## 4 Discussion
### System Dynamics Modeling for Comparison of GHG Emissions from Electric and Fossil Fuel Cars
#### 4.1.3 For Fossil Fuel-Powered Vehicles  
Similar to electric vehicles, the GHG emissions from gasoline combustion (after considering technological innovations for GHG emission reduction) can be expressed as:  
\[GHG_{out,g}=GHG_{in,g}-\left(R_{in,g}*GHG_{in,g}\right)\]  
where \(GHG_{out,g}\) is the final GHG output from the internal combustion system for gasoline-operated vehicles, \(GHG_{in,g}\) is the GHG from the system before the application of the GHG emission reduction technology, \(R_{in,g}\) is the GHG reduction potential of the technology that is employed to reduce GHG emissions in the gasoline combustion system. Figure 3 depicts a comparison of GHG impacts for electric and gasoline-powered vehicles (with the inclusion of illustrations for GHG reduction efficiency through technological innovations in some of the processes). Depending on the actual procedures that are followed in the plant, the GHG efficiency reduction potential can be adapted for any individual fuel use at the electricity power plants, petroleum refining plants, and other industrial processes. Note that although Figure 3 showed a system dynamic model comparison for gasoline-powered vehicles and electric vehicles, for a comparison of other fossilfuels, gasoline can be replaced with any fossil fuel that is used for the vehicle. The relevant GHG emissions for the fuel can also be updated in the model. The climate and health impacts that are associated with the production, consumption, and exchange of electricity should be given close attention [5]. The vehicle of choice in terms of environmental impact is the one with the minimal amount of emissions of concern (i.e., minimum emissions from either electric-powered vehicle \(GHG_{ev}\), or fossil-powered vehicle, \(GHG_{fpv}\)). \[Vehicle\ of\ choice\ V_{ch}=MIN\Big{(}GHG_{ev},GHG_{fpv}\Big{)}\]  
The system dynamic model allows for the simulation of various scenarios over a wide range of values. The above system dynamic model can be used to show that:  
The GHG impact of the electric vehicle is dependent on the GHG impact of the associated fuel that is used in the production of electricity. The GHG impacts for electric vehicles will increase as the GHG emissions increase for the extraction and processing of the fuel that is used to power the electricity generation station. The GHG impacts for electric vehicles will increase as the GHG emissions increase in the electricity generation processes at the electricity power station. The GHG impacts for electric vehicles (from the power stations with non-renewable power sources) will reduce as the efficiency of the GHG reduction technologies increase. The GHG impacts of fossil fuel-powered vehicles will increase as the GHG emissions increase for the extraction and processing of fossil fuel. Figure 3: System dynamic model for the evaluation of GHG impacts from electric and gasoline-powered vehicles, with consideration for the efficiency of technological innovations for GHG reduction (for illustrative purposes only). The GHG impacts (from tailpipes) of fossil fuel-powered vehicles will reduce as the efficiency of GHG emission reduction technologies is improved in fossil-powered vehicles. Note that, depending on the inputs, even though an electric-powered vehicle may show less GHG impacts in some situations, from a sustainability perspective, other factors such as social and economic will still need to be considered while the world is gradually transitioning to renewable energy forms. From the perspective of expected impacts from GHG emissions, the vehicle of choice will be the one with lesser GHG emissions from a holistic point of view. If desired, the model can be further expanded in future studies to include GHG from the manufacturing of various industrial components that are used in the production of vehicles, and in the production of equipment for the generation of electricity. The model can also be expanded to include expected emissions from wear and tear such as tire wear, road abrasion, and brake wear.