Community-Scale Biomass Energy: The Facts

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When community-scale biomass energy systems are well-designed, well-run, and sustainably supplied, it is a positive, proven, renewable energy option that can be practical and safe, can strengthen our economy and security, and can help ease the urgent strain on our planet’s ecosystem. And, in regions throughout the United States with abundant forest resources, it is available now.

Community-scale biomass energy systems burn biological material—most often wood from low-quality trees—in highly efficient, high-temperature combustion systems to produce heat. Sometimes, these systems also produce a certain amount of electric power (this is called CHP, combined heat and power). But the most efficient use of biomass for energy is to provide space heating and domestic hot water. Community-scale systems typically provide this to single buildings, such as schools and hospitals, or to groups of buildings such as college campuses, industrial parks, or whole towns or cities through “district heating” systems.

Woodchip conveyors

Community-scale biomass systems that produce heat or CHP are different from electric power plants, which are generally much larger and mainly produce electricity for broad distribution. Biomass-fueled technology is only about 20-25 percent efficient at producing electric power; at producing heat, it is 70-90 percent efficient. Power plants sometimes (though this is rare) sell the excess heat they generate, where it is economically feasible and if there is an appropriate user nearby; this is only 40-45 percent efficient. Technology is also being developed that can use biomass to produce liquid biofuels. Community-scale thermal applications are the most efficient biomass energy technologies—they do the best job of turning biomass fuel into energy, with the least waste.

Systems of this type have been in use since the early 1980s, and have built a track record of safety and reliability. Today, a growing number of community-scale systems, most fueled with woodchips and some with wood pellets, are delivering heat and hot water to schools, businesses, colleges, hospitals, city centers, and whole communities across the northern United States, Canada, and north and central Europe.

Middlebury College Biomass Facility

Biomass fuel can be used in a wide range of technologies, from home woodstoves to power plants. Because community-scale thermal systems combine high-efficiency combustion with sophisticated emission controls, this technology meets and exceeds all emission-safety standards, while providing heat energy at relatively stable fuel prices from a local fuel source.

When wood fuel is harvested responsibly from well-managed forests, community-scale biomass energy is a sustainable whole system. It keeps energy dollars circulating in the local and regional economy, by using a renewable fuel that is harvested nearby—and its carbon emissions are re-captured as the forests that supply the fuel continue to grow. In contrast, fossil-fuel systems extract carbon that is buried underground in geological deposits, then add it to the atmosphere over time.

Finally, by developing a reliable, local market for low-quality wood, biomass energy can create a new financial incentive for forestland owners to manage their forests for long-term productive health, lessening the pressure to “high-grade” (cut only the most valuable trees and leave the rest). The revenue stream for biomass fuel can help landowners make ends meet, also relieving the pressure to sell woodland for development.

Benefits of Using Biomass at the Community Scale

Modern Community-Scale Biomass Energy Systems Use Sophisticated Emission Controls
These systems burn very hot, at 70-90 percent efficiency, producing about 1/10 of the fine-particle emissions of traditional wood stoves, with virtually no smoke or odor. Modern biomass energy is far cleaner than old-fashioned woodstoves or wood boilers, and is equipped with highly effective pollution-control technology, ensuring that final emissions meet and exceed the most stringent air-quality standards.

Emission-control technology continues to develop and improve. While in recent years most systems have made very effective use of fabric filters and collection bags to screen out particulates, today’s state-of-the-art control technology is electrostatic precipitators. These powerful filters use an electrostatic charge, similar to the pull of static electricity, to extract fine particles from system exhaust.

Biomass energy systems emit 1/6 of the sulfur oxides, which contribute to acid rain, than do oil-fired systems. Nitrogen oxide emissions are about the same as oil.

When Their Fuel Is Harvested Responsibly from Sustainably Managed Forests, Biomass Systems Can Be Low-Carbon, or Carbon Neutral Over Time
Carbon dioxide (CO₂) is a major contributor to climate change—and at the stack, biomass systems emit about twice as much CO₂ per million Btu of energy produced as do oil-fired systems. But the CO₂released by biomass combustion is drawn from forests, which are continually absorbing and releasing carbon over time. If the carbon dioxide that biomass systems release into the atmosphere is reabsorbed over time by new forest growth, then biomass technology can replicate this natural cycling and provide a low- or no-carbon source of renewable energy, In contrast, fossil-fuel systems, which burn fuel extracted from underground, add CO₂ to the atmosphere. For this reason, converting from fossil-fuel to biomass energy can help lower carbon emissions and reduce climate change over time.

Woodchipping Good forest management is essential to realizing the carbon benefits of biomass energy. Key factors include: where trees are harvested, how they are harvested, how this plays out over the landscape and over time, and whether management practices support long-term forest health. It is also important that biomass energy systems be well-designed and efficiently run. When these positive factors are in place, converting from oil- or gas-fired energy to biomass can reduce net CO₂ emissions by 75-90 percent.

A Well-Managed Biomass Fuel Industry, Coupled with Sustainable Growth in Demand, Creates New Incentives to Protect and Preserve the Working Forest Landscape
The current growth in demand for biomass fuel is creating a vital new market for low-grade wood. This market provides a financial incentive for landowners to implement forest management plans, do ecologically sound forest management, keep their woods in production, and manage them for mixed use: fuel, timber, wildlife, recreation, and natural beauty. In this way, harvesting low-quality wood for biomass energy can support healthy forests as part of a working landscape.

In many regions of the United States, there is an abundant supply of low-quality wood for biomass energy. In the forested regions of the Northeast, annual new forest growth exceeds the current demand for wood fiber, including biomass fuel. As long as demand remains in balance with supply, using woody biomass for energy in the most efficient, community-scale applications can help us meet our energy needs in ways that make us less dependent on distant, not-always-stable, sources of fuel.

Image Captions (from top to bottom)

A typical below-grade woodchip storage bin at a public school.

Woodchips being conveyed from the storage bin to to the boiler room.

The 2010 installation of Middlebury College in Middlebury, Vermont exemplifies a community-scale biomass application.

Woodchips burning inside the combustion chamber of a biomass boiler.

The chipping of low-grade wood from harvesting operations in the forest.