When a construction and demolition (C&D) recycling facility separates wood from other processed debris, it can be used as mulch, compost, alternative daily cover (ADC) for landfills and biomass fuel.
Biomass fuel is processed wood that can be used to produce heat, electrons, biochemicals or bioproducts. According to Jordan Solomon, president of Toronto-based biomass feedstock supplier and consulting firm Ecostrat, these byproducts have a number of applications: Electrons can be used in a power plant to produce electricity; heat can be used in thermal applications, such as for heating a building or greenhouse; biochemicals can be used to produce specialty chemicals such as ethanol; and bioproducts can be used to produce mulch, panelboard or particleboard, or sound barriers that could be mixed with cement for highway construction.
“The wood fiber part of the C&D stream can be used in a number of different applications,” Solomon says.
Catch and release
Biomass fuel is produced when wood fibers from the C&D stream are sorted and crushed or ground. The process of crushing can be as simple as driving an excavator over the debris and using a grapple to put it in a truck.
“Otherwise, they take it, segregate it at the MRF (material recovery facility) or bring it in as segregated wood waste in 40-yard containers at the transfer station, and they will put it in a grinder and process it to different sizes,” Solomon says. The sizes usually range from 3 to 6 inches but can vary depending on the application.
According to Solomon, the value of biomass feedstock depends on its cleanliness and the availability of local markets.
“The cleaner it is, the higher the value is,” he says. “If it has metal in it or dirt or concrete, it perhaps becomes valueless. If you put it in a MRF and positive pick the lumber from the stream, grind it, put it through a wash tank to get out the grit, you can move it to some high-end markets like mulch or particleboard where it can run $70 to $80 per ton.”
In terms of generating a product that has demand, Solomon says geographical factors can be important, “The feedstock that works best depends on the markets available,” he says.
An example he provides is in Chicago, where there’s “almost no” market for C&D wood, except for ADC for landfill. “They don’t care if there’s grit, plastic or it’s mixed with painted wood or contaminated wood,” he says. “The best biomass [use is the one] that meets the specifications of the top-paying and most reliable customer.”
Solomon says using biomass fuel can make good business sense depending on the customer.
“In many cases, [locations that use biomass fuel] qualify for environmental credits,” he says. “In Canada, they qualify for certain subsidies. In Detroit, some of the wood-to-energy facilities have significant subsidies because they use biomass fuel.”
Solomon added that finding uses for biomass fuel is also good for the environment since it is carbon neutral because of its source, whereas “if you use fossil fuel to create power or heat, you burn it and contribute to global warming because you’re [releasing] a net carbon into the atmosphere."
Biomass fuel, particularly wood fuel, is carbon neutral because, unlike fossil fuel such as coal, oil and natural gas that has been sequestered in the earth for years and removed from the carbon cycle, biomass fuel uses material that is in the carbon cycle.
“When you’re using a tree, that tree grew and sucked about one ton of CO2 (carbon dioxide) out of the atmosphere,” Solomon says. “Had that tree fallen in the forest, it would have released its carbon into the atmosphere. If you use it as fuel, it holds in the carbon and releases it when it’s burnt. So, the CO2 is released regardless of how it is used.”
Keeping it stable
Solomon admits that while economic and environmental benefits exist with using biomass fuel, there are logistical and market-driven challenges. Storing biomass fuel and feeding it into a combustor is more challenging than using fossil fuels, which only require the flick of a switch.
“If you use C&D wood, you have to pile it in the back. It’s unsightly, it gets rained on, you have to go out in the winter to load it. It can spontaneously combust, become contaminated,” he says. “When there’s a price differential, companies will switch.”
Solomon cites an example of how owners of greenhouses with 15 acres under glass might endure keeping a stockpile of wood on hand and feed it into a combustor seven to 10 years ago when natural gas prices were spiking. But when oil drops to $60 per barrel with little chance of it increasing anytime soon, there’s less of an incentive.
Because of these challenges and the lack of consistent federal and state subsidies, Solomon says there are no new markets for biomass fuel. However, those markets that opened when natural gas prices were high remain up and running.
“If you want to open a market for biomass fuel, you need to go to a market that’s currently operating and using virgin wood fiber,” he says. “If you go to a paper plant that’s been using biomass fuel for 30 years and using virgin wood, you can tell them that you’re positive picking, cleaning it up to [specification], then you can convince them to use C&D wood.”
Markets have been stable for the past five years, but fluctuations can be caused by end users ceasing operations. Solomon cites power company NRG Energy’s Buffalo, New York, power plant that was shuttered about two years ago. “It crushed the price of wood fuel,” he says.
“The biggest thing that affects the cost of wood fiber is loss of markets or a new market that can drive the price of wood fiber,” Solomon says. “Everything is so locally affected—it’s not affected by the price of oil or other macroeconomic factors as much, it’s all within geographic markets.”
Finding the answer
Solomon says market factors could be stabilized if there were a long-term offtake for clean power, but cites the cheaper price of renewable energy sources like solar and wind as a blow to the biomass fuel market.
When the California government set renewable power requirements, power plants like Duke Energy were told they needed a certain percentage of the power they produced to come from renewable sources. When these requirements were first put into place, Solomon says, biomass fuel was booming.
“Now, it’s cheaper to create energy from solar, so now Duke Energy isn’t renewing its contract with the power plant because it’s cheaper through solar,” Solomon says. “[The government] provides huge subsidies for wind and solar, but the subsidies for biomass aren’t even close. Because of that, wood can’t compete.
“That’s what would have to happen [for biomass to become more viable],” he continues. “The government would need to support power made from wood fiber and biomass.”