Utilizing Urban Wood Waste

As efforts to conserve and recycle natural resources increase, urban wood waste utilization projects are becoming more popular in cities across the U.S.
By Meghan Martin | February 22, 2016

Utility companies trim trees along the highway in order to avoid interaction with electrical wires, city governments cut down dangling branches in local parks to ensure safety of visitors, and when a big storm hits, felled limbs and debris are bundled and picked up by garbage companies. But where does this urban wood waste go? Most times, it is either openly burned or sent to the local landfill.

As efforts to conserve and recycle natural resources increase, urban wood waste utilization projects are becoming more popular in cities across the U.S. These projects take urban wood waste from tree removals, untreated salvaged lumber and scrap wood from pallets or crates, nonmarketable limbs and stumps, dying trees and trees infected by invasive insect species in order to give the wood a second life and communities a new source of thermal energy.

Urban wood can fuel entire cities, and provide a clean alternative to other types of heating fuels such as coal and heating oil. For example, St. Paul, Minnesota, has had great success in using urban wood to heat 80 percent of its commercial, residential, and industrial buildings in the downtown area. Heat is provided by District Energy, which operates a hot water district heating system. The primary source of hot water comes from a combined-heat-and-power plant (CHP) that is primarily fueled by urban wood residues.

When Dutch elm disease started killing off St. Paul’s urban forests, the CHP plant proved an ideal opportunity for the city to reduce reliance on coal, while simultaneously reducing unhealthy particulate emissions and saving taxpayer dollars that would otherwise be spent on hauling the diseased trees to landfills. St. Paul is not the only example of using what would otherwise be considered wood waste as a productive source of energy and a savings of public funds. 

 Colorado’s Boulder County is working on installing a biomass burner in its jail, in order to provide heat for more than 450 inmates. This facility is to be powered by wood thinnings from nearby forested land, not only reducing the jail’s carbon footprint, but also lowering the likelihood of forest fires or reducing the intensity of those that might occur.

The reuse of waste wood is not simply limited to its use as a source of thermal energy. As communities look to better utilize resources that were once considered valueless, they are now transforming it into a host of products from mulch to furniture. For example, in 2014, members of Chicago Sculpture International partnered with the Chicago Park District to transform sick and dying trees into public art. These trees can now be found in an array of parks in downtown Chicago; they vary from stumps embellished with mirrors and yarn to carved masterpieces that brighten the city’s public spaces.

Similarly, the furniture industry is increasingly using recycled wood, in addition to lumber harvested from plantations. For example, Starbucks Coffee Co. is making its stores greener through recent renovations that include new tables and chairs built from recycled wood. Local furniture manufactures are starting to use urban wood from trimmings to create cabinet doors and shelving units. Thrifty individuals are even creating their own coffee tables and household décor from urban wood found around their towns.

While urban wood utilization projects are effective in conserving natural resources, increasing the number of jobs in a community and displacing coal, certain roadblocks can be encountered. In the case of using urban wood for mulch, there are environmental concerns around the recycling of wood that has been treated with chemicals. These chemicals can leach into the soil; therefore, measures must be taken to ensure that the wood being used is free of harmful elements. Facilities that rely on urban wood waste for energy sometimes struggle to have enough wood to keep it running, but in cases like St. Paul, these facilities can use a backup source of timber such as material provided by state’s forestry industry.

As the popularity of these types of projects increase, communities throughout America will continue to see nature-inspired art and a decreased dependence on coal and other nonrenewable sources of energy. The artistic and practical usage of urban wood waste is helping to engage creative, scientific, and environmentally focused minds in moving toward a path of sustainability in urban settings.

Author: Meghan Martin
Clean Energy Fellow, Biomass Thermal Energy Council