Non-Technical Problem Statement
As of now, transitioning to an electrical grid of primarily renewable energy sources is very difficult without the implementation of effective energy storage systems that can store their energy at all times of the day. The electrical grid consists of the entire network of getting electricity from the producers to those that use it, so having the electrical grid being supplied by mainly renewable energy sources, like solar and wind, is something that will require considerable change based on the current energy outlook of the U.S. Many major governments and economies have made it a priority to reach net-zero by 2050, which is the state at which the amount of greenhouse gas (GHG) that is being emitted into the atmosphere equals the amount that is leaving. In order to combat this problem, we want to create a system that:
- Could store and release energy generated by renewable energy sources while being economically favorable and easy to maintain.
- Could be scalable to meet the user needs of electrical grid operators within the context of projected electric vehicle (EV) growth to reduce (or possibly eliminate) greenhouse gas emissions since EVs run on electrical power rather than gasoline.
Scalability and Goals
Compressed Air Energy Storage systems (CAES) are typically utility-scale, but we are looking at delivering to a smaller end-user scale of residential/commercial. Due to the constraints and budget of our project, we made a design decision to design and build an even smaller scale project that can be computationally scaled up to our desired size with the help of Chemical Engineering students next semester.
This encouraged certain design decisions that may have not been made if the constraints of our project were not as narrow as they were. Considering this, we most definitely can still develop a prototype that we can effectively analyze as a real-life application in which others could benefit by determining the physical feasibility of our system.
- Compressor and Expander: When deciding on which air compressor/pressure vessel and air motors to purchase, there were numerous choices to pick from. For the compressor, there were 20 gallon, 30 gallon, or 60-gallon pressure vessels with different size compressors. A 30-gallon pressure vessel with a 2-stage reciprocating engine was purchased due to various factors discussed in the compressor design matrix, but this does not inhibit analyzing this system for bigger configurations. Since it is just a pressure vessel and the performance of the compressor is not being affected, the system can be scaled for any size pressure vessel to analyze how it would fit in different applications and integration to the electric grid. For the air motor, different horsepower motors were considered in the design matrix, but eventually, a decision was made to purchase the 1.8HP air motor. This allows for high power output and long-running time, which helps us perform accurate tests while still being economically feasible.
- Heat Exchanger Team: The best choice of the heat exchangers was one that was inexpensive and easy to repair, both of which are important to the prototyping, testing, and overall end-stage. This choice was the coiled heat exchanger, and although others like the brazed plate or shell and tube heat exchangers (seen in the heat exchanger design matrix) have high efficiencies, the coiled is the best for our application. This heat exchanger can easily be scaled up or down, and can even be scaled up by swapping our parts during the prototyping stage as the parts are inexpensive and easy to maintenance.