## 4 Discussion  
The presented results show that current options for mitigating fossil-based kerosene are not able to achieve the expected CORSIA impact (10% saving) when considered independently. There is no single LCAF technology that can reach the required 10% reduction even if deployed to its maximum technical potential. When deployed together, interactions do not allow for simply adding together the expected GHG reduction potentials. Some of the refining levers are not truly independent; for example, improved energy efficiency reduces the use of imported energy and thus reduces the opportunity for deploying lower-carbon energy. To address this, the levers should be applied sequentially, with levers being applied to the energy/hydrogen demand resulting from the application of its predecessor; this as determined based on industry and policy trends, which were triangulated with CO\({}_{2}\) abatement cost and technical feasibility in 2030. In particular: (i) energy efficiency; (ii) renewable energy; (iii) low-carbon hydrogen (blue and green); (iv) refinery-wide CCS. Following refinery efficiency improvements, renewable energy is likely to be the next lever deployed fully. In addition to broad decarbonisation measures, the RED II targets renewable energy specifically, requiring it to make up about one-third of the electricity mix by 2030. These targets are currently under revision, and they will likely be increased. Progress in policies and technologies have caused sharply falling costs of renewable electricity, contributing to rising renewable electricity shares. However, by 2030 the EU-average grid mix will not be completely renewable (estimated GHG intensity of 71 gCO\({}_{2 eq}\)/MJ [19]); therefore, access to lower carbon-intensity electricity would require dedicated renewable electricity capacity. Despite significant momentum behind green hydrogen production, demand looks poised to surpass supply by 2030 without significant innovation and scaling up of electrolysers. The EU Hydrogen strategy [36] is expected to contribute to the rapid increase of green hydrogen production and to overcome several technical and non-technical barriers. Thus, this EU Hydrogen strategy aims to achieve the installation of at least 6 GW of renewable-powered electrolysers in the EU by 2024, and 40 GW by 2030. This depends on the availability of low-cost renewable electricity. Several projects are being funded in the EU to ramp up hydrogen production [37]. Blue hydrogen is likely to have a significant role in satisfying the growing hydrogen demand due to lower costs compared to green hydrogen, abundant gas and pre-existing infrastructure. The Clean Hydrogen Partnership \begin{table}
\begin{tabular}{c c c c} \hline \hline  & **Lever** & \
\begin{tabular}{c} **WTW Emissions** \\ **(gCO\({}_{2 eq}\)/MJ)** \\ \end{tabular} &
\begin{tabular}{c} **\% Technical Potential** \\ **for Reduction** \\ \end{tabular} \\ \hline \multicolumn{2}{c}{Base Case} & 89.0 & - \\ \hline \multirow{3}{*}{Upstream levers} & Energy use & 86.7 & 2.6\% \\ \cline{2-4}  & Flaring reduction & 87.8 & 1.3\% \\ \cline{2-4}  & Methane emissions control & 84.0 & 5.6\% \\ \hline \multirow{3}{*}{Refinery-wide levers} & Energy efficiency improvements & 87.7 & 1.5\% \\ \cline{2-4}  & Renewable energy & 87.0 & 2.2\% \\ \cline{2-4}  & Refinery-wide CCS excl. H\({}_{2}\) production & 85.1 & 4.3\% \\ \cline{2-4}  & Refinery-wide CCS incl. H\({}_{2}\) production & 84.0 & 5.6\% \\ \cline{2-4}  & Use of low-carbon hydrogen & 87.9 & 1.3\% \\ \hline \multirow{3}{*}{Jet fuel-specific levers} & Use of low-carbon hydrogen in KHT & & \\  & (SMR-CCS or electrolyser H\({}_{2}\)) & 88.3 & 0.8\% \\ \cline{2-4}  & Use of renewable power in KHT & 88.4 & 0.7\% \\ \cline{2-4}  & Alternative desulphurisation & 87.6 & 1.5\% \\ \hline \hline \end{tabular}
\end{table} 
Table 7: Summary of WTW emissions of jet fuel arising from each lever, and the percentage reduction compared to the base case (ICAO).