  We address the experimentally observed non-Gaussian fluctuations for the
energy injected into a closed turbulent flow at fixed Reynolds number. We
propose that the power fluctuations mirror the internal kinetic energy
fluctuations. Using a stochastic cascade model, we construct the excess kinetic
energy as the sum over the energy transfers at different levels of the cascade.
We find an asymmetric distribution that strongly resembles the experimental
data. The asymmetry is an explicit consequence of intermittency and the global
measure is dominated by small scale events correlated over the entire system.
Our calculation is consistent with the statistical analogy recently made
between a confined turbulent flow and a critical system of finite size.
