PNNL

Decarbonizing today’s energy system is essential to a clean energy future. This means reducing and eventually eliminating the use of carbon-based fuels for generating electricity and powering our vehicles.

Some solutions may sound simple—use more wind and solar energy—but we must overcome several science and technology hurdles to get there.  

For example, renewable sources like solar or wind can generate more power than needed on sunny or windy days, but we need better ways to store that energy so it can be used on cloudy, calm days when sun and wind are in short supply.

Energy storage is just one piece of the clean energy puzzle that researchers will address in the new Energy Sciences Center (ESC) being dedicated at the Department of Energy’s Pacific Northwest National Laboratory this week.

The $90-million facility will bring together existing and new scientific instrumentation, as well as about 250 researchers from various disciplines, so their collective capabilities and innovation can be focused on the nation’s most pressing energy needs.

One approach to storing excess energy generated by renewable resources starts with using that extra energy to split water molecules into oxygen and hydrogen via a process called electrolysis.

This “green” hydrogen can go into fuel cells to put electricity back onto the grid.

And, because it’s carbon-free, it also can help to decarbonize heavy-duty transportation and shipping; produce chemicals, such as ammonia fertilizers; and reduce the amount of iron ore needed to manufacture steel.

Storing and transporting hydrogen, however, comes with its own set of challenges. As a gas, hydrogen must be stored at refueling stations at high pressure. Liquid hydrogen must be kept at a frigid −423 degrees Fahrenheit or colder, which can take a lot of energy.

Scientists at PNNL are exploring a third option for storing hydrogen: in chemical bonds. They are studying how to design and control chemical reactions that allow hydrogen to be added or removed from stable molecules. These molecules serve as “hydrogen carriers,” literally carrying the hydrogen in their molecular bonds.

For example, researchers are studying catalysts that selectively release or bind hydrogen to a liquid molecule for seasonal energy storage, a need not easily met by conventional batteries.

Ethanol is among the potential liquid hydrogen carriers being studied by our researchers. The existing infrastructure for storage and transport of ethanol is part of this option’s appeal.

As one way to implement this, energy generated in the summer by roof-top solar panels on long, sunny days would be used to make hydrogen.

Then, with the help of the right catalyst, hydrogen would be bound to a specific molecule, creating ethanol, which can store the hydrogen for the season. The reaction could be reversed in the winter to release the stored energy for heating and lighting on cold and dark days.

Researchers at PNNL are combining their strengths in computational science, chemistry and economics to examine the entire system for chemical hydrogen storage—from the design of new catalysts to the reactors where the chemical processes take place, as well as the end products and applications.

They are going beyond exploring theoretical possibilities and delving into how systems for storing and releasing hydrogen would operate in real-world conditions, at neighborhood scales.

As the ESC prepares to welcome its new occupants, researchers dedicated to developing these novel approaches and testing their feasibility are getting ready to move into their new offices and laboratories.

They will be joined by colleagues who are advancing scientific discovery in chemistry, materials science and computing. And, through collaboration with industry, academia and others, they will accelerate progress toward the clean energy future we all want.

Steven Ashby, director of Pacific Northwest National Laboratory, writes this column monthly. To read previous Director's Columns, please visit our Director's Column Archive.