## 1 Introduction
### Tenerife Energy System  
Tenerife, Canary Islands, with an area of 2034.38 km2 and a population of 944,107 inhabitants is the largest and most populated island in Spain. Located in the Atlantic Ocean and close to the African coast (see Figure 1), Tenerife is one of the European Union's outermost regions. A basic representation of this isolated energy system is depicted in Figure 2, developed with the most recent published data (2022) [38]. Oil (mainly heavy fuel oil, diesel, and petrol) is the dominant primary energy source, exceeding the 22 TWh of energy import. The two main demand sectors are power-generation (29.06%) and transportation (70.94%). Oil consumption in the industrial/service sectors and LPG, although existent, has been omitted as its values are relative low. Renewable sources (mainly WE and PV) only represent 2.8% of the total primary energy consumption, making clear the great dependence on fossil fuels across all sectors. Figure 1: Geographical location of Tenerife, Canary Islands. In 2022, the electricity demand was 3.4 TWh/year, with a peak power of 557 MW. A total share of 84% of this demand was covered with conventional sources, a common factor in other isolated power systems [11; 38; 39]. The current structure of the power-generation sector is summarised in Table 1, which includes the technology, power capacity, generation share, and fuel type. Combined Cycles and steam turbines supply most of the required power and provide the base load, with a total share of 74%. The rest of the technologies are two-stroke marine-derivative compression ignition engines and gas turbines, the latter being mainly used to support peaks and provide a spinning reserve. With no infrastructure in place to deploy natural gas, gas turbines make use of diesel fuel, whereas heavy fuel oil is the current fuel to feed the two-stroke engines and steam turbines. As a result of the technical difficulties to reach large RE penetration percentages [40], the current contribution of RE technologies to the electrical energy produced on the island is 19.2% (17% across this archipelago) [38]. This percentage is considerably far from interconnected systems such as mainland Spain, where the current figure is 48.4% [41]. The road transport sector, with a fleet mainly powered by internal combustion engines (ICEs), has an oil demand of 5.79 TWh (25.68% of the total demand). The breakdown consumption, grouped by vehicle application and fuels, is shown in Table 2. The oil demand of LDVs, including passenger cars and vans, represents 65% of the total road transport demand. The fleet (approximately 800k vehicles) [42] is dominated by petrol \begin{table}
\begin{tabular}{c c c c c c} \hline \hline
**Technology** & **Gross Installed [MW]** & **Generation [GWh]** & **Share [\%]** & **Fuel** &
\begin{tabular}{c} **Average Thermoelectric** \\ **Efficiency [\%]** \\ \end{tabular} \\ \hline Combined Cycle & 457 & 1943 & 54.2 & Diesel & 47 \\ Steam turbine & 160 & 706 & 19.7 & HFO & 33 \\ Gas turbine & 248 & 99 & 2.8 & Diesel & 24 \\ Diesel engine & 48 & 149 & 4.1 & HFO & 43 \\ Wind energy (WE) & 222.6 & 508 & 14.2 & - & - \\ Solar photovoltaic (PV) & 107.6 & 168 & 4.7 & - & - \\ Small hydropower & 1.2 & 3 & 0.1 & - & - \\ Biogas plant & 1.6 & 9 & 0.3 & Biogas & - \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Description of the current power-generation system of Tenerife. Data extracted from [38]. Figure 2: Sankey diagram of current energy system of Tenerife island. Data extracted from [38]. engines, as the consumption per fuel type evinces. The rest of the conventional vehicles uses LPG as fuel (energy demand of 7.73 GWh), representing only 0.21% of the total fleet [38]. Plug-in vehicles account for 0.54% of the LDV fleet [42]. Their share in the new registered vehicles has moved from 1.37% in 2019 to 12.28% in 2023 [42], confirming a progressive technology shift due to government incentives. HDVs represent 36% of the road transport energy demand and almost 10% of the total oil imported to the island.