Future-proofing the Attack class (part 1): propulsion and endurance

A major challenge in the decades-long program to build the Royal Australian Navy’s new submarines, the Attack class, will be ensuring that they incorporate emerging transformational advances in propulsion technology.

Between 2025 and 2030, the continuing rapid evolution of lithium-ion battery technology will enable the Attack-class boats to stay fully submerged on low-speed patrols for up to 40 days without recharging. By 2035, that could increase to up to 60 days. And by 2050, it’s conceivable that the next generation of light-metal batteries will enable the boats to go on an 80-day long-transit mission without the need to resurface and recharge.

In ASPI’s Agenda for change 2019, Marcus Hellyer recommended that the government commission an independent review of the Royal Australian Navy’s plans for its future submarines. That wouldn’t be easy, considering that many independent experts have already approved crucial aspects of the program.

Hellyer suggests that significant issues include the adequacy of the scheduled delivery date in light of Australia’s deteriorating strategic circumstances, and he urges another look at nuclear propulsion.

Neither of those things should preoccupy Defence Minister Linda Reynolds. While managing the schedule for the Attack class is certainly important, a bigger challenge is aligning design and construction plans with the advances in propulsion technology that will revolutionise conventional submarines. If that’s not done, the program is unlikely to meet its objectives, with consequences that could undermine Australia’s strategic posture.

While nuclear propulsion is attractive because of the high performance it provides, Australian studies conducted from the late 1960s have concluded that the problems associated with going nuclear far outweigh the performance gains. That remained the advice in 2016 when the preferred design partner was selected for the future submarines.

It’s unlikely that the new minister will receive different advice. Nuclear propulsion isn’t a form of maritime whitegood. Some idea of what would be required to adequately sustain a RAN nuclear submarine fleet entering service in around 2044 was provided in a recent ASPI study.

The sticking point is that Australia doesn’t have a nuclear power industry on which the RAN can draw. Personnel and technical support for safety, operational deployment and sustainability would have to be developed, and funded fully by taxpayers. Expertise to manage the complex regulatory regimes that affect acquisition and sustainment would have to be generated wholly within government.

Even countries with extensive nuclear experience have had problems in this area. Development of the French Barracuda class has been delayed for three years by new nuclear norms and controls, and the UK hasn’t been able to dispose of any of the 20 nuclear submarines it has decommissioned over the past 40 years.

It’s now clear that Australia will never have its own nuclear power industry. In electricity markets, nuclear energy has been judged to be uncompetitive against coal. And coal-fired power is now likely to be moribund in the face of the rapid progress being made with renewable energy generation, advanced storage technologies and increased options for power distribution. These alternatives to fossil fuels are projected to provide electricity at historically low prices by 2030, with continuing price falls beyond 2040.

Much of this development rests on light-metal batteries, which have accelerated rapidly in performance in recent years.

In 1988, Southern California Edison commissioned the world’s largest storage system for lead–acid battery energy, with a 40-megawatt-hour capacity and 10-megawatt power rating. The plant was decommissioned in 1997 because it was unable to cope with grid load demands.

In December 2017, a Tesla Powerpack system was commissioned in South Australia. It’s currently the world’s largest lithium-ion battery storage system, with a 40-megawatt continuous, 100-megawatt peak power rating and a 130-megawatt-hour capacity.

That’s comparable to the effective capacity of 10 main lead–acid batteries in a Collins-class submarine, which provides less than a week’s submerged endurance. And it’s the same order of capacity that will be available for the Attack class by 2030, which will enable a boat to remain deeply submerged for 30 to 40 days without having to raise its snorkel to ‘breathe’ while running its diesel engines to recharge its batteries.

The South Australian system has now been working continuously for more than 500 days at levels of operational tempo and intensity well in excess of those experienced in the Collins.

The South Australian installation will soon be overtaken by a system under construction in California, and then by another, larger system to be commissioned in Florida in 2021. A 1,000-megawatt-hour, 250-megawatt system has been proposed for the Robertstown region in South Australia.

The technology used for utility storage systems is directly transferrable to submarine propulsion and will transform conventional submarines.

If the emerging opportunities are taken, lithium-ion battery technology will enhance major objectives of Australia’s submarine program. The two most important influences determining this process are the concept of operations (CONOPS), which is focused on deploying submarines at great distances in an adversary’s sea approaches, and control over intellectual property, which needs to be sufficient to allow Australia to maintain a sovereign submarine capability.

The CONOPS requires a submarine with long range and enhanced endurance.

The designs of both the Collins and Attack classes achieve this through large hull displacement to accommodate a big battery and big electrical-generation capacity (a combination that obviated the need for air-independent propulsion in the Collins class).

Light-metal battery propulsion power will greatly enhance the mission effectiveness of such a submarine at long range.

The requirement for a sovereign submarine capability is in part a response to deficiencies in the development and sustainment of the Collins class. It also recognises the need to safeguard our strategic independence in developing and operating the submarine force for perhaps 50 years—a horizon over which Australia’s strategic circumstances and the politics of potential technology partners are difficult to predict. Australia is well suited to generating its own intellectual property in light-metal battery technology and manufacture and to becoming a world leader in the field.

If Australia misses its opportunity, the RAN’s submarines could be at risk if they attempt to operate against a regional counterpart operating lithium-ion-battery-powered boats. Our ally Japan has already launched its first lithium-ion-battery-powered submarine, South Korea isn’t far behind, and other regional players including China are likely to acquire lithium-ion submarines soon.

In part 2, we’ll look in more detail at the transformative potential of light-metal batteries for submarine propulsion and, in part 3, we’ll discuss the consequences of failing to integrate the technology into the Attack-class program.