For all the advances in solar power technology over the last century, the dark shrouds of night and overcast skies still loom ominously over mankind’s hopes to run continuously off the abundant energy of the sun. Over 120,000 terawatts of power are delivered each day to the Earth — roughly ten thousand times what humankind needs to power its activities. Even in the world’s sunniest place, Yuma, Arizona — where the sun is out 94% percent of the time, or 4,127 hours a year — photovoltaic cells are still useless 4,633 hours a year.

Last Thursday, Dr. Greg Rohrer from Carnegie Melon University gave a talk to a group of graduate students and faculty on his research entitled “The dipolar field effect and photochemical reactions on titania/ferroelectric heterostructures.” The material sciences and engineering professor said that new advances in nanotechnology have made solar fuel cells a facet of renewable energy research that may have profound implications for the future of the renewable energy source.

Solar energy has come a long way since Auguste Mouchout used a parabolic trough to produce steam for the first solar steam engine in 1866. Solar power moved into the electrical age when Charles Fritts constructed the first solar cell prototype using selenium in the 1880s. During the energy crunch of the 1970s, the price of photovoltaic cells approached economic viability and economies of scale began working to deliver some advances in efficiency and cost. President Jimmy Carter even had solar panels installed on the roof of the White House.

Still, solar power, like other renewable sources, is intermittent as opposed to “dispatchable,” which makes it difficult to integrate into existing power networks. Dispatchable sources, such as coal, oil and nuclear can be controlled to a reasonable degree to handle outages, surges and other anomalies in the power grid. This allows the entire grid to be moderated with production turned on or off as needed, while intermittent power sources are at the mercy of natural forces like the weather.

Rohrer thinks Barium Titanate/Titania (BaTiO3/TiO2) particles might give researchers a way to keep the power running through the night. These particles may be able to produce hydrogen gas in fuel cells using the activation energy of sunlight. Because the particles are ferroelectric, meaning they have a permanent electric charge, a fuel cell using these particles may help produce clean fuel more efficiently than a traditional fuel cell. When charge separation occurs along the axis of these particles, a reaction occurs, liberating a small amount of hydrogen gas. This phenomenon, — known as photoelectrolysis — was identified in the 1950s, but recent advances in nano and micro technology have opened the door for applications in clean fuel technology.

It’s long been known that water can be broken down into oxygen and hydrogen by simply passing a current through it, a process known as electrolysis. However, this method of producing hydrogen results in a net loss of usable energy, making it economically unfeasible. But certain chemicals can experience electrolysis simply when exposed to light.

In the realm of solar power, photovoltaic cells have traditionally taken most of the focus because of their ability to convert sunlight directly into electricity. Professor Tobias Hanrath, chemical engineering, in cooperation with faculty from chemistry, physics, materials science and electrical engineering, is utilizing modern advances in nanotechnology to develop better materials to convert solar energy into electrical power. Recent advances even show promise in surpassing the limit of 31 percent efficiency proposed in 1961 by Shockley and Queisser.

Other researchers are looking to harvest the Sun’s power in more indirect ways. New approaches include using algae to produce biodiesel from the energy stored in non-feedstock biomass, which plants originally obtained from the Sun through photosynthesis. Nature already converts the solar energy that is stored as sugars in plants to crude oil over thousands of years, but companies like Solazyme hope to reduce the millennia-long process to a single growing season.

Using their unique dual material setup, Rohrer and his group hope to match the energy necessary for charge separation to that of the incoming sunlight. With enough particles suspended in water, large amounts of hydrogen could be produced from sunlight and stored as fuel, allowing fuel-cell powered cars, electric plants and other sources to more fully harvest the bounty of sunlight delivered to Earth on a daily basis.