In Depth

Biomass as a Source of Energy

According to the U.S. Energy Information Administration, “Biomass is non-fossil fuel material of biological origin constituing a renewable energy source.”1 Some common biomass fuel sources are wood, municipal waste and alcohol fuels. For purposes of this section, woody biomass is explored in more detail–and particularly–its use as a source of energy.

Common terms and defintions

Wood energy: is derived from the following sources: roundwood, used primarily in the industrial and electric utility sectors; woodfuel, used predominantly in the residential and commercial sectors; and wood byproducts and wood waste, which are usually used in the industrial sector.1

Woody biomass: trees and woody plants, including limbs, tops, needles, leaves, and other woody parts, grown in a forest, woodland, or rangeland environment, that are the by-products of forest management.2

Waste energy: is derived from the following sources: mass burning of garbage; conversion of garbage to refuse-derived fuel pellets for eventual burning; collection of methane gas from landfills; and burning or anaerobic digestion of wastes.1

Alcohol fuel: refers to ethanol, typically derived from corn and used primarily in the transportation sector.1

Using woody biomass for energy

The majority of the paper manufacturing industry in the U.S. uses self-generated and renewable energy for paper manufacturing.3 Most of the mills that use self-generated energy are “integrated mills”, which are mills generally defined as one that produces pulp and paper on-site. A non-integrated mills is generally defined as a mill that purchases their pulp and usually does not have access to self-generated energy most commonly derived as a by-product of the pulping process. Non-integrated mills have the choice of off-setting carbon emissions or purchasing renewable energy to power their manufacturing process.

Paper mills that are able to use biomass can reduce the need to purchase energy off the grid, which is often generated by burning fossil fuels. In some cases, the use of biomass has allowed paper mills to operate with net-zero carbon emissions when their forests are replanted depending on the calculation method. [For more on how greenhouse gas is calculated in the pulp and paper sector see the WRI/WBCSD Greenhouse Gas Protocol].4

 

The forest products industry is the leading producer and user of biomass energy and produces more energy from biomass than all the energy produced from solar, wind, and geothermal sources combined.



Source: U.S. Department of Energy (2006)3

 

Source: Canadian Industry Program for Energy Conservation (CIPEC) (2006)3

Biomass and carbon neutrality

The Intergovernmental Panel on Climate Change (IPCC) currenlty considers biomass emissions to be carbon neutral. The IPCC views biomass emissions as part of the natural carbon balance (called biogenic carbon which has been part of te Earth’s biosphere for millenia) and states that such emissions do not add to atmospheric concentrations of carbon dioxide.5 The Energy Information Administration (EIA) 1605(b) reporting instructions contain a footnote citing the IPCC guidance and stating that “reporters may wish to use an emission factor of zero for wood, wood waste, and other biomass fuels.”

Energy-rich biomass carbon – derived from wood chips, bark, sawdust and pulping liquors recovered from the harvesting and manufacturing processes – is atmospheric carbon dioxide that is transformed and sequestered by trees during their growth. When these biomass fuels are burned, the CO2 that is emitted is in fact the atmospheric carbon dioxide that has been sequestered during growth, and it becomes part of the natural carbon cycle that includes trees, air and other normal CO2 emissions. This cycle is a closed-loop: new tree growth keeps absorbing atmospheric carbon dioxide; hence, there is no net contribution to the atmospheric CO2 level.

Perspectives: Is burning woody biomass for fuel always better?

The pulp and paper manufacturing supply chain is complicated–and similar to many aspects of the paper life cycle–the answer is never a simple “yes” or “no”. Regarding biomass for energy, there are studies that question how the impacts of the use of biomass on carbon storage in ecosystems is measured.

There are two basic approaches to carbon measurements and balances.  First, basic measures of non-biogenic (fossil based) carbon discharges from all human activities like burning fuels, decomposition of wastes in landfill and industrial processes.  This is basically the simple accounting approach that the IPCC is driving globally whereby emitters just measure their fossil fuel carbon emissions.  Second, measuring all carbon discharges (biogenic and non-biogenic), all carbon uptake, and the change in carbon storage levels.  This approach is an inventory of carbon stores that looks at how much is being added by use of fuels (including biomass) and how much is being removed through sequestration into the trees, oceans and soil.

There are a number of environmental groups that challenge the notion of whether biomass should be considered carbon neutral. According to a report by the Environmental Paper Network (EPN); “The question of carbon neutrality in forest ecosystems or plantations needs to be explored on different levels, including the landscape level and the forest or plantation stand level. We are seeking to understand how our many specific activities and decisions regarding how many trees to harvest and at what intervals ultimately will lead to landscape level changes if they are widely employed.” 6

A copy of the EPN report “Carbon Neutral Paper: Fact or Fiction” is available at here.

1. U.S. Energy Information Administration. “EIA – Energy Glossary.” U.S. Energy Information Administration – EIA – Independent Statistics and Analysis. (http://www.eia.doe.gov/glossary/index.cfm).

2. U.S. Forest Service. Memorandum of Understanding On Policy Principles For Woody Biomass Utilization for Restoration and Fuel Treatments

On Forests, Woodlands, and Rangelands”. (http://www.fs.fed.us/woodybiomass/whatis.shtml)

3. U.S. Energy Information Administration. “2006 Manufacturing Energy Data Tables.” U.S. Energy Information Administration – EIA – Independent Statistics and Analysis. 2006. (http://www.eia.doe.gov/emeu/mecs/mecs2006/2006tables.html).

4. World Resources Institute and World Business Council for Sustainable Development. “The Greenhouse Gas Protocol”. Copyright 2010. (http://www.ghgprotocol.org/about-ghgp)

5. Natural Resources Canada. “Comprehensive Energy Use Database.” Office of Energy Efficiency | L’Office De L’efficacité énergétique. 2006. (http://oee.nrcan.gc.ca/corporate/statistics/neud/dpa/trends_id_ca.cfm).

5. IPCC. Carbon Dioxide Capture Aand Storage. Rep. no. ISBN-13 978-0-521-86643-9. Ed. Bert Metz, Ogunlade Davidson, Heleen De Coninck, Manuela Loos, and Leo Meyer. New York: Cambridge UP, 2005. (http://www.ipcc.ch/pdf/special-reports/srccs/srccs_wholereport.pdf)

6. Ford, Jim. Carbon Neutral Paper Fact or Fiction? Rep. Ashville: Environmental Paper Network, 2009. (www.environmentalpaper.org/carbonneutralpaper/EPN_CNPaperFINAL.pdf)