Though it is often ignored in national conversations about renewables, wood energy dominates renewable energy portfolios in many developed countries—and is poised for exponential growth. Francisco Aguilar sets the record straight about this salient energy source.
Considered to be the first form of energy harnessed by humans, wood was long the primary source of heat and illumination for people in every corner of the globe. Today, it is estimated that more than 2 billion people in developing countries rely primarily on wood and other forest products for their daily cooking and heating needs, causing the public to associate the use of such resources with tropical deforestation and poverty. Meanwhile, energy headlines in developed economies have been dominated by stories about coal and oil since the mid-1800s, making it easy to forget that the exploitation of those fossil sources by humans has been a relatively recent development.
Both ideas—that energy derived from forests is used primarily in developing nations and that its importance in the energy portfolios of developed economies is negligible—fail to capture the reality of current energy markets. Wood energy represents the leading source of renewable energy in many developed countries across North America and Europe. And in the United States, wood energy accounts for 25 percent of renewable energy consumption, second only to hydropower and more prominent than wind and solar energy. This high level of generation has been achieved thanks to healthy forest resources supported by a combination of recent market and policy developments.
Wood Energy in the Twenty-First Century
The term “wood energy” refers to energy derived from solid, liquid, and gaseous wood fuels, including raw firewood, processed charcoals, pellets, briquettes, residual fibers, and black pulping liquors. Some of these fuels can be sourced directly from forests or indirectly as by-products from the wood processing and pulp industries, whereas others can be created from processed wood products that are recovered and repurposed at the end of their consumer life cycles. About 58 percent of wood fuels across the United Nations Economic Commission for Europe (UNECE) region—a group of 56 countries that includes the United States, Canada, European nations, the Russian Federation, and the Commonwealth of Independent States—come from indirect sources. The rest are attributed to direct sources (32.9 percent), recovered wood (3.8 percent), and unspecified supplies (5.4 percent).
Wood fuels are ultimately converted to energy through combustion using one of three main processes. Direct firing or co-firing with other fuels—such as coal—is likely the method most familiar to consumers and requires the least amount of pre-processing in order to render fuels usable. Woody feedstock can also be biochemically transformed (using chemicals or enzymes) into sugars for the production of biofuels, or thermochemically transformed (using heat, pressure, and catalysts) into biofuels and other co-products.
The wide range of feedstocks and conversion processes available today allows for a diversity of sectors that manufacture and use wood energy. Forest-based industrial producers, such as pulp and paper manufacturers, burn wood-based fuel to generate electricity or heat used internally to support production. So do plants designed to generate electricity or combined heat and power to sell to third parties. And residential consumers use wood-burning fireplaces or pellet stoves for home heating. Technological progress has allowed an increase in energy output while reducing the amount of associated pollution, including particulate matter, that limited wider adoption in the past.
Modern Wood Energy Markets
One of the most comprehensive sources of information about wood energy markets in developed countries comes from the Joint Wood Energy Enquiry, a survey of wood energy consumption in the UNECE region. The most recent results, from a 2011 Joint Wood Energy Enquiry answered by 27 UNECE member countries, revealed that wood energy accounted for 3.3 percent of the region’s total primary energy supply (Figure 1). Although absolute wood energy consumption tends to fluctuate in the United States and Canada, the European Union has experienced an increase in consumption of more than 104 percent in the last two decades. Notably, the share of wood used for energy jumped during the recent recession, suggesting that energy production may have provided an alternative market for wood fibers while demand for more traditional products, such as paper and cardboard, declined.