An energy production system that relies almost completely on the incineration of fossil fuels is wasteful, inefficient, unreliable, and unclean. Burning coal to make electricity is a crude and outdated approach, but alternative energies [1] have still not advanced far enough to allow the old nineteenth century methods of producing power to be fully phased out.
Alternative energy sources such as wind and solar would at first glance seem to offer great hope for a better future. However, the progress of renewables has been held back by persistently high production costs [2]. Off-the-gridders and other intrepid souls who are not afraid to think outside the box have found ways to affordably capture sufficient solar energy to provide for a decent proportion of their power needs, but the immense potential of solar has remained largely untapped because efficient and cost-effective conversion of sunlight to electricity has been limited by the underdeveloped state of the technology.
Traditional silicon solar panels properly installed and located can only collect 20 percent or so of the sun’s energy at maximum, and the conversion process that this energy must go through before it can be distributed as usable electricity adds a further level of entropy into the system. Despite the technology’s sophistication, the engineering principles involved in the fabrication of the best modern solar panels are inhibited by the laws of physics, making the manufacture of solar energy systems capable of surpassing the 20 percent efficiency level all but impossible.
Or at least, all but impossible up until now.
Atomic Layer Deposition: Unlocking The Door To Nano-Solar
Much of the trouble with traditional solar technology has been based on conflicts of scale. The photons that carry the sun’s electromagnetic energy and the electrons that are responsible for electrical flow are subatomic particles that operate on an extreme microscopic level that has been inaccessible in the main to human inventors and engineers, who generally must operate on far larger scales. Our scientific understanding of the world of quantum physics is profound [3], but our ability to manipulate it denizens the way we would move pieces on a chess board has been severely limited by our natural confinement to a macro-perspective.
But now, finally, nanotechnology has progressed to the point that it is becoming possible for human engineers to construct or re-construct physical objects almost literally from the ground up, molecule by molecule. In engineering, precision and cracker-jack efficiency walk together hand-in-hand, and physical objects fashioned molecule by molecule represent the pinnacle of precision because they allow engineers to structurally align manufactured artifacts so that near-perfect functioning becomes possible. In molecular- and atomic-level construction, the laws of quantum physics become an asset rather than an obstacle, and this is why nano-technology is drawing so much interest from researchers in a wide variety of fields [4]. At the present time, breakthroughs are coming along at warp speed, and as a result, we are currently in the middle of a small-scale technological revolution that may dramatically alter the way a multitude of products are designed and manufactured in the very near future.
Solar energy technicians and researchers have known for quite some time that solar cell arrays made up of nano-sized units could conceivably boost efficiency levels from the standard 20 percent to perhaps as high as 70 percent. The problem is that nano-solar cells, which are called rectennas, need to be manufactured so that the tips of their electrodes are separated by no more than one or two nano-meters (one nanometer=one millionth of a millimeter), in order to promote the smooth and steady flow of electrons for the purposes of producing electricity. Only then will electrons energized by the absorption of solar photons be able to make the jump from one electrode to the other, thereby permitting an instantaneous and unadulterated flow of electrical current following the capture of the sun’s energy by the highly precise and efficient nano-solar cells. But up until now, the best the lithographic fabrication techniques normally used to create nano-solar cells have been able to achieve is a separation between electrodes of about ten nanometers, which is far short of the required distance.
Because of this difficult engineering problem, nano-solar research has been stalled in recent years, but a 2012 breakthrough may have finally opened the door for a great leap forward [5]. Using a new version of an established technique known as atomic layer deposition (ALD), University of Connecticut [6] chemical engineering professor Brian Willis has developed a dependable and repeatable method that allows him to coat the sharpened tip of one electrode in a nano-solar cell with a layer of individual copper atoms thick enough to close the electrode gap to about 1.5 nanometers, which is obviously within the required one-to-two nanometer range. This separation distance gives electrons sufficient space to jump the gap between electrodes, facilitating the unidirectional flow of electric current across the whole range of a nano-solar rectenna array.
Harness the power of the sun for your energy needs… [7]
It is the simultaneous capture of solar radiation and its direct unmediated conversion to electric current that will allow an array of nano-solar cells to achieve that 70 percent efficiency ratio. Rectennas will soak up more of the solar energy that hits them to begin with, and by skipping the extra conversion step, the whole set-up will gain even more of an advantage over the traditional solar panel. Of course the advantages of a three-and-a-half fold improvement in energy production capacity would be cancelled out if costs for the new technology were to be prohibitively expensive, and given the normal assumptions about sophisticated technology, we might assume that this would indeed be the case. But in fact, atomic layer deposition is a relatively simple form of microtechnology that can easily be modified for production at mass scales, and it has already been used successfully in a number of other microelectronic applications. Once the new industry has gotten off the ground, thanks to their sleek and superefficient design and operation, construction costs figure to be lower for nano-solar panels than for the traditional models, meaning that in this case, cheaper will actually be synonymous with better. In the short term, ALD techniques could be used to produce enhanced versions of the more traditional style of solar panels, so even if it takes a few years of research and development before nano-solar panels are ready for mass production, nano-level engineering techniques may be in position to make an impact on the home solar market much sooner.
Milking The Sunrise
One of the great advantages of a nano-solar array will be its ability to harvest energy from across a broad swath of the sun’s electromagnetic emission spectrum, ranging from long wave infrared up through the short, fast wavelengths of visible light. Much of the future development work in this area will concentrate on the refinement of rectennas so they will be able to “tune in” on the most promising solar wavelengths, maximizing the efficiency of the solar energy-collection process during daylight hours. Natural cloud cover and other atmospheric interference will obstruct some types of solar radiation, but solar panels that can capture photon energy coming in at various wavelengths will continue to function even when visible light cannot penetrate cloud cover. Conventional silicon solar cells only collect energy from one narrow portion of the solar electromagnetic spectrum, so nano-solar’s ability to scan the skies more thoroughly would give it a competitive advantage even if all other costs were equal – which they won’t be, once nano-solar is truly ready for mass production.
One noted disadvantage of the traditional solar panel is its rigidity and inflexibility. It requires a separate infrastructure and network of specialized wiring for power delivery, and the unyielding nature of the panels partially inhibits their ability to effectively harvest solar radiation, thereby adding another layer of inefficiency into the technology. But in 2011 another chemical engineer, Dr. Patrick Pinhero from the University of Missouri [8], announced that he had developed a type of super-flexible solar panel for use with nano-solar arrays [9] that can be installed directly into a building’s skin, possibly as roof shingles or as window coverings. Building-integrated solar is already a growing area of interest in the energy industry, and with Dr. Pinhero’s new type of solar panel hitting the market some time in the next five years or so (according to his estimates), it will be incredibly easy for prospective solar consumers to meld nano-solar panels into the walls or roofs of their homes, making this new type of solar energy installation even more effective and convenient for the user.
In addition to their great flexibility, Dr. Pinhero claims that these pliable sheets of nano-solar cells are capable of capturing up to 90 percent of the sun’s radiation that hits them, so perhaps those initial 70 percent efficiency estimates for nano-solar were unnecessarily pessimistic.
Welcome To Oz
The “gee-whiz” rhetoric of the technological utopians, who love to make bold predictions about all the wondrous coming inventions that will change the course of civilization forever, is frequently exaggerated and sometimes downright foolish – where are those flying cars [10] they promised us, anyway? But the wheel of innovation does in fact continue to turn, and as the arrival of the digital age has shown us sometimes technological revolutions really do sweep through with the force of a Kansas tornado as they lift us up and carry us forward into a whole new world filled with unimaginable sights and sounds and miraculous transformations.
While alternative energy has been plagued by more than its fair share of overly enthusiastic boosters, some of whom seem to be little more than flim-flam artists, for once it appears that we may be on the verge of a true world-changing breakthrough in the field of renewable energy. Nano-solar is the wave of the future, and it has the potential to elevate the eternally nascent solar energy industry into a position of real prominence for the first time in its existence. Off-the-gridders and others interested in decentralized energy technologies will benefit tremendously from the coming innovations in the solar industry, and from the progress that has already been made in nano-solar, it appears that for once the techno-boosters may actually be guilty of underselling a new technology rather than the opposite.
©2013 Off the Grid News
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