  In this letter, dark energy is obtained using dual roles of the Ricci scalar
(as a physical field as well as geometry). Dark energy density, obtained here,
mimics phantom and the derived Friedmann equation contains a term $\rho^2_{\rm
de}/2 \lambda$ with $\rho_{\rm de}$ being the dark energy density and $\lambda$
being the cosmic tension. It is like brane-gravity inspired Friedmann equation,
which arises without using the brane-gravity theory. It is found that
acceleration is transient for $\lambda < 0$, but for $\lambda > 0$, expansion
is found to encounter big-rip problem. It is shown that this problem can be
avoided if dark energy behaves as barotropic fluid and generalized Chaplygin
gas simultaneously. Moreover, time for transition (from deceleration to
acceleration of the universe) is derived as a function of equation of state
parameter ${\rm w}_{\rm de} = p_[rm de}/\rho_{\rm de}$ with $p_{\rm de}$ being
the pressure for dark energy fluid..
