Despite strenuous efforts, the military has not been able to find renewable substitutes for the major consumers of fuel in the field. Large fuel cells are slow to arrive ready for use in a combat zone. The one bright spot has been two older technologies.
One is solar panels. A system weighing less than 10 kg (22 pounds) contains the foldable solar panel, batteries for storing power and adapters for recharging various civilian and military type batteries. For Special Forces patrols, and isolated outposts, these solar kits are very valuable, as they provide all the juice needed for many smaller electronic devices. These means a lot fewer batteries have to be flown or trucked in). For long range Special Forces patrols, there is usually no resupply for a week or more, while deep in hostile territory. The solar panel is the primary method for resupplying batteries.