News: Harvesting rain and sun at Fort Sill
Story by Sara Goodeyon
FORT SILL, Okla. - At Fort Sill, the U.S. Army Corps of Engineers is taking positive steps to increase energy efficiency and preserve resources by harvesting rain and sunlight.
The design and construction of some of the new facilities at the Army post includes innovative systems for collecting rainwater and using sunlight to improve energy efficiency. In a region with little rain and abundant sunshine, it makes sense to hoard the one and exploit the other.
“The idea behind it is great,” said Brant Purdum, Tulsa District USACE mechanical engineer, E&C, Fort Sill Area Office. “You are conserving energy, conserving water, and conserving resources.”
The rainwater collection system harvests water from the building’s roof to water the grass. The gutter system feeds into giant fiberglass tanks stored underground preventing evaporation, which happens to be a real threat to water supplies in this region. A first check filter flushes out things like bird waste and sticks, whatever is on the roof, to keep it from getting into the system. Each tank has a pump tied into the irrigation system so that water from the underground tanks serves the sprinkler heads.
“We can capture the rain when we get it and use it when it’s needed,” said Paul Panter, mechanical technician, USACE Fort Sill Area Office. “There is actually a formula to use to calculate the amount of rain that can be harvested. For instance, in a 2 inch rainfall event, 6,000 gallons of water runs off of a 4,000 square foot roof.”
Moreover, Panter said rainwater is actually better for the landscape than treated water because it is softer water.
The Energy Monitoring and Control System (EMCS) at Fort Sill monitors the collection system. EMCS is a computer software system that monitors water, gas, and electricity usage mainly through the management of the HVAC systems. Operators can track tank levels and filter alarms, watch the pump operation and verify that everything is in working order. If something does go wrong, it sends an alarm and operators can check on the problem.
The buildings with the rainwater collection systems are the Thermal High Altitude Air Defense (THAAD) project, Reception Battalion Complex, and the Tactical Equipment Maintenance Facility (TEMF). The THAAD has two 50,000 gallon tanks, the Reception Complex has one 30,000 gallon tank, and the TEMF has two 25,000 gallon tanks.
Eventually the system could be connected to other buildings.
“The system on the TEMF is designed with this in mind,” said Purdum. “It could pull water from all four buildings around it. It could be the beginnings of a beneficial system.”
In a small way, the rainwater collection system will assist with cooling the building. It ties into the building’s cooling tower water supply, so that it would start utilizing rainwater first rather than pulling from the building’s water supply.
The first rainwater system should go online this summer.
At the Mission Training Complex, photovoltaic panels on the roof collect sunlight and turn it into electricity. The big solar panels charge batteries in the building’s inverter room and those batteries assist with the building’s power. This helps to shave off the peak demand loads so the Army isn’t paying premium rates.
“You don’t have to burn fossil fuels to use it,” said Purdum. “As the sun moves the panels track the sun; they are designed to always be in the sun and to catch light from both sides.”
Purdum said even though there is an initial high cost to install both systems, ultimately they pay for themselves. The life cycle for the rainwater system is about 25 to 30 years, and about 15 years for the photovoltaic panels.
Both systems are an example creative thinking about energy efficiency and conservation can help preserve resources and save the U.S. Army money.