Getting fuel to soldiers in the field has been a problem since machines replaced horses.

   But according to a new report, by 2025 soldiers could make fuel and electricity where they are, instead of relying on long supply chains to transport energy to them.

   "Opportunities in Biotechnology for Future Army Applications," a report released by the National Research Council's Board on Army Science and Technology, says future U.S. Army operations in the field could rely on alternative fuels and biological methods to produce electricity through photosynthesis.

   The report was prepared by a 16-member committee of university and industry scientists. Purdue University's Michael Ladisch, distinguished professor of agricultural and biological engineering and distinguished professor of biomedical engineering, chaired the NRC committee.

   One of the most well-known examples of a military energy crisis occurred near the end of World War II. As U.S. Gen. George Patton raced through France, he quickly outran his supply lines and the ability to refuel his trucks and tanks.

   On Aug. 28, 1944, Patton declared, "At the present time our chief difficulty is not the Germans, but gasoline. If they would give me enough gas, I could go all the way to Berlin!"

   Three days later, despite the efforts of the famed Red Ball Express, a convoy of trucks hurrying fuel to Patton's army, he and his men were stranded dry. The chance to sweep through France into Germany soon passed.

   Robert Love, study director for the National Research Council, says such situations could be avoided in the future by employing alternative fuels made from natural and renewable resources.

   "The real issues for the Army are the ability to simplify logistics requirements, to remain flexible with battlefield fuels, and to capitalize on alternative fuels, such as methane, instead of restricting ourselves to fossil fuels," he says. "With fossil fuels, logistics can become difficult because you have to have this long supply chain."

   Although using non-petroleum sources of energy would have obvious environmental and social benefits, Love says this didn't factor into the committee's considerations.

   "Obviously there are always spin-offs of military innovation, but the committee was concerned with what would improve the operations of the Army."

   Scientists are already working on making fuel from waste plant materials such as cellulose and hemicellulose. Grasses, surplus grains, spoiled food, food wrappers, paper or even cotton cloth could be converted into fuel using this method.

   "In theory, these materials could be produced in the field (if the theater of operation were in a temperate zone) and used as fuels," the report states.

   "The Army needs to be investigating surrogate fuels, such as ethanol and biodiesel, and make sure their engines can run on a variety of fuels," Ladisch says. "Actually, I think this can be done with a minimal amount of modification. They're in pretty good shape in this area."

   Another energy need for modern soldiers in the field is electricity, and batteries are bulky and very heavy. Biological systems may provide a solution, the NRC committee suggests.

   "Right now the Army is dependent on batteries, and they can't take seriously other energy sources such as solar power," Love says. "One of the things the report investigated was photovoltaic energy, and how bioelectronics might make it possible to increase the efficiency of converting sunlight to usable energy. If you put this together with fuel-cell storage techniques, this would have a large impact on how the military operates, especially for small unit operations."

   The NRC recommends that the Army investigate how plants convert photons to energy because plants are so good at grabbing energy from the natural environment. Millions of years of natural selection has optimized plants to the particular wavelengths of sunlight, and because of this, plants convert 98 percent of the sunlight they receive into energy.

   Conversely, current solar energy systems are only 10 percent to 15 percent efficient.

   Using plants to produce electricity is an area of research known as biological photovoltaics. The NRC report suggests that coupling the light-harvesting capabilities of plants with protein-based devices could lead to solar energy systems capable of converting solar energy at 40 percent to 50 percent efficiency.

   The report's authors also envision protein-based photovoltaic coatings on the Kelvar military helmets that could produce enough energy for the soldier's electronics. Other equipment and vehicles could also be covered with these protein-based solar converters.

   A side benefit of such technology, the report notes, is that the protein coatings would make whatever they coat more difficult to detect by electronic means since they would mimic the natural environment.