After nonrenewable energy sources are consumed in what some authors call this " fossil fuel age ", mankind must turn to longer-term, permanent energy sources.
(nonrenewable energy sources; are consumed; L:in what some authors call this " fossil fuel age) (some authors; call; this " fossil fuel age) (mankind; must turn; to longer-term; permanent energy sources; T:After nonrenewable energy sources are consumed in what some authors call this " fossil fuel age)
nonrenewable energy sources some authors mankind
are consumed call must turn
L:in what some authors call this " fossil fuel age
this " fossil fuel age
to longer-term permanent energy sources T:After nonrenewable energy sources are consumed in what some authors call this " fossil fuel age