In this paper, we propose a Soft-thresholding Orthogonal Matching Pursuit (ST-OMP) technique for efficient signal reconstruction in compressive sensing applications. The proposed ST-OMP recovers less significant signal elements using a low-complexity procedure without sacrificing much reconstruction quality. We apply the proposed ST-OMP in systems powered by non-deterministic renewable energy sources. The threshold of employing the efficient reconstruction is made dynamically adjustable according to the performance requirements and energy levels. Simulation results demonstrate that the ST-OMP can achieve good recovery performance while significantly reducing the energy consumption as compared to the original OMP implementation.