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Leon Kaye headshot

Could Coal Find a New Life as a Green Building Material?

By Leon Kaye

To say the current presidential administration is “coal-friendly” is an understatement, but market forces have made it clear there is no room for coal in America’s evolving energy portfolio. Nevertheless, the loss of jobs in the industry is one that resonates with many, and various organizations and businesses are trying to fill that gap.

But what if we could find ways of using coal that could not only salvage some jobs, but also help the construction industry become more sustainable? TriplePundit recent spoke with Ohio University professor Jason Trembly, an associate professor of mechanical engineering and director of OU’s Institute for Sustainable Energy and the Environment. Dr. Trembly is currently researching alternative coal uses, one of which he says is close to being tested in a commercial setting. If these products can take off, the green building sector could benefit from a material that has long been blamed for being a major contribution to climate change.

Dr. Trembly’s vision for coal is one in which it is a material used in plastic composites. Plastic decking, usually made out of a composite of recycled plastic and wood, has taken off over the past decade. Various companies like Trex, ChoiceDek and Fortress Deck offer these products and they can be found for sale at big retailers including Home Depot and Lowe’s. The products are popular with consumers who may be concerned with deforestation or see the products as practical solutions to avoid splintering and dry rot. Companies in this sector also support waste diversion, taking used plastic and giving it a second life.

The problem is that someday, this decking will suffer enough wear and tear to warrant its replacement, or a new home or building owner may decide to tear out those planks and railings for an updated look. “From a sustainability standpoint, we’ve got all of this composite lumber out there,” said Dr. Trembly, “so the real problem ends up being that many of these projects have already been around a for a decade, but what happens at their end of life?”

Dr. Trembly argued that as more of these materials are placed, recycling them will become problematic. “You have to heat these planks up in order to separate the plastic resin from wood,” he explained, “but that degraded plastic is unlikely to be reused, so most likely what will happen is that it will end up in landfill or burned.”

These problems may not exist for another 15 years, but they will still be there; and landfill space then will be even more constrained and expensive. Whether these building materials contain infill of wood byproducts, or are entirely solid with wood and plastic mixed together, Dr. Trembly’s point is the sustainability of these products will be questioned once they outlive their use and need to be replaced.

Coal, however, could be the key material that could solve these future recycling challenges, and Dr. Trembly’s research indicates this once-common fuel could improve these products’ durability, and even lower their costs, as well.

Indeed, coal has similar chemical structure to wood. It is, after all, compressed biomass. But tests Dr. Trembly and his students have conducted that at the end of life stage, plastic composites comprising coal stand a better chance at becoming recycled because the coal and resins can be separated far more seamlessly. And coal could strengthen these products’ as well. “Coal is more thermally stable compared to wood, so we can heat it to a higher temperature before it starts degrading,” he said.

From an aesthetics perspective, coal-plastic composites could appeal to consumers. The leading composite decking companies often sell a few grades of these materials, as builders have their various needs and budget restrictions. Cheaper building products may warp or fray after years in the sun – or something like grease from a barbecue could stain this decking. Dr. Trembly says that can occur as wood has a relatively high water content – but replacing it with coal could solve those problems.

There has been talk of using fly ash, the waste product of building coal in building materials, but those ideas have never taken off. Dr. Trembly said his research indicates that it is not an option in decking materials, as coal in its original form is a much more durable material.

In addition, coal itself is been touted as a building material that could outright replace wood. One artist has even made sleek sculptures out of this cheap source of fuel. Those ideas, however, have not taken off.

For Dr. Trembly, the next stage is taking this idea out of the lab and elevate it to commercial testing. To that end, he is hopeful that he can start applying is research into practice at a plastic extrusion factory in the near future. “Hopefully, in the next six months, we will have real deck boards we can test out,” he said as he wrapped up last Friday afternoon’s conversation with 3p.

Image credit: Fiberon/Flickr

Leon Kaye headshot

Leon Kaye has written for 3p since 2010 and become executive editor in 2018. His previous work includes writing for the Guardian as well as other online and print publications. In addition, he's worked in sales executive roles within technology and financial research companies, as well as for a public relations firm, for which he consulted with one of the globe’s leading sustainability initiatives. Currently living in Central California, he’s traveled to 70-plus countries and has lived and worked in South Korea, the United Arab Emirates and Uruguay.

Leon’s an alum of Fresno State, the University of Maryland, Baltimore County and the University of Southern California's Marshall Business School. He enjoys traveling abroad as well as exploring California’s Central Coast and the Sierra Nevadas.

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