Four Reasons Why Hybrid Electric Drive Would Be Good for the Navy’s Future Frigate
The U.S. Navy is moving ahead smartly to acquire a new frigate or FFG(X). Last year, it awarded five contracts for conceptual designs to Austal USA, Lockheed Martin, General Dynamics Bath Iron Works, Fincantieri Marine and Huntington Ingalls. To shorten the time between design and production, the Navy required that the FFG(X) be based on an existing ship already in production either in the U.S. or overseas. The current plan is to finalize the frigate’s requirements in the next few months, release a formal Request for Proposals around mid-year and downselect to a single winner for the 20-ship program in 2020.
The five companies competing for the FFG(X) face a number of challenges in developing their designs. The Navy has articulated a demanding set of requirements. It wants a multi-mission ship that can contribute meaningfully in a high-end combat environment involving anti-submarine (ASW), air and missile defense (AAW), and surface warfare (SUW) missions. At the same time, the Navy has been pushing hard to lower the projected costs for the FFG(X), publicly announcing that it had reduced the projected average cost for the new frigate by $150 million, or nearly 20%. Also, the competitors are inevitably constrained by the limits of the characteristics of the existing ship designs on which their proposals will be based.
The U.S. Navy has made it quite apparent that it is looking for a highly capable, multi-mission combatant but that it wants it “on the cheap.” As a result, the five companies involved have to look for ways they can cut the procurement cost for their offering. While the Navy also wants to reduce the long-term operations and maintenance costs for the FFG(X), the way RFPs are typically written gives priority to reducing a system’s initial procurement cost.
The Navy may be unintentionally foregoing an option for a propulsion system that would provide benefits for the new frigate’s combat capabilities as well as long-term reductions in operating costs. I am referring to a hybrid electric drive (HED) engine. HED is an electric motor mounted on the propulsion shaft that is powered by the ship’s generators. HED provides a very quiet and efficient means of propulsion at lower speeds, up to 16 knots. Because HED is marginally more expensive to procure than traditional power plants, it may not be receiving the attention it deserves.
Here are four reasons why HED on the FFG(X) makes sense:
- HED is an advantage in anti-submarine and anti-air warfare.
HED is particularly well-suited for a ship intended for the ASW and AAW/missile defense missions, both of which involve long periods of cruising at relatively slow speeds. Because the HED is decoupled from the gearbox and main propulsion engines, there is zero gearbox noise and vibration during anti-submarine warfare operations. This is increasingly important as our potential adversaries improve the quietness of their submarines. The quieter vessel has the advantage.
The Navy recently considered retrofitting more than 30 Arleigh Burke-class destroyers with HED. The primary reason given was its superior performance at cruising speeds, the typical operating mode for ships conducting anti-submarine and missile defense missions. The Navy also believed that HED would be a major fuel saver.
HEDs and improved energy storage will be key to meeting the Navy’s growing need for power generation to support the ever-growing demands of future sensors and directed energy weapons. Since retrofitting the FFG(X) would be prohibitively expensive, building in a HED power plant makes sense.
- HED enhances survivability.
Enhanced quietness also contributes to improved survivability. This is why the U.S. Navy’s stealthy Zumwalt class DDG-1000 and the Columbia-class ballistic missile submarine both employ a HED propulsion system. In addition to the dangers the US. Navy faces from quieter Russian and Chinese submarines. There is also the threat from their improved acoustic sensors that support torpedo and missile strikes. HED is one of a set of stealth measures, including hull shaping, low probability-of-intercept communications and electronic warfare, which future surface ships will require.
- HED would reduce the FFG(X)’s life cycle costs.
HED systems have lower operations and maintenance costs than traditional diesel and gas turbine power plants. One recent analysis suggested that hybrid diesel-electric propulsion can reduce fuel consumption and CO2 emissions by 10% to 25% compared to gas-turbine-electric propulsion. As a result, frigates with HED power plants have significantly greater cruising range than those that don’t. Also, HED causes less wear-and-tear on the main propulsion system. It is quite possible that the long-term savings associated with HED would more than pay for any higher procurement costs associated with such a system.
- HED is the standard for modern frigates.
Virtually every modern frigate in production or being designed today includes a HED propulsion system. As far back as the early 1990s, the UK’s Type 23 Duke-class frigates, designed for anti-submarine warfare, were equipped with HED. Its replacement, the Type 26 frigate, as well as the new Type 45 destroyer and the Queen Elizabeth-class aircraft carriers, have HED propulsion systems. A derivative of the Type 26, the Global Combat Ship, has been ordered by both the Australian and Canadian Navies.
Most U.S. allies are all in for HED. The Franco-Italian-designed European multi-purpose frigate, or FREMM, employs HED. It is operating with five different navies: France, Italy, Egypt, Morocco and Greece. Spain’s F110, Germany’s F125 and South Korea’s FFX-II frigate all have some type of HED. Japan’s newest destroyers also have a HED power plant.
To date, only one of the five competitors for the FFG(X) program, Fincantieri Marine, is known to have proposed a HED option. The Navy, at a minimum, should ask the other four to include an option for HED in their designs. Better still, the Navy should consider specifying requirements for quietness, cruising range and power generation that incentivize the incorporation of HED.
Dan Gouré, Ph.D., is a vice president at the public-policy research think tank Lexington Institute. Goure has a background in the public sector and U.S. federal government, most recently serving as a member of the 2001 Department of Defense Transition Team. You can follow him on Twitter at @dgoure and the Lexington Institute @LexNextDC. Read his full bio here.