A soldier conducts dismounted maneuvers wearing a photovoltaic solar panel harvester during an energy-harvesting technology demonstration. (Photo: David Kamm, NSRDEC)

Batteries or Bullets: A Tool to Estimate Dismounted Unit Power Requirements

Marines and soldiers conducting dismounted operations under logistically austere conditions often have to make hard choices as to what and how much to carry. In the past, operational experience was generally sufficient to make zero-sum tradeoffs among ammunition, water, and food depending on the length of mission, likelihood of enemy contact, and environmental conditions. The increasing integration of electronic technology to increase the connectivity and situational awareness of dismounted units added a new commodity to the mix, namely energy (usually in the form of batteries). Commanders, planners, and materiel developers now needed an easy-to-use tool that would allow them to make energy-informed decisions for dismounted operations.

The USMC Expeditionary Energy Office sponsored the development of just such a tool, called the Intelligent Power Optimization with Environmental Reactivity (IPOWER) simulation model. IPOWER predicts power requirements for dismounted units based on a number of factors that can be varied to assess power consumption. Recently, a Naval Postgraduate School operations research student, LCDR David Medici, completed his thesis titled, “A Sensitivity Analysis of IPOWER: A Small Unit Energy and Mission Planning Tool” in which he describes the development and use of a software wrapper that gives IPOWER users the capability to automatically run efficient experiments consisting of thousands of runs while varying multiple input parameters and mission durations. LCDR Medici used this new capability to perform a sensitivity analysis by conducting over 4,000 simulated missions that varied input parameters such as mission duration (24– and 72–hour durations) and whether energy harvesters (solar panels) were used or not.

In analyzing the results from the 4,000 simulated missions, LCDR Medici discovered that IPOWER delivered intuitive results as long as energy harvesters were not included in the scenario. Once harvesters were included, however, IPOWER began to deliver unexpected results such as missions where harvested energy did not result in batteries being recharged. He also noted that errors and data anomalies occurred when mission durations were extended to 72 hours. It is suspected that the introduction of harvesters results in possible system-level interactions that make the simulation more complex. LCDR Medici concluded that while IPOWER is useful for its intended purpose, further research and investigations are required to account for increased simulation complexity when energy harvesters such as solar panels are included in scenarios.