Session: 07-01 Air-Based Energy Storage Systems

Paper Number: 80426

80426 - Liquid Air Combined Cycle 

Hybrid integration of thermal energy storage with combustion turbines can provide compact and cost-effective long-duration energy storage while reducing the fuel consumption of dispatchable resources needed for the reliability of renewable dominant electric grids.  The Liquid Air Combined Cycle™ (LACC) is a hybrid energy storage system using cryogenic liquid air as an energy storage medium, and a combustion turbine exhaust heat to extract stored energy.  Unlike Compressed Energy Storage (CAES), also a hybrid energy storage technology, which uses underground caverns to contain high-pressure air, cryogenic liquid air is contained in a storage tank at low pressure.

Air is plentiful, free, and non-toxic, and liquid air is a very dense storage medium that can safely store tens of GWh of energy in storage tanks like those customarily used for Liquefied Natural Gas (LNG).  The compactness of LACC energy allows energy to be stored close to the load to provide very long-duration (days to weeks) to manage both short and long-term variability of remote renewable resources.

The storage tank is charged using liquefaction processes employing an electric motor-driven compressors to pressurize the air, heat exchangers to reject heat of compression, and expanders to reduce the temperature and liquefy the air.  Proven cryogenic refrigeration processes can selected based on capital cost (per kg/s of liquid air produced), efficiency (kJ per kg of air produced) and operating factors including speed of startup and load following capability.

As with CAES, energy is discharged with the aid of exhaust heat from an open cycle combustion turbine (CT).  The exhaust is delivered to heat regasified air to power an open cycle air turbine (AT) exhausting to atmosphere and to a working fluid in a closed Organic Rankine Cycle (ORC) that produces additional power and rejects heat to pressurized liquid air.  High discharge efficiency is obtained by the cascade of CT, AT, and ORC due to the high overall temperature difference of the working fluids, from roughly 1800°K at the CT combustor exit to about 180°K at the ORC condenser.  CT inlet air chilling can be provided to maintain constant operating conditions during discharge, while also adding useful heat into the cascade.

This paper presents results of studies undertaken for the U.S. Department of Energy to evaluate cost and performance trades for charge and discharge cycle components, optimize charge and discharge cycles, and assess the techno-economic potential of LACC technology.

Presenting Author: William Conlon Pintail Power LLC

Presenting Author Biography: Dr. William M. (Bill) Conlon, P.E. is the founder and President of Pintail Power LLC, and inventor of patented liquid air and liquid salt energy storage technologies that bridge renewable and conventional generation by synergistic integration of thermal energy storage with thermal generation. <br/><br/>After receiving a Ph.D. in Nuclear Engineering and Science from Rensselaer Polytechnic Institute, he worked on Pacific Gas &amp; Electric Company’s Diablo Canyon Project. At International Power Technology he was responsible for control systems and received three patents for the Cheng Cycle steam injected gas turbine, led new product development, and transferred technology to international licensees. <br/><br/>Following forays in water treatment, industrial controls and software, Bill returned to energy to lead Ausra’s turn-around to price-performance leadership in the solar thermal market, and was instrumental in its merger with AREVA. As Chief Engineer and Senior VP he helped secure more than $1 billion of new business within 18 months of the merger and was responsible for Engineering, Commissioning and Operations teams on three continents. <br/><br/>Bill is a licensed Mechanical Engineer in California, a life member of IEEE and ASME, and serves on the ASME PTC-53 Committee, which is drafting the Performance Test Code for Energy Storage Systems.

Authors:

William Conlon Pintail Power LLC
Milton Venetos Pintail Power LLC
Aaron Rimpel Southwest Research Institute