A framework for energy-balance audits in laboratory OWC experiments

Wave energy conversion (WEC) systems have long promised a sustainable source of renewable energy. However, their progress remains constrained by persistently low conversion efficiencies and the absence of standardized practices for comparing system performance across studies and devices. Energy auditing is a critical element of experimental methodology for establishing confidence and credibility in laboratory investigations and the subsequent design of wave-energy systems. Its implementation is challenging: the energy input (decomposition of incident and reflected wave power), the useful output (device absorption), and especially losses (leakage, pneumatic, viscous, and radiative) are difficult to quantify. Recognizing these challenges, this paper presents an energy-balance framework for oscillating water column (OWC) laboratory studies and reports preliminary experimental results. The measurements integrate a four-probe incident/reflected decomposition and synchronized chamber-power measurements with a baseline loss model to evaluate overall energy closure. Two analysis windows—pre-rebound (Region 1) and post-rebound (Region 2)—are used to examine the influence of wave re-encounters and finite-flume effects. Application to initial flume measurements reveals a modest yet non-negligible range of unaccounted power and identifies conditions under which frequency-dependent losses may become significant. On the basis of these observations, the study offers lessons learned and best-practice recommendations for probe placement, calibration and leakage checks, and transparent reporting of residuals. The proposed framework establishes a reproducible foundation for OWC experimentation, enabling systematic optimization and informing design improvements.