# Impact of Plasma Combustion Technology on Micro Gas Turbines Using Biodiesel Fuels
## 1 Introduction  
The use of fossil fuel technology in the operation of gas turbine engines (GTE) faces issues that include low thermal efficiency, poor atomization, low vapor pressure, and high greenhouse gas (GHG) emissions [1, 2]. Thus, our research motivation was to re-structure the design principle of gas turbines to enhance performance and reduce fuel consumption and GHG emissions [3]. The use of biofuel as an alternative energy source in transportation systems has gained attention and interest as an alternative for automobiles in developed nations [4, 5, 6]. The environmental benefits motivated this study, considering the low greenhouse gas (GHG) emission content of sulfur and hydrocarbons in bio-renewable fuel resources, as well as the associated improved engine performance [7, 8, 9]. In particular, the benefits of biodiesel as an alternative aviation fuel have attracted research interest in addressing the inefficient performance of conventional fossil fuels [10]. The incomplete combustion of fossil fuel hydrocarbons adversely impacts GTE performance in terms of the GHG emission levels, fuel consumption, engine running cost [11, 12, 13]. A typical gas turbine is characterized by a continuous-flow engine and steady flame production during the combustion process, with high hydrocarbon emissions from conventional fossil fuel resources [14, 15]. However, these emissions may negatively impact the environment by depleting the ozone layer. The gas-turbine architecture permits various fuels that support complete combustion in the engine. Some GTE features, such asmoderate compression ratios, robust mechanical designs, and versatile combustion systems enhance the engine's potential to utilize a wide variety of biofuels (such as alcohols, biodiesel, low-calorific-value (LCV) gasified biomass, synthetic gas, hydrogen [16], and natural gas) [15; 17]. It is worth mentioning that fuel properties influence the performance efficiency of gas turbines and also determine the final composition of emitted greenhouse gases (GHG), such as nitrogen oxide (NO\({}_{2}\)) and carbon monoxide (CO) [18; 19; 20]. Efforts have been made to apply biodiesel fuel sources to power GTEs for improved performance efficiency and reduced GHG emissions [18; 21]. High emissions of sulfur oxide (SO), CO, and NO are known to result from the combustion of conventional fossil fuels in typical GTE systems [21; 22]. Factors such as injection timing, adiabatic flame temperature, radiation heat transfer, and injection delay are also responsible for higher NO\({}_{2}\) emissions in reciprocating engines [23; 24]. The antioxidant additives in biodiesel mainly contain phenolic groups, which are more likely to form soot than glyceride impurities, even with the potential to burn more cleanly than fossil fuels [25; 26; 27]. Control of emission levels remains an challenge; there is a need for more sustainable, cheaper, and environmentally friendly alternative energy sources for GTE aerospace applications. Animal fats are a promising alternative for biodiesel production but require more complex processing than natural oils. In Kuwait, fat waste from sheep is the primary feedstock for biodiesel production with high contents of free fatty acids (49.1 mgKOH/g). Fat waste is sustainable, abundant, and inexpensive and reduces handling and risk of impacting on the environment without economic competition, as seen in vegetable oils [28]. In addition, use of jet fuel in the operation of engines has the disadvantages low thermal efficiency, poor atomization or vitalization, and low vapor pressure. These factors, if not addressed, result rapid evaporation and high operation cost, leading to increased fuel consumption [29]. To overcome these limitations, effective deployment of biodiesel fuel in GTE operation is among the best options to reduce GHG emission levels. Plasma technology requires a higher temperature for effective biodiesel combustion and enhanced performance in a gas turbine engine.