Technology News
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-HVPE Technological Breakthrough Will Reduce the Time to Make a Solar Cell
EOM Adopts Pioneering Solar Dome Technology for Sustainable Desalination Project
NEOM will now adopt pioneering solar technology to produce low cost, environmentally friendly water, strengthening its reputation as an emerging hub for innovation and conservation. The company has signed an agreement with U.K.-based Solar Water Plc. to build the first ever “solar dome” desalination plants in NEOM, located in northwest Saudi Arabia. The pilot project promises to revolutionize the water desalination process, helping solve one of the world’s most pressing problems – access to freshwater. Work will commence in
The scientists successfully integrated an aluminum source into their hydride vapor phase epitaxy (HVPE) reactor, then demonstrated the growth of the semiconductors aluminum indium phosphide (AlInP) and aluminum gallium indium phosphide (AlGaInP) for the first time by this technique. III-V solar cells—so named because of the position the materials fall on the periodic
February and is expected to be completed by the end of 2020.
table—are commonly used in space applications. Notable for high efficiency, these types
At an estimated $0.34/m3, the cost of producing water via “solar dome” technology
of cells are too expensive for terrestrial use, but researchers are developing techniques to
will be significantly lower than desalination plants using reverse osmosis methods. The technology will also significantly reduce the impact on the environment by producing
reduce those costs.
more concentrated brine, a potentially harmful byproduct of the water extraction process.
One method pioneered at NREL relies on a new growth technique called dynamic hydride
Solar Water’s ground-breaking approach, developed at the U.K.’s Cranfield University, represents the first use, on a large scale, of Concentrating Solar Power (CSP) technology
vapor phase epitaxy, or D-HVPE. Traditional HVPE, which for decades was considered
in seawater desalination. The process sees seawater pumped into a hydrological “solar
the best technique for production of light-emitting diodes and photodetectors for the
dome” made from glass and steel, before it is superheated, evaporated and eventually precipitated as fresh water.
telecommunications industry, fell out of favour in the 1980s with the emergence of MOVPE.
The “solar dome” desalination process, which can also operate at night due to the stored
Both processes involve depositing chemical vapors onto a substrate, but the advantage
solar energy generated throughout the day will reduce the total amount of brine that is
belonged to MOVPE because of its ability to form abrupt heterointerfaces between two
created during the water extraction process. Typically, the high salt concentration in brine makes it more difficult and expensive to process. The solar dome process helps prevent any damage to marine life as no brine is discharged into the sea. With over one billion people around the world lacking access to clean water every day, NEOM’s solar desalination project will serve as a test case for other water scarce countries
different semiconductor materials, a place where HVPE traditionally struggled. That’s changed with the advent of D-HVPE. The earlier version of HVPE used a single chamber where one chemical was deposited on a
that are struggling to generate environmentally safe and sustainable sources of fresh water.
substrate, which was then removed. The growth chemistry was then swapped for another,
NEOM, the flagship project of Saudi Arabia’s post-oil diversification plan, is being built on
and the substrate returned to the chamber for the next chemical application. D-HVPE
a 26,500 km2 area in northwestern Saudi Arabia. It offers unique investment opportunities in economic sectors and real-estate development.
relies on a multi-chamber reactor. The substrate moves back and forth between chambers, greatly reducing the time to make a solar cell. A single-junction solar cell that takes an hour
C
ovestro’s Insqin Technology Granted Solar Impulse’s Label
or two to make using MOVPE can potentially be produced in under a minute by D-HVPE. Despite these advances, MOVPE still held another advantage: the ability to deposit wide band gap aluminum-containing materials that enable the highest solar cell efficiencies. HVPE has long struggled with the growth of these materials due to difficulties with the chemical nature of the usual aluminum-containing precursor, aluminum monochloride. The researchers always planned on introducing aluminum into D-HVPE, but first focused their efforts on validating the growth technique. The scientists used an aluminum trichloride generator, which was heated to 400 degrees celsius to generate an aluminum
Covestro’s waterborne technology called Insqin for sustainable textile coating has been
trichloride from solid aluminum and hydrogen chloride gas. Aluminum trichloride is much
granted the Solar Impulse Efficient Solutions Label by the Solar Impulse Foundation. The
more stable in the HVPE reactor environment than the monochloride form. The other
label signifies its credibility and a guarantee of quality for those looking for clean solutions.
components—gallium chloride and indium chloride—were vaporized at 800 degrees
The project has been proven economically profitable and environmentally protective. Covestro’s solar-powered greenhouses for drying food to preserve it have also got the Solar Impulse Efficient Solutions Label. With its Insqin technology, Covestro significantly increases the sustainability of textile coating. The technology is based on waterborne polyurethane coatings, making textile production more eco-friendly and easier to handle.
Celsius. The three elements were combined and deposited on a substrate at 650 degrees Celsius. Using D-HVPE, NREL scientists previously were able to make solar cells from gallium arsenide (GaAs) and gallium indium phosphide (GaInP). In these cells, the GaInP is used
Using Insqin, the production of coated fabrics also requires up to 95 per cent less water
as the “window layer,” which passivates the front surface and permits sunlight to reach
and 50 per cent less energy.
the GaAs absorber layer below where the photons are converted to electricity. This layer
The solar greenhouse dryer is an efficient, decentralised, cost-effective and sustainable
must be as transparent as possible, but GaInP is not as transparent as the aluminum
solution for reduction of post-harvest losses in agricultural products. The high efficiency of
indium phosphide (AlInP) used in MOVPE-grown solar cells. The current world efficiency
the dryer is achieved through the use of polycarbonate for construction of a parabolically
record for MOVPE-grown GaAs solar cells that incorporate AlInP window layers is 29.1%.
shaped greenhouse. The material is transparent to visible and in particular infrared light and shows good thermal insulating properties, allowing the dryer to heat up quickly. The World Alliance for Efficient Solutions, founded under the auspices of the Solar Impulse Foundation, collaborates with start-ups, companies, institutions, NGOs and investors to create synergies, share knowledge and build relationships for speeding up the implementation of clean and profitable solutions.
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With only GaInP, the maximum efficiency for HVPE-grown solar cells is estimated to be only 27%. Now that aluminum has been added to the mix of D-HVPE, the scientists said they should be able to reach parity with solar cells made via MOVPE. The HVPE process is a cheaper process, showing a for a cheaper technique.
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