Okay, the user wants me to translate "fossil-fuel-based" into Japanese. Let me think about the correct term here. "Fossil fuel" is 化石燃料 in Japanese. The suffix "-based" usually translates to "に基づく" or "ベースの". So combining them, it would be "化石燃料ベースの" or "化石燃料に基づく". But I need to check which is more commonly used.
Looking up similar terms, "fossil-fuel-based energy" is often translated as "化石燃料ベースのエネルギー". So "fossil-fuel-based" as an adjective would be "化石燃料ベースの". Alternatively, "化石燃料に依存した" might be another way, but that's more like "dependent on fossil fuels". The user might be looking for a direct translation of the adjective form.
Since the user specified to translate all content into Japanese and provide only the translation, I should go with "化石燃料ベースの". Let me confirm there's no existing Japanese content here. The original term is in English, so no need to leave it as is. The translation should be straightforward. I think that's the correct term.