After recent power outages throughout Texas due to inclement weather conditions, it became apparent that many base load power plants are not designed to handle an interrupted supply of natural gas. In February of 2021, roughly 4.5 million homes or businesses were left without power over the course of two and a half weeks, and an estimated 150 people died either directly or indirectly due to the outage. Damages amounted to nearly $200 billion, making it the most costly disaster in Texas history. Our project aims to solve this issue by designing a backup system able keep the plant operational for up to three days after natural gas supply fails. Natural gas storage is a difficult task. As a vapor, natural gas is extremely flammable and not easily or efficiently stored. Our proposed solution focuses on the liquefaction of natural gas to easily store a sizable three days worth of natural gas. Liquid natural gas (LNG) takes up 1/600th of the volume and can be regasified as needed to continue standard operations of the power plant. Our design includes implementing a C3-MR liquefaction process where natural gas is pre-cooled using propane and liquefied using a mixed-phase hydrocarbon refrigerant. This process is fueled using excess energy generated during grid off-hours, so economic cost is minimized. A 10,000 cubic meter on-site tank stores excess LNG to be used as emergency supply when needed. The LNG is regasified using water before being used to fuel energy turbines. Chilled cooling water is then used to pre-cool air used in the combustion process. This increases the efficiency of the combustion reaction significantly (2.5-5%), further recouping energy costs required for the liquefaction process. Our goal for the future is to further optimize our backup system as well as expanding on engineering deliverables (P&IDs, safety and material analyses, etc.).
