Navy’s Energy Magazine supports higher power demands on ships
The Energy Magazine concept will use new peak-shaving technology and next generation DC interfaces to make electric ships more combat mission-ready.
The Navy is working to build more efficient electric ships by eliminating the need for most intermediary power systems and improving electric pulsed combat systems with the next generation Energy Magazine and Energy Magazine Mk II.
According to Steve Markle, Director of the Electric Ships Office, at the Navy League’s Sea Air and Space Exhibition, the Energy Magazine concept currently in development is being designed to solve two challenges facing the Navy: a demand for more dynamic power and a demand for higher power.
The demand for more dynamic power comes from the electric pulsed combat systems installed on board ships, such as sensor radar, directed energy weapons, and electronic warfare systems. Rather than the consistent power flow at constant voltage provided by the ships generators, these mission payloads ebb and flow in their power usage.
“You have a radar, so you have a ramp-on, leading up to a ripple, and then a ramp-down. You have a directed energy weapon, a laser, which powers on for a certain amount of time, then goes off. Then, you have an electric warfare system that…is stochastic in nature. These systems together create a combined power demand that is somewhat difficult for our existing 1399 systems to be able to manage,” said Markle.
The solution to a randomly determined power demand, according to Markle, is the Energy Magazine concept, which has two components: energy storage and advance control capabilities.
“The Energy Magazine uses energy storage to push and pull power off the grid to be able to provide these spiky loads,” explained Markle.
It is designed to supplement the generators using a peak-shaving method. Energy storage technology will store energy and add it to the generator’s constant power current to meet the level of the combat systems’ spiked energy demands. At the same time, the lulls in energy demand would allow the excess generator power to go toward recharging the energy stores.
The advanced controls component is the distribution mechanism that will dictate the flow of energy from the power generators to the ship’s systems, as well as to the ship’s onboard electric payloads, while at the same time controlling the flow of energy to and from the energy storage mechanism. Energy will go to the electric payload systems when their energy demand spikes, and be directed back to the energy storage unit for charging during lulls, according to Naval Sea Systems Command.
The exact energy storage technology is still being thought out. However, the Energy Magazine Mk II prototype makes use of a lithium ion phosphate battery that is slightly bigger than a D-Cell battery, said Markle.
“Not every storage device is the perfect answer for every situation,” he explained. “So it may end up being a hybrid, it may end up being a combination of different types of storage.”
In terms of providing more power to ships, efficiency is key. Yet while advancements in power generation technology and their acquisition has occurred in stages over time, the need for more power on board ships has grown exponentially.
Size, weight, and power cost is already disproportionate for the amount of power that actually comes out of these systems, reports Markle, and intermediary power conditioning systems will only get larger with the size of the electronic system they are supporting.
The Energy Magazine will also help address this power inefficiency. The Navy Power and Energy Systems Technology Development Roadmap reports that AC loads will continue to help support ships, powering onboard heating and lighting, for example. However, according to NAVSEA, the future MIL-STD 1399 interface will rely more on DC power, specifically low and medium voltage DC power.
By reducing the need for individuated intermediary systems, the future DC interface will enable ships to use a common architecture among the different electric payloads.
“What we are trying to do is go after that 30 to 40 percent of what goes into the top side of our ships with a common system that serves multiple users,” explained Markle.
The final aspect of the updated electric ship is the actual power generator. The Advanced Power Generation Module (APGM) is in the early stages of study and prototype development, with study contracts currently being prepared, according to Markle. The system will be designed to use DC voltages and support randomly determined electric payloads as part of the Energy Magazine concept. Simulated testing is currently being performed by Sandia National Laboratories, and the next generation power generator is scheduled to enter the testing phase in FY23.