Energy Security: How Fort Knox Learned to Create Self-Sustaining Power

When people hear the name Fort Knox, many immediately think of the gold depository. But what the Kentucky military installation really should be synonymous with is energy security, resiliency and efficiency, considering it could run indefinitely "off the grid" on power its learned to generate over the years.

Fort Knox, which sits on 109,000 acres of land in north central Kentucky, has won numerous Defense Department and Energy Department awards for its energy initiatives over the past 20 years. But the process to reach full sustainability has taken just about as long, and it's constantly evolving. The program is something that other military installations could use as a blueprint to reach their own energy efficiency goals.

For many decades, Fort Knox has received natural gas and coal-fueled electrical power from its local utility company, Louisville Gas & Electric. Through a separate agreement with the United States Department of Interior, the company is allowed to use the land below Fort Knox to stockpile gas that both the base and the surrounding communities use.

In the 1990's, Knox officials decided they wanted to fully utilize the installation's resources and ingenuity to save money and move toward self-sustainment. So, members of the post's Directorate of Public Works energy program started brainstorming ways to create their own heating, cooling and power. They eventually found it through a mix of sources, focusing heavily on natural gas and geothermal energy.

Trial and Error

In the 1990's, Knox's energy program experts initially tested a wind turbine project, but that wasn't the answer because of Kentucky's lack of consistent wind. Later, a solar array of about 10,000 panels - the largest in the Army at the time - was installed on 10 acres of land.

That array is still in use, but because of Kentucky's temperate and humid weather, the power it generates fluctuates based on that. It can produce about 2.1 megawatts of power, according to Knox's energy program manager, R.J. Dyrdek. That isn't nearly enough to make the base fully sustainable.

Next, energy officials considered the state's vast network of caves and tried geothermal technology, which provides heating and cooling by using the earth's natural cool and constant temperature.

"The idea is that the ground below 48 inches deep is roughly 55 degrees all year," said Jason Root, director of the Fort Knox Directorate of Public Works. "In the summertime, 55 degrees is great because you can use that temperature to help absorb air-conditioning heat from the cooling process in the summer. In the winter, 55 degrees helps as you attempt to cool the soil further, having the heat generated in the air-conditioning process sent to the building to heat it. This is done via deep wells and sealed water piping called ground source heat pumps."

The base has been reaping the benefits of that system for decades, with at least 250 facilities connected to it. Knox has produced multiple well fields to circulate water for most buildings on the base.

"It's about three times as efficient as buying an electric heater and standard air conditioner at your house," Dyrdek said. "It saves us money and can pay back the added expense of pipes and wells in under eight years."

Finding a New Way to Create Power

While geothermal was great for heating, cooling and reducing energy costs, it didn't help the base create power. Officials discovered that when a major ice storm in 2009 took out the utility company's wires that provided electricity to the base.

"We didn't have power for 10 days," Dyrdek said, explaining that there was no water or heat, either, since the geothermal water pumps and related air-conditioning didn't have electricity to run. "That quickly became way more important than just no lights."

The base eventually got back up and running, but the garrison commander vowed that scenario would never happen again. "That ice storm forced us into a completely new way of understanding energy and approaching resilience and security," Root said.

The energy team started brainstorming ideas to eliminate their reliance on the utility company. They came up with the system that's gaining a lot of attention today: decentralized power generation.

Natural gas was chosen as the fuel for the new system due to the presence of gas deposits below Fort Knox and its favorable environmental impact compared to coal or diesel. A natural methane reservoir that the team discovered right at the edge of the base was tapped to be a source of fuel.

In January 2010, several 700-foot-deep wells were drilled to capture biogenic methane from the reserves. Two years later, more were drilled. Some of those wells have since been closed, but the base now has a total of 20 usable wells, with several in full production.

The post also purchases natural gas from a trans-continental pipeline that runs through the northwest section of the base. In 2014, the energy program got approval to directly access it by cutting a city gate, which now feeds the majority of Knox's power grid needs.

The gas from both of those sources is then sent to a compressor site. That site compresses and purifies the gas from the Knox-run wells, then adds odor to that gas and the gas from the transcontinental pipeline. Next, it pumps all the gas onto the grid and to six on-post substations, each of which have two locomotive-sized gas generators that produce and distribute electricity throughout the base's power microgrid.

Cutting Costs Through Automation, Technology

The $62 million decentralization power project has paid for itself in savings, Dyrdek said. For example, in July 2015, the generators were able to save the base more than $400,000 that month compared to the prior July, before the energy generation project came online.

Part of that savings is in thanks to the automated central control hub located at a bunker on base that runs the entire system. The screen-filled room highlights in real-time how many megawatts of power are coming through the electrical supply feeds from LG&E. Those changing numbers help the team know when energy demand is about to go up. When it does, the system will automatically spin up more of the base's own power to counter new demands and keep the costs down.

The ability to generate power also allowed the installation to transition to a utility rate that rewards generation during high-cost periods and allows the post to purchase lower-cost electricity in off-peak hours, Dyrdek said.

The system generation and control protocol allow officials to schedule maintenance on the generators without negative effects. If one substation were to be taken offline, power to the sector it operates would be transferred to another substation until it came back online.

The automated system is tested twice a year during exercises where the utility company turns off power to the base to see how well it can stand up on its own. Energy monitors then test uninterrupted power source batteries in items such as exit lights and elevators all over the post to make sure they're still working.

"Every time we do this, we absolutely learn something about our systems," Root said.

For example, when extreme cold blanketed much of the country on Dec. 23, 2022, Root said the utility company had to cut power to the base without warning. Within 90 minutes, however, everything was back up and running again.

Reducing Their Carbon Footprint

The decentralized power generation program is also helping to cut down on greenhouse gases, as Knox's gas-fired power is much cleaner than the utility's coal-fired systems. In the natural gas extraction process, heat can be captured at the generator and sent to an absorption chiller. That machine translates the excess heat into cooling energy for distribution to buildings instead of being ejected as is into the environment.

"We can take all that and put it into another source," Dyrdek said. The secret ingredient in the absorption chiller process? Lithium bromide.

"The absorption chiller pumps all this free heat into the bottom of this pressure cooker, and that lithium bromide changes phase - it goes from a gas to a liquid. It absorbs a massive amount of heat, so the water in that same pressure cooker turns cold," Dyrdek said. "You make chilled water from heat."

The absorption chillers at each substation can make as much as 600 tons of air conditioning at no excess cost. That A/C is used in buildings near the chillers, including the one-million-square foot Maude Complex, home to Army Human Resources Command. It's the sixth biggest building in the DOD and houses the Army Data Center, which requires a lot of power to run, Dyrdek said.

The Maude Complex also gets energy savings from a nearby 6-million gallon geothermal pool. To passersby, it looks like a small lake with a spray-water feature in the middle. But at the bottom of 25 feet of water are two semitruck-sized heat exchangers that cool water to create a large portion of the building's air conditioning.

"It requires 320 tons to keep the data center cold. Two-hundred tons of it comes from the pond," Dyrdek said, explaining that it saves them more than $10,000 a month.

What's Next?

When the DOD chartered a natural gas pilot program in 2022, it designated Fort Knox as the installation to study since its program was already up and running. Root said his program's mission under that charter is to try to find the best energy-efficient way forward, then provide that data to the DOD on whether they think it's scalable at other installations.

Under the DOD charter, the Knox energy program is exploring more opportunities for natural gas storage on post. Dyrdek said they're also working to get Enterprise Mission Assurance Support Service certification and expand the automated central control bunker, as well as all of its attached communications systems.

"We're always trying to do what makes sense," Root said.

With the help of a Department of Energy grant, the base is also in the process of designing and purchasing a moderately sized electrochemical fuel cell and battery storage for use at one of the substations. The cell uses natural gas to produce more environmentally friendly electricity.

"These fuel cells, even though they're using natural gas, it has 50% less carbon dioxide emissions just by the way it processes," Root explained. In the future, the fuel cells might be deployed portably for downrange use in the field.

The Army is also working on a real estate action to come to an agreement with LG&E that's more beneficial to the base. Since the early 1940s, the Army and the Department of the Interior's Bureau of Land Management have leased more than 4,000 acres of Knox land to LG&E. There, the utility company stores natural gas and runs a compressor site that holds 2 trillion cubic feet of gas that is saved for winter sales to LG&E's customer base.

That site has a minimal impact on base operations, but the lease agreement hasn't always been in the base's best interest, energy program managers said. What comes of the real estate action will eventually work its way up to the DOD as part of the charter reporting.

In total, each piece of the energy-efficiency puzzle has taken years to develop and will continue to take more time as the process is fine-tuned and updated. But as Root says, glacial speed is still moving.

"It takes time to move things through a legislative process, a design process, a construction process, an implementation process," he said. "Our job is to take as many steps as we can, hand the baton to somebody else, and then let them continue moving that forward."