Into the Woods

Forests are our master recyclers, guardians of the air, water and soil – the very lungs of the planet and iconic symbols of the beauty and power of nature.

Forests also store vast amounts of carbon and energy. For more than a million years, wood was our major source of energy until it was usurped by coal in 1850. Globally, at least 2 billion people still use wood for heat and cooking.

Now, as fossil fuel supplies become more difficult to extract and energy needs soar, scientists are again looking to the forest as a source of energy – one they say pollutes less than coal or oil. Right now, the resurgence in wood bioenergy is just getting going. In the United States, it accounts for just 2 percent of total primary energy consumption, but that could soon change.

Many nations and states are issuing renewable electricity standards, requiring as much as 20 percent of power to come from low-carbon, renewable sources and offering feed-in tariffs and carbon credits to get there. Wood-based bioelectricity could be an important part of that renewable energy mix. With its consistent supplies, wood provides an alternative to nuclear power by complementing renewables such as wind and solar, which can only produce energy intermittently.

Combine this with a drop in demand for wood products, especially paper, and the result is a perfect storm of economics and energy policy spurring bioenergy. Power plants making electricity from woody biomass and other agricultural feedstock are cropping up around the world, with 180 operating in the U.S. alone, and more awaiting approvals. With modification of currently operating plants, wood may also displace some coal. Several studies, including a 2012 report from the Union of Concerned Scientists, project that 680 million tons of biomass from various plants could be available every year by 2030 – enough to produce 19 percent of U.S. electricity consumption at its current level.

In Finland and Sweden, where approximately 65 to 75 percent of the land is covered in boreal (northern) forest, bioenergy already contributes 19 percent of total primary energy, according to a UN report. With its vast boreal forest, Canada exports about 1.3 million tons – or 84 percent – of its wood pellets to Europe for bioenergy. Meanwhile, it uses wood waste and residues to power its own pulp and paper mills and provide community heat and power in some rural areas.

In addition, scientists may be close to efficiently converting woody biomass into transportation biofuel. In the not too distant future, some estimate, energy from biomass could displace 19 to 30 percent of our fossil fuels use.

By 2022, waste wood alone could produce 2.8 billion gallons of advanced biofuel

“Woody biomass has tremendous potential, if sources such as forests are managed properly,” says Evan Delucia, a forest ecologist and professor of plant biology at the University of Illinois. “We aren’t there yet – we don’t have the technology for wood-based fuels – but we’re close. It’s within reach.” (See Delucia interview, "Why I'm a Grass Guy")

A Burning Controversy

Tapping forest biomass for electricity, however, has become at least as controversial as using food crops for biofuel. “There’s great trepidation about using forests for energy,” says Delucia. “People think of the iconic forests – the old growth forests – and the whole litany of good services they provide.” In addition, some scientists and environmentalists assert that wood for energy may not be sustainable.

“We started to have some real concerns about the use of this energy source,” says Kevin Bundy, senior attorney at the Center for Biological Diversity. “We’re going to end up in a situation where we’re putting excessive demands on the forest, with damage to wildlife habitat, with damage to water quality … and also potentially making the climate problem worse in the name of making it better.”

Unlikely, say forest managers such as William Stewart, co-director of the Center for Forestry, Agriculture and Natural Resources, University of California, Berkeley. “Forests have been harvested for bioenergy long before it became a controversy,” he says. “They benefit from thinning, and they are healthier because there is less competition for water and nutrients.”

The Dogwood Alliance, the Center for Biological Diversity (CBD), the National Resources Defense Council (NRDC), the Global Forest Coalition, Friends of the Earth International, Greenpeace, and others vigorously oppose the use of whole trees from natural forests for bioenergy. But The Nature Conservancy and the World Resources Institute support managed forests and using thinning and selective cutting for bioenergy, and the Environmental Defense Fund is exploring “pathways to sustainability” for forest biomass exports to Europe, including forest certification and mixed sourcing.

In addition, some non-governmental organizations (NGOs) support certain uses of woody biomass but not others: the NRDC, for example, sees potential in plantations of fast-growing trees, like willows or poplar, but draws the line at replacing natural forests or grasslands with tree plantations. The Sierra Club also supports using existing tree plantations but has “deep concerns” about wood waste projects in natural forests.

Laurie A. Wayburn, co-founder, co-CEO and President of the Pacific Forest Trust, has impeccable environmental credentials. A “green diaper baby” (her late father, Edgar Wayburn was a many-times-over president of the Sierra Club), her organization has conserved more than 70,000 acres of Pacific forestlands, and she and her family live part-time off the grid in Mendocino County, Calif.

But unlike some environmentalists, she and her organization view forest management as a key to their preservation.

“We promote the use of restoration waste materials for small-scale energy generation,” she says. “We show how it can be applied in a way that is demonstrably beneficial in terms of forest health, as well as lowering net carbon emissions over time.”

The U.S. forests are in bad shape, she says, especially those in states where there are often 20 to 30 percent too many trees to the acre that need to be selectively thinned to improve forest health. “Even if we find other energy sources, we still have to manage our forests, to help them be healthy and resilient. We need them for all the things they give us and to balance our climate. Why not use the waste products from managing and restoring them for energy?”

The Carbon Question

Perhaps the most burning woody biomass controversy centers on carbon. Far from being carbon neutral, some researchers and environmentalists say, it creates a “carbon debt” – both by removing trees that recycle CO2, and then through burning that releases CO2 stored in the biomass.

The arguments reflect several crucial factors in the life-cycle of wood biomass to electricity. One factor is energy density. For example, it takes more woody material to produce the same electricity output as coal because wood contains more water and the carbon is more oxidized. “Biomass-fueled power plants emit significantly more CO2 at the smokestack per kilowatt produced than power plants that burn fossil fuels — even coal,” says Kevin Bundy of the CBD.

This argument has been promoted by the much-quoted statement from the “Forests Are Not Fuel” campaign of the Dogwood Alliance, which contends: “Burning trees for electricity creates more carbon pollution than coal, gas and oil. It’s a dirty process.”

But that is not a complete view, according to Heather Youngs, a scientist with the Energy Biosciences Institute at UC Berkeley. “It’s true that old biomass boilers are about 10 percent less efficient than the current average for coal plants,” she says. “The difference is that fossil carbon adds to the atmospheric load. With biomass we have a chance to recover energy from the natural carbon cycle, if we manage things well and keep the long-term life cycle in mind.”

So the question is, what would have happened to the carbon sequestered in the wood or forest without bioenergy? Whether harvested or not, the turnover of any plant, including trees, is part of the life and carbon cycle. “Trees are always growing and getting old and dying,” Stewart says, “and as they decay, they emit CO2 and other greenhouse gases like methane anyway.”

What has happened in the Canadian boreal forest over the last 20 years is a striking example. Normally the forest is a healthy carbon sink, removing from 120 to 150 million tons of CO2 from the atmosphere each year. However, there have been several years where the forest actually emitted millions of tons of carbon instead. In 1995 and 1998, forest fires were the cause, but from 2002 to 2004, the emissions were triggered by trees dying from pine beetle infestations worsened by climate change.

Stewart contends that forest management means that trees “aren’t just rotting in the forest,” giving off CO2 without any energy advantage. Instead, some trees and residue from harvest could be used to replace fossil fuels such as coal and oil.

Firefighters in helicopters; photo credit: iStock by Getty Images. Thomas Tidwell, USDA Forest Service chief, has testified that “on average, wildfires burn twice as many acres compared to 40 years ago...The last two decades have seen fires that are extraordinary in their size, intensity, and impact.”

It will take a while before Life Cycle Assessment (LCA) determines the true costs of using woody biomass. It’s true that trees stop absorbing CO2 when they are cut, and they do release that carbon when harvested and burned, says John Stanturf, U.S. Forest Service senior scientist. But the important thing, he says, is that “this carbon offset is fast cycling, from living biomass to atmosphere back into living matter. Fossil fuels are stored, they’re relic carbon, and not offset by uptakes” – in our lifetimes, at least. (See "Manomet: The Storm Over Carbon Accounting").

Taking Inventory

While deforestation is still an important issue in some developing nations, some forests are seeing substantial regrowth. In the U.S., an estimated 72 percent of the land that had been forest in 1630 was again wooded by 2007. The same is true in Europe and some parts of Asia, where forest areas have been steadily increasing over the last 20 years.

It’s not just acreage that has increased in the last few decades. The standing inventory of trees has also increased. In the U.S., lumber sales are down, due in part to the recession and the drop in new housing. The market for newsprint and other paper products has also been flat-lined since 1999 for reasons that include the demise of many newspapers, the boom in electronic advertising, and campaigns to reduce paper packaging. Hundreds of mills have shut down in the U.S. – 450 in the Southeastern states alone since 2005 – putting thousands out of work.

The loss of some wood markets offsets the increased use of wood for fuel, says Stewart.

He and others have pointed out that U.S. forest biomass actually increased 10 percent between 1997 and 2007.

Some forests have also gotten more crowded.

In California, small trees, which act to fuel forest fires, have increased as the state’s forests continue to age without regular maintenance. Density has increased from 70 trees per acre in the early 1900s to 400 trees per acre with high mortality, while timber harvest has decreased 90 percent in the last 25 years.

Annually, 230 million tons of the 24.4 billion tons of standing forest biomass is harvested each year, less than 1 percent of available biomass and less than 60 percent of annual growth.

The warming climate, overcrowding and piles of dry forest residue contribute to the recent intensity of forest fires –which release huge amounts of carbon with no energy benefit, at great costs and loss of property and lives. Estimates of carbon emissions from wildfires range from 1-2 percent to roughly 25 percent of total emissions. The Nature Conservancy (TNC) has joined with forestry organizations in calling for proactive forest management and thinning.

2011 Status of U.S. forest products industry
Hundreds of mills have shut down in the U.S. – 450 in the Southeastern states alone since 2005 – putting thousands out of work.
credit: Pulp & Paperworkers' Resource Council, 1991-2011

But many environmentalists, including the John Muir Project of Earth Island Institute, say that forest fires have a place in forest ecology, and when human lives and buildings are not endangered should be left to burn.

The debate is bound to resurface. As of September 2013, 34,000 wildfires from this year alone has burned property, damaged sensitive habitat, and taken lives. This summer's Rim Fire raged through California’s Sierra Nevada into Yosemite National Park, burning over 400 square miles for more than two months. With wildland fire suppression costs consuming about 40 percent of the Forest Service budget, it is easy to understand why states are considering woody bioenergy a viable option.

Using forest debris, slash and other wood waste for power is already on the rise in some rural areas where forests abound but natural gas isn’t easily available. The decline of the timber market has left overgrown and fire-prone forests in rural Oregon, where woody waste that might have been burned by the roadside is being used to heat a dozen country schools in high-efficiency stoves that have significantly lower emissions.

But woody biomass doesn’t come exclusively from whole living trees—one of the hot buttons for many environmentalists. Other sources include products that would otherwise be wasted, including clean construction and demolition debris that would end up in landfills; leftovers from lumber, paper and pulp mills which have traditionally been burned to power machinery at those sites; and logging residue such as branches, trimmings and other debris known as slash.

Sacramento-based Greenleaf Power LLC, for example, makes and sells 120 megawatts of electricity at several California power plants by specializing in recycling woody waste and other biomass leftovers from tree trimmings, construction and agriculture. They own no land and use no whole trees, says president and CEO Hugh Smith. (See our web exclusive, “Avoiding the Landfill,” for more.)

Environmental groups are split on this issue, with most supporting recycling of woody waste, although they express concerns about emissions and other unintended consequences of wood waste to energy.

In Upstate New York, Cornell researchers using waste left after timbering for bioenergy, including tree tops and branches, discovered that collecting it left unprotected seedlings that were rapidly eaten by an over-population of deer. They found that leaving more of the slash protected the saplings – and the future forest – from the hungry herds.

The Matter of Scale

But even as new biomass plants are being built, economics may stand in the way of wide scale use. It takes a lot more wood mass than coal to create energy, and the costs for woody biomass are significantly higher than fossil fuels. This challenge is highlighted in California where, according the University of California, “(Biomass power) facilities may stop operating if prices drop or if they have difficulty sourcing enough fuel.”

Wayburn of the Pacific Forest Trust argues that to be most effective, the big energy grids could be supplemented with decentralized, small-scale power plants in forested areas of the U.S. – one-third of the country – using nearby forest and wood waste materials to generate the smaller amounts of heat and electricity that can fulfill local, mostly rural needs. Larger-scale energy demands could be met by aggregating the small plants, she adds.

“If you took some of the people in those areas off the (big) grid with small-scale power plants, you could lower our carbon footprint and our dependency on fossil fuel, revitalize many rural communities with homegrown energy and jobs – and restore our forests,” Wayburn says.

The U.S. Forest Service’s Stanturf concurs, musing that perhaps the most efficient biomass set-up would be a short-rotation tree planation next to a bioenergy plant, producing energy for regional use. Take willow shrubs, for example. They can be harvested every three years, rapidly sequestering carbon equal to that released when they were harvested. They can also be grown on marginal cropland as an alternative to converting natural forests, an idea the NRDC supports.

“I think managing our forests for truly healthy forests and habitats is an important public priority,” says Nathanael Greene, director of the NRDC Renewable Energy Policy. “This is not about not touching the forests – it’s about not pretending that cutting trees is good for the climate without figuring out the true costs.”

Can Regulation Prevent A “Biomess”?

Perhaps the biggest question for woody bioenergy is whether policy can mend the gap between those who see an underutilized resource that can address climate change and provide other sustainability benefits, and those who fear that our forest will be pillaged to feed our energy addiction.

Right now, Sustainable Forest Management (SFM) regulations are a patchwork at federal, state and local levels. California has the most comprehensive set of bioenergy policies in the U.S., if not the entire world, much of it focused on the reduction of greenhouse gas emissions, says Jody Endres, an assistant professor of law at the University of Illinois’ Department of Natural Resources and Environmental Sciences. (See “Tangled Up in Green”)

Confounding the issue of management and certification is the problem of regulating privately owned lands. More than half of U.S. forestland – 56 percent – is privately held by individuals, tribes and corporations. Public lands are subject to some restrictions that don’t apply to private lands. But if the public wants restrictions on the use of private forests, some argue that private landowners should be reimbursed for giving up potential revenue.

“Some environmental groups are very skeptical of the concept of a working forest; instead, they say there should be areas where biodiversity is preserved without significant disturbance,” says Endres. “Ecological boundaries don’t respect legal boundaries, and vice versa. The question from landowners is justifiable: Who is going to pay to set up ecosystem services for the common good that go beyond what is good for the economic bottom line?”

Central Massachusetts images, 1880s (top) and the same scene in 2000 (bottom). credit: Harvard Forest

Perhaps we need to strengthen persuasion at the consumer end, say Delucia and many others, by vigorously requiring certification that the wood biomass is environmentally harvested and handled.

Sustainability a Mutual Goal

The search for renewable energy is fired by urgency. But when pressed for suggestions about the best energy source, environmentalists and scientists alike agree, there is no one-size-fits-all.

 “We keep looking for a silver bullet,” says Timothy Volk, a senior research associate at the College of Environmental Science and Forestry at the State University of New York. “We’re better off seeking silver buckshot.”

When it comes down to it, almost everyone is on the same side – economists, environmentalists, industry and biomass promoters alike – although they come at it from differing points of view. The same question consumes us all: How can we lower greenhouse gas emissions, protect our environment and sustain our forests, both as an essential natural resource that recycles carbon and purifies water and as a renewable source of energy? Destroying forests kills the goose that lays the golden egg. Sustainability has to be a mutual goal – for economic as well as environmental reasons.

All things considered, Jody Endres feels cautiously optimistic. “I’ve been working on sustainability standards for biomass for quite a while, and I’m optimistic,” she says. “I do see progress. We’re confronting issues systemically, and some industry officials are talking about issues that we never would have ten years ago – such as how much water will we have? How much food? How can we more fairly assess the benefits of bioenergy? Progress is in the dialogue.”

Meanwhile, sustainable harvesting is key. As Glenn Prickett , chief external officer of The Nature Conservancy, has said, “Woody biomass can be a great source of renewable energy and offers an excellent incentive so landowners can maintain their forests as forests – as long the forest is managed responsibly.”

Greg Breining and Chris Woolston contributed additional reporting.


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