A growing industry that’s harvesting “woody biomass” from forests for energy generation could gain a toehold soon in the Chesapeake Bay watershed. Like virtually every other form of energy, it’s also generating intense debate about its environmental impact.

Biomass from trees is already used to generate a small amount of power in the United States; wood chips generate electricity at several small plants owned by Dominion, the Virginia-based energy company. (The term “biomass” generally refers to any plant material used for fuel. Woody biomass is made from trees.)

The big demand for pellets made from woody biomass, though, comes from utilities in Europe and the United Kingdom that are trying to reduce their reliance on fossil fuels. This is driving the harvesting of low-value trees and “slash,” or debris left by logging, in the Southeastern United States, from just south of the Bay watershed to the state of Mississippi.

A spokesman for the nation’s largest wood pellet manufacturer, Enviva Partners LP, said that the company has no plans to move farther north, but added that “it’s not outside the realm of possibility.”

Based in Bethesda, MD, Enviva has a pellet manufacturing plant in Southampton, VA, about 50 miles south of the Bay watershed. It owns and is using a deepwater port in Chesapeake, VA, which is also just outside the watershed.

The company is planning to build another pellet plant in Virginia, south and west of the Southampton plant, said Enviva spokesman Kent Jenkins.

Three Dominion-owned power stations in Southside Virginia and one just south of the North Carolina border together burn 100 tractor-trailer loads daily of wood chips and other biomass taken from nearby forests, said Ernie Reed, president of Wild Virginia, a nonprofit advocacy group.

But demand in Europe dwarfs the local market for woody biomass, Reed said, and much of what’s produced in the United States gets exported.

About 5.5 million tons of wood pellets from Southeastern U.S. forests will be shipped overseas this year for energy generation in the European Union, said David Carr, a lawyer with the Southern Environmental Law Center.

Power companies there are converting coal-fired power plants to burn wood pellets to meet European Union renewable energy goals. One-fifth of their electricity must come from renewable resources by 2020 and even more by 2030. Some countries are providing subsidies to support the conversion.

But several U.S. and European environmental groups are lobbying the European Union to take woody biomass out of its renewable energy goals, Carr said.

Forests are widely recognized as the best land use for sequestering climate-altering carbon dioxide and for preventing polluted runoff of nutrients and sediment into waterways.

According to the environmental law center, using Enviva’s mainly hardwood pellets from North Carolina and Virginia to generate power in the United Kingdom releases 2.5 times as much carbon dioxide into the atmosphere as would burning coal.

Carr contended that using wood pellets to generate electricity is bad for the Earth’s climate. Trees sequester or absorb carbon from the atmosphere as they grow, so regenerating forests — either naturally or through planting seedlings — can offset the impact of logging them. But trees grow slowly, and Carr contended that the carbon dioxide released by burning woody biomass from mature forests won’t be recaptured for many decades.

Nathanael Greene, renewable energy director at the Natural Resources Defense Council, concurred with Carr’s assessment, but added that he supports the collection and use of woody biomass for one purpose: bio-jet fuel. But the deployment of any other green technology capable of powering commercial aircraft is at least 30 years away, Greene said.

The industrial wood pellet industry maintains that when all aspects of preserving working forests and replanting logged-over tracts are taken into account, generating electrical power from wood pellets produces much lower greenhouse gas emissions than coal.

Seth Ginther, executive director of the U.S. Industrial Pellet Association, said the industry is “actually expanding forest cover, among other things, by giving forest owners a financial incentive to maintain working forests and stay in business — rather than [cutting them down] and selling out to developers or other non-forest land users.”

And, Ginther noted, “One of the biggest threats to the Chesapeake Bay watershed is the conversion of forest areas to non-forest uses, including urban sprawl and real estate development.”

The National Renewable Energy Laboratory, an arm of the U.S. Department of Energy, sides with the industry in part, saying that using biomass for energy has the potential to greatly reduce greenhouse gas emissions.

Burning fossil fuels like coal and oil releases carbon dioxide captured millions of years ago; creating essentially new greenhouse gas. In contrast, the laboratory says on its website, burning biomass emits carbon dioxide that is in a matter of years offset by the regrowth of forests cut to produce it.

But in an added observation that seems to buttress critics of the industry, the laboratory says that “recent studies have found that clearing forests to grow biomass results in a carbon penalty that takes decades to recoup, so it is best if biomass is grown on previously cleared land, such as under-utilized farm land.”

The analysis does not address the impact of taking biomass from the debris left on the ground after a forest tract has been logged for timber. Nor does the NREL examine the question of whether the extra income forest owners receive from biomass collection leads them to stay in the business, instead of selling out to developers or farmers.

One peer-reviewed study of the issue cited by the pellet industry suggests that hardwood forest owners will switch to raising softwood pines, which regrow much faster, in as little as 20 years in warm climates.

Another study by the U.K. Department of Energy and Climate Change offered several scenarios, including a benign one based on an expansion of forest cover in the Southeastern United States. But the adverse scenario found that the use of Southern U.S. wood pellets to fuel U.K. power plants would have life-cycle greenhouse gas impacts worse than coal.

Carr said the pellet industry has no qualms about using wood from clear-cut forest parcels adjacent to water bodies, pointing to an SELC photo showing a denuded forest parcel adjacent to the Roanoke River.

Enviva spokesman Jenkins said the photo has been “recycled by environmental groups for years” and does not reflect Enviva work.

Wood pellet manufacturing facilities generally tap forests within a radius of 100 miles of each plant and sometimes more, Jenkins said. The facilities are located within a similar range of deepwater ports, as the products are heavy and expensive to transport over land.

Jenkins said that Enviva is considering using rail to ship biomass from hundreds of miles west to the Eastern Seaboard.

Just what makes up that biomass has been one of the hotly contested issues, with environmentalists asserting that industry is responsible for the clear-cutting of forests, including “low-land” forests.

Jenkins conceded that Enviva accepts woody biomass from lowland parcels, wetlands where trees cannot be commercially grown. But he said that trees will still regrow naturally in lowlands.

In any case, the company uses only what’s left over from forest tracts harvested for telephone poles, lumber, wood floors, furniture and the like. More than 80 percent of a parcel’s value is from trees sold for the “high value” uses, Jenkins said.

The low-value wood can include whole pulpwood trees traditionally used by the paper industry and whole hardwood trees that are too narrow, misshapen or partially diseased or rotten, the company spokesman said. Enviva also uses “slash” from high-value timber, Jenkins said, such as tree tops and branches that cannot easily be debarked.

Forests are the most effective land cover for soaking up rain and keeping nutrients and sediment out of water bodies. The 2014 Bay Watershed Agreement seeks to promote the expansion of forest cover in the watershed.

If the industry moves into the Bay watershed, it could badly set back efforts to expand forest cover, Carr predicted.

But two other environmental advocates suggested that as long as good forest management practices are followed, the wood pellet industry would not set back Bay restoration efforts.

“If the manufacturers follow best silviculture practices they can avoid significant damage to the environment,” said Kenny Fletcher, spokesman for the Virginia office of the Chesapeake Bay Foundation.

Ann Jennings, Virginia director for the Chesapeake Bay Commission, suggested that, “As with any land-based industry, effective use of appropriate best management practices would moderate nonpoint source nutrient and sediment pollution.”

A relatively small amount of woody biomass from the western edge of the watershed is currently being harvested in the George Washington National Forest to generate power for a paper mill in Covington, VA.

The timber harvesting and biomass collection there is being done under U.S. Forest Service rules and supervision, according to Russ MacFarlane, a silviculturist with the U.S. Forest Service.

MacFarlane said that biomass collection there is only permitted in conjunction with tree harvests done for other purposes. No naturally fallen trees may be taken, and 30 percent of the woody debris must be left on the ground to nourish the soil.

More than 80 percent of forest land in Virginia, though, is privately owned, as is the case throughout the Bay watershed.

The Virginia Department of Forestry has no authority to regulate private forests. It does provide technical assistance to landowners to expand the production of high-value timber. Woody biomass collection supports that, said Charlie Becker, the forestry department’s utilization and market manager.

Becker said that when low-value and diseased trees of any age are selectively removed, high-value hardwoods and pine flourish. And forest owners appreciate the extra income from the removal of so-called “junk” wood.

While exports of 5.5 million tons of wood pellets to Europe from the United States sounds like a lot of wood, Becker said Virginia already harvests nearly three times as much for other uses. In 2014, he noted, 16 million tons of forest products were produced in the state, such as wood pulp for paper mills, pallets, lumber, flooring boards and furniture, and whole logs exported abroad.

“It’s easy for people to lose perspective,” Becker said.