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Carbon Research Highlight Features

Rodney Andrews and Steve Lipka
Dr. Rodney Andrews and Dr. Steve Lipka

CAER Researcher Receives Two Large Grants for Renewable Energy Storage

Steve Lipka works at the high tech end of the energy research world. When he talks about his research, he describes batteries, capacitors, portable electronics and cars - not coal, ash, or combustion.

This researcher, who came to us five years ago as a faculty member from Florida Atlantic University's Department of Ocean Engineering, was recently rewarded for his role in future energy storage by two diverse groups: utility giant E.ON International and the U.S. Office of Naval Research (ONR). The E.ON award is intended to promote promising technologies for renewables and 'point-of-use' energy supply. The ONR is interested in light-weight, highly portable, yet dense, power sources for the US Marine Corps.

E.ON sees energy storage as one of the keys to greater renewables development. To make widespread use of renewable energy more feasible, they are funding research that tackles renewables' inability to meet base-load demand at the power plant level by funding innovative storage technologies.

Lipka (and his team, Chris Swartz and Victor Kunadian) are working on the design of new materials for highly-efficient electrochemical capacitors.

To get around the vagaries of renewable electricity generation that only produce electricity under favorable environmental conditions, they are researching how to store energy on a large scale. The idea is this: the energy harvested from wind turbines or photovoltaics is used to charge banks of capacitors from which energy can then be retrieved when the demand for electricity is needed. This would enable renewables to be an attractive, sustainable form of energy harvesting.

Early electrochemical capacitors were used in niche applications, such as after-market automotive sound systems. Recently, they have matured into a variety of applications and are viewed as a tool in the renewable energy portfolio. Their advantage is that they can quickly absorb and deliver energy, which makes them suitable for many applications, including the emerging micro-hybrid automotive market. And since the energy is not stored chemically, electrochemical capacitors have a superior cycle life.

The funding ($1.2M over three years) allows the research to be made public. The findings are available to the public through publications.

Lipka's second recent grant is part of a larger effort at the Office of Naval Research to advance the state-of-the-art of electrochemical capacitors for use in lightweight hybrid power systems for the U.S. Marines. The $515K grant was awarded in December 2007.

Carrying compact, light-weight, portable power sources with high energy and power densities presents challenges. This research is geared towards developing a lightweight alternative to the standard military primary battery. Combining a metal-air battery with a high energy-density capacitor (called an electrochemical double layer capacitor (EDLC)) or asymmetric EDLC, could provide enough power to overcome the peak power limitations of today's batteries.

Lipka's group focuses on developing energy-dense activated carbons from inexpensive precursor materials. Its approach is to develop carbons with optimized pore size and distribution and increased surface roughness. One approach the group is using is to create high surface area and surface roughness by drilling pores of desired dimensions from the surface into the interior of the carbon using catalytic nanoparticles. With the greater surface area, theoretically more energy can be stored as capacitance is directly proportional to area.

Early results are very positive. Activated carbons have been prepared with energy densities exceeding those currently available from more expensive, commercial-grade capacitor carbons. Further exploration and development may yield energy-dense activated carbons suitable for EDLCs to alleviate the power limitations of current battery and fuel cell technologies.

Both research projects illustrate the enormous challenges of using renewables to satisfy intense energy needs and the strides being taken to accomplish this.