There’s a huge pile of tree debris. It’s growing. And there are no good solutions.

Piles and piles of wood waste, some more than 30 feet tall, are stacked near the Mississippi River in St. Paul.

The heaps are growing and they’re not the only ones in the metro. Experts are struggling with how to get rid of the debris.

The emerald ash borer infestation and recent storms have left the metro area with too much wood, and few options to dispose of it.

The metro area generates about 550,000 tons of wood waste annually, a figure expected to grow in the coming years, according to Jon Klapperich, wood-waste specialist for the Minnesota Pollution Control Agency.

“The volume is so great that there are no good choices,” said Rep. Rick Hansen, DFL-South St. Paul, who chairs the House environment and natural resources committee.

Experts warn that this wood could spontaneously catch fire, especially given the current drought in Minnesota.

Ben Cooper, general manager of Rainbow Treecare, said that this year, the state will reach peak infestation levels of the invasive ash borer, leading to an increase in ash tree removals.

“We’re at this kind of breaking point or tipping point,” Cooper said. “Unfortunately, one of the consequences is that the prices to get rid of debris have gone up, like fourfold in some cases, just this year.”

Much of the wood waste in the metro area is sent to a processing site near Pig’s Eye Lake in St. Paul, where it is stored before being burned to produce energy at the St. Paul Cogeneration plant downtown.

Cogeneration provides power to about half of downtown and was originally built to manage elm-tree waste in response to Dutch elm disease. The plant burns approximately 240,000 tons of wood each year, according to Michael Auger, senior vice president of District Energy in St. Paul.

Jim Calkins, a certified landscape horticulturalist who has been involved in discussions about the problem, said he thinks using wood for energy is the most logical solution.

“The issue is, we don’t have enough facilities to be able to handle that, at least in the Twin Cities,” Calkins said. “So there has to be dollars to support transportation to get the wood to those places, or in some cases, to upgrade some of those facilities such that they are able to burn wood.”

Plans are in place to convert Koda Energy in Shakopee to burn ash wood, which could potentially handle around 40,000 tons of wood waste, but that would take around two years to establish, according to Klapperich.

In some areas of the state, cities have resorted to burning excess wood waste because they felt they had no other option. Open burning wood releases a lot of carbon into the air, Klapperich said.

Some of the wood is converted into mulch, but demand for mulch isn’t keeping up. Additionally, efforts to check the spread of the invasive jumping worm have led to strict regulations on creating and exporting mulch, according to Calkins.

Klapperich said other proposed solutions include converting wood into sustainable aviation fuels, biochar, or through gasification. But these options would require significant funding and time to develop the necessary infrastructure.

Cottage Grove is one suburb struggling to deal with wood waste. According to Mayor Myron Bailey, the city collected wood debris from residents after August storms that cost the city an estimated $600,000. Now, the city has a large pile of wood debris at a local composting site.

“It was the right thing to do, but now we’re left to figure out what to do with this thing,” Bailey said.

There is $1 million in funding available from the state for wood waste removal grants, Klapperich said.

“That is barely scratching the surface of need on the issues,” he said.

Stakeholders plan to lobby for additional funding during the next legislative session, which starts in January.

Grace Henrie is a University of Minnesota student on assignment for the Star Tribune.