, for an initial outlay of <$500. If everyone did this, overall electric, gas and oil consumption would be considerably reduced.

FYI, large schemes are useless on or near the equator (too much cloud cover). You need to go to the edge of the tropics (desert regions) to get much sun.
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Unread postby EnergySpin » Tue 19 Jul 2005, 12:29:40

You need to go to the edge of the tropics (desert regions) to get much sun.

Hi devil, since you know more about that stuff than we do, any chances of using solar space based generators beeming microwave down the Sahara?
It seems we can get the stuff in space, and connecting North Africa grids to the European Grids seems (to the untrained eye and brain) easy!
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Unread postby geronimo » Tue 19 Jul 2005, 17:06:25

Aaron i think you would find that the eroei is much higher for this type of technology than 1:1.2 (maybe you are thinking of photovoltaics?). The raw materials and production of the heliostat field, glass & steel, represent the largest energy input but i think you'll agree there is an order of magnitude more energy required to refine the silicon & manufacture photvoltaics, and yet we are stil obtaining 20% efficiency (comparable to PV). In a dry desert environment you can expect your heliostat field to last a lot longer than PV as well.
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Unread postby Antimatter » Wed 20 Jul 2005, 02:15:19

Aaron wrote:
Solar Two has around 20% efficiency


It's not that these techniques are bad per se...

But comparing them to conventional hydrocarbons is like pissin in the Grand Canyon.

1:1.2

vs

1:50

Not hard to understand now huh?

It's also worth noting that cheap hydrocarbon power is part of the efficiency calculation for this technology. As oil becomes more expensive, this will degrade the efficiency lower than it's anemic 20% projection.


I think you are confusing thermal efficiency with EROEI.
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Unread postby Devil » Wed 20 Jul 2005, 09:42:02

EnergySpin wrote:
You need to go to the edge of the tropics (desert regions) to get much sun.

Hi devil, since you know more about that stuff than we do, any chances of using solar space based generators beeming microwave down the Sahara?
It seems we can get the stuff in space, and connecting North Africa grids to the European Grids seems (to the untrained eye and brain) easy!


I don't really mean to be rude but guys like you really piss me off, because it appears you have lost the ability to think and to reason.

1. If you are in the desert, why the hell should you beam inefficient microwave when you can set up the same PV cells on terra firma (or at least on sand :) ) and get better results. We do not have the technology available to do it. A CW transmitter in the 0.3 - 1 cm wavelength region is, at best, 50% efficient and is limited to a few watts with our current available components. Not to mention the costs. The light reaching the desert on a clear day in a PV-sensitive spectrum is >85% of that in outer space, so land-based PV is more efficient, as well as cheaper.

2. As far as I'm aware, any N. African grids are independent of each other; there is no transnational grid.

3. Even if there were a N. African transnational grid, how do you propose crossing the Med? The nearest place would be Morocco to Gibraltar. The most powerful generation in N. Africa is in Egypt, roughly (as a guess) 1500 km from Morocco. The biggest European consumption is in Germany, more than as much again from Gibraltar. Can you imagine the losses? Not to mention the losses in the submarine cable which must be DC (like the Straits of Dover submarine link), the double conversion being very lossy. (France has 2 nuke power stations close by and London is only 100 km away, so you have a different set of conditions there.)
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Unread postby EnergySpin » Wed 20 Jul 2005, 09:49:13

I don't really mean to be rude but guys like you really piss me off, because it appears you have lost the ability to think and to reason.

Lol ... good response ... actually EU paid for such a study and I wanted to get an independent verification.
Did not want to piss you though :)
Correction: The study was about the superiority of space based generation compared to Sahara based generation. Anything is actually better than something which cannot possibly work :)
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THE Solar Thermal Energy Thread (merged)

Unread postby Caoimhan » Tue 02 Aug 2005, 14:58:43

I've been fascinated by what Sterling Energy Systems has been doing with their Stirling solar-thermal devices. But here's another solar-thermal solution: http://pesn.com/2005/08/02/9600142_IAUS_Solar/

Here's a snippet:
There are two key factors in the IAUS technology that enable a cost-effective conversion of solar energy into usable power: their thin-film solar collectors, and their bladeless turbines, which have a much wider application than just converting solar thermal energy to electricity.

The company also will be combining this new development with existing catalytic technology to generate methanol fuel cleanly from carbon dioxide and hydrogen. All this can be done at a price comparable to gasoline, if not even a little less expensive, considering the present high price of gasoline.

The solar collectors do not operate as photovoltaic cells. Rather, the sun's rays focus onto a heat exchanger which then transfers the heat to a highly efficient turbine, which in turn hooks directly to a regular AC electricity generator.

Solar panels resemble magnifying glass lenses. Approximately 1/8-inch thick, resilient material, withstands strong winds.
Though the panels resemble a magnifying glass, they are in fact composed of thousands of microscopic refracting lenses on a thin substrate that is only about 1/8th of an inch thick, and held in place by a frame. The "thin film" manufacturing process is far less expensive than the photovoltaic cell manufacturing process.

The prototype is rectangular in shape, with 15 panels on each half, each focusing on a separate heat exchanger that will reach around 1000 degrees Fahrenheit, driving the turbine.

However, the manufactured product will be shaped like an octagon, about 22 feet in diameter; and will focus all the rays on a larger heat exchanger, which could get as hot as 4000 ºF. That unit will put out about 6-10 kilowatts of AC power, enough to power a few homes.
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Unread postby gnm » Tue 02 Aug 2005, 16:17:49

Don't they mean "Methane" ? Methanol is wood alchohol not natural gas....

Solar to Methanol -- Natural Gas

Another process that the company is capable of involves a method of producing methanol from carbon dioxide and hydrogen. This technology is already developed and in existence elsewhere, but their apparatus will make it more economical, to the point where methanol could be made available at approximately the same cost as gasoline.

The UV energy from the sun will split CO2 (carbon dioxide) into CO (carbon monoxide) and O2 (oxygen). Then the CO along with hydrogen (H) bubbles through a catalytic unit containing copper and zinc powder suspended in a kind of oil. The CO and H combine into CH2OH (Methanol). The H is released through electrolysis from water.

The catalytic process requires about 600 psi, and 500ºF. The heat from the solar collectors initiates the process, and once it takes off, it generates excess heat, which can then be used to turn the turbine, to create more electricity by which they can run the electrolysis.

The IAUS concept is to produce methanol fuel using carbon dioxide -- a primary greenhouse gas -- from the environment -- at a cost comparable to gasoline. The CO2 could come either from ambient air, or from a smoke stack, to help clean it up the atmosphere.

Being a very small molecule, methanol, or natural gas, burns much more cleanly and efficiently, resulting in less emissions when it is used as a fuel.

This method solves the Hydrogen transport problem as well. The solar panels generate electricity to split off hydrogen from water, and rather than having to then ship the hydrogen, which is problematic, IAUS runs the hydrogen through this process to convert it to methanol, which can easily be contained and shipped.



I'd be more interested in details about thier "turbine"

I dunno man, I'm suspicious - this smacks of pump it and dump it!

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