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Wood waste need not go to waste

Most woodshops hire a dumpster service to drop off a container and haul away sawdust and wood scraps. Unfortunately, about 80 percent of the material they collect will end up in a landfill. Think about how much waste accumulates through the decades — just five yards a week over 30 years is almost 8,000 cubic yards. That’s about the same volume as a couple of dozen ranch-style homes!

Weima America’s Tiger 400 horizontal shredder.

That kind of volume can have a significant impact on a local landfill. If burying bothers you, there are options. In most cases, the woodshop will still pay to have the waste hauled away. But by choosing the right dumpster service, a cabinet shop’s excess can be used to make products such as paper, particleboard and wood stove pellets. Some species can even be used as animal bedding, in nursery applications for weed control or even as a base in playgrounds.

The stark economic reality is that shops in larger metropolitan areas usually have much better choices when it comes to hauling dust. There aren’t too many paper mills or particleboard factories in small towns.

However, there are fireplaces. And new technology is making it a lot easier to make briquettes and pellets out of wood waste.

A burning question

Weima America, based in Fort Mill, S.C., manufactures shredding equipment for cabinet and millwork shops, furniture makers and sawmills. Shredders can process hardwood, softwood, particleboard, plywood and MDF scrap, and even bulky residue such as rejected drawers or doors. Once shredded, waste can be transported off site to be recycled. However, if there’s enough product to make it economically viable, the waste can be briquetted on site. In that case, the woodshop has a new product line than can be sold or used to heat the shop or both.

Briquettes have a high calorific value — much higher than regular firewood and comparable to brown coal. They burn longer and more evenly than uncompacted wood waste and produce less ash. They’re used in boilers to generate heat and, in some cases, to also generate electrical power on a small scale in remote locations.

Briquette presses can also process a variety of materials without the use of a binding agent (that is, an introduced resin or glue). With no chemicals added, the product burns cleaner so it’s safer to use in heating solutions. And as it started out a lot drier than freshly sawn or even seasoned green firewood (most shop waste is already kiln-dried), it burns better. Being dry, it is also lighter in weight, so it’s less expensive to transport briquettes than taking raw waste to the dump or buying the firewood that it can replace.

One of Weima’s customers, Southern Lumber & Millwork in Charleston, S.C., produces structural components for framing as well as interior and exterior trim. About 90 percent of its products go to residential housing construction, which has been booming of late. When company managers began to notice an increase in the volume of wood waste they were hauling to the landfill each week, they started researching options for ways to resell that waste. The concept was to not only cut costs, but also to possibly increase revenue. After serious study, they decided to invest in the purchase and installation of a Weima Tiger 400, a horizontal shredder fed by a vibrating in-feed conveyor. The grindings and dust are discharged through an air system and conveyed into a trailer that is filled and hauled off about every three weeks. The shredded wood and wood dust is then sold to a local paper plant. That also helps reduce the number of trees needed in the papermaking process.

Weima makes single-shaft shredders that are ideal for small- to medium-sized wood shops and can process a variety of smaller pieces of wood waste. They feature a log spacer design in the hopper. This prevents sticks from bridging inside the hopper, causing jams. The feed motion of the ram is load-dependent, which ensures that the shredder won’t become overloaded.

Better barn wood

Another Weima client, Barnyard Salvage in Lynchburg, Va., is a seven-person shop that specializes in processing old barn siding into furniture and décor items. Green manufacturing is important to Barnyard Salvage president and owner Rich Marilla. The business’s marketing rests on the fact that the end product is not only beautiful, but also environmentally friendly.

The first step in processing old siding is to remove nails, bullets and other debris from the wood. Those pieces are then run through a ripsaw, usually to a 1-inch thickness. For the next phase, Marilla bought a Weima TH1500M briquette press to compact the residue: dust and shavings are collected and sent to a 2.5-ton silo behind the building that feeds the briquette press throughout the day using a screw auger.

The briquette press was an investment, but it has provided significant returns. The briquettes that are produced are vacuum-sealed in packs of 12 and sold to a broker. The broker then sells them to various hardware stores to be used for fire starters. Barnyard Salvage produces about 8,000 of these briquettes each week.

For Marilla, one key factor in making the decision to handle waste this way was safety. Instead of using a gravity box to load a truck and send everything to be burned at a local power plant, his new system is confined and controlled. The briquette press technology uses only pressure — no glues or additives.

These machines are somewhat expensive and justifying one for a small shop might be difficult. But considering all the factors — not paying to haul waste to the dump and receiving revenue for briquettes — Marilla estimates that the payoff is just four years. After that, the new revenue and the cost savings are all profit.

Even if a shop can’t justify such a quick payback because of lower volumes of waste, there will usually be another wood-waste producer close by who might be interested in a joint purchase. If there aren’t any casework or furniture builders, then businesses such as pallet recyclers, contractors and even demolition companies come to mind. A cooperative venture might be relatively easy to arrange. After all, those businesses are facing the same challenges as the woodshop.

Biomass roots

Weima’s model WLK4 shredder.

A sharp increase in pellet and briquette press manufacturers in the last few years can, in part, be credited to the increased interest worldwide in biomass energy. All across the planet, in places where coal and oil are rare and electricity is eccentric at best, people have been scrambling for centuries to find enough fuel to cook. Vast regions of the globe are devoid of trees and, in those areas, biomass briquettes are contributing in a big way. Lightweight and easy to handle to transport, briquettes can be manufactured from grasses, grain crop residue, leaves and a host of other green waste sources. They’re very quickly renewable and, compared to fossil fuels, they produce very low volumes of greenhouse gas emissions.

For a woodshop, the benefits of this movement are substantial. High demand has led to lots of technical innovation in this field, so turning a shop’s waste into a marketable commodity is constantly becoming more efficient. Larger production runs of presses and more manufacturers (especially in China) in the market are two trends that tend to lower the cost of investing in a briquette press.

RUF Briquetting Systems is a German manufacturer of presses that has been in this market for more than 30 years. This company echoes the point that briquettes save space, time and costs in handling, storage and transportation. But RUF also adds a few less palpable impacts of shifting from landfill to recycling. For example, most presses require little or no human interaction during the course of a day, so there are some minimal personnel cost savings. Briquettes, the company says, not only command a higher price than loose waste in a dumpster, but they are also far more marketable. In most cities there’s only one landfill and a few power plants or paper factories, but there are literally thousands of businesses and even individuals who can burn briquettes.

Biomass Briquette Systems is a privately held company in Chico, Calif. On its website, under “listings,” is a briquette exchange. Here, the company provides a free service that allows registered buyers and sellers of briquettes to meet and exchange information. In May, the first listing that showed up was a Colorado company that was offering hardwood briquettes for $80 a ton and could supply 4,000 tons a year. A new producer in New York City was seeking to partner with a manufacturer of green fireplace logs. And a shop in Kentucky was looking for somebody with a briquette press to handle eight to 10 tons of MDF dust every two weeks.

As landfill space becomes more expensive, the concept of installing a wood-waste processing system right at the woodshop will become increasingly appealing in the next few years. And when oil prices rebound (and they will), the costs of both hauling and heating will hurt again.

Contact information

• Biomass Briquette Systems. Tel: 877-474-5521.

• RUF Briquetting Systems.

• Weima America. Tel: 803-802-7170.

This article originally appeared in the June 2016 issue.

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