Energy Storage

New Materials Meet the Need for Better Batteries and Capacitors

The increased deployment of renewable generation of energy, coupled with the high cost of managing peak grid demand, is driving interest in stationary energy storage technologies within the utilities industries. Grid reliability and the large capital costs of upgrading the nation's electrical transmission systems are sparking interest in distributed energy generation and storage. And in the transportation sector, the volatility of fuel prices and the desire to create a competitive domestic battery manufacturing industry have all led to rapid growth in research in advanced energy storage technologies.

The potential is out there: enough wind energy over land to supply our peak summer electricity demand eight times over; enough concentrated solar power in the Southwest states to supply seven times our electrical energy needs. But what happens when the winds die down or the sun drops below the horizon? If we want to incorporate large amounts of renewable energy into our national energy grid, we need to be able to rely on a smooth, steady supply of electricity.

studying the life cycle of rechargeable lead-acid batteriesToday, less than 3 percent of US electricity demand is filled by wind and solar. Almost half, 48.7 percent, is produced from burning coal, a depleting resource and a still highly polluting way to get our energy. If the 39 states that have enacted some form ofrenewable energy standards want to meet their goals, we will have to incorporate exponentially more fluctuating energy from wind and solar into the grid.

A large contingent of Penn State researchers, working with colleagues across the university, in industry, and at national laboratories, is contributing to the search for improved materials and devices to store and manage the energy that will one day, perhaps in the next decades, power our society. "The big drivers in energy storage research are the smart grid and hybrid vehicles," says Chris Rahn, co-director of Penn State's new Battery and Energy Storage Technology Center, and a professor of mechanical and nuclear engineering. The BEST Center, as it is known, is a university-wide, multidisciplinary initiative that will focus on energy storage solutions for renewable energy, vehicle electrification, and smart grids.

Currently located in the Reber Building, planning is underway to relocate the BEST Center to a renovated Materials Research Institute Building, along with a sizable number of the faculty groups involved in energy research. "It's a very exciting opportunity," Rahn enthuses. "There will be a real spectrum of researchers together under one roof working from materials to systems. The opportunities for collaborations are unique." The federal government is supporting energy storage technologies, with a big push from stimulus funds.

In March 2011, $1.5 billion was promised to U.S. manufacturers to produce high-efficiency batteries and their components. Looking forward to 2012, the Department of Energy is requesting a 44.4 percent increase in funding over 2010's appropriation for solar energy, advanced vehicle technologies, and hydrogen fuel cell technologies, and a similar increase for grid reliability, including stationary energy storage. The federal government is not alone. Car makers are also investing in the struggle to figure out how to build and sell electric drive vehicles with a range comparable to internal combustion engine vehicles. But the use of batteries and electric motors is more challenging than internal combustion engines, Rahn says.

"Auto manufacturers know about all the parts of a vehicle system, except the battery and how to integrate it into the system. In an internal combustion engine, the battery is basically used for starting and may discharge once an hour. In a hybrid, the battery is undergoing constant charge and discharge."

This accelerates degradation of the battery, which needs to last for 15 years and go through thousands of charge/discharge cycles. The manufacturers' solution to extending battery life is oversizing, which is a large part of the reason that electric drive vehicles are so expensive, according to Rahn. A better long-term solution is to find cheaper materials that pack more energy into a smaller space and lose energy more slowly. That is exactly what several groups in the BEST Center are working on now.

For a complete overview of BEST, visit www.best.psu.edu