Breakdown of Если бы мы использовали энергию солнца, мы бы спасли планету.
мы
we
бы
would (conditional particle) / concessive particle
если
if
солнце
sun
Questions & Answers about Если бы мы использовали энергию солнца, мы бы спасли планету.
Why are the verbs использовали and спасли in the past tense when the sentence means "If we used... we would save"?
In Russian, unreal or hypothetical conditions (things that aren't actually happening right now) are formed using the particle бы plus the past tense form of the verb. Even though the verbs are grammatically in the past tense, the бы makes them conditional, referring to a hypothetical present or future.
Why is использовали imperfective, while спасли is perfective?
The verb aspects reflect how the two actions are viewed. Использовали (from использовать, to use) is imperfective because using solar energy would be an ongoing process or habit. Спасли (from спасти, to save) is perfective because saving the planet is viewed as the successful, completed result of that ongoing process.
Why does the sentence use солнца (of the sun) instead of an adjective for "solar"?
Using a noun in the genitive case—энергию солнца (energy of the sun)—is a very natural and common way to express this in Russian. You could absolutely use the adjective form instead and say солнечную энергию (solar energy); both are perfectly correct and mean the same thing.
Can I put the second бы somewhere else in the phrase мы бы спасли планету?
Yes! The particle бы is quite flexible. It often goes right after the subject (as it does here: мы бы спасли), but it can also go directly after the verb it modifies. Saying мы спасли бы планету is just as natural and correct.