Compressed Air Energy Storage Plant

Energy Systems Design and Analysis Project

Fig 1. Typical CAES Plant Schematic

The undergraduate Energy Systems Design and Analysis course is a project based class. I worked in a group of four students to design the theoretically most efficient and economical Compressed Air Energy Storage (CAES) Power Plant.

Compressed Air Energy Storage (CAES) is a technology that utilizes off-peak load power generation from renewable sources like solar or wind to compress air and store it underground, which is then used to generate power during peak power loads. A CAES plant consists of 4 main phases: the compression phase, the heat storage which acts also as a heat exchanger phase, the cavern & air containment phase and the expansion phase.

The work was equally divided between the team by phase of the plant. My role on the team was to perform thermodynamic and economic analysis of the containment and expansion phases, assist in material selection, and calculate and optimize the total efficiency and profitability of the plant.

I used MATLAB and Engineering Equation Solver to numerically simulate the thermodynamic processes that take place in the different phases. A different script was created to carry out the economic analysis of the phases. The scripts were parametric which made it easy to vary key parameters and automate the simulation and optimization process.

Fig 3. Proposed CAES Plant Design

Fig 2. Cavern Design Parameters

Development of the containment phase required extensive knowledge of Bernoulli’s Principles as well as an understanding of realistic assumptions one could make in this scenario. The benefits and drawbacks of constant pressure caverns and constant volume caverns had to be weighed in terms of cost and feasibility. The compression phase had a similar process, with isothermal and adiabatic compression cycles being weighed against each other.

The final CAES facility was optimized for the lowest levelized cost of energy, which would in turn result in the highest profitability. Fixed as well as yearly costs were taken into account. It was determined decreasing the size of the heat storage, sacrificing efficiency, as well as using more natural gas per day than initially thought would save money over the lifetime of the plant and bring the LCOE down to 0.0703 cents per kilowatt hour.

Though designing a CAES facility that exceeds current capabilities without increasing cost will take much longer than a single semester, our relatively shallow investigation still revealed room for improvement in the heat storage, heat exchanger, and expansion subsystems. Once technological advancements in heat storage application for CAES occur, CAES will without a doubt be a significant energy source alongside other renewable energy resources.

CAES Plant Animation

 

 

Examples of Thermodynamic and Economic Analysis