What’s up down under

Scientists and engineers are on top of the quest for non-steel alternatives for tank construction, breaking new ground in researching suitable composite materials slated for below-grade applications.

Scratches to a freshly painted, shiny new underground propane storage tank can lead to corrosion over time.

Underground composite tanks are still three to four years away from entering the American marketplace, mainly because any new designs will have to first meet rigorous testing and code requirements promulgated by the National Fire and Protection Association.

Interest in underground tank technology continues to surface as upscale homeowners increasingly ask that their propane tanks be hidden from view. In the meantime, propane marketers eager to meet these consumer desires must deal with steel’s high cost and its propensity to rust or corrode when the coating is compromised.

Research Project Details

A composite underground tank mockup attracted considerable industry attention on display in Chicago at the Global Technology Conference in Chicago in October, according to Robert Nicholson, chairman of the board at New Jersey-based Eastern Propane. He has long been an advocate of buried residential tanks.

“I started putting them in during the 1970s, when nobody else was doing it,” Nicholson recounts. “I saw a marketing opportunity for my business.”

The majority of the builders were pleased with the buried steel vessels and the aesthetics they were able to maintain in their residential projects. (See sidebar story.)

“Based on the information from marketers like Mr. Nicholson, it appears there is a substantial demand for underground tanks in high-end developments,” says Rodney Osborne, associate manager of the Applied Energy Systems group at the Battelle Memorial Institute in Columbus, Ohio, which is researching composite tank construction for the Propane Education & Research Council.

Although the National Basketball Association has reverted back to its leather Spalding ball after an unsuccessful tryout of a composite model, within the propane arena PERC is mounting a full-court press toward perfecting an alternative to below-grade steel tanks.

Research Project Details

Competitive pricing sought

According to Greg Kerr, PERC’s research and development director, “The propane industry is keenly interested in exploring new materials and methods for tank construction that can not only provide a more durable and lower maintenance container but also do so at a price that is competitive with current steel tank prices.”

In addition to the tripling of steel’s cost over the past five years, the sacrificial anode cathodic systems that provide anti-corrosion protection must be monitored to ensure they remain viable and operating.

Phase 1 of a three-pronged PERC/Battelle alternative tank materials initiative has been completed at a cost of $67,000. The $192,000 Phase 2 is ongoing; Phase 3 is to commence next fall or with a yet-to-be-determined price tag.

Construction-for-analysis of a 500-gallon tank is the initial goal.

“It looks like a composite tank is feasible,” Osborne observes. “The materials have been used for underground storage tanks for decades,” he adds, referring to gasoline and diesel fuel applications.

Lincoln Composites Inc. of Nebraska, formed in 1963 to produce Polaris rocketry components, is pursuing the project’s finer points of propane-tank engineering and cost-effective manufacturing utilizing an isophthalic polyester with glass-fiber enforcement.

“We can use either glass-or carbon-fiber in an epoxy resin,” reports Norman Newhouse, Lincoln’s vice president of technology. “There’s a bit of development yet to do, but the basic technology is already there.”

Osborne says how the vessel’s suitability for propane is likely to be a slam dunk – assuming the price is right once the manufacturing process is perfected. Lincoln has successfully produced hydrogen tanks able to withstand 10,000 pounds per square inch of pressure, plus compressed natural gas tanks at 3,000 to 4,000 psi. A propane tank requires just a 250 psi rating.

Composite 20-pound tanks are already seeing limited grilling duty in the United States. “They are about two-and-a-half times the cost (of traditional steel units), but people are willing to pay that now,” says Osborne.

The translucent shell permits the chef to immediately see the volume of product. Of course, that quality is unnecessary for an underground tank because no one will see it, but Osborne relates how steel tanks can rust at the bottom leave a rust ring on a customer’s deck or in their car.

Jumping through hoops

Once an underground composite tank is developed, a code change will be needed to allow it to be used in the United States.

“We’re at least three to four years away from a product that a marketer can actually go out and buy,” Osborne says.

Nicholson is aware of this daunting code challenge, yet he remains encouraged by the progress.

“I can see the approvals taking longer than the research. After we get the report from Battelle, then we have to jump through all kinds of hoops to get approvals,” he says.

The composite underground tank should neutralize the ongoing struggle with corrosion issues. Nicholson recalled a litany of problems he faced when trying to achieve an optimum finish – even getting to the point of developing his own paint-spraying processes.

In addition to adhesion, application-thickness and material-content issues, Nicholson discovered that “most painters don’t like to bend over, so the legs at the bottom were not well-coated. If there’s one bare spot, that’s where corrosion is going to attack.”

Noting how disclaimers in a tank’s packaging void warranties if a scratch is inflicted, one false move with a backhoe or even a pebble tossed by a child can render a steel tank compromised.

“The installer can have no scratches on those tanks,” Nicholson stresses. “It takes a lot of marketer training to ensure the tanks are installed properly. Even if you just have a pinhole, corrosion attacks that pinhole and that’s where you have a leak.”

Nicholson is particularly distressed that certain propane retailers are burying tanks without adequate sacrificial anode cathodic systems and the requisite follow-up inspections.

“Most do it now, but there are some marketers who believe their soil is not corrosive,” he says, pointing out that something as simple as pet urine patches can generate tank-threatening acidic conditions.

At age 78, Nicholson is eager to see his younger industry colleagues carry on his goal of seeing sound installation practices whether a tank is made of steel or a composite.

“I’ve been studying some of the foreign markets and how they’re handling underground tanks. I’m hoping we can get an educational program going” in the United States as well.

PERC survey: Home builders digging underground tanks

According to a 2006 survey by the National Association of Home Builders Research Center on behalf of the Propane Education & Research Council, 34 percent of homes built over the past 12 months in locations with partial or no access to natural gas feature an underground propane tank.

While access to natural gas plays a role in influencing a decision to use underground tanks, outdoor rooms and stand-by generators are also driving builder interest.

The survey found that overall awareness of underground propane tanks was high, with eight out of 10 builders surveyed noting they are aware of the use of underground tanks. Underground tanks are strongest among builders in the Northeast, followed by builders in the Midwest and Western regions.

“More and more, residential propane customers are finding that underground containers are aesthetically more pleasing and provide the same high reliability that above-ground propane tanks have provided in the past,” says Greg Kerr, PERC’s research and development director.

The survey found that once builders understood the benefits of underground propane tanks, their intention to use propane in the next 12 months jumped from 18 percent to 29 percent in homes they intend to build.

The greatest gains for propane were in regions without access to natural gas. But even in regions with access, the likelihood of builders using underground tanks increased, with interest driven by outdoor living areas and identifying a reliable energy source for stand-by generators.

Highlights from the survey:

• Outdoor living rooms and stand-by power generators are the top drivers for builder interest in underground propane tanks.
• Geography plays a major role in interest in propane and underground storage, with builders whose homes have partial or no access to natural gas noting they were four times more familiar with propane and twice as likely to use underground propane tanks.
• High-efficiency, hydronic heating systems such as radiant floor heat appear to be adding to builder interest in using propane, with builders saying they would install radiant floor heat in 13 percent of their homes in the next 12 months, an 11 percent increase over current usage of just 2 percent.
• Custom builders are far more likely to use underground propane tanks, with outdoor living spaces playing a large role in driving use. Sixty percent of the homes built by the custom builders surveyed feature propane by preference, and 44 percent of their homes feature an underground storage system to fuel outdoor room applications.

“As builders work with homebuyers to design cost-effective homes that deliver added value, home builders can count on their local propane retailer to help them understand the benefits of building a home that maximizes the benefits of an underground storage system,” says Jim Hitzemann at Ray Murray Inc. in Huntersville, N.C.

“Propane-fueled appliances such as tankless water heaters and high-efficiency gas furnaces help to fuel interest in propane, but the added value propane delivers for outdoor rooms and stand-by power generation are also important drivers,” he notes.

Underground tanks are becoming increasingly popular among home builders. They are constructed of heavy steel and painted with a mastic coating to prevent corrosion. Once the tanks are buried, the only evidence of the tank is a small dome with filling connections that protrude just inches above the ground where the supplier fills the tank.

Single-family homes can be fueled by tanks of varying sizes, depending on demand. Generally, 500-gallon tanks easily accommodate an average four-bedroom home. One hundred gallon tanks can be installed to provide energy for specific applications such as outdoor rooms, while 1,000-plus gallon tanks can fuel large homes with applications such as swimming pools and hot tubs.

However, entire developments are now also using underground storage systems, with centralized systems that feature a gas main and metered access to propane.

Admiring the aesthetics

Two housing developments fueled by underground tanks were recently named PERC’s Exceptional Energy Award winners for 2006.

Sable Developing of Rockford, Mich., was chosen for its use of centralized underground propane tanks to fuel an 82-home community, with piping sized to serve all applicable residential applications from pool heating to outdoor grills to clothes dryers.

Real Estate Service of Connecticut was recognized for its use of propane to fuel the Spinnaker Community in East Lyme, Conn., which features 77 detached condominium units, all fueled by a metered propane fueling system featuring underground storage tanks.

“Underground tanks are clearly the way to go,” says Bruce Bylsma, director of sales and marketing for Sable Developing.

“Buyers like the aesthetics with the absence of the tank, and they see propane as more cost effective than electricity and better for developing both off the grid and off the natural gas main. Propane gives homeowners all the benefits they need to live comfortably in a home,” he says.