The present application relates to the field of energy recovery and in particular to the use of shape memory alloys (SMA) for same. An energy recovery device is provided which comprises a one way drive mechanism for incrementally winding a spring. An SMA engine comprising a length of SMA material is fixed at a first end and connected at a second end to the one way drive mechanism. The SMA engine is housed in an immersion chamber and adapted to be sequentially filled with fluid to allow heating and/or cooling of the SMA engine to enable high frequency contractions and expansion. An output transmission is provided which is coupled to and driven by the spring. In this manner, repeated contractions of the SMA material incrementally wind the spring to store energy. The spring is restrained by a release mechanism which may be activated to allow the spring to drive an output transmission.