  In this paper, we aim to analyse the impact of hydrogen production
decarbonisation and electrification scenarios on the infrastructure
development, generation mix, $CO_{2}$ emissions, and system costs of the
European power system, considering the retrofit of the natural gas
infrastructure. We define a reference scenario for the European power system in
2050 and use scenario variants to obtain additional insights by breaking down
the effects of different assumptions. The scenarios were analysed using the
European electricity market model COMPETES, including a proposed formulation to
consider retrofitting existing natural gas networks to transport hydrogen
instead of methane. According to the results, 60% of the EU's hydrogen demand
is electrified, and approximately 30% of the total electricity demand will be
to cover that hydrogen demand. The primary source of this electricity would be
non-polluting technologies. Moreover, hydrogen flexibility significantly
increases variable renewable energy investment and production, and reduces
$CO_{2}$ emissions. In contrast, relying on only electricity transmission
increases costs and $CO_{2}$ emissions, emphasising the importance of investing
in an $H_{2}$ network through retrofitting or new pipelines. In conclusion,
this paper shows that electrifying hydrogen is necessary and cost-effective to
achieve the EU's objective of reducing long-term emissions.
