A new power source – fuel cells

- Over the past few years, a handful of supermarket companies have been trying out a novel way to generate electrical and heat power in their stores — fuel cells.

Fuel cell technology dates back many decades and has been employed in diverse settings, including buildings, consumer electronics, cars — even the Apollo moon missions. As a commercial source of on-site power, fuel cells have evolved to where they are being increasingly adopted by businesses that need around-the-clock power and can take advantage of the release of heat.

Some examples of fuel cell users in the supermarket industry include two stores operated by Whole Foods Market (with a third coming this year), one Price Chopper, one Star Market and two Wal-Mart supercenters. These stores typically employ a fuel cell in concert with the U.S. electrical grid — with most of the energy coming from the fuel cell — and as a stand-alone generator when the grid is unavailable.

Fuel cells are designed to be efficient, quiet and green. Like batteries, they use electrochemical power, not fossil fuel combustion; unlike batteries, they use a continuous source of fuel like natural gas, from which hydrogen gas is obtained. The hydrogen is made to react with oxygen from the air to generate electricity, heat and water.

Whole Foods' fuel cells are made by UTC Power, South Windsor, Conn. Incorporating phosphoric acid, they are rated a little more than 40% in terms of electricity-producing efficiency, compared to about 35% efficiency achieved by traditional power plants, said Neal Montany, director of UTC's stationary fuel cell business. (Other fuel cell designs differ in efficiency.)

But by capturing the heat it produces, the UTC fuel cell can increase its efficiency to as high as 90%, depending upon how much of the heat is used, Montany said. By contrast, almost two-thirds of the energy potential in traditional power plants is lost to the atmosphere as waste heat or in transmission line losses.

In a San Jose, Calif., Whole Foods store expected to open this fall, the UTC fuel cell system will generate 90% of the store's electricity, and thermal energy will be used for store heating, cooling and refrigeration for an overall efficiency of more than 60%. In a Glastonbury, Conn., Whole Foods store that has used a UTC fuel cell since 2008, the technology's efficiency has cut energy costs by 30% compared to a conventionally powered store.

Carbon dioxide, the principal greenhouse gas, is a by-product of fuel cells — but much less than what is released by the combustion of fossil fuels like coal and petroleum. And unlike fossil-fuel combustion, fuel cells produce virtually no other pollutants. In the Boston market area, a 400 kilowatt fuel cell using natural gas with 60% thermal utilization annually prevents the release of 1,313 metric tons of carbon dioxide and 1.62 metric tons of nitrogen oxides when compared to the electrical grid, while conserving 213,000 gallons of water, according to UTC Power.

The fuel cell's chief drawback is its cost. In stores that have incorporated this technology, the cost has been defrayed by state and federal incentives. However, as more fuel cells are installed, their cost is expected to drop, making them a potential green alternative to conventional power sources.

Whole Foods, based in Austin, Texas, was initially approached by UTC Power in 2006. At that time, hurricanes like Katrina and Rita had left retailers with a need for "larger back-up power requirements," noted Kathy Loftus, global leader, sustainable engineering, maintenance and energy management for Whole Foods, in a session last fall at the Food Marketing Institute's Energy & Technical Services Conference in Indian Wells, Calif. In addition, incentive programs for fuel cells were springing up in several states. Still, she said, the economics justifying an investment "were close, but not there."

A year later, UTC approached Whole Foods again about taking advantage of "lucrative incentives" from the Connecticut Clean Energy Foundation (CCEF) to install a fuel cell at a store being constructed in Glastonbury, not far from UTC's headquarters, said Loftus.

Whole Foods was already well into the design of the Glastonbury store. Moreover, Whole Foods' own engineers weren't sure about how a fuel cell could be incorporated into a supermarket. As a result, there was considerable doubt over whether "we could pull this off," said Loftus.

But the chain decided to move forward, hiring two engineering firms — Energy Efficiency Services, Hopkinton, N.H., and Harriman Associates, Auburn, Maine — as well as UTC, to "hammer out" a plan to use a 200-kilowatt fuel cell in the Glastonbury store, said Loftus. "It helps to have a third-party independent engineer with heavy refrigeration, HVAC and plumbing knowledge," she said.

It's also better to have ample time in the design and engineering process to incorporate a fuel cell - something Whole Foods didn't have with its Glastonbury store but did have with its next fuel cell project, a new store in Dedham, Mass., that opened last fall, and with its current project in San Jose.

The fuel cell began operation in Glastonbury in 2008, generating about half of the store's electrical power load and providing heat for all of its hot water production and about 60% to 80% of the store's overall heating needs, said Willis McCullough, UTC's sales manager for retail and grocery. The system has the ability to produce just enough power to match a store's momentary needs, said Montany. Its up-time is about 99%, including planned maintenance.

In the Glastonbury and Dedham stores, the fuel cell's waste heat is channeled into space heating, dehumidification, domestic water preheating and chilling of liquid refrigerant. This eliminates the need for a hot water boiler and enables the refrigeration compressor to be used less. "Sixty percent of what the fuel cell is producing is heat," Montany said. "Doing something with the heat is really the key to making it viable."

The ability of a fuel cell to integrate with a store's refrigeration system and provide some of the heat necessary to run the system, thereby lessening the burden on electrically driven compressors, is what makes the fuel cell an especially good fit for the supermarket industry, said McCullough.

UTC is working with refrigeration system vendors like Hill Phoenix to help it design its systems to better accommodate the waste heat from the fuel cell.

After the first year, the Glastonbury store's total electrical and heat energy costs, including the cost of additional natural gas needed for the fuel cell, were 30% lower than a comparable store in West Hartford, Conn., said Loftus. On an annual basis, the store reduced its carbon footprint by 90 metric tons and its nitrogen oxide emissions by two metric tons when compared to the electrical grid.

The "cell stack" — the part where the energy is produced — in the 200-kilowatt unit at the Glastonbury store has a five-year lifespan, after which it will be replaced, said Montany. The cell stack and other components of the 400-kilowatt unit have a 10-year lifespan.

Rather than invest in the full up-front cost of a fuel cell — about $4,500 per kilowatt, or $900,000 in Glastonbury and $1.8 million in Dedham — Whole Foods is leasing the system on a monthly basis from UTC Power through a 10-year "energy services agreement." The agreement includes the cost of the unit, installation and all services and associated equipment.

Montany acknowledged that state and federal support is needed at this time to make fuel cells an economically viable energy solution for retailers. "Up-front capital cost is an issue with the introduction of a new technology," he said. "[Government] incentives can offset that until costs go down with greater volume." Currently, the states with the best incentives for fuel cell installations are Connecticut, California, New York, New Jersey and Massachusetts, where Whole Foods received help from the Massachusetts Renewable Energy Trust.

The government incentives, which are received by UTC Power in the case of the leased Whole Foods installations, enable the payback for the investment to fall to three to five years, from 11 years, said Montany.

In Dedham, Whole Foods' 400-kilowatt fuel cell has been operating since December 2009, a few months after the store opened, and the retailer has yet to report an energy savings. The 400-kilowatt model, now the standard version that UTC Power provides, is also being used at a Price Chopper store in Colonie, N.Y., and at a Star Market store in Chestnut Hill, Mass. Stop & Shop plans to begin operating the fuel cell in a new Torrington, Conn., store in a few months, while Whole Foods will use one at its new store under construction in San Jose.

In December and January, Wal-Mart Stores installed a 400-kilowatt solid-oxide fuel cell from Bloom Energy, Sunnyvale, Calif., in two supercenters, located in Lancaster, Calif., and Hemet, Calif., respectively. These fuel cells, which can accommodate up to 60% of the stores' energy needs, do not allow waste heat to be used, but are designed to offer high electrical efficiencies.

Unlike the Glastonbury store, at the Dedham store "the entire fuel cell system was designed into the building documents," said Loftus. The design encompassed mechanical, electrical and plumbing (MEP) elements "up to all points of equipment connection, allowing construction to be a far smoother process" than in Glastonbury, she said.

The Dedham store's fuel cell generates 90% of the power needed by the store. Its integrated design and greater power allows it to generate enough heat for 90% of the store's heating needs — 1.7 million BTUs/hour, double the Glastonbury store's output. Between 50% and 60% of the fuel cell's heat in Dedham is utilized.

The heat from the fuel cell is channeled into four areas in Dedham: a 1-million BTUs/hour hydronic hot water coil in central Seasons-4 HVAC unit, domestic hot water preheating, a receiving area air-handler with a hot water fan coil, and an absorption chiller for rack-mounted liquid refrigerant subcooling.

The UTC fuel cell operates in a grid-connect or a grid-independent mode. In the former, the fuel cell supplies more than 90% of a given electrical load, while the rest comes from the traditional electrical grid. "In this case, we've agreed to manage the fuel cell to produce less than the store demand," said Montany. "If we were to produce more, it would go to the grid. So we need a buffer."

On the other hand, a key benefit to supermarkets is that when the grid goes down — because of a hurricane or some other event — the fuel cell operates in a grid-independent mode, providing uninterrupted power to the store. While traditional back-up generators cover front-end registers and lights, they "can't do much with refrigeration," said Loftus. But when the fuel cell acts as a back-up, it "absolutely" generates enough power to accommodate refrigeration, she said.

And unlike a traditional back-up generator, which has a finite amount of fuel, the fuel cell has a continuous fuel supply and can maintain operation over longer periods of time.

"The goal is to operate all refrigeration, IT/POS equipment and 50% sales area lighting and all back room lighting to continue to operate the store" during a grid outage in Dedham, said Loftus.

At the same time, the fuel cell is electrically isolated from the main service with a transfer switch. "Should anything ever happen to the fuel cell, the store operations will not be affected, even momentarily," said Loftus.

At the Glastonbury and Dedham stores, the fuel cell is located in the back of the building, though it can be placed on a roof or in a basement. "The closer it is to the mechanical and electrical interconnects, the better" because distance increases installation costs, said McCullough.