This is the 4313th most frequent Polish word.
energetycznych
"Energetycznych" means "energetic" or "related to energy."
Here 'energetycznych' is used as an adjective modifying 'materiały', referring to materials related to energy.
Zapotrzebowanie na materiały energetycznych stale rośnie.
The demand for energy materials is constantly growing.
Here 'energetycznych' serves as an adjective describing 'przemysł', indicating the industry related to energy.
Przemysł energetycznych rozwija się szybko.
The energy-related industry is developing quickly.
In this sentence, 'energetycznych' is an adjective qualifying 'technologii', describing that the technologies are related to energy.