The U.S. Marine Corps learned a valuable lesson about logistics in Afghanistan and Iraq. It was an old lesson made more urgent because modern warfare requires lots more electricity in the combat zone. So in the last decade the marines have been seeking ways to reduce the need for electricity or fuel used to supply it (via generators). The latest example of this is a combined solar/generator power supply for a new medical unit (STS, Shock Trauma Section) created to provide complex surgical procedures for badly injured marines. STS does this to stabilize patients very close to the fighting so they can be transported to a hospital with more elaborate surgical and intensive care facilities. The STS fits in a truck that can be carried by air via a V-22 or heavy helicopter. STS requires a lot of reliable electrical power in order to function. To supply that a combined solar/generator/battery system was built into an ammunition trailer that is towed by the STS truck. This power system weighs less than a ton (about 900 kg) and when tested under realistic field conditions was silent (the fuel hungry generator was not needed) over 60 percent of the time because the solar panels and stored energy in the batteries was sufficient.
Lightweight and more powerful batteries, as well as more efficient solar power panels and generators contribute to these energy saving efforts. But many other improvements also make small contributions that add up. One of these recent innovations is the LED light display. While lighting consumes less than two percent of the fuel shipped to the war zone (heating and air conditioning get 12 percent and aircraft more than half), the LED devices (which generate little heat) consume only 15 percent of the electricity required by incandescent bulbs and less than half what fluorescent fixtures use. Plus the LED bulbs last longer and are more rugged. While the overall savings is small, it adds up. Combat troops are already very familiar with LED lighting as they have been using lightweight LED lights (often mounted on their weapons) for years and noted that the batteries last a lot longer on LED flashlights while producing the same amount of light as the older incandescent bulb units.
Since 2006 American army and marine commanders have become determined to reduce fuel consumption, mainly because electrical needs in combat have increased so much. The troops are dealing with some dramatic changes. For example, during World War II, the first war in which American forces were mechanized each soldier required 4-5 liters (one gallon) of fuel per day. But by 2003, and the invasion of Iraq, fuel consumption was twenty times higher. In reality this meant that when you sent a modern mechanized division into combat you had to supply those troops at the rate of 80-120 liters (20-30 gallons) of fuel per man per day. As the 3rd Infantry Division moved from Kuwait to Baghdad in 2003, some 20,000 troops were involved. That required some 200 tanker loads of fuel per day. Initially, the vehicles in the division carry enough fuel to go 200-300 kilometers on internal fuel. But you don't want your vehicles to run until their tanks are dry, so at least once a day, you try to top everyone off. The route of the 3rd Infantry Division covered about 700 kilometers of road. In addition to fuel, you need about a 45-90 kg (100-200 pounds) of other supplies per man per day (mostly ammo, but also batteries, food and the like.) Once inside Baghdad, and no longer moving all the time, the fuel requirement came way down. But on the march, the advancing combat brigades were tethered by convoys of fuel trucks going back and forth to the supply bases in Kuwait. But once the U.S. began building bases for the combat brigades, it was found that the use of generators, especially for air conditioning, kept fuel requirements high (over 80 liters per man per day), which is why most of the supply trucks were still carrying fuel.
There are no easy solutions for this. Vehicles are larger, and require more fuel than they did 70 years ago. Tanks weigh twice as much, as do most other armored vehicles. There are more trucks and armored vehicles, as well as a lot more electronic equipment and air conditioning to keep the electronics cool. It was found that air conditioned living quarters were a huge boost to morale, and a way to reduce combat stress. That required lots of fuel. So far, the army and marines have sought to equip the troops with more energy sources that do not require fuel to be trucked, or flown, in. This is especially important for troops who are out on operations that might last a few days.
Batteries, and the fuel to run generators for recharging, have become a major supply item. For example, a three day operation by an infantry platoon (30 men), consumes six kg (6.6 pounds) of batteries per man. Rechargeable batteries cut that by more than half, as long as you have some way to recharge them. Special Forces are particularly hard hit by this, as they often have to go in by foot, to avoid detection, and set up a surveillance operation that consumes a lot of batteries. This is very common in Afghanistan.
Solutions have long been sought. For example in 2010 company (about 200 personnel) of American marines conducted a desert training exercise to see how long they could run how much equipment using solar power. This was done via solar panels that were incorporated into equipment (like a cloth like panel that was draped over a tent) or set up with a number of solar panels to act as a "solar generator.") As a result, for eight straight days, the marines were able to power all their radios and laptops (by recharging batteries) via solar panels. There is a lot of other battery powered gear, but radios and laptops are the big energy eaters. Feed them, and you have eliminated most of the power demand for troops operating on foot. The equipment and techniques used doing were sent to marines in Afghanistan and was much appreciated. This sort of thing saves lives and money. Marines have to guard a lot of their supply convoys, two-thirds them carrying fuel or water, and for every 45 truckloads brought in a marine is killed or wounded. This is sometimes avoided by hiring locals to provide convoy security, but that option often creates another warlord in the area.
Thus all American commanders in Afghanistan wanted more renewable fuel sources. Combat commanders had done the math, and with more combat units out and about these days, they are demanding more solar panels and fuel cells, in order to lower the demand for generator fuel and batteries. With all those computers and electronic gadgets out there, the demand for electricity, especially by units in combat, is huge and growing.
For decades, it was believed that hydrogen powered fuel cells would replace fossil fuel (JP-5, similar to jet fuel) powered generators. But fuel cells have been the next-big-thing for nearly a century. That said, small fuel cells are beginning to appear. The U.S. Army is installing them in tanks and trucks, as a source of auxiliary power. This points out that the larger fuel cells are now quite ready to replace the large generators (the main consumer of all that fuel). While the fuel cells cost more than ten times as much as JP-5 powered generators, that JP-5 costs about 40 times more than the same fuel used back in the United States. That's because of the transportation cost (up to $25/liter or $100/gallon) of fuel. Thus fuel cells are still a cheaper alternative and the more expensive fuel cell generator quickly pays for itself in a combat zone, and saves the lives of those operating and protecting all those fuel convoys. Another use for small fuel cells is to ease the growing load of batteries carried into combat.
A major problem with these small fuel cell devices is that it is mainly for items like cell phones and iPods, or anything that can get its charge via a USB connector. For military use, you need a device that can recharge common batteries, and specialized ones for military equipment. Technically, that is a simple matter, as is scaling up the current miniature fuel cell devices (about the size of a hand held game player) to provide more power. The problem with fuel cells remains their temperamental technology and high cost. But the military is willing to buy one that can stand rough handling, even at a high price, because of the even higher cost of getting fuel to the combat zone.