Expeditionary Energy Faces Real-World Tests
A joint Army and Air Force initiative is underway to develop expeditionary energy alternatives that will help reduce the number of dangerous fuel convoys required in theater.
By Rod Fisher
With improvements to the efficiency of the small BEAR shelters as well as the ECUs used to heat and cool them, two tents can be temperature controlled with one ECU.
A U.S. Air Force-U.S. Army research project designed to save nearly 50 percent of the energy consumed at expeditionary or “bare” bases ultimately will save more than just money. It also will save lives.
This multi-tiered joint project focuses on energy reduction and generation within the Air Force’s Basic Expeditionary Airfield Resources (BEAR) system. The BEAR program provides expeditionary facilities to bed down up to 3,300 people in austere locations. A BEAR base is self-contained, providing everything a unit needs to perform its mission and when fully occupied typically consumes about 10-MW of power and up to 13,000-gal of fuel a day.
Reducing the energy demand at BEAR bases is not only a cost-saving pursuit, but a life-saving measure as well. On average, for every 29 convoys delivering fuel to remote contingency locations the life of one service member is lost. Reducing the need for fuel reduces the number of military troops put in harm’s way by fuel convoys and allows them to concentrate on their actual combat mission.
Both the Army and Air Force have been researching technologies to reduce the energy demand at expeditionary bases since 2008. This research included tests on regular, heat-shielding tent flies and flies covered with photovoltaic panels that generate power, as well as more efficient environmental control units (ECUs), insulated liners and energy-saving technologies in other areas, such as lighting.
JOINT RESEARCH PROGRAM
The Department of Defense Director of Operational Energy Plans and Programs is sponsoring a joint Air Force-Army program, “Advanced, Energy Efficient Shelter Systems for Contingency Basing and Other Applications,” under the Operational Energy Capabilities Improvement Fund. The program will combine all the energysaving lessons learned to date and continue research on new technologies to reduce energy at expeditionary bases by a minimum of 50 percent.
Participants in the program include: the Army’s Natick Soldier Research, Development and Engineering Center (NSRDEC) and the Army Materiel Command-Product Manager Force Sustainment Systems (PM-FSS), both located at Natick, Mass.; the BEAR Global Management Office, Langley AFB, Va.; the Air Force Civil Engineer Center (AFCEC) and the Air Force Research Lab (AFRL), both at Tyndall AFB, Fla.; and the U.S. Army Corps of Engineers, Engineer Research and Development Center-Construction Engineering Research Laboratory (ERDCCERL), Champaign, Ill.
Replacing the traditional zippered tent flap in the BEAR shelters with an actual rigid door and vestibule area will help conserve energy. This is especially resourceful in contingency environments where temperatures well above 100°F are a way of life. The door operates on a spring mechanism so it automatically closes behind each person. U.S. AIR FORCE PHOTOS BY EDDIE GREEN
At expeditionary bases, approximately 60 percent of the power used on a daily basis goes toward cooling the shelters with air conditioning. For small shelters, currently it takes one ECU to cool or heat one tent. With the new technologies in place, researchers are hoping to cool two shelters with one ECU. So by improving shelter efficiency, the number of ECUs needed is effectively cut in half, which means for a 3,300-person base about 125 units can be left at home, cutting the total amount of power needed (10-MW) by 2.25-MW.
The benefits are two-fold. Since the tents must be shaded to improve the energy efficiency, solar panels can be added to generate power. The panels on each tent can currently generate about 3-kW of power—or about 1-MW of power for an entire base. Installing insulated liners inside the tents also makes them more energy efficient, keeping cool air in and hot air out. Using vestibules and actual hard doors rather than zippered tent flaps helps with the insulation process as well.
All of this equates to fewer ECUs, fewer generators and less power distribution equipment needed to support them, and consequently, fewer fuel convoys. The modifications also improve sound attenuation and create a better living environment, enhancing occupants’ quality of life in a contingency environment.
The BEAR program and all of the research is about to be put to the test in a real-world application. In the spring of 2013, the Air Force and the Army will each ship eight energy-efficient shelters to a location in Southwest Asia for set up and evaluation. This setting will test the new technologies beyond any conditions they have seen to date. Researchers expect to see temperatures exceeding 130°F, along with high winds and sandstorms—the actual environment in which the shelters have to perform and survive. Researchers will collect environmental and performance data from the 16 test shelters such as temperature variables and maximum cooling capacities and power demands. They also will glean personal feedback straight from the tents’ occupants.
This first phase will overlap with the program’s second phase—continuing technology development. Phase Two will occur in the continental U.S., with AFCEC and AFRL continuing to investigate technologies to improve the energy efficiency of medium and large shelters used in expeditionary settings for such things as maintenance, supply and storage. Some of the technologies being tested include treatment of the outside of the tents with low emissivity coatings to limit solar loading and the development of adjustable liners that can drop down to reduce the ceiling height in the shelters. This serves to limit the volume of air that needs cooling and creates an “attic” that can be vented. The goal is to minimize energy consumption for BEAR assets in the field as well as vulnerability to energy supply disruptions.
Meanwhile, the Army’s ERDC-CERL will study modeling, simulation and analysis to create a more efficient design by looking at the interaction between the shelter fly, shelter skin, thermal liner and air gaps. They also will investigate energy efficiencies for rigid wall shelters.
Liners have been added to the inside of the BEAR tents to provide insulation. This helps reduce the workload for the ECUs and keeps the temperature regulated inside the tent.
NSRDEC will focus on advanced high performance insulation, working to develop a liner that provides an improved thermal barrier, minimizes the logistics burden, and withstands harsh environments. Each of these efforts will cross-feed information to achieve the best possible results.
Phase Three will include a follow-on demonstration in Southwest Asia in the spring of 2015. This will include building optimized shelter systems based on the lessons learned in the initial demonstrations and during the technology development phase.
Beginning in FY2014, AFCEC will initiate three additional projects to continue the long-term, end-to-end effort to improve BEAR energy efficiency. The first project, the BEAR System for Load and Installation Management (BSLIM), aims to provide the capability to truly manage BEAR power and loads from the power plant by manually or automatically turning off loads during critical demand periods or to conserve energy, and to integrate renewable energy into the BEAR grid.
The second project will be development of the Smart Shelter Energy Management System (SSEMS), an autonomous, in-shelter smart control system for expeditionary structures. The system will use machine vision and artificial intelligence to determine the occupancy state of a shelter and provide occupants with energy usage information. SSEMS will interface with BSLIM to minimize shelter energy demand when unoccupied. The third project will develop a system for using phase-change material to precondition incoming air to improve ECU performance and reduce heating and cooling energy demand. It also will investigate the potential use of phase-change material to improve shelter liner performance.
When fully fielded, these technologies will provide an initial end-to-end modernization of BEAR to save energy and improve the quality-of-life for deployed personnel. The ultimate goal is for the new shelters to demonstrate energy savings of at least 50 percent in a relevant environment by reducing energy demand, fuel requirements and the numbers of convoys necessary to transport fuel across theater environments. These innovations will save dollars, and more importantly, they will help save lives.