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Wednesday, June 19,2013

Biomass in b minor

MSU plan to burn trees for energy raises a forest of questions

by Lawrence Cosentino
“MSU Plant Switches to Wood Biomass Fuel” was the headline June 5 on the MSUToday website — a boast on par with one of Monty Python’s more obscure skits, “Man Jumps Across English Channel.” Michigan State University’s T.B. Simon Power Plant burns less than 2 percent biomass (plant matter) and still runs overwhelmingly on coal.

But hyperbole isn’t the biggest concern over MSU’s plan to ramp up the burning of wood at the Simon plant and, possibly, all over the state.

To critics, scrounging the state for wood to burn or growing “energy plantations” of young trees is an unsustainable solution to energy demand, poses a potential threat to the state’s forests and amounts to an excuse for extending the life of aging power plants. What is more, the claim that burning woody biomass — trees or parts of trees — is carbon neutral is dubious and easy to manipulate. 

Marvin Roberson, the Sierra Club’s Michigan forest specialist, called the MSU program a “green Band-Aid.”

Roberson said it takes the annual growth of about 10,000 acres of forestland to produce 1 megawatt of electricity.

“If you want to produce 1 megawatt indefinitely out of wood, you have to have 10,000 acres under cultivation for it,” he said. “We don’t have enough forestland in Michigan to make a significant dent in our electricity needs.”

Ray Miller, the forestry professor heading the MSU biomass program, said MSU and Lansing’s Board of Water and Light have “significant capital investment in their power plants and if they could find a way to keep running them and meet renewable fuel standards, they would be very happy.”

To Brad van Guilder, organizing representative for Sierra Club’s Beyond Coal campaign, that’s “a win-win for the status quo.”

The MSU plan has two parts. The first is to start up plantations of quick-growing poplars or other quick-growing trees, with the goal of creating “energy farms” on campus. The first 10-acre block was planted this year, with a plan to start five more in the next five years. 

“In the sixth year, we would harvest the first block, replant it and so on every year,” Miller said.

Think of a Christmas tree farm where the tree is burned instead of decorated. Years of patient growth lead up to the big day. Voosh. If that sounds like a long game of catch up, it is.

Miller admitted that the 10-acre plots will only supply “a small fraction” of the total that could be burned at the Simon power plant. That’s where the second part of the biomass plan, proposed by Miller but not yet adopted by MSU, comes in.

In Miller’s vision, “depots” would be set up all over the state where bulky, moisture-laden wood could be dried and pressed into coal-like chunks that power plants can use. The process is called torrefaction.

Torrefied biomass, unlike the raw stuff, could be burned in any of the Simon plant’s boilers. It retains 80 percent of the woody mass, wrings out most of the moisture and it’s dry and crumbly, like coal.

Two years ago, Lansing’s BWL put 100 tons of torrefied wood shipped from Quebec through its pulverizers, with mixed results. The chunks went through, but too slowly. Torrefaction sucks out so much moisture that the pieces were too light.

“You can’t shove it through fast enough,” BWL planning director George Stojic said. “You’re getting less BTUs.”

Stojic said the BWL is contracting for torrefied wood that has been pounded into denser pellets. If it’s efficient enough, they’ll add it to the fuel mix. A thousand-ton test is in the works, but supply is still dodgy.

“At this stage, we can’t get as much as we want on a commercially consistent basis,” Stojic said.

All parties agree that burning biomass produces carbon emissions. The MSU release incorrectly quoted Miller saying it doesn’t. The burning question is whether the process is carbon neutral, i.e., whether it puts more carbon into the air than it sucks back in.

Skip Pruss is a former director of Michigan’s Department of Energy, Labor and Economic Growth and advisor to Gov. Jennifer Granholm. He is now a consultant at 5 Lakes Energy & Environmental Consultants.

“It depends on how you define ‘carbon neutral,’” Pruss said. “How far back do you go?”

The carbon in natural gas and coal has been buried in the earth for aeons. Burning it “un-sequesters” the carbon and releases it into the atmosphere, adding to the greenhouse gas miasma baking the planet. Almost everybody agrees that is not carbon neutral.

But burning biomass, Miller said, only “closes the loop” in a short-lived cycle by putting recently stored carbon back into the air.

Never one to mince words, Roberson called the claim that burning biomass is carbon neutral “bullshit.”

When a tree falls in the forest, he explained, it starts decomposing into soil and releasing its stored gases, including carbon dioxide. But it does so very gradually — at a rate of about 4 or 5 percent of stored gases in a hundred years.

“Burning trees is absolutely not carbon neutral, because we’re taking trees that have been storing carbon for decades and releasing it immediately,” Roberson said.

It’s far from clear whether enough trees would ever be planted and left to grow to offset the burned-off carbon. 

And even if the process were carbon neutral, there are other costs to consider.

“It’s more than the combustion of the biomass and the greenhouse gas emissions,” Pruss said. “It’s using fertilizers, harvesting, transportation and storing of the biomass.”

Stojic touched on the same theme.

“We like to call it a zero emissions cycle, but really, you’ve got energy invested in cutting it, preparing it and moving it to the fuel stage,” Stojic said. 

Finally, there is the question of supply.

About half the forests in Michigan are privately owned, a quarter is owned by the state, and another quarter is federal forest. Miller said the private owners are already “unresponsive to timber markets” and aren’t likely to sell them off. State and federal forests are closely managed for multiple uses.

Miller would like to see “energy plantations” grown all over the state. He estimated that 2 million acres of agricultural land in Michigan have become idle.

However, while assessing the potential wood supply, Miller quickly wandered off the plantation. Overall, he said, “we are far from harvesting at the annual increment of our forests. With every year that goes by, there are more trees, larger trees in our forests than there were last year, and this has gone on for decades.”

But that’s because Michigan’s forests are still recovering from a coast-to-coast logging holocaust of 100 years ago that turned the state into a stumpy wasteland. Longer-lived species like white pine are still young on the centuries-spanning Tom Bombadil time scale. Creating a new demand for short-lived species, Roberson said, will “arrest the development of our forests” and possibly even reverse the state’s painfully slow progress of reforestation.

Miller suggested that tree-huggers get real.

“Whether that’s paying more at the pump for gasoline or cutting down a few trees, we need to have an adult conversation about this and stop thinking the Lone Ranger is going to come up riding up on a white horse and save us for free,” he said.

It looks like Pruss is trying on his mask. He’s working on a super-study summarizing recent advances in technology, from cheap photovoltaic shingles to offshore wind turbines, that could take Michigan through a “complete transition to clean energy technologies” by 2050.

“We have practical, economical and technically feasible alternatives,” Pruss declared. “The impediments are social and political.”

The Sierra Club’s Van Guilder sees the biomass program at MSU as a late-in-the-game screen pass to big agriculture. “Why pursue this when we’ve got renewable energy options staring us in the face?” he asked. “Why continue to pursue the idea that we absolutely have to burn things?”

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