Decarbonising a Gas Processing Facility: Optimisation through Innovative Solar Thermal Technology in Northern Africa

Abstract Integrating power from renewable energy sources (RES) into existing gas processing facilities to reduce their electricity and fuel consumption plays a crucial role in decarbonising the industry. However, the volatile nature and seasonal intensity fluctuations of RES introduce significant uncertainties when designing or optimising process facilities for technological and cost effectiveness to achieve the highest possible fuel and CO2 emission reduction. Detailed models and simulations based on historical weather and operational data supported by traditional engineering approaches and tools are required for this multidisciplinary iterative optimisation. With the initial project goal to create a technology blueprint for decarbonisation initiatives in the gas processing industry, a comprehensive case study focusing on the integration of an innovative solar thermal technology into the gas processing facility of the Nawara gas field in Tunisia was conducted. The study's novel core technology is an inflatable concentrating solar thermal collector of proprietary design that is made of recyclable plastics suitable for sunbelt conditions. The primary objective was to demonstrate the engineering approach required for its optimal integration into the facility's existing process heat supply system, consisting of a single gas-fired heater and multiple consumers at various temperature levels, to reduce overall fuel consumption and increase economic viability. Thermodynamic models of the solar thermal farm and its integration into the process heat cycle were developed for performing time series calculations based on hourly resolved historical heat demand and solar radiation data to investigate optimal system tie-in, sizing, and operation. Additionally, design-relevant parameters like media temperatures and volume flows were determined to assist a projected basic engineering phase. As the study showed, the substitution of heat from the natural gas-powered heater with energy from a solar thermal source is highly dependent on the design of the collector farm, its tie-in point, and the operational flexibility of the existing process heat supply system. During the evaluation of the various scenarios with different equipment sizes and integration approaches, fuel savings between 13 and 29% were attainable even without the implementation of a thermal energy storage unit for operation during nighttime. A follow-up risk assessment based on the study's results provided crucial insights into the operational aspects of the integration of the considered solar thermal technology, enabling significant risk reduction potential for the future development of respective assets. The case study is the first to examine the integration of solar thermal energy into a gas processing facility and is also the first commercial demonstration of the inflatable solar thermal collector technology at megawatt-scale.