Boone trucking company experiments with keeping its cabbage cool

May 21, 2023

Hollar & Greene Produce is a 60-year-old Boone company that transports millions of heads of cabbage annually up and down the East Coast. If you have eaten cabbage or coleslaw in North Carolina, there's a good chance a farmer brought it to Hollar & Greene's warehouses and it was transported by the company to distributors and grocery chains.

One logistical challenge the company faces is keeping the cabbage cold after it is loaded in a trailer for transport. Traditionally, this has meant burning diesel fuel to run refrigeration units on tractor-trailers. Hollar & Greene has figured how to reduce its reliance on diesel and reduce its carbon footprint. It has done this with the help of the Surry-Yadkin electric co-op.

In a pilot project, while the trailer filled with cabbage is parked for hours waiting for a driver, it is being cooled by equipment powered by electricity and not diesel.

The innovation is called the electric transport refrigeration unit, eTRU, which goes on the trailer behind the driver's cab and plugs into equipment at the warehouse installed by the co-op.

To understand why eTRU is such an important piece of equipment, it helps to look at the logistics of cabbage and the requirements of big customers, such as Walmart.

One of the leading experts is Tony Greene, Hollar & Greene's vice president of transportation and a son of Dale Greene, who co-founded the company in 1963 in the North Carolina mountains with his father-in-law, Lige Hollar. Tony's two brothers, Jeff and Tim, are executives on the sales side.

The supply chain

Hollar & Greene works with farmers from Florida to Canada. It has two main processing and warehouse hubs, in Bunnell, Florida, south of St. Augustine, and in Mount Airy, near a couple of big interstates, which you need if you are one of the biggest cabbage shippers in the country. It also has branch offices in other states near the farmers.

"We start in Florida," says Tony Greene. "That's January to May. Then Georgia. Then Carolina, Virginia, Pennsylvania, western New York state, which is a great producing area, then, if needed, Canada. Then, by the end of the year, we’re back to Florida."

Hollar & Greene is also a grower. "We do have farms of our own," he says, "because Walmart and other customers want us to have skin in the game."

Cabbage comes to Hollar & Greene facilities where it is processed, placed in boxes and then put on pallets and loaded into truck trailers.

Trucks load in the morning, says Greene, "because that's when the crew's available." But the driver won't come in until later. The trailer can sit from six to 12 hours.

The trailers have refrigeration units that run on diesel to keep the cabbage cool, whether it is waiting for the driver or being driven on the interstates to a customer's loading dock. That is because customers want the cabbage at a specific temperature.

"With Walmart, they want the pulp temperature of the cabbage to be 36 degrees, so that's why we have to have that unit running continuously, to reach and maintain that pulp temp," says Greene. In the old days, if the refrigeration unit on the truck was running when it pulled up to the dock, they would accept it. Today, when Hollar & Greene shows up, someone on the customer side takes temperature readings with a probe. Sticking it into the cabbage, front, back and middle of the trailer. If the cabbage isn't the right temperature, the load will be rejected.

Reduce carbon

A lot of companies like Walmart are trying not just to reduce their own carbon footprint but also their suppliers’.

"Our customers are almost requesting that we reduce our carbon footprint, but they’re rewarding us for that," says Greene. "So there's a ‘You show us how you’re reducing your carbon footprint. That helps what we’re saying we’re going to do, and you become a favored vendor to us.’ And that's a lot of incentive to us."

There's also regulatory changes looming. What electric co-op folks here were seeing was a use of technology like eTRU in California, the largest fruit and vegetable producing state.

"There are limitations about burning diesel because of all the air regs," says Jim Musilek, vice president of innovation and business development for the NC Electric Cooperatives.

"If those regulations kind of migrate east, we want to make sure our folks are in a position for success," he says. "So that's why we wanted to test the technology, so we could understand it and see what benefits there are, because, frankly, we want to take this pilot and leverage it for all of our other cooperatives."

Hollar & Greene three months ago acquired the new trailer with an eTRU unit from Thermo King. Surry-Yadkin managed the installation of the transformer and other infrastructure at the Mt. Airy site to plug into the trailer.

"After we load the truck, the product is at its warmest point," says Greene. "Even if it was in the cooler, because it was out of the cooler while it was being loaded. So we pull up and plug up to the eTRU. The unit asks, ‘Do you want to run eTRU?’ We answer ‘Yes.’"

When the driver arrives, the first thing he does is unhook the eTRU, "and it asks, "Do you want to run diesel?’ At that point he's on diesel." And he's on his way.

The unit is saving $100 a day by being able to run off electricity for hours at the warehouse after it's loaded and before the driver shows up, instead of the diesel tank in the belly of the trailer. Savings of $15,000 to $20,000 a year means that Hollar & Greene can pay for a new $100,000 trailer in around five years.

"We have a way to get a big return on investment with this new option," says Greene. Five more eTRU-equipped trailers are on order.

"It's low-hanging fruit," says Muselik. "Or maybe, in this case, low-hanging cabbage."

The role of the co-ops

The Hollar & Greene case highlights the importance of North Carolina's electric co-ops to the state's economy. The agribusiness sector is North Carolina's largest industry, with a $103 billion annual contribution to the state's economy. It is largely based in North Carolina's rural counties, and the electric cooperatives – like Surry-Yadkin – are the power companies in many of those counties, serving 45% of the state's land area, getting the majority of their power from nuclear . The emergence of those co-ops beginning in the 1930s – the electrification of rural North Carolina – is one major reason there is an $103 billion ag sector today.

"It's very important for the North Carolina co-ops to partner with our agriculture community," says Muselik, "because agriculture is North Carolina's most important industry."

And that means looking for innovative ways, including a broader portfolio of renewable projects, to help the industry improve operations by reducing emissions while lowering costs. The term that was heard last week at the co-ops’ Electrify NC 2023 conference in Raleigh was "beneficial electrification," using electricity to power processes and equipment in place of other fuel sources. And one of the examples being talked about was Hollar & Greene.

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