  We propose and test a scheme for entanglement renormalization capable of
addressing large two-dimensional quantum lattice systems. In a translationally
invariant system, the cost of simulations grows only as the logarithm of the
lattice size; at a quantum critical point, the simulation cost becomes
independent of the lattice size and infinite systems can be analysed. We
demonstrate the performance of the scheme by investigating the low energy
properties of the 2D quantum Ising model on a square lattice of linear size
L={6,9,18,54,inf} with periodic boundary conditions. We compute the ground
state and evaluate local observables and two-point correlators. We also produce
accurate estimates of the critical magnetic field and critical exponent beta. A
calculation of the energy gap shows that it scales as 1/L at the critical
point.
