Renewable energy is growing. So far in 2018, 70 percent of net global power capacity additions were renewables, according to the 2018 Global Status Report by REN21. A fifth of the world’s energy already comes from renewable sources — a figure that’s only rising.

In this transition, solar power stands up front as one of the most promising and quickly growing renewable energy sources.

In this article, we chronicle the growth of solar energy and highlight the efforts of university researchers across the globe working to develop new solar technologies.

A blossoming industry

As the world transitions to sustainable energy, solar figures to be at the center of the renewable revolution as one of the major sources of energy that we will use to power the planet.

Already, solar has seen remarkable growth in the past decade. At the end of 2017, the total operating solar power in the world reached 405 gigawatts, 89 percent of which was installed in the last 7 years.

Though a set of tariffs on imported solar panels recently imposed by the Trump administration threaten to slow the U.S. solar production for the next couple years, there is no slowing the solar revolution.

Fifty-five percent of new renewable power installations in 2018 worldwide were solar photovoltaics, more than the additions of fossil fuels and nuclear combined. China leads the pack, having installed 52.8 gigawatts in 2017 — over half of new solar capacity added last year. In the first quarter of 2018, 55 percent of all electricity (that includes fossil fuels, nuclear and renewable energy sources) added in the U.S. was solar.

The bullish market seems to suggest that Elon Musk may have been right when he said that solar power will be the world’s largest energy source by 2031.

But there is still work to be done before solar energy can reach its full potential. Universities across the world are making significant contributions to the effort to switch to solar, whether by supporting groundbreaking research, developing solar technologies, or installing solar energy on campus.

Stanford — water-based battery to store solar & wind energy

Stanford University researchers have developed a low-cost water-based battery that could be used to store solar and wind energy, potentially providing a solution to one of the most significant roadblocks to fully transitioning to renewable energy.

They have developed a small prototype that stands only three inches tall and generates only a modest 20 milliwatt hours of electricity, but they are confident they can scale their model up to an industrial-grade system.

The manganese-hydrogen battery works based on a chemical reaction between water and manganese sulfate, a cheap and abundant industrial salt. The reaction was developed in the lab of Yi Cui, a professor of materials science and engineering and senior author on the paper.

“What we’ve done is thrown a special salt into water, dropped in an electrode, and created a reversible chemical reaction that stores electrons in the form of hydrogen gas,” Cui said in a statement.

When power is fed into the battery, the electrons react with the manganese sulfate in the water, leaving manganese dioxide clinging to the electrodes. This process produces electrically-charged hydrogen gas, which can be converted back into electricity.

Transitioning to solar and wind power will require significant changes to the way that energy is stored and dispersed. These two energy sources are highly variable. That is, the sun is not always shining and the wind is not always blowing.

This puts a burden on the energy grid. If there is a surge in demand when the sun is not shining, utilities must have a way to send significant amounts of energy on short notice. Typically, utilities will have so-called “dispatchable” power plants that can turn on within minutes to produce quick energy. This strategy is effective, but the power plants typically rely on fossil fuels, so it is not exactly climate-conscious.

Storing wind and solar energy for use during peak hours in high-capacity batteries offers a clean alternative. Consider this option a rainy day fund for utilities. When demand is high and the sun is low, utilities can simply draw from energy stored in the batteries.

The challenge is creating a battery that is both reliable and low cost. Rechargeable lithium ion batteries, like those in your phone and laptop, use rare materials and so are too expensive to use on a large scale.

“Other rechargeable battery technologies are easily more than five times of that cost over the life time,” Cui said in a statement.

The new battery, composed of cheap and abundant materials, may be the solution.

Yale, Princeton, Lincoln & NASA — solar energy from algae

Long before the invention of solar panels, algae was already harnessing the sun’s energy. Algae — like all photosynthetic organisms — has been biologically optimized for light absorption by billions of years of evolution.

Now, a team of researchers from Yale University, Princeton University, Lincoln University and NASA has found out how to harness the photosynthetic abilities of algae to enhance the performance of organic solar panels.

The research was led by André Taylor, an associate professor of chemical and environmental engineering at Yale, who runs the university’s Transformative Materials and Devices Laboratory.

When sunlight strikes an organic solar cell, electrons in the “active layers” pick up energy and begin moving the energy through the core of the solar panel.

The materials used to create the active layer are very rare and expensive. This fact has presented a problem for solar panel developers.

But, the researchers found that an abundant species of algae known as “diatom”, or the “jewels of the sea,” can be used to enhance the performance of the active layer.

They dispersed diatoms throughout the active layer of the solar cell, effectively reducing the amount of material needed for the active layer while maintaining the same levels of electrical output.

“We were able to see what the right concentration was and how much of this material we needed to put into our solar cells to get enhancement,” Lyndsey McMillon-Brown, a doctoral student in Taylor’s lab and lead author of the study, said in a statement. “It’s really beneficial because the active layer materials we use are expensive and very rare.”

As they continue to develop their technology, the researchers are experimenting with different strains of algae in the hopes of optimizing their solar panel’s performance.

“We hope that this work will shed more light on the opportunity to utilize biomimicry or bio-inspired designs to solve engineering problems,” said McMillon-Brown.

“Nature has developed many solutions that can be used to address many of our engineering problems – we just have to learn how to adapt and apply them.”

Michigan State — transparent solar panels

A group of Michigan State University engineers contend that transparent solar panels, which appear identical to a slate of glass, could revolutionize energy generation.

In 2014, MSU researchers developed a new type of solar concentrator that is capable of collecting invisible light from the sun and for conversion into usable energy. The panels are completely transparent, so they can be placed over a wide variety of glass surfaces — from windows to cell phones.

In a more recent paper, the scientists reported that the technology, once it is further optimized, could open up countless new opportunities for solar energy harvesting.

“Highly transparent solar cells represent the wave of the future for new solar applications,” Richard Lunt, the Johansen Crosby Endowed Associate Professor of Chemical Engineering and Materials Science at MSU, said in a statement.

“We analyzed their potential and show that by harvesting only invisible light, these devices can provide a similar electricity-generation potential as rooftop solar while providing additional functionality to enhance the efficiency of buildings, automobiles, and mobile electronics.”

The researchers note that there is an estimated 5 billion to 7 billion square meters of glass surface in the U.S. If all of that glass was covered by transparent solar panels, we could extract 40 percent of the U.S. energy demand from that source alone.

The estimated potential of opaque rooftop solar panels is also about 40 percent. The researchers suggest that the transparent cells could be used in conjunction with rooftop solar panels.

“The complimentary deployment of both technologies,” Lunt said in a statement, “could get us close to 100 percent of our demand if we also improve energy storage.”

For the time being, transparent solar cells are still far less efficient than traditional solar panels. They are recording efficiencies above 5 percent, compared to about 15 to 18 percent for most traditional solar panels.

However, Lunt said that they could be come at least close to as efficient as traditional solar panels with more development. He emphasized that transparent solar panels are still a very new technology and are only at about a third of their realistic overall potential at the moment.

“That is what we are working towards,” Lunt said in a statement.

“Traditional solar applications have been actively researched for over five decades, yet we have only been working on these highly transparent solar cells for about five years. Ultimately, this technology is a promising route to inexpensive, widespread solar adoption on small and large surfaces that were previously inaccessible.

University of Maryland — sustainable “house as a kit of parts”

A student team from the University of Maryland placed first in the U.S. and second in the world at the U.S. Department of Energy’s Solar Decathlon 2017, for its entry of a prototype energy-efficient, solar-powered house, named resilient Adaptive Climate Technology (reACT).

The decathlon is an annual, international competition that challenges teams from around the world to design a full-size solar-powered house.

The prototype designed by the UMD team is described as a “house as a kit of parts.” It is made up of five adaptable modules centered around an interior courtyard.

The courtyard functions as the focal point of the house. It serves both as a comfortable sunroom as well as a spacious solar collector to preheat air and water.

The house also includes a paneled interior with living systems separate from its structure, giving owners the ability to adapt the house to their needs and desires. It operates with complete self-sufficiency and includes systems that capture waste, water and energy.

 

The researchers said that reACT was designed to be in complete harmony with nature.

“Integrated and holistic design solutions were sought in as many places as possible in order to construct a home in harmony with nature where nothing organic is wasted,” said Chris Cestello Hinojosa, assistant director of communications and external relations for the School of Architecture, Planning and Preservation.

“We based our design on the philosophy of Biophilia and regeneration; that is finding a use for the ‘waste’ product of one process that can serve as a resource for another.”

UC–Irvine, Caltech & Carnegie Institution for Science — sourcing U.S. energy from wind and solar

A joint study by researchers from the University of California–Irvine, the California Institute of Technology and the Carnegie Institution for Science found that with major investments, the U.S. could reliably source 80 percent of its electricity demand from wind and solar power alone.

The research helps to dispel concerns that solar and wind power are too unreliable because they are dependent on weather, which is variable by nature.

“The sun sets, and the wind doesn’t always blow,” Steven Davis, an associate professor of earth system science at UCI and co-author of the study, said in a statement. “If we want a reliable power system based on these resources, how do we deal with their daily and seasonal changes?”

The researchers analyzed 36 years (1980-2015) of hourly U.S. weather data in an effort to understand how significant the variability of sun and wind would impact the reliability of those two sources.

“The 80 percent number boils down to natural variability in sun and wind,” said Davis. “If we want to get more than 80 percent of our power from those two sources, the required amount of energy storage or solar and wind generating capacity rises sharply.”

In order to reach the 80 percent mark, the U.S. would have to make substantial investments in every aspect of solar and wind energy so that we can capture energy but, more importantly, have large enough reserves to withstand variations in weather.

“The analysis assumes we’d build lots of solar panels and wind turbines to harness those resources,” said Davis.

“But getting to 80 percent would also require substantial increases in either energy storage or our ability to shift electricity around the country via transmission lines.”

This investment would include the construction of a continental-scale transmission network or facilities that could store up to 12 hours of energy for the entire nation. Such a project could cost hundreds of billions of dollars — if not trillions — in today’s dollars, but declining prices could make it more feasible in the future.

Sourcing 100 percent of our energy from wind and solar is less likely. The costs rise sharply past the 80 percent threshold. That would require building twice as many solar panels and wind turbines or having several weeks worth of storage.

This suggests that we will need to supplement solar and wind with other energy sources, which could include both renewable options, such as hydropower or clean, non-renewable sources like nuclear.

Nevertheless, the results of the study bode well for the future of renewable energy.

“The fact that we could get 80 percent of our power from wind and solar alone is really encouraging,” Davis said in a statement.

“Five years ago, many people doubted that these resources could account for more than 20 or 30 percent.”

So, where does this leave us?

There is clearly still a great amount of work to be done. As of right now, we are working backwards in the fight against climate change. We have already used up our natural resources for the year, and the effects of climate change are becoming ever-clearer and more dangerous.

However, significant advances in solar may offer a way out — or at least a way to feasibly transition to renewable energy in the coming years. In 2017, only 1.3 percent of U.S. energy was sourced from solar. With continued investment into and development of solar technologies, that number is sure to rise in the coming years.

Getting there will be impossible without the pioneering efforts of university researchers across the world.