Clean air mandates pushed the U.S. Department of Defense (DoD) to start developing renewable energy technologies. But the benefits of energy security and independence are what finally converted many military leaders into believers.

“Renewable sources make us less vulnerable,” said Joe Sikes, director of Facilities Energy for the Office of the Deputy Under Secretary of Defense. “Our goal is to take advantage of all available resources.”

In combat zones, the Army is exploring mobile solar and wind generators to replace fuel trucks, which are frequent targets for insurgent attacks. More than 1,000 Americans have died while delivering fuel in Iraq and Afghanistan in recent years. The DoD hopes renewable energy can make military bases energy-independent and, ultimately, immune from threats to the utility grid.

Congress in 2007 gave the DoD marching orders to draw 25 percent of its energy from renewable sources by 2025. After President Obama called for 20 percent by 2020, the DoD established a Strategic Sustainability Performance Plan, which targets improvements in greenhouse gas emissions, waste management and energy efficiency.

Some say a federal Renewable Portfolio Standard would increase the likelihood of achieving these goals. Others want an energy bill that permits the Army and Air Force to secure Power Purchase Agreements (PPAs) beyond the 10-year cap in the Federal Acquisition Regulation (FAR) so more investors will consider utility-scale projects.

“To meet those goals and achieve energy security, this is the time for public officials to step up and make sure this fledgling market has long-term success,” said Karen Butterfield, director of federal accounts for SunPower Corp., which has developed the largest utility-scale solar arrays on federal property.

As a policy matter, the military has officially embraced the idea of becoming the federal government’s testing ground for renewable technology.

“The DoD can go on to serve as an early customer, thereby helping create a market, as it did with aircraft, electronics and the internet,” Dorothy Robyn, Deputy Under Secretary of Defense for Installations and Environment, said during a House Armed Services Committee in February.

The military is in various stages of planning for hundreds of megawatts of renewable energy projects, including a 15-MW solar PV array a Luke Air Force Base in Arizona. It will be the largest solar installation on federal property and supply 25 percent of power needs at the base.

An even larger 500-MW solar plant is planed for the Army’s Ft. Irwin base in California. SunPower Corp. will develop the Luke AFB project near Glendale, Arizona. The company installed the previous record-holding array in 2007 with 14-MW at Nellis AFB near Las Vegas.

“There is definitely growing interest” by the military, said Monique Hanis, a Solar Energy Industries Association spokeswoman. “We’re actively engaged with the military right now.”

Karl Gawell, executive director of the Geothermal Energy Association, has also noticed an increase in military interest for utility-scale projects.

“It’s a total shift in priorities. The Defense Department has made a fundamental shift in looking at renewable energy,” Gawell said. “And it’s not just because the commander in chief ordered it; they’ve decided how fundamental it is to achieving the military’s own mission.”

Air Force and Navy leaders say they are on target to meet Obama’s 2020 goal, known as Executive Order 13514. The Air Force is negotiating contracts for about 500 MW of solar power within the next three years, up from a capacity of 70 MW in 2007.

“We’ve learned so much in just three years,” said Ken Gray, Chief of the Renewables Branch of the Air Force Facility Energy Center. “What took us three to four years for Nellis is now taking 1 ½ years” for project development.

The Air Force is also developing the largest biomass power plants in the nation. Two wood waste plants with capacities of 15 MW to 25 MW are planned for Florida’s Eglin Air Force Base and Georgia’s Robins Air Force Base, respectively. The Florida project will incorporate sustainable forestry practices. Gray expects those projects to start in 2013 and 2014.

(Left: Buckley AFB, Colorado: Construction is nearly complete on a 1.2 MW solar project on 6 acres of land that will use more than 5,000 photovoltaic modules to help power the base. This project is expected to come on line in October 2010.)

The Navy, which pioneered the use of nuclear power on submarines, has long been an early adopter in use of renewable energy. The Navy is considering Small Modular Reactors, so-called “mini nukes” to power military bases. Since 1987, the Naval Air Weapons Center at China Lake in California has generated 270 MW of geothermal power. The power plant provides more than 100 percent of the base’s power needs.

Tom Hicks, Deputy Assistant Secretary of the Navy for Energy, said the Navy plans to install three more geothermal plants in Arizona, California and Nevada in the next five years. The plants will have capacities of 10 MW to 50 MW each.

“Having that vision and support from the leadership has been a tremendous asset and really been reflected in the way the Navy and Marine Corps stepped up to meet those goals,” Hicks said.

The Navy is particularly proud of its research in hydrokinetic energy projects that use ocean currents near Puget Sound and Hawaii, he said. The Navy also has established an ambitious goal for half of its facilities to become net-zero by 2025. Naval commanders are looking to accomplish the goals through a combination of energy efficiency initiatives and renewable energy projects. The Navy installed about 30,000 smart meters throughout its facilities last year.

Own the Assets or Purchase the Power?

The gradual greening of the armed forces has sparked some debate about the funding and effort needed to comply with mandates.

“I applaud the military’s leadership, but some are asking, ‘What exactly is the military’s role here?’” said Les Shephard, director of the Institute for Conventional, Alternative and Renewable Energy (UTSA) at the University of Texas at San Antonio. “My personal observation is that they want to focus on things they do extraordinarily well, while (renewable energy) should be left up to experts.”

Shephard, who worked for Sandia National Laboratory for 28 years before joining UTSA, said the military’s foray into research, development and installation of renewable energy could detract from the military’s core mission. He is among a group of experts who think the military could achieve its goals by purchasing renewable energy from local utility companies through innovative PPAs instead of actively procuring and developing projects.

The Air Force’s Gray estimates that about 80 percent of USAF renewable projects would be funded privately through PPAs similar to the Nellis AFB array. Through a 20-year land lease and PPA with a fixed rate, the Air Force purchases power from the array investors, who also benefit from selling Renewable Energy Credits (RECs) to a Nevada utility company. For the Luke AFB project, SunPower will install the 15-MW plant on military property, the utility company will own it and the Air Force will purchase power from the utility at a fixed rate.

By taking an active role in the development of these unique utility-scale PPAs, the military is ensuring it moves closer toward its 2020 goals, said Sikes, the DoD’s director of facilities energy.

“Obviously, we could eventually reach our goals by waiting for utility companies to develop renewable energy on their own,” he said. “Our intention is to take advantage of opportunities because it helps improve security issues.”

Robert Crowe is a technical writer and reporter based in San Antonio, Texas. He has written for Bloomberg, the Houston Chronicle, Boston Herald, StreetAuthority.com, San Antonio Express-News, Dallas Business Journal, and other publications. He covers renewable energy and sustainability for various publications. As a consultant, he works closely with companies to develop technical materials for renewable energy and sustainability strategies.