SolarEngineers working to make solar cells more cost effective ended up finding a method for making sonar-like collision avoidance systems in self-driving cars.

The twin discoveries started, the researchers say, when they began looking for a solution to a well-known problem in the world of solar cells.

Solar cells capture photons from sunlight in order to convert them into electricity. The thicker the layer of silicon in the cell, the more light it can absorb, and the more electricity it can ultimately produce. But the sheer expense of silicon has become a barrier to solar cost-effectiveness.

So the engineers figured out how to create a very thin layer of silicon that could absorb as many photons as a much thicker layer of the costly material. Specifically, rather than laying the silicon flat, they nanotextured the surface of the silicon in a way that created more opportunities for light particles to be absorbed.

Their technique increased photon absorption rates for the nanotextured solar cells compared to traditional thin silicon cells, making more cost-effective use of the material.

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By: Joshua D. Rhodes, University of Texas at Austin

Renewable grideScience is messy, but it doesn’t have to be dirty.

On June 19, a group of respected energy researchers released a paper in the journal Proceedings of the National Academy of Sciences (PNAS) that critiqued a widely cited study on how to power the U.S. using only renewable energy sources. This new paper, authored by former NOAA researcher Christopher Clack and a small army of academics, said that the initial 2015 study had “errors, inappropriate methods and implausible assumptions,” about using only the sun, wind and water to fuel the U.S.

What followed was a storm of debate as energy wonks of all stripes weighed in on the merits of the PNAS analysis. Mark Z. Jacobson, a Stanford University professor who was the lead author of the 2015 study, shot back with detailed rebuttals, in one calling his fellow researchers “fossil fuel and nuclear supporters.”

Why the big kerfuffle? As an energy researcher who studies the technologies and policies for modernizing our energy system, I will try to explain.

In general, getting to a clean energy system – even if it’s 80 percent renewable – is a well agreed-upon goal and one that can be achieved; it’s that last 20 percent – and how to get there – that forms the main point of contention here.

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SolarA 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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Water purificationAccess to adequate water and sanitation is a major obstacle that impacts nations across the globe. Currently 1 in 10 people – or 663 million – lack access to safe water. Due to the global water crisis, more than 1.5 billion people are affected by water-related diseases every year. However, many of those disease causing organisms could be removed from water with hydrogen peroxide, but production and distribution of hydrogen peroxide is a challenge in many parts of the world that struggle with this crisis.

Now, a team of researchers from the U.S. Department of Energy’s SLAC National Accelerator Laboratory and Stanford University have develop a small device that can produce hydrogen peroxide with a little help from renewable energy sources (i.e. conventional solar panels).

“The idea is to develop an electrochemical cell that generates hydrogen peroxide from oxygen and water on site, and then use that hydrogen peroxide in groundwater to oxidize organic contaminants that are harmful for humans to ingest,” says Chris Hahn, a SLAC scientist.

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BatteryOne of the keys to developing a successful electric vehicle relies on energy storage technology. For an EV to be successful in the marketplace, it must be able to travel longer distances (i.e. over 300 miles on a single charge).

A team of researchers from Georgia Institute of Technology, including ECS fellow Meilin Liu, has recently created a nanofiber that they believe could enable the next generation of rechargeable batteries, and with it, EVs. The recently published research describes the team’s development of double perovskite nanofibers that can be used as highly efficient catalysts in fast oxygen evolution reactions. Improvements in this key process could open new possibilities for metal-air batteries.

“Metal-air batteries, such as those that could power electric vehicles in the future, are able to store a lot of energy in a much smaller space than current batteries,” Liu says. “The problem is that the batteries lack a cost-efficient catalyst to improve their efficiency. This new catalyst will improve that process.”

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Hitting the 100% Renewable Mark

Las Vegas renewable energyFor 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.”

Wind TurbinesGoogle is going green.

Tech giant Google announced that it will run entirely on renewable energy in 2017. This will be a huge shift for the company that, according to the New York Times, consumed as much energy as the city of San Francisco in previous years.

Google states that both its data centers and offices will reach the 100 percent renewable energy mark in 2017, with the majority of power derived from wind and solar. According to a press release by the company, going green makes the most sense economically in addition to Google’s goal of reducing its carbon footprint to zero. With wind energy prices down 60 percent and solar down 80 percent over the past six years, Google’s move to renewables will both make an environmental impact and help the company cut operating expenses.

In part, Google is able to make this transition due to the number of large-scale deals the company has made with renewable energy producers over the past few years. Google has guaranteed to purchase energy from renewable start-ups, which then allows those start-ups to obtain the capital necessary to expand their business.

“We are the largest corporate purchaser of renewable energy in the world,” Joe Kava, Google’s senior vice president of technical infrastructure, told the New York Times. “It’s good for the economy, good for business and good for our shareholders.”

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How to Make Solar Work

Solar energyGlobal 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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Wind powerNew research shows another step forward in the goal of developing energy storage systems robust enough to store such intermittent sources as wind and solar on a large-scale.

Their work explores the opportunities in solid oxide cells (SOCs), which the group believes to be one of the best prospects in energy storage due to their high efficiency and wide range of scales.

ECS member John Irvine and his team from the University of St. Andrews have set out to overcome traditional barriers in this technology, developing a new method of electrochemical switching to simplify the manufacturing of the electrodes needed to deliver high, long-lasting energy activity.

This from the University of St. Andrews:

The results demonstrate a new way to produce highly active and stable nanostructures – by growing electrode nanoarchitectures under operational conditions. This opens exciting new possibilities for activating or reinvigorating fuel cells during operation.

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Krishnan Rajeshwar is a professor at the University of Texas, Arlington. Raj, as he is known, is also the current ECS President. His research over the years has touched on semiconductors, photoelectrochemical conversion, toxic waste, solar hydrogen production, and renewable energy just to name a few.

Rajeshwar was the editor of Interface, ECS’s membership magazine, for 14 years starting in 1999.

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