A Clean Solution to Global Wood Waste

Burning and then re-burning wood waste as an environmentally friendly disposal method

Aerial view of an Air Burners unit burning wood waste
Aerial view of an Air Burners unit burning wood waste
Air Burners

At the beginning of this century, the US Forest Service approached Air Burners to evaluate the Air Curtain Burner (ACB) as an essential tool for forest fuels management. They published the results of their inquiry in several often-cited reports supporting ACB as an effective way to manage forest fuels for forest fire mitigation; create defensible zones between homes, businesses, public facilities, and the woodlands; and clean up dead trees produced by post-fire cleanup measures, forest rehabilitation, and removal of invasive species.

Disposal of woody and vegetative biomass is a worldwide problem. According to agencies like the US EPA and the World Bank, it accounts for about 20–30% of all waste. In 2014, US EPA reported that, in the US, approximately 70 million tons of “urban” biomass waste was collected, and only 30% was recycled. The balance went into our already at-capacity landfills.

Forestry, parks, and waste management organizations know that current practices aren’t working—expensive options like chipping and grinding are harmful to the environment, require large quantities of fuel and energy, and still leave the same amount of biomass in the end. Open burns also aren’t sustainable because they create air pollution and the release of too much particulate matter, posing a threat to our health and air quality.

One option available today is the air curtain burner (ACB). The ACB was designed principally as an air pollution control device. They provide an alternative to open burns and support the burning of wood and vegetative waste quickly and cleanly. The waste material is allowed to burn naturally: no hydrocarbon-based fuels are used to support combustion. The primary objective of an ACB is to reduce the particulate matter (PM), or smoke, which results from burning clean wood waste. Using a technology that employs a high velocity “air curtain,” they trap the smoke particles and re-burn them, reducing them to an acceptable limit as per US EPA standards. Air Burners technology meets some of the most stringent environmental regulations in the US and around the world. They are the only machines tested by the US EPA, the US Forest Service, the US Department of Energy, and the US Armed Forces to prove their specifications and performance.

Air Burners FireBoxes arrive fully assembled and ready for use. They are built on a strong steel skid base, allowing you to drag the ACB around your site if necessary. The burn chamber is lined with thermal ceramic panels, containing the fire and protecting your system. You can easily transport your FireBox on a flat deck or Lowboy trailer, or you can opt for the BurnBoss, a trailer-mounted FireBox. To lower your operating costs, our diesel-powered machines only consume .35 to 2.1 gallons of diesel fuel per hour depending on the machine. No other fuels are required.

Ms2001 26 1The Air Burners’ PGFirebox reduces wood waste by 98%.

Should we make power from this wood and vegetative waste material? In 2015, the US EPA reported that, of the 16.3 million tons of wood waste generated, only 2.5 million tons were converted to energy recovery via combustion methods. When you consider the amount of energy stored in wood, it only makes sense to extract this energy instead of depositing it in a landfill and losing it forever. Wood has been used as a fuel for centuries but extracting its energy on a large scale has been cumbersome and expensive.

Because we have not invested in developing technology to produce biomass energy, the industry lags far behind wind and solar. But unlike wind and solar, we must solve this waste problem. So why not develop technology that helps eliminate the waste and produce biomass energy? Biomass power generation has always been economically difficult due to 1) the high costs of preprocessing the waste material generally requiring two grinding processes to prepare it for the grinder; 2) the high costs of transporting the waste material; and 3) the high capital costs of the initial installation.

Air Burners Inc. has developed a system that addresses most of the difficulties surrounding today’s biomass energy systems. The PGFireBox system does not require the waste material to be preprocessed and will accept whole logs, branches, and roots. It is a portable system and does not require any permanent facilities. This significantly reduces the upfront costs as well as allowing the system to be moved in a few years when the wastestream is reduced. This system is available in power-generating capacities of 100 kW to over 1 MW.

The Power Generating FireBox accomplishes five important tasks:

  1. It reduces wood waste by 98%. 10 tons of logs produce a few hundred pounds of ash. This remainder is clean, natural ash and biochar—a highly desirable recycled product for agriculture, growers, and nurseries.
  2. It captures energy from the wood waste and converts it to electricity, providing an additional income from its use or sale and thus reducing our dependence on coal and oil.
  3. It is an ideal component for a power company’s goal of better “distributed power.” Distributed power helps provide a more secure electrical grid less susceptible to interruptions.
  4. It significantly reduces greenhouse gas emissions compared to the current methods of disposal, grinding, and landfilling.
  5. It is easily relocated. One of the major problems for biomass energy is the Waste Travel Zone—the distance waste must travel to the biomass facility. It is not uncommon for a permanently placed biomass energy plant to close because it has become too costly to transport the waste.

The residual of this natural burning process is a product called “biochar.” Biochar is an important soil component that should occur naturally, but in the dying forests, it is no longer found. Using air curtain burners to tackle our wood and vegetation problem, biochar is naturally created and can be spread onsite—or it can be collected for use and resale. Biochar is considered an important part of forest health—so much so, in fact, that the US Forest Service entered into a Cooperative Research and Development Agreement with Air Burners Inc. to look at enhancing the production of biochar while using an air curtain burner in the wildfire prevention efforts. Today, some customers of Air Burners are collecting their biochar from each burn and selling it to biochar brokers. Currently, these brokers are paying $125 to $150 per cubic yard. Biochar from an air curtain burner is desirable because it is created naturally without any contamination from hydrocarbon-based fuels.

Ms2001 26 2An Air Burners Burn Boss shows its mobility.

As a global community, we should be investing in biomass energy because we have an enormous waste problem to solve—a problem that is only getting worse. We can’t continue to deplete our energy sources grinding and hauling this waste material. We can’t continue to create the emissions from processing this waste material. We can’t continue to overload our landfills with a waste material that was one of the first energy sources on our planet. We do not need to drill for oil or dig for coal, but we do need to eliminate wood and vegetative waste. Let’s put this waste to work for us. 

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