Virginia Tech’s MULti-body LinEar Terminator (MULLET) wave energy converter combines two fundamental findings published by British and American wave energy pioneers in the 1970s and 80s. MULLET’s linear terminators derive from the Bristol Cylinder modeled by Professor David Evans and his colleagues in the UK, benefiting from more than three decades of Bristol University’s published research about the behavior of and interactions among horizontal circular cylinders floating on or submerged beneath ocean waves. The Bristol Cylinder developed by this group in the late 1970s and early 1980s was a fully submerged, monolithic, reinforced concrete cylinder, with double-acting hydraulic pumps incorporated into rigid mooring struts connecting the cylinder to the seabed.
MULLET’s primary wave energy absorber differs from the Bristol Cylinder, in that it is floating, with single- acting power take-off (PTO) units incorporated into flexible tethers connecting the primary absorber to a fully submerged reaction plate. This enables Virginia Tech’s MULLET to realize the advantages of a single-acting PTO, first demonstrated in the 1980s by the late Michael Pleass and his former student at the University of Delaware, Douglas Hicks, for a heaving-buoy point absorber. Hicks and Pleass showed that by freeing downward motion of the buoy from PTO damping, the buoy would sink more deeply into a wave trough, adding potential energy to be recovered as useful work on the next wave crest. MULLET’s floating single-acting primary absorber would behave similarly, in either heave or pitch or any combination of the two.