Powered by the Sun: Breakthrough Solar Cells

solar1In addition to becoming cheaper, and increasing in efficiency and yields, solar cell technology is also growing in terms of innovative design. By going beyond the conventional design of silicon panels and electrical cables, researchers are ensuring that solar technology can go farther. And the latest advances in design are especially far-sighted, aiming to merge solar technology with just about any surface, and even sending it into space.

In the former case, researchers at Michigan State University have created a fully transparent solar concentrator, which could turn any window or sheet of glass – from highrise buildings to the screens on smartphones and tablets – into a photovoltaic solar cell. And whereas other “transparent” solar panels have been designed in the past, this one is the first that truly lives up to the word.

transparent-solar-cellScientifically, a transparent solar panel is something of an oxymoron. Solar cells, specifically the photovoltaic kind, make energy by absorbing photons and converting them into electrons. If a material is transparent, by definition it means that all of the light passes through the medium. This is why previous transparent solar cells have actually only been partially transparent, and usually cast a colorful shadow.

To get around this limitation, the Michigan State researchers use a slightly different technique for gathering sunlight. Instead of trying to create a transparent photovoltaic cell, they used a transparent luminescent solar concentrator (TLSC), which consists of organic salts that absorb specific non-visible wavelengths of ultraviolet and infrared light, which they then luminesce (glow) as another wavelength of infrared light (also non-visible).

https://i0.wp.com/www.extremetech.com/wp-content/uploads/2014/08/transparent-luminescent-solar-concentrator-colorful.jpgThis emitted infrared light is guided to the edge of plastic, where thin strips of conventional photovoltaic solar cell convert it into electricity. Currently, the Michigan TLSC has an efficiency of around 1%, but they think 5% should be possible. On their own, these aren’t huge figures, but on a larger scale — every window in a house or office block — the numbers quickly add up to a significant electrical yield.

Moreover, the researchers are confident that the technology can be scaled all the way from large industrial and commercial applications, down to consumer devices, while remaining “affordable.” So far, one of the larger barriers to large-scale adoption of solar power is the intrusive and ugly nature of solar panels. But if large amounts of solar power can be produced from sheets of glass and plastic, it would go a long way to making the scaling process feasible.

solar_panel_origamiAnother major innovation comes from Brigham Young University, where researchers have been working with NASA’s Jet Propulsion Laboratory to address the challenge of Space-Based Solar Power. For some time, scientists have understood that a solar array in orbit of Earth would be ideally suited for solar power collection, since it would be immune to weather, cloud cover or diurnal cycles (aka. nighttime).

Unfortunately, getting solar cells into space is a bit of a problem. In order to be effective, solar panels need to be thin have a large surface area to soak up more rays. This makes it difficult to transport them into orbit, and requires that they be broken down,and flown up piece by piece, and then assembled once in orbit. Given the cost of mounting a sending a single rocket into orbit, this prospect becomes very costly very fast.

solar_panel_origami1However, the Brigham team came up with a simple and elegant solution to this problem, and found it in the form of origami. By working with complex origami folds, they were able to design a solar array that can shrink down to one-tenth of its original size. Folded up, the device is 2.7 meters (8.9 feet) across and can easily wrap around a spacecraft. Once it reaches space, the array would then unfold to become as wide as 25 meters (82 feet).

Given that solar panels deal with large, flat, thin structures, the origami concept seems like a natural fit. And this is not the first time that it has been used in space equipment design – in the 1990’s, Japanese astrophysicist Koryo Miura created a prototype for another folding solar panel. However, that project was abandoned for various reasons, not the least of which was lack of funding.

space-solar-headTo make the concept work and renew interest in the application, he Brigham team worked with Robert Lang, a world-renowned origami expert who also happens to be a mathematician and engineer and once worked at JPL himself. As Brian Trease, a mechanical engineer at the Jet Propulsion Laboratory, said:

He was trained as a physicist, used to work at JPL, and then got tired of the formal bureaucracy and left to start folding paper. Now he’s a world expert… We see value in going directly to any artist, even if they don’t have his credentials, because they have the thousands of hours or folding and tinkering to realize what can and can’t be done. Anytime you can bring in other disciplines, they just visualize things differently and bring in different solutions to your problems.

The new solar panels could be used to power spacecraft and potentially also on orbiting power stations that could wirelessly send energy to Earth via microwaves. A similar design could also be used on Earth to provide new options for portable solar power in remote locations. The same type of design might also be used in architecture or product design because of its unusual looks and function.

NASA_suntowerAccording to Trease, the Department of Defense has already been in touch with them regarding applications for soldiers in the field:

Soldiers right now might carry around 100 pounds, 15 of those pounds are batteries and fuel. If you can eliminate that, you’ve dramatically reduced their load… It’s different from opening an umbrella, because it can accommodate rigid material. You could do something like a deployable glass chandelier or a table. When it’s deployed, it looks like a flower blooming–it’s got a nice aesthetic to it.

In the next few weeks, Trease will also meet with other experts to consider different potential applications for space equipment, like antennas and reflectors, that could also deploy using origami. And given the rapidly-dropping prices associated with placing objects into orbit, this could prove to be the basis for the dream of Space-Based Solar Power – where all our energy needs are met by solar arrays in orbit that then beam them to Earth.

 

Source: extremetech.com, fastcoexist.com

The Future of Solar: The Space-Based Solar Farm

space-solar-headThe nation of Japan has long been regarded as being at the forefront of emerging technology. And when it comes to solar energy, they are nothing if not far-sighted and innovative. Whereas most nations are looking at building ground-based solar farms in the next few years, the Japanese are looking at the construction of vast Lunar and space-based solar projects that would take place over the course of the next few decades.

The latest proposal comes from the Japan Aerospace Exploration Agency (JAXA), which recently unveiled a series of pilot projects which, if successful, should culminate in a 1-gigawatt space-based solar power generator within just 25 years. Relying on two massive orbital mirrors that are articulated to dynamically bounce sunlight onto a solar panel-studded satellite, the energy harvested would then be beamed wirelessly to Earth using microwaves, collected Earth-side by rectifying antennas at sea, and then passed on to land.

lunaringJAXA has long been the world’s biggest booster of space-based solar power technology, making significant investments in research and rallying international support for early test projects. And in this respect, they are joined by private industries such as the Shimizu Corporation, a Japanese construction firm that recently proposed building a massive array of solar cells on the moon – aka. the “Lunar Ring” – that could beam up to 13,000 terawatts (roughly two-thirds of global power consumption) to Earth around the clock.

Considering that Japan has over 120 million residents packed onto an island that is roughly the size of Montana, this far-sighted tendency should not come as a surprise.  And even before the Fukushima disaster took place, Japan knew it needed to look to alternative sources of electricity if it was going to meet future demands. And considering the possibilities offered by space-based solar power, it should also come as no surprise that Japan – which has very few natural resources – would look skyward for the answer.

solar_array1Beyond Japan, solar power is considered the of front runner of alternative energy, at least until s fusion power comes of age. But Until such time as a fusion reaction can be triggered that produces substantially more energy than is required to initiate it, solar will remain the only green technology that could even theoretically provide for our global power demands. And in this respect, going into space is seen as the only way of circumventing the problems associated with it.

Despite solar power being in incredible abundance – the Earth’s deserts absorb more energy in a day than the human race uses in an entire year – the issue of harnessing that power and getting it to where it is needed remain as stumbling blocks. Setting up vast arrays in the Earth’s deserts would certainly deal with the former, but transmitting it to the urban centers of the world (which are far removed from it’s deserts) would be both expensive and impractical.

space-based-solarpowerLuckily, putting arrays into orbit solves both of these issues. Above the Earth’s atmosphere, they would avoid most forms of wear, the ground-based day/night cycle, and all occluding weather formations. And assuming the mirrors themselves are able to reorient to be perpetually aimed at the sun (or have mirrors to reflect the light onto them), the more optimistic estimates say that a well-designed space array could bring in more than 40 times the energy of a conventional one.

The only remaining issue lies in beaming all that energy back to Earth. Though space-based arrays can easily collect more power above the atmosphere than below it, that fact becomes meaningless if the gain is immediately lost to inefficiency during transmission. For some time, lasers were assumed to be the best solution, but more recent studies point to microwaves as the most viable solution. While lasers can be effectively aimed, they quickly lose focus when traveling through atmosphere.

spaceX_solararrayHowever, this and other plans involving space-based solar arrays (and a Space Elevator, for that matter) assume that certain advances over the next 20 years or so – ranging from light-weight materials to increased solar efficiency. By far the biggest challenge though, or the one that looks to be giving the least ground to researchers, is power transmission. With an estimated final mass of 10,000 tonnes, a gigawatt space solar array will require significant work from other scientists to improve things like the cost-per-kilogram of launch to orbit.

It currently costs around $20,000 to place a kilogram (2.2lbs) into geostationary orbit (GSO), and about half that for low-Earth orbit (LEO). Luckily, a number of recent developments have been encouraging, such as SpaceX’s most recent tests of their Falcon 9R reusable rocket system or NASA’s proposed Reusable Launch Vehicle (RLV). These and similar proposals are due to bring the costs of sending materials into orbit down significantly – Elon Musk hopes to bring it down to $1100 per kilogram.

So while much still needs to happen to make SBSP and other major undertakings a reality, the trends are encouraging, and few of their estimates for research timelines seem all that pie-eyed or optimistic anymore.

Sources: extremetech.com, (2)

Powered by the Sun: Efficiency Records and Future Trends

solar_panelThere have been many new developments in the field of solar technology lately, thanks to new waves of innovation and the ongoing drive to make the technology cheaper and more efficient. At the current rate of growth, solar power is predicted to become cheaper than natural gas by 2025. And with that, so many opportunities for clean energy and clean living will become available.

Though there are many contributing factors to this trend, much of the progress made of late is thanks to the discovery of graphene. This miracle material – which is ultra-thin, strong and light – has the ability to act as a super capacitor, battery, and an amazing superconductor. And its use in the manufacture of solar panels is leading to record breaking efficiency.

graphene-solarBack in 2012, researchers from the University of Florida reported a record efficiency of 8.6 percent for a prototype solar cell consisting of a wafer of silicon coated with a layer of graphene doped with trifluoromethanesulfonyl-amide (TFSA). And now, another team is claiming a new record efficiency of 15.6 percent for a graphene-based solar cell by ditching the silicon all together.

And while 15.6 efficiency might still lag behind certain designs of conventional solar cells (for instance, the Boeing Spectrolabs mass-production design of 2010 achieved upwards of 40 percent), this represents a exponential increase for graphene cells. The reason why it is favored in the production of cells is the fact that compared to silicon, it is far cheaper to produce.

solar_power2Despite the improvements made in manufacturing and installation, silicon is still expensive to process into cells. This new prototype, created by researchers from the Group of Photovoltaic and Optoelectronic Devices (DFO) – located at Spain’s Universitat Jaume I Castelló and the University of Oxford – uses a combination of titanium oxide and graphene as a charge collector and perovskite to absorb sunlight.

As well as the impressive solar efficiency, the team says the device is manufactured at low temperatures, with the several layers that go into making it being processed at under 150° C (302° F) using a solution-based deposition technique. This not only means lower potential production costs, but also makes it possible for the technology to be used on flexible plastics.

twin-creeks-hyperion-wafer-ii-flexibleWhat this means is a drop in costs all around, from production to installation, and the means to adapt the panel design to more surfaces. And considering the rate at which efficiency is being increased, it would not be rash to anticipate a range of graphene-based solar panels hitting the market in the near future – ones that can give conventional cells a run for their money!

However, another major stumbling block with solar power is weather, since it requires clear skies to be effective. For some time, the idea of getting the arrays into space has been proposed as a solution, which may finally be possible thanks to recent drops in the associated costs. In most cases, this consists or orbital arrays, but as noted late last year, there are more ambitious plans as well.

lunaring-3Take the Japanese company Shimizu and it’s proposed “Luna Ring” as an example. As noted earlier this month, Shimizu has proposed creating a solar array some 400 km (250 miles) wide and 11,000 km (6,800 miles) long that would beam solar energy directly to Earth. Being located on the Moon and wrapped around its entirety, this array would be able to take advantage of perennial exposure to sunlight.

Cables underneath the ring would gather power and transfer it to stations that facing Earth, which would then beam the energy our way using microwaves and lasers. Shimizu believes the scheme, which it showed off at a recent exhibition in Japan, would virtually solve our energy crisis, so we never have to think about fossil fuels again.

lunaring-2They predict that the entire array could be built and operational by 2035. Is that too soon to hope for planetary energy independence? And given the progress being made by companies like SpaceX and NASA in bringing the costs of getting into space down, and the way the Moon is factoring into multiple space agencies plans for the coming decades, I would anticipate that such a project is truly feasible, if still speculative.

Combined with increases being made in the fields of wind turbines, tidal harnesses, and other renewable energy sources – i.e. geothermal and piezoelectric – the future of clean energy, clear skies and clean living can’t get here soon enough! And be sure to check out this video of the Luna Ring, courtesy of the Shimizu corporation:


Sources:
gizmodo.com, fastcoexist.com

Towards a Cleaner Future: Solar and Wind Drones

solar_cell_galliumWith supplies of easily accessible fossil fuels diminishing, pushing us towards dirtier sources of oil and natural gas (such as tar sands and frakking), researchers are looking for ways to make renewable energy more efficient and accessible. Towards this end, they are pushing the boundaries of solar cells and wind turbines are capable of, but the constraints of land and weather limit where vast solar or wind farms can be set up.

Luckily, a UK-based company known as New Wave Energy has spent the last few years developing the technology to produce an army of power-generating drone aircraft to overcome these very problems. Basically, each craft is a 20x20m (65ft) flat surface fitted with solar panels and turbines to generate power from the sun and wind, and four small propellers that keep it aloft.

solar_dronesThe drones would be capable of flying at altitudes of up to 15,240 meters (50,000 feet), putting them far above the clouds that can obscure the sun. The propellers would allow the craft to track the course of the sun to remain in optimal position for as long as possible. At these altitudes, the wind is also more consistent and powerful, which means smaller turbines can be used in place of the giant towers necessary down near the ground.

In terms of transmitting that power, the key is in the use of microwaves. In essence, power from the drones would be beamed down as a low-energy microwave and collected by antenna arrays on the ground. These antennas can then be used to turn the electromagnetic radiation into usable DC power and then send it to where it is needed.

solar_drones1One of the benefits of this design is that the proposed drone power plants wouldn’t need to land to refuel themselves. Supposedly, they will be able to power themselves entirely with the energy generated on-board, and still produce 50kW of power. This that means several thousand drones would be needed to power a large city of 205,000 homes.

However, these swarms of robotic power plants aren’t just a way to replace the power infrastructure we already have. They could be used to augment our current power supplies as demand increases, removing the need to expand on large, expensive power plants. Also, they bring power to remote areas with poor service, or to restore power in regions affected by natural disasters.

solar_panelThus, the cost of building and deploying the drones will determine whether or not that’s feasible. At present, the company plans to raise about $500,000 on Kickstarter to fund the construction of a prototype for testing and marketing. If this campaign does turn out to be successful, the first flying power plant could be aloft within six months.

Combined with other improvements that are making wind and solar power more efficient and affordable, and future prospects for space-based solar power (SBSP) that are being made possible thanks to space startups like Google X, we could be looking at a near-future where solar and wind meet the lion’s share of our energy requirements.

Source: extremetech.com