Greening Tinker: Base installing solar hot-water heating panels

TINKER AIR FORCE BASE, Okla. -- If supporting the Air Force's renewable energy goal is a base New Year's resolution, Tinker is right on track. Solar hot-water heating panels are being installed on the rooftops of six buildings.

With completion scheduled for June, officials said the panels will offset 50 to 75 percent of the fuel ordinarily needed to heat the water.

"Tinker doesn't have a renewable energy goal, however we're supporting the Air Force goal, which is 7.5 percent of energy to be renewable by 2013," said Britton Young, Tinker's Energy Team point-of-contact in the 72nd Air Base Wing Civil Engineering Directorate. "It makes more sense to have renewable energy goals in Florida, California or Arizona where utility rates are higher than here."

Depending on their respective missions, Air Force bases on the coasts tend to pay 8 to 12 cents per kilowatt hour. Private firms will pay 12 to 21 cents per kilowatt hour; whereas at Tinker the rate is 3.2 cents per kilowatt hour.

The panels are designed to collect sunlight and convert it to heat in a solar collector. The solar panels work as long as the sun is out; peak times are between noon and 7 p.m. Under the right conditions, the water temperature can rise 100 degrees.

The solar panels are primarily being installed on industrial facilities versus dormitories or commercial and recreational buildings because of when the heat is absorbed and the amount of water being used. Solar panels will collect the majority of their heat in the afternoon hours.

Paul Garnaas, 72nd ABW/CE Resource Efficiency manager, said a residential shower usually runs a gallon-and-a-half to two gallons per minute. The average person may use up to 15 gallons. Most residences use 15 to 20 gallons of hot water a day per person to wash clothes and clean. But, unless they perform hot water-related activities in the mid-afternoon, the solar panels will prove less effective.

Whereas, many of Tinker's industrial facilities performing hot-water consuming tasks, such as washing an aircraft, will use 240 to 400 gallons per minute of hot water, and that activity has a better chance of being performed during the early afternoon hours.
"At that time the demand for the heated water and the sun's rays are synchronous," Mr. Garnaas said.

The solar hot-water heating concept isn't perfect and will require regular maintenance.
"These panels will have a 20-year life and they take more maintenance than a standard water heating system," Mr. Garnaas said. "We have this red dirt in Oklahoma that kind of films everything, so they need to be washed off periodically with rain and we don't have a lot of that in Oklahoma."

The panels should pay for themselves in 12 years, but it is a far better deal than photovoltaic panels, which convert sunlight into electricity. Photovoltaic panels are more expensive to manufacture and to install, and only 15 percent effective, said Mr. Garnaas.
"Plus, the energy coming off of them will be about 12 to 17 cents per kilowatt hour. That kind of makes the economics upside down," Mr. Garnaas said. "It's too difficult to justify the cost."