Alternative Energy and Propulsion Power for Military

Much has been written on the dependency of the US military on oil. However, most of the writings focus on the supply side of the issue and emphasize the role of technology primarily on alternative fuel production. A US Army research paper by Colonel Fields is rather different. That is why this post is about his paper.

Col. Fields argues that “A country equal or near equal in economic and military power but considerably less depend on fossil-fuel-based technologies would pose a major threat to our nation.” In the context of Peak Oil, which he seems to be subscribed to, this argument makes sense. But the role he gives to the military in this particular issue is rather too much: “Our nation would benefit enormously if the US military were provided the resources needed to solve this fossil-fuel dependence problem. No one entity has a bigger reason for solving the foreign energy dependence problem than our military.”

Inefficient nature of combat platforms, i.e. platform inefficiency, puts a big burden on operational effectiveness. Much quoted phrase about the need to move and protect fuel detracts from combat effectiveness by adding to sustainment costs and diverting and endangering in-theater force capability.

More efficient platforms would not only enhance range, persistence, and endurance but also would reduce the burden of owning, employing, operating, and protecting the people and equipment needed to move and protect fuel from the point of commercial purchase to the point of use. In other words, more efficient platforms increase warfighting capability.

This can be demonstrated with an example on the Army’s peacetime and wartime fuel consumption patterns, which differ considerably. During peacetime, fuel consumption by Army aircraft makes up almost 50% of its total. However during wartime, generators become the largest single fuel consumers on the battlefield. Note that JP-8 is used by the military in everything from tanks and aircraft to generators.

That is why Defense Advanced Research Projects Agency (DARPA) had focus on creating JP-8 by other means. Initial biofuels research was focused on converting agricultural crop oils (canola, jatropha, soy, palm oils, and others) to a JP-8 surrogate. Currently the most promising research has expanded to cellulosic and algal feedstocks to produce a second generation biofuels that is noncompetitive with food sources. Because, they have great promise and because agricultural crop oil-based biofuels, or the first generation, have showed dissimilar composition and could not be approved for use in tactical vehicles. 

Col. Fields goes here to the hearth of the issue: When considering alternative fuels, it is very important to understand that the primary consideration must be gravimetric (energy per unit mass) and volumetric (energy per unit volume) energy densities. The bad news is that other than uranium, the liquid hydrocarbons offer the most attractive combination of volumetric and gravimetric energy densities.

Why biofuels and not hydrogen? It is true that the first hydrogen-power-based engine was conceived in 1820 but aggressive technological progress was condensed in the past decade or more. Why no more progressive push on hybrids for military applications, especially for medium-duty trucks? For instance, hydraulic hybrid (the diesel or gasoline engine and the hydraulic components) technology captures and uses a large percentage of the energy normally lost in vehicle braking. It can quickly and efficiently store and release great amounts of energy due to a higher power density. Besides, it is significantly better than hybrid electric systems.

How about energy storage (especially battery energy storage) technology? Fortunately, there is recently a big push for this area. This technology still remains the single greatest obstacle to achieving the enabling technologies necessary to advance fuel cell, hybrid electric, and pure electric mobility systems. The ideal energy storage technology currently does not exist. The ever growing electric power needs of modern combat systems have been driving the need for electrical storage capacity for some time. The Army has engaged in designing high-power, high-energy-density lithium-ion batteries for use in hybrid electric vehicle propulsion systems. This energy storage research area is being considered for other critical applications including auxiliary power units and to support emerging new operational requirements for tactical platforms.

Why nuclear energy is not explored for its potential for military application other than Navy ships? In 1950s, the Army had fully operational nuclear power plants—the first in the US. Ford Motor Company had developed a concept automobile called the Nucleon in 1958. By the early 1960s, there were a few portable plants built and even a nuclear power plant on a couple of ships. In 1970s no significant steps were taken to implement any nuclear initiative. Had nuclear concept been given the proper support, the currently discussed technical matters might have been overcome by now.

Why technologies to improve platform energy efficiency in existing fossil fuel-powered propulsion based systems are been treated as a step-son?

Col Fields lists three technologies with the potential to fundamentally alter DoD capabilities and enable new concepts of operations. These offer the potential of double-digit percentage improvements in energy efficiency over current technologies, and to propel our domestic industrial base to new levels of performance.

 The three technologies are:

 blended wing body (for fixed-wing, heavy-lift aircraft, such as tankers, bombers and transport aircraft), offers the possibility of two times the gain in range and payload and of five to ten times the gain in system level fuel efficiency over traditional fixed-wing aircraft.

 variable speed tilt rotor (for vertical lift aircraft), holds hold promise of far greater range, speed and operational flexibility with substantially reduced fuel consumption over traditional military helicopters. It would increase payload and range five times over current military helicopters, achieve twice the speed, and consume five times less fuel.

 Badenoch “blast-bucket” design concept (for light-armor ground vehicles, to replace the HMMWV). The armored vehicle design technology is highly IED resistant, weighs three times less than a current comparable up-armored vehicle, and consumes five times less fuel.

These technologies are viewed as having the greatest potential for military application, achieve much cost saving over the life cycle of tactical ground and aircraft systems, and notably reduce or eliminate dependence on foreign petroleum sources.

In sum, Col. Fields lists the following technologies worth pursuing now:

·         Alternative fuels/energy, specifically, hydrogen fuels used in hydrogen-powered internal combustion engines (ICE) and second generation biojet/biofuels.

·         Fuel cells
·         Electric and Hydraulic Hybrid Power Propulsion
·         Electrical Energy Storage
·         Technologies to improve platform energy efficiency

I congratulate Colonel Fields for pointing out the real issues and going beyond the rhetoric. If I were him I wound end the paper with a much clear message: No doubt that energy technology is a critical element of military superiority.  But it is energy end-use technologies  that should be the primary focus, not the energy production technologies.  

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