Who's the greenest of them all?

With the rise of the environmentally conscious consumer and the growing importance of sustainability to corporate boardrooms, more and more companies are looking to reduce their carbon footprint and the amount of waste they send to the landfill.

One area that is increasingly being viewed through a green lens is packaging. Pallet companies and trade groups have responded by touting their particular type of pallet—wood, corrugated, plastic, or metal—as a sustainable choice. But if you dig a little deeper, you'll find that each material has both strengths and weaknesses.

Here's a rundown of each type of pallet's impact on the planet.

Wood is by far the most common type of material being used to make pallets today, and it has a lot to recommend it as far as sustainability goes. Wood is a renewable resource, and, according to the National Wooden Pallet and Container Association (NWPCA), it requires far less energy to produce than any other common type of pallet material. "You plant a tree, you leave it, it grows," says Patrick Atagi, the group's executive vice president of advocacy and external affairs.

Of course, it's not quite as simple as that. Trees do not grow overnight; it takes 30 to 40 years before a tree is large enough to be harvested for wood. But decades of forest management efforts mean that the United States is in little danger of running low on wood, even if housing starts return to the levels seen during the housing bubble. According to the "National Report on Sustainable Forests" published by the U.S. Forest Service in 2010, the number of acres of forest in the United States has remained stable for the last 50 years and the amount of wood being produced per acre has actually increased.

Wood pallets are also reusable and/or recyclable. If damaged, a wooden pallet can easily be repaired—typically, all that's required is to pull off the old board and hammer on a new one. When a pallet can no longer be repaired or remanufactured into a recycled pallet, it can be reprocessed and the wood fibers used in such products as mulch, particleboard, and animal bedding. All of these end-of-life efforts, however, require that the pallet user have effective waste management processes in place, typically working with a pallet recycler. (Companies looking to locate a pallet recycler near their facilities can search the online directory available on NWPCA's website.)

Not everyone believes that wood pallets are the best choice for the environment. A nonprofit organization launched last year called Change the Pallet is making aggressive claims that switching to corrugated cardboard pallets could greatly reduce carbon emissions. The group was heavily involved in an attempt to pass a bill in Oregon's House of Representatives to require state agencies to switch to cardboard pallets where appropriate. While the bill never made it out of committee, the governor did approve a pilot with the Department of Corrections.

The reason that cardboard pallets lead to reductions in carbon emissions, according to the group's executive director, Adam Pener, is weight. While wood pallets typically weigh around 50 pounds, cardboard pallets weigh about 10. When trucks transport less weight, he says, they consume less fuel.

A case in point is the global furniture company Ikea, which made headlines in 2012 when it announced an initiative to switch from wood pallets to cardboard or paperboard pallets. According to Ikea, since 2012, the company has cut its carbon emissions by more than 300,000 metric tons and reduced the number of trucks it uses by 15 percent, while transporting the same volume of goods.

The one area where cardboard pallets do not measure up to their competitors is in length of life. Although cardboard pallets can be made as strong as wood, they are typically designed to be used only once. Skeptics have also expressed concern about their durability and water resistance, although Pener insists that they can easily be treated with a waterproof coating.

Cardboard pallets, however, are much easier to recycle than other pallet types. According to Pener, companies can simply toss their cardboard pallets into a baler and recycle them along with their other corrugate.

In contrast to their counterparts over on the cardboard pallet side, makers of plastic pallets stake their sustainability claims on their pallets' longevity. According to Adam Gurga, national account manager, consumer packaged goods supply chains, for the plastic pallet manufacturer Rehrig Pacific, plastic pallets often last five to six years. "And I've been in some of our customers' facilities where they're still using pallets they purchased 10 years ago," he says.

That durability also helps the pallet to better protect the product it is transporting. The less damage that occurs to both the pallet and the product, the fewer resources will be consumed in making replacements. On top of that, companies will be minimizing their carbon footprint because they won't be transporting as many replacement pallets and goods.

No matter how durable a pallet is, however, if you run it over with an 8,000-pound forklift, it's going to break. While some plastic pallets are repairable, most are not. Still, plastic pallets can be recycled, and many plastic pallet companies will even pick up the damaged units from you. The pallets are ground down into plastic resin, which can be reused to make recycled plastic pallets (although the quality is not as high as it is with new ones) or other plastic products.

That said, potential plastic pallet users must weigh the environmental costs of simply manufacturing plastic. Unlike wood or cardboard, plastic pallets are typically made from high-density polyethylene or polypropylene, which requires nonrenewable resources such as oil or natural gas to produce.

Finally, for plastic pallets to be truly sustainable (not just environmentally but also economically), companies either need to use a pooler or have some way of guaranteeing that they can get their pallets back.

The weight of most metal pallets makes them unsuitable for many applications. Aluminum pallets, however, weigh on average less than 40 pounds, and aluminum pallet companies like to tout their environmental benefits.

To be sure, the environmental cost of producing aluminum is high. For starters, the raw material, bauxite, must be mined from the earth. On top of that, processing and manufacturing aluminum consumes a great deal of energy.

However, once it is produced, aluminum is "infinitely recyclable," in the words of Peter Johnson, president of Eco Aluminum Pallets. And unlike the situation with plastic, the recycling process does not degrade the quality of aluminum. So one way to lessen the pallets' environmental impact is to use pallets made out of recycled aluminum. Recycled aluminum is readily available, and Johnson has no concerns about the supply's decreasing.

Aluminum pallets are also durable. Eco Aluminum Pallets, for example, guarantees its pallets for 10 years. While the majority of metal pallets are nonrepairable, Eco Aluminum Pallets has created a repairable version that is riveted together.

Aluminum pallets are not for everyone, however. They are best suited for closed-loop or captive environments, where the company can maintain control of the pallet and runs little risk of losing a valuable asset.

If you take a close look at each type of pallet, you'll see that there are pluses and minuses for each in terms of sustainability. The best advice might be to evaluate which type of pallet makes the most sense for your operation and product. It might be that a change could benefit your particular operation.

But no matter what type of pallet they use, most companies could benefit from thinking about their pallets in terms of the three Rs: reduce, reuse, and recycle.

Companies can start by asking themselves whether there are ways they can reduce the number of pallets they use. For example, can they redesign their pallet load so they can add an extra layer of product on the pallet? The more product you get on one pallet, the fewer pallets you use (and ultimately, the fewer trucks you'll need). This means fewer resources used to create the pallet itself and fewer trucks on the road, which cuts down on carbon emissions. (For a few examples, see "Six small packaging changes that can save big money,"DC Velocity, March 2016.)

When it comes to reuse, are there ways the company can get more use out of its pallets? Could its pallets be designed to last longer, maybe by using a higher-quality material? Many wood pallet companies can use special pallet design software to create a pallet that is optimized to your needs. In addition, effective education on pallet handling—particularly for those who operate pallet jacks and forklift trucks—can reduce the amount of damage that a pallet sustains and the number of replacement pallets needed.

Finally, does the company have an effective recycling program in place for pallets that have reached the end of their life? And do your employees know what that policy is?

Such changes may have as much to do with creating a sustainable pallet operation as the type of material that the pallets are made of.