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New solar energy developments

Home Forums Archive Infrastructure New solar energy developments

This topic contains 23 replies, has 8 voices, and was last updated by Avatar of J.L.-Frusha J.L.-Frusha 3 years, 4 months ago.

Viewing 15 posts - 1 through 15 (of 24 total)
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  • #1210
    Avatar of i_is_j_smith
    i_is_j_smith
    Participant

    I’m partial to solar thermal systems, so news that Google has developed some new materials that might cut costs in half is promising:

    http://www.reuters.com/article/idUSTRE61P58V20100226

    Not to be outdone, researchers at the California Institute of Technology have come up with a new material that they say can make solar cells that are just as efficient as current cells (15-20%) but only use 1/100th as much silicon. It could make very cheap cells that are very easy to install:

    http://www.reuters.com/article/idUSN1316303620100214

    I’d read about this a month or two ago, but it’s still very interesting. A group is using nanoprinting technology to create cheap, flexible solar cells that are 80% efficient and can convert all forms of electromagnetic energy including infrared into electricity. They are still a few years out…it works but they don’t have any way to store the energy the panels create. Still, it’s an interesting tech:

    https://inlportal.inl.gov/portal/server.pt?open=514&objID=1269&mode=2&featurestory=DA_101047

    All good news for potential seastead power systems.

    #9760
    Avatar of J.L.-Frusha
    J.L.-Frusha
    Participant

    While living in the country, with a high-tension line running through, I thought of using an antenna to recieve the 60Hz from the lines… Never got around to trying it, but it should work, lie a crystal radio converts radio waves to electrical impulses to drive the headphones. On the other hand, using loops is illegal, since it uses a coile to use inductance, a tuned antenna would work different, but theoretically, it would work. Not very efficient, but…

    Later,

    J.L..F.

    If you can’t swim with the big fish, stick to the reef

    #9773
    Avatar of
    Anonymous

    …but mirrors seem kind of fussy. They need alignment (at the very least seasonal and often continously during the day), which costs money on land and probably more so bobbing around on the water, and a fair amount of cleaning. A simple matt black surface with a fluid running through it seems more robust to me. Then a heat pump sucks the heat out and stores it in a thermal reservoir. To generate electricity you run a stirling engine.

    Leeching electricity from HT wires was on Mythbusters. I don’t think it worked very well, and even if it did it’s just stealing. Not to mention that HT wires aren’t very common on the ocean… :-)

    #9777
    Avatar of i_is_j_smith
    i_is_j_smith
    Participant

    Carl wrote:
    …but mirrors seem kind of fussy.

    Very true. Hopefully you would have the entire system (tower and mirrors) on one platform so the movement due to waves will move the entire system as a whole. If the mirrors are parabolic then their orientation to the sun isn’t as important, but it does have affect the efficiency a bit.

    Carl wrote:
    A simple matt black surface with a fluid running through it seems more robust to me. Then a heat pump sucks the heat out and stores it in a thermal reservoir. To generate electricity you run a stirling engine.

    I would wonder how efficient a system like that is. Can you really extract enough heat to make it worth while? If so then it would definately be more robust.

    #9778
    Avatar of J.L.-Frusha
    J.L.-Frusha
    Participant

    Carl wrote:

    …but mirrors seem kind of fussy. They need alignment (at the very least seasonal and often continously during the day), which costs money on land and probably more so bobbing around on the water, and a fair amount of cleaning. A simple matt black surface with a fluid running through it seems more robust to me. Then a heat pump sucks the heat out and stores it in a thermal reservoir. To generate electricity you run a stirling engine.

    Flat ‘Hunters Green’ with about 25% Flat Black is more effective at heat absorption. Mirrors can add to the recieved amount of energy, but also increase the absorbed heat, so solar cells need more cooling, for the increase…

    Carl wrote:

    Leeching electricity from HT wires was on Mythbusters. I don’t think it worked very well, and even if it did it’s just stealing. Not to mention that HT wires aren’t very common on the ocean… :-)

    Radio frequency emissions/signals are free, otherwise unrecoverable energy. All you have to do is tune them in, thus the example of a crystal radio. I did say it wouldn’t likely be too effective, however, using di-electrics for tuned antennas should be more efficient. Add a couple of collectors and a reflector (Yagi antenna) and you can increase the effectiveness. This is not an inductive load, draining the electricity, this is a radio reciever, tuning to a band-width that saturates most cities and areas with alternating-current supplies and creates havoc with electronics, thus the need for grounded shielding in electronics, to reduce/eliminate the interferrance. The micro-antennae innitially described use the same exact principle to try to recieve and convert the infra-red emmissions… Are they trying to steal from the Sun, or make use of radiated energy, of a measurable frequency?

    Is it theft of service to listen to a radio? All I’d be doing is using radio equipment to pick up a signal… How I use that signal is my business.

    Later,

    J.L..F.

    If you can’t swim with the big fish, stick to the reef

    #9799
    Avatar of
    Anonymous

    i_is_j_smith wrote:

    I would wonder how efficient a system like that is. Can you really extract enough heat to make it worth while? If so then it would definately be more robust.

    I really don’t know, but considering that PV, for instance is only about 20% efficient, and knowing that black surfaces get really hot in the sun, my gut feeling is that it would make sense economically. I know there are companies making roof tiles with a greenhouse design (clear plastic with absorptive surface inside then the air is piped to the heat pump of the house.

    Another benefit is that you might be able to use the surface to walk on or do other things. Put a runway of this stuff on top of a cruise/container ship and you have an airport for light airplanes and energy production squared away.

    Is it theft of service to listen to a radio? All I’d be doing is using radio equipment to pick up a signal… How I use that signal is my business.

    No, listening to radio is not theft. The radio transmission is not lessened because more people listen to it. Siphoning power off the grid does however lessen the available power for the paying customers.

    In other words, the former is copying and the latter is stealing. Also, the sun has no rights. :-)

    But maybe I misunderstood what you were suggesting.

    #9800
    Avatar of Melllvar
    Melllvar
    Participant

    Could always build a gyroscope into each mirror for a computer-controlled power tower that’s unaffected by wave motion. Don’t even need the mirrors on the seastead, they can be buoys floating in a radius around the tower. Or have one of the long solar troughs dragged behind a boat, and use ballast tanks to tilt it along one axis as the sun moves across the sky. Absorbing sunlight without concentrating it will never get you as much temp. difference as a more concentrated form, so I’d say if you have the money then power tower > trough > sheets. The flat, non-concentrated set ups are better for small scale use, like solar water heaters, ovens, etc.

    There’s also this stuff, which seems pretty cheap, although I’m not sure how it compares on price, reflectivity, durability to other stuff. Thought I’d seen similar reflective film for about half that price somewhere, but I can’t find the link right now.

    #9819
    Avatar of J.L.-Frusha
    J.L.-Frusha
    Participant

    Transmission losses from power lines, in the form or radio waves that are there, vs ‘Siphoning’? I’m not even talking about causing ANY loss to the power-line. THAT would require tapping into it with a transforme of some sort… ‘Inductive’ losses are transformers. Radio waves dissipate over distances, thus the loss of reception of that favorite radio channel, on a long drive.

    To put your analogy into use, I’d have to make an inductance loop/transformer, to tap the lines.

    I’m talking about making use of radiant losses that propagate as radio waves. Tuning a radio, to recieve it is not causing any addittional drain on the system, any more than tuning your radio to recieve ‘Bob FM’ drains the area of those radio waves. All I’ve done is propose capturing the otherwise lost energy.

    As far as we KNOW, the Sun doesn’t have rights… The jury is out on that one. I know I am in no position to tell it what it can or cannot do.

    Is the Earth alive? Jury is out on that, too. However, it behaves as though it is, in many aspects. We, the fleas of the Earth, have created toxic conditions on the ‘skin’ and it is reacting. Habitats are dieing out because of human excess. Our waste has fouled the planet and the reaction is to wash-off the fleas. If we don’t eat, we die. If our excesses kill our food, we die. Has the ecosystem changed and recovered from external damage? Yes. Each time, there’s a return to balance. We’ve irritated the surface and the ecosystem is scratching back at us.

    Later,

    J.L..F.

    If you can’t swim with the big fish, stick to the reef

    #9830
    Avatar of
    Anonymous

    Could always build a gyroscope into each mirror for a computer-controlled power tower that’s unaffected by wave motion.

    Could, yes. But gyroscopes and computers aren’t free. The bottom line is the amount of kilowatt-hours produced per dollar, after all.

    Don’t even need the mirrors on the seastead, they can be buoys floating in a radius around the tower. Or have one of the long solar troughs dragged behind a boat, and use ballast tanks to tilt it along one axis as the sun moves across the sky.

    Again, yes, one could do all these things. But would it be cheap, easy and fault-tolerant?

    Absorbing sunlight without concentrating it will never get you as much temp. difference as a more concentrated form

    Well, the temperature difference inside the system is not everything. The economical bottom line is what matters. And for the record, heat pumps are pretty good at concentrating heat.

    The flat, non-concentrated set ups are better for small scale use, like solar water heaters, ovens, etc.

    I’m interested in any data supporting this assertion, if you have it.

    There’s also this stuff, which seems pretty cheap, although I’m not sure how it compares on price, reflectivity, durability to other stuff. Thought I’d seen similar reflective film for about half that price somewhere, but I can’t find the link right now.

    $32 per m²? I wonder how many square meters I could wallpaper with aluminium foil for that money…

    #9834
    Avatar of
    Anonymous

    I guess I misunderstood what you were suggesting. Now it sounds kind of like one of those “free energy” schemes though… If you have a source with some data I’d love to see it.

    And I’d love to debate Gaia theory and Solarians with you (in a nutshell: I don’t believe in them). Perhaps not here though. :-) Lots of things are “as far as we know”. As far as we know, there is no Flying Spaghetti Monster in the sky. So we act as if there isn’t. And that’s a good thing, because anything resembling a civilized human life would be impossible if we took into account every “what if”.

    J.L.Frusha wrote:

    Transmission losses from power lines, in the form or radio waves that are there, vs ‘Siphoning’? I’m not even talking about causing ANY loss to the power-line. THAT would require tapping into it with a transforme of some sort… ‘Inductive’ losses are transformers. Radio waves dissipate over distances, thus the loss of reception of that favorite radio channel, on a long drive.

    To put your analogy into use, I’d have to make an inductance loop/transformer, to tap the lines.

    I’m talking about making use of radiant losses that propagate as radio waves. Tuning a radio, to recieve it is not causing any addittional drain on the system, any more than tuning your radio to recieve ‘Bob FM’ drains the area of those radio waves. All I’ve done is propose capturing the otherwise lost energy.

    As far as we KNOW, the Sun doesn’t have rights… The jury is out on that one. I know I am in no position to tell it what it can or cannot do.

    Is the Earth alive? Jury is out on that, too. However, it behaves as though it is, in many aspects. We, the fleas of the Earth, have created toxic conditions on the ‘skin’ and it is reacting. Habitats are dieing out because of human excess. Our waste has fouled the planet and the reaction is to wash-off the fleas. If we don’t eat, we die. If our excesses kill our food, we die. Has the ecosystem changed and recovered from external damage? Yes. Each time, there’s a return to balance. We’ve irritated the surface and the ecosystem is scratching back at us.

    Later,

    J.L..F.

    If you can’t swim with the big fish, stick to the reef

    #9836
    Avatar of Melllvar
    Melllvar
    Participant

    From Wikipedia:

    “Where temperatures below about 95°C are sufficient, as for space heating, flat-plate collectors of the nonconcentrating type are generally used. The fluid-filled pipes can reach temperatures of 150 to 220 degrees Celsius when the fluid is not circulating. This temperature is too low for efficient conversion to electricity.

    The efficiency of heat engines increases with the temperature of the heat source. To achieve this in solar thermal energy plants, solar radiation is concentrated by mirrors or lenses to obtain higher temperatures — a technique called Concentrated Solar Power (CSP). The practical effect of high efficiencies is to reduce the plant’s collector size and total land use per unit power generated, reducing the environmental impacts of a power plant as well as its expense.”

    So, is running a bunch of heat pumps to concentrate the heat going to be more efficient than using reflective film/mirrors to do it? Seems most people building big solar thermal stations think not, since all the big solar thermal stations (that I’ve heard of) are either troughs or power towers. For one thing, without dealing with actual numbers, the heat pump efficiency runs against the heat engine efficiency, since one operates best at low temp. differences and the other operates best at high temp. differences. You’ll also have to run a ton more fluid through the heat pump(s) to get the same amount of thermal being used in the engine. But if you think you can make it more cost effective than mirrors, I’m all ears.

    I’m not sure how cost effective gyroscopes are for a floating solar thermal power tower, honestly, I was just throwing the idea out there. It might also be possible to just use a water-filled chamber as a gyroscope, so that even as the buoy rotates in the waves the mirror’s orientation is independent. Vertical motion will still occur either way, but that won’t affect the amount of sunlight, as long as it is still pointed the right way. Or screw the gyroscopes, just make the buoys into spar-type things that are minimally affected by wave motion.

    As for aluminum foil though, you’ll get such crappy reflectivity I doubt you’ll really save money in the end. There’s a reason at-home pot growers spring for the more expensive mylar film rather than just use aluminum foil.

    #9839
    Avatar of i_is_j_smith
    i_is_j_smith
    Participant

    Carl wrote:
    As far as we know, there is no Flying Spaghetti Monster in the sky. So we act as if there isn’t.

    BLASPHEMER!!!

    His Noodliness exists. Here is the proof!

    I think any floating power tower concept would have to be pretty stable to work. That means either inside a large breakwater that also protects the seastead, or mooring to the seafloor like a semi-sub or TLP. Mooring is probaby the best bet since semi-subs and TLPs have hardly any heave or roll.

    #9840
    Avatar of
    Anonymous

    Mellvar, I am sure you and wikipedia are right about all the efficiency numbers. But has anyone ever built a floating concentrated solar energy plant? On land you clearly have an advantage with regards to alignment.

    I am not sure about what temperatures you can achieve with heat pumps, or what temperatures are required for Stirling engines. Maybe low-temp collectors aren’t feasible for electricity generation. I’m just suggesting it as an alternative that on the face of it seems to have some advantages over mirrors.

    On the reflective film, I really don’t have a clue what the going rate is. I just saw $32/m² and thought it sounded expensive for what seems like a simple product. Pot growers (I would presume) probably are limited by area though, so they can afford to use expensive stuff. And they don’t need a whole lot in comparison with a power plant.

    #9841
    Avatar of cscoggin
    cscoggin
    Participant

    Looking over the current state of Solar Thermal options. It looks like something along the lines of the Sterling/Dish system would work best (in theory).

    Each unit is self contained with a 25Kw rating. As each operates independently, if you need more power just add more. If a subset of the population breaks off they can take theirs with them with the only system level impact being the a reduction in generation equal to the number of unit lost. But as the load will be reduced as well that would (in theory) be balanced. They are also relatively small at only 38 feet (11.5 meters) across (using the SunCatcher model as an example). The only ongoing maintenance is cleaning the mirrors (where again smaller size is an advantage).

    I can’t find anything about cost per unit so I can’t say how it compares cost wise. The lack of thermal storage also means that it will only generate when there is light available.

    #9842
    Avatar of i_is_j_smith
    i_is_j_smith
    Participant

    The single-unit systems like the SunCatcher, and the large 250kW industrial systems from Solar & Thermal Systems, are nice since you don’t have to worry about focusing the beam on a single point. Thus wave motion shouldn’t have too much of an impact. The downside of these systems is that their overall efficiency isn’t much better than PV. I just read a report from 2008 that they were able to get 31.25% efficiency out of one of the SunCatcher dishes. Now I think that might have been one of their early models…they’ve just done a complete re-design of the dish so the new efficiency might be better. But with all the maintenance you need to do on these systems I don’t know if the extra 10-15% efficiency over PV is worth it.

    And, as was rightly pointed out, these systems only produce power when the sun is out. You still need to add an energy storage mechanism that will eat away even further at the net efficiency and add cost to the system.

    Power towers using two-tank molten salt designs can reach efficiencies as high as 99% and can continue to provide power for hours, days, or even weeks without sunlight. I really don’t think wave motion would have a big impact on the system as long as the entire system…mirrors, tower, etc…were all on the same large platform. Sure the platform might heave and roll a bit, but since everything is heaving and rolling together the beam will remain on target. The worst that might happen is that the mirrors will pick up less light.

    Then again, the mirrors are usually made to track the sun as it moves across the sky. If the tracking motors were fast enough, and the roll action not too crazy, I’m sure the mirrors could continue to track the sun as the platform rolled.

    But you still want a moored semi-sub or TLP platform for best results, there’s no doubt about that.

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