Scientists have created a nanoscale light detector that can convert light to energy, combining both a unique fabrication method and light-trapping structures.

In today’s increasingly powerful electronics, tiny materials are a must as manufacturers seek to increase performance without adding bulk. Smaller is also better for optoelectronic devices—like camera sensors or solar cells—which collect light and convert it to electrical energy.

Think, for example, about reducing the size and weight of a series of solar panels, producing a higher-quality photo in low lighting conditions, or even transmitting data more quickly.

However, two major challenges have stood in the way: First, shrinking the size of conventionally used “amorphous” thin-film materials also reduces their quality. And second, when ultrathin materials become too thin, they are almost transparent—and actually lose some ability to gather or absorb light.

The new nanoscale light detector, a single-crystalline germanium nanomembrane photodetector on a nanocavity substrate, could overcome both of these obstacles.

“We’ve created an exceptionally small and extraordinarily powerful device that converts light into energy,” says Qiaoqiang Gan, associate professor of electrical engineering in the University at Buffalo’s School of Engineering and Applied Sciences and one of the paper’s lead authors. “The potential applications are exciting because it could be used to produce everything from more efficient solar panels to more powerful optical fibers.”

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Researchers have developed a new kind of semiconductor alloy capable of capturing the near-infrared light located on the edge of the visible light spectrum.

Easier to manufacture and at least 25 percent less costly than previous formulations, it’s believed to be the world’s most cost-effective material that can capture near-infrared light—and is compatible with the gallium arsenide semiconductors often used in concentrator photovoltaics.

Concentrator photovoltaics gather and focus sunlight onto small, high-efficiency solar cells made of gallium arsenide or germanium semiconductors. They’re on track to achieve efficiency rates of over 50 percent, while conventional flat-panel silicon solar cells top out in the mid-20s.

“Flat-panel silicon is basically maxed out in terms of efficiency,” says Rachel Goldman, a professor of materials science and engineering, as well as physics at the University of Michigan, whose lab developed the alloy. “The cost of silicon isn’t going down and efficiency isn’t going up. Concentrator photovoltaics could power the next generation.”

Varieties of concentrator photovoltaics exist today. They are made of three different semiconductor alloys layered together. Sprayed onto a semiconductor wafer in a process called molecular-beam epitaxy—a bit like spray painting with individual elements—each layer is only a few microns thick. The layers capture different parts of the solar spectrum; light that gets through one layer is captured by the next.

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By: Joshua D. Rhodes, University of Texas at Austin; Michael E. Webber, University of Texas at Austin; Thomas Deetjen, University of Texas at Austin, and Todd Davidson, University of Texas at Austin

U.S. Secretary of Energy Rick Perry in April requested a study to assess the effect of renewable energy policies on nuclear and coal-fired power plants.

Some energy analysts responded with confusion, as the subject has been extensively studied by grid operators and the Department of Energy’s own national labs. Others were more critical, saying the intent of the review is to favor the use of nuclear and coal over renewable sources.

So, are wind and solar killing coal and nuclear? Yes, but not by themselves and not for the reasons most people think. Are wind and solar killing grid reliability? No, not where the grid’s technology and regulations have been modernized. In those places, overall grid operation has improved, not worsened.

To understand why, we need to trace the path of electrons from the wall socket back to power generators and the markets and policies that dictate that flow. As energy scholars based in Texas – the national leader in wind – we’ve seen these dynamics play out over the past decade, including when Perry was governor.

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By: Jens Blotevogel, Colorado State University

Without knowing it, most Americans rely every day on a class of chemicals called per- and polyfluoroalkyl substances, or PFASs. These man-made materials have unique qualities that make them extremely useful. They repel both water and grease, so they are found in food packaging, waterproof fabric, carpets and wall paint.

PFASs are also handy when things get heated. Consumers value this property in nonstick frying pans. Government agencies and industry have used them for decades to extinguish fires at airports and fuel storage facilities.

However, widespread use of PFASs has led to extensive contamination of public water systems. Today, these substances can be found in the blood serum of almost all U.S. residents. Exposure to PFASs has been linked to kidney and testicular cancer, as well as developmental, immune, hormonal and other health issues.

But removing them from the environment is not easy. Chemical bonds between fluorine and carbon – the backbone of PFAS molecules – are extremely strong. PFASs can be removed from water by filtering them out, but the used filters have to be disposed of afterwards, and landfilling only transfers the problem to another location. The best solution to the problem is to break down PFASs completely – and on that score, we’re making progress.

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A newly created material may have the capacity to double the efficiency of solar cells.

Conventional solar cells are at most one-third efficient, a limit known to scientists as the Shockley-Queisser Limit. The new material, a crystalline structure that contains both inorganic materials (iodine and lead) and an organic material (methyl-ammonium), boosts the efficiency so that it can carry two-thirds of the energy from light without losing as much energy to heat.

In less technical terms, this material could double the amount of electricity produced without a significant cost increase, according to the new study in Science.

Enough solar energy reaches the earth to supply all of the planet’s energy needs multiple times over, but capturing that energy has been difficult—as of 2013, only about 1 percent of the world’s grid electricity was produced from solar panels.

The new material, called a hybrid perovskite, would create solar cells thinner than conventional silicon solar cells, and is also flexible, cheap, and easy to make, says Libai Huang, assistant professor of chemistry at Purdue University.

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In an effort to purify water, researchers from the University at Buffalo are using carbon-dipped paper to make dirty water drinkable.

Those behind the research believe this new development could be a cheap and efficient way to address a global shortage in drinking water, specifically in developing areas.

(MORE: See what ECS members are doing to address global water and sanitation issues.)

“Using extremely low-cost materials, we have been able to create a system that makes near maximum use of the solar energy during evaporation,” says Qiaoqiang Gan, lead researcher. “At the same time, we are minimizing the amount of heat loss during this process.”

This from University at Buffalo:

The team built a small-scale solar still. The device, which they call a “solar vapor generator,” cleans or desalinates water by using the heat converted from sunlight. Here’s how it works: The sun evaporates the water. During this process, salt, bacteria, or other unwanted elements are left behind as the liquid moves into a gaseous state. The water vapor then cools and returns to a liquid state, where it is collected in a separate container without the salt or contaminants.

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Recent trends in solar technology have led to transforming mundane surface to energy harvesting powerhouses. First, Elon Musk proposed his new solar roof. Now, rural France is taking a page from that book with the recent paving of paths with solar panels.

The solar road is part of the Wattway projects, which aims to pave nearly 3,000 roadways with solar panel tiles.

According to reports, the 1 kilometer road will produce 767 kWh hours of electricity every day. Because the panels are flat, the amount of energy produced is limited. However, the energy generated is enough to power an average family home for one year.

“We are still experimenting with Wattway,” says Jean-Charles Broizat, CEO of Wattway, in a statement. “Building an application site of this magnitude is a real opportunity for our innovation. This application site has enabled us to improve our process of installing photovoltaic panels as well as their manufacture, in order to optimize our solution as best as possible.”

For the last decade, the city of Las Vegas has been working toward generating 100 percent of its energy from renewable source. Now, city officials state that goal has been met.

About one year ago, the city partnered with the company NV Energy, a public utility that distributes energy across the state of Nevada, to help Las Vegas reach its clean energy goal. NV Energy official recently announced that everything from City Hall to community centers are now running on clean energy after the finalization of Boulder Solar 1.

The Boulder Solar plant was built by California sustainable energy company SunPower. The 100-megawatt solar plant is located in the Eldorado Valley of Boulder City, NV.

Las Vegas’ major, Carolyn Goodman, hopes that this move will but the city on the path to be a “world leader in sustainability.”

Global energy demands are predicted to reach 46 terawatts by 2100. That number is a far reach from the 18 terawatts of energy currently generated around the world. According to one expert in the field, a major shift in the way we produce and consume energy is necessary in order to meet future demands.

Meng Tao, ECS member and Arizona State University professor, discussed how society could move toward meeting those demands at the PRiME 2016 meeting, where he presented his paper, “Terawatt Solar Photovoltaics: Roadblocks and Our Approaches.”

“We just cannot continue to consume fossil fuels the way we have for the last 200 years,” Tao told ECS. “We have to move from a fossil fuel infrastructure to a renewable infrastructure.”

For Tao, the world’s society cannot set on a path of “business as usual” by producing energy via coal, oil, and natural gas. And while solar energy has experienced a growth rate of nearly 45 percent in the last decade, it still only accounts for less than one percent of all electricity generated.

The shift to solar

Historically, solar technology soars when oil prices are at their highest. This is especially true during the oil embargo of the 1970s. During that time, private and public investments began to shift away from fossil fuels and toward solar and other renewable energies. That trend emerged again in the early 2000s when oil prices skyrocketed to a record-setting $140 per barrel.

“In the 1970s, the motivation to invest in solar and other forms of renewable energy was geopolitical,” Tao says. “Now, that motivation tends to focus more on the environment and sustainability.”

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Researchers from the University of California, Riverside recently combined photosynthesis and physics to make a key discovery that could lead to highly efficient solar cells.

Nathan Gabor, a physicist, began exploring photosynthesis when he asked himself a fundamental question in 2010: Why are plants green? This question probed him to combine his physics training with biology.
Over the past six years, Gabor has been rethinking energy conversion in light of these questions. His goal was to make solar cells that more efficiently absorb intermittent energy from the sun and increase past the current 20 percent efficiency. In this, he was inspired by the plants that had evolved over time to do exactly what he hoped solar cells would be able to do.

This from University of California, Riverside:

[The scientists] addressed the problem by designing a new type of quantum heat engine photocell, which helps manipulate the flow of energy in solar cells. The design incorporates a heat engine photocell that absorbs photons from the sun and converts the photon energy into electricity.

Surprisingly, the researchers found that the quantum heat engine photocell could regulate solar power conversion without requiring active feedback or adaptive control mechanisms. In conventional photovoltaic technology, which is used on rooftops and solar farms today, fluctuations in solar power must be suppressed by voltage converters and feedback controllers, which dramatically reduce the overall efficiency.

Read the full article.

At the core of the research, Gabor and his team are looking to connect quantum mechanical structure to the greenest plants.