Noise-free stochastic resonance is demonstrated numerically in a model for Rayleigh--Bénard turbulence in a spatially extended system, based on a one-dimensional array of coupled chaotic Lorenz cells. The system shows spatiotemporal intermittency as the control parameter --- equivalent to the temperature difference between the upper and lower surface of the liquid layer --- is increased. If the temperature difference is slowly modulated periodically, the signal-to-noise ratio, obtained from the output signal reflecting the occurrence of laminar and turbulent phases in a given point in space, shows maximum as a function of the mean value of the control parameter. The results suggest that experimental observation of noise-free stochastic resonance in spatially extended systems is possible.

PACS numbers: 05.45.--a, 47.52.+j, 05.40.--a