Session: 09-01 Compressed (CAES) and Liquid (LAES) Air Energy Storage

Paper Number: 152338

Diabatic Liquid Air Energy Storage Systems 

Long-Duration Energy Storage (LDES) can align the large and accelerating deployment of variable renewable wind and solar generation resources with the needs of Load Serving Entities (LSE) to reliably meet the demand for, low-carbon power.  Pumped Storage Hydro (PSH) is proven at large scale, but topographic, geotechnical, and environmental concerns constrain future deployment opportunities. Liquid Air Energy Storage (LAES) is comparable in scale to PSH and avoid its siting constraints. 

As an energy storage medium, liquid air has many attributes.

·         Air is safe, free, ubiquitous and without supply chain constraints.

·         Cryogenic refrigeration is a mature industry with global suppliers experienced in large scale production of industrial gas and liquefied natural gas (LNG).

·         Liquid air is safely stored within insulated tanks at atmospheric pressure

·         The self-discharge rate is extremely low to permit very long-term storage.

·         Large storage tanks, customarily used for LNG, can hold an unprecedented amount of energy in a compact footprint.

There are a variety of cryogenic liquefaction approaches employing different work fluids and processes, but generally they employ compression, heat rejection, and Joule-Kelvin cooling.  The principal challenges of LAES are the capital intensity of the charging equipment (cryogenic refrigeration) and the efficiency by which the input charge energy is converted to output discharge energy. 

There are two general approaches to LAES discharge: adiabatic and diabatic.  In either approach the stored liquid air is pressurized, heated and then expanded through turbomachinery to deliver useful work. Adiabatic approaches typically capture and store heat of compression during charging for use during discharging. High pressure ratio is favored during expansion and typically results in the discharge of cold air, which is used to cool a cold storage medium for use during a subsequent charging phase.  The adiabatic efficiency improvements come at the expense of additional capital expense for the hot and cold storage, in addition to the cryogenic storage, and operational constraints due to the need to match the available hot stored energy during discharging and cold stored energy during charging.

The diabatic LAES approach uses exhaust heat from a fired turbine to regasify pressurized liquid air, which after expansion is exhausted to atmosphere at near-ambient temperature.  The diabatic approach dispenses with hot and cold storage, which simplifies the design and operation of the cryogenic equipment.  Importantly, the diabatic approach reduces the specific discharge air consumption, which reduces the size and capital cost of the cryogenic charging system.

This paper compares several approaches to diabatic LAES discharge.  The Liquid Air Combined Cycle (LACC), described previously by the authors, is comprised of a gas turbine generator, an air turbine generator, and an Organic Rankine Cycle (ORC), which rejects heat absorbed from the gas turbine exhaust gas to regasify the liquid air.  In Liquid Air Power & Storage (LAPS), the compressor section of the gas turbine is removed, and regasified air is introduced to a combustor at about the same pressure and temperature as the gas turbine.  Various LAPS arrangements are presented and compared on the basis of power output, efficiency, specific discharge air consumption.

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.

After receiving a Ph.D. in Nuclear Engineering and Science from Rensselaer Polytechnic Institute, he worked on Pacific Gas & 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.

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.

Bill is a licensed Mechanical Engineer in California, a life member of IEEE and ASME, and serves on the ASME PTC-53 Committee, which has developed the performance test code for mechanical and thermal energy storage systems.

Authors:

William Conlon Pintail Power LLC
Milton Venetos Pintail Power LLC