Life-Cycle Costs

The full life-cycle cost of providing power for soldier electronics is not being taken into account by the Army. The serious cost consequences of not using energy-efficient technology to design LW must be considered when determining the investments needed for reducing the power demand. The cost saving from requiring fewer batteries and other energy sources over the lifetime of the OFW system will more than pay for the development of highly optimized, low-energy solutions. For example, a 10 percent savings in power could be expected to reduce the number of batteries required by a comparable amount. This would have reduced the logistics cost of delivering batteries in Operation Iraqi Freedom, saving an estimated $50 million.

Soldier Communications

Power requirements for soldier communications are too great to ignore. As pointed out in Energy-Efficient Technologies (NRC, 1997), the requirements for soldier communications account for a considerable fraction of the overall energy consumption. The absence of reliable, more definitive estimates for the energy expected to be consumed by future OFW radios is thus of considerable concern. The solution being pursued by the OFW LTI is to use whatever radio is available in the time frame required for integration with OFW-ATD without any particular direct control of the radio design or its power requirements. In addition, the actual communication requirements and mission scenarios planned for JTRS are not necessarily synchronized with emerging requirements for network-centricity, and their lack of definition further obscures an already murky picture of what the OFW power demand will be.

In particular, the JTRS program, while certainly visionary in its goal of achieving compatibility with multiple communication waveforms, is, perhaps, overly ambitious. The software-defined radio on which the soldier radio is based will require advanced use of integrated circuit technology (highly integrated, mixed-signal SoC chip designs) as well as breakthroughs in protocols and architectures. Further, the design approach is unique to DOD, which effectively prevents the military from leveraging the gains in energy efficiency that are expected in commercial communications gear.

The OFW-ATD and LW program place considerable reliance on these JTRS developments with no guarantee that power reduction enjoys an equally high priority in the JTRS program. Without question, the power budgeted for communications is excessive considering the state of the art in communications electronics.

The power sources community understands well the inherent limitations to achieving large, short-term, step function improvements in the energy:weight ratio of power sources. However, on the demand side, the communications-electronics (circuits and systems) community continues to use traditional military approaches to circuit and systems design that are based on mechanical transport and modular interchangeability. These approaches lag well behind the capabilities of private industry and will prevent the Army from reducing energy consumption for soldiers who must communicate to survive on the battlefield.

Design Approaches

Use of application-specific integrated circuits (ASIC) and SoC design techniques are essential and could reduce power by more than an order of magnitude for digital computing and communications processing, making it negligible in comparison to analog sensor and display demand. There has been no effort in this direction in spite of the recommendations of the earlier study. Effort is also needed in reducing the power required by the analog portions of OFW electronics, particularly in communications devices.

Incentives for Reducing Power

The present focus on improving combat effectiveness may not result in net power reductions. While development, integration, and procurement contracts may contain goals for power, there are no financial (or other) incentives to make improvements beyond requirements. In fact, there is a disincentive to reduce power—namely, the potential for increasing risk and near-term cost.

The Army should turn the potential for logistics savings into an incentive. For example, a design saving 1 W could result in a savings of 864 Wh per LW system if the soldier participates in one 72-hr mission a month. Assuming 200 Wh/kg batteries, this would eliminate the need for almost 10 pounds of batteries per year. At $35,000 per ton to deliver supplies to a combat area, the transportation savings is over $100 per system per year. Assuming a 10-year system life and 1,000 soldiers, such a design that saves 1 W is worth $1 million in transportation savings alone.

It took an estimated $500 million to ship (not buy) the batteries used in the first Iraq conflict. By reducing average power demand 10 percent, a $50 million savings could be realized. This would easily cover the development cost of five chips at $10 million per chip or pay for several iterations of a custom ASIC design. If the cost of batteries and related power source hardware, such as chargers, envisioned for the OFW electronics suite is added to the calculation, the savings per soldier would be substantially greater than 10 percent. Perhaps most important, reductions in power demand may well reduce the complexity of energy sources needed and provide additional dollar savings.

Therefore, a reasonable recommendation is for the Army to perform its own life-cycle cost analysis before deciding what it can and cannot afford in the way of development costs. The committee believes the savings revealed by such an analysis would easily justify paying contractor incentives and increasing development activity on energy-efficient design approaches to future Land Warrior systems.



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