Energy Storage Methods for Renewable Energy Integration and Grid Support

The inherent intermittency of the two fastest growing renewable energy sources, wind and solar, presents a significant barrier to widespread penetration and replacement of fossil-fuel sourced baseload generation. These intermittencies range from short term ramp events experienced by wind farms to the diurnal fluctuation of solar installations. In this paper, two options for short-to-medium term energy storage are presented: compressed air and gravitational potential. While similar to Compressed Air Energy Storage (CAES) techniques, they differs in that an incompressible liquid is the working fluid in the turbine, thus eliminating the need for supplementary combustion when the energy is recovered. This family of approaches combines the best concepts attributed with pumped storage hydroelectric and CAES in a system that is not site-specific, has no additional carbon footprint and has the potential for being very efficient.