As renewable sources of energy like wind and solar gain traction, scientists and engineers are eyeing new ways to store that energy in a cost-efficient manner -- laying the groundwork for a future in which renewables rival fossil fuels in powering our homes and vehicles.

Paul Mutolo, a chemist and director of External Partnerships for the Energy Materials Center at Cornell University, has worked in the energy sector for over 16 years. He says the sector is entering a pivotal new phase and that hydrogen will be an essential component in developing energy storage technologies that take hold.

Mutolo says, "Electrical energy storage (EES) is going to change the way we use energy -- it already is. Tomorrow's grid will be more efficient, less expensive, and greener because of it. This is about to get really interesting: in the next few years, we will introduce EES systems at the neighborhood, or distributed, scale. It will be like a neighborhood sized backup power generator, and a lot more.

"It's great that we have started with batteries. They are easy to make and connect, but they are not suited to deliver the fast-responding, very versatile duty cycles that we're used to from fossil fuels. On the grid and in our cars, the differences are clear. Batteries don't work like fossil fuels. Lithium ions act like a caravan of super camels, efficiently carrying electricity -- in when charging, out when using. Even super camels (and lithium ions), can only carry so much, so fast. Today's electric vehicles with short range and long recharge times, are the result.

"The future is in redox flow batteries and hydrogen fuel cells. These work like clean, hyper-efficient fossil fuels. They couple well with renewables, and so can be completely carbon-free. Hydrogen stores energy by being formed -- literally forged -- from water and electricity. It has the same fast-response, wide dynamic range, as natural gas or gasoline. One kilogram of hydrogen holds the same energy content as a gallon of gas -- 34 kWh. These aspects of flow batteries and fuel cells will let EES deliver on its promise to be the Swiss-army knife of functionality for the grid -- and literally change the way we use energy for the better."