An energy harvesting system includes a first heat engine, a second heat engine, and an nth heat engine. The heat engines each include at least two rotatable pulleys and a first shape memory alloy (SMA) member. The SMA member is disposed about the at least two rotatable pulleys and defines an SMA pulley ratio. The second heat engine is disposed adjacent the first heat engine. The nth heat engine is disposed such that the second heat engine is disposed between the first heat engine and the nth heat engine. The first SMA member, the second SMA member, and the nth SMA member are configured such that a thermal energy conversion efficiency between the hot temperature region and the cold temperature region is nearly 100%.
STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT
 This invention was made with U.S. Government support under ARPA-E Contract number DE-AR0000040, awarded by the Department of Energy. The U.S. Government may have certain rights in this invention.