# Potential of Onshore Wind Turbine Inertia in Decarbonising the Future Irish Energy System
## 4 Results  
OpInMod provides a large set of results of which system costs, RES penetration, storage units state of charge or cross border flows can be analysed. Since it is the objective of the work at hand to assess the potential of SI provided by WTs, results like the SI provided by WTs itself, RES curtailment, carbon dioxide emissions and system costs will be focused on. The NT scenario is once optimised without the provision of SI by WTs, only considering inertia provision from synchronously connected generators, representing current state of research and acting as the base scenario in this work. The combination of the two ROCOF threshold parameters (1 Hz/s and 2 Hz/s) and two \(H_{dem}\) parameters (3.5 s and 5 s) result in four additional scenarios optimised. All optimisation problems designed with respect to the parameter combinations of the future Irish power system are solvable. Hence, the inertia and power demand constraints are satisfied. Figures 3 and 4 depict results of a 24 h time series, which is an extract from the whole modelled year. The time series is selected randomly with no specific purpose other then illustrating model functionality, i.e., the influence of inertia constraints on the behaviour and output of dispatchable units. Figure 3 shows results of the base scenario and Figure 4 shows results of the same time period and a ROCOF threshold of 2 Hz/s and a demanded inertia constant of 3.5 s.  
The top subplot of Figure 3 illustrates the electric power flow of dispatchable and non-dispatchable units and the bottom subplot the thereof resulting inertia provision. The x-axis shows the time of the day and the y-axis of the top subplot shows the electric power flows, imports and exports in MW and the y-axis of the bottom subplot depicts the provided moment of inertia in kg\(\cdot\)m\({}^{2}\). Previous publications depicted the provided inertia represented by the accumulated stored kinetic energy of the connected synchronously rotating masses [15; 16; 39]. However, since this work incorporates SI provided by WTs and applies the inertia provision methodology introduced by [PERSON] et al. [19], the stored kinetic energy in the WT's rotor is not a valid representation of the actual provided SI. \begin{table}
\begin{tabular}{l l r r r r r} \hline \hline \multirow{2}{*}{**Prime Energy**} & \multirow{2}{*}{**Generator Type**} & **O\&M** & **Efficiency** & **Min. Stable** & **CO\_2 Emissions** & **Inertia** \\  & & **[EUR/MWh]** & **[\%]** & **Op. [\%]** & **[t\({}_{\text{CO}_{2}}\)/MWh\({}_{\text{el}}\)]** & **Constant[s]** \\ \hline Nuclear & - & 9.00 & 33.0 & 50.0 & 0.0 & 5 \\ Hard coal & - & 28.68 & 40.0 & 43.0 & 0.8495 & 3.125 \\ Lignite & - & 30.57 & 40.0 & 43.0 & 0.9127 & 3.5 \\ Natural gas & Conventional old 1 & 16.49 & 36.0 & 35.0 & 0.5700 & 4.25 \\ Natural gas & Conventional old 2 & 16.49 & 41.0 & 35.0 & 0.5005 & 4.25 \\ Natural gas & CCGT \({}^{\text{a}}\) old 1 & 16.99 & 40.0 & 35.0 & 0.513 & 4 \\ Natural gas & CCGT old 2 & 16.99 & 48.0 & 35.0 & 0.4275 & 4 \\ Natural gas & CCGT present 1 & 16.99 & 56.0 & 30.0 & 0.3664 & 4 \\ Natural gas & CCGT present 2 & 16.99 & 58.0 & 30.0 & 0.3537 & 4 \\ Natural gas & CCGT new & 16.99 & 58.0 & 35.0 & 0.3537 & 4 \\ Natural gas & OCGT \({}^{\text{b}}\) old & 16.99 & 35.0 & 30.0 & 0.586 & 5.25 \\ Natural gas & OCGT new & 16.99 & 42.0 & 30.0 & 0.4885 & 5.25 \\ Light oil & - & 22.16 & 35.0 & 35.0 & 0.8022 & 3.25 \\ Heavy oil & - & 24.36 & 37.5 & 35.0 & 0.7524 & 3.25 \\ Shale oil & - & 30.30 & 29.0 & 40.0 & 1.0822 & 3.5 \\ Biomass & - & 10.00 & 40.0 & 43.0 & 0.0 & 3 \\ Other RES & - & 10.00 & 37.5 & 35.0 & 0.0 & 2 \\ \hline \hline \end{tabular} \({}^{\text{a}}\) Combined cycle gas turbine (CCGT); \({}^{\text{b}}\) Open cycle gas turbine (OCGT).  
\end{table} 
Table 3: Generator characteristics. Additionally, in future systems inertia should be a tradeable commodity [4]. Therefore, the actual and emulated moment of inertia in kg\(\cdot\)m\({}^{2}\) is illustrated. Figure 3 depicts results of the base scenario.