Building With Bioplastics
Atmosperic Carbon Storage in Construction Materials
Residential bioplastic building materials when managed and recycled could sequester carbon dioxide for centuries.
Plastics: A technological marvel and an environmental nightmare all in one. There's no need to even attempt to list all the uses of plastics. You know where they are: everywhere. There's no question that they've improved our lives making possible new, durable, low cost products that weren't available before. That's the technological marvel part.
The environmental nightmare part is that so much of the plastic products we use are associated with waste. Discarded plastic products are filling our landfills and trashing our oceans. The products we use fail, become obsolete, or end their useful life in a relatively short period of time, while the plastic they are made can survive for decades. A plastic soda bottle has a useful life of only a few minutes (or less), but unless recycled lives on and on. The plastic bumper guard on a car might, without accident, last for a decade or more, but then, unless ground up and recycled, could remain in a landfill for centuries. Biodegradable plastic that decays over a few months or years is helpful for some products, like those soda bottles, but for products needing a longer durable life, biodegrading isn't wise idea.
But there's a whole subset of plastics that are numerous and deserve to be set aside from consumer plastics for their long term usefulness and durability: Plastics used as construction materials. If you're unfamiliar with those, many can be found at your home improvement store:
--- foam insulation
--- composite decking material
--- composite roofing material
--- plumbing fixtures such as sinks, bath tubs and shower pans
--- solid surface and stone composite counter tops
--- electrical fittings
--- electrical conduit
The huge difference between plastics used for construction materials and consumer products can be summed up in two words: life span. Consumer products might have a life span of anywhere from a few seconds to a little over a decade, like your car.
Building materials, on the other hand, are designed to last for decades, some for centuries. PVC (polyvinyl chloride) pipes working underground to carry away waste water could feasibly last 1000 years or more, while those above ground might be expected to last 50 -100 years, possibly more. (Yes, I know, there have been premature plastic pipe failures.) Foam insulation should last the life of the building, which should be 100 years. PVC and plastic/wood composite decking material, which by the way is often made of recycled plastic, should last 50 years. Other materials made all or in part of plastic like windows, doors or plumbing fixtures might lose functionality or aesthetic appeal and be replaced long before the plastic material they are made of fails or decays. Expect 20 - 30 years for these. One material that should last as least as long as the building (probably a lot longer} is solid surface and quartz countertops. Aesthetically they might lose their appeal, or the room in which they are installed in might be redesigned and remodeled, or the cabinets they are on might fall apart, but the countertop material should last for quite a long time, decades, even if they have to be refurbished at some point. (What's called “quartz” countertop material is really stone chips embedded in a plastic resin.)
To date it's most likely that long-lived plastic building materials are made from petroleum sources. Yet made of non-biodegradeable bioplastics those materials would be sequestering atmospheric carbon for their life span. With proper management these bioplastic building materials could be recycled over and over extending their sequestration period to perhaps hundreds of years on average. The PVC drainage pipe pulled out of the ground a hundred years from now might become part of a new decking material lasting another 50. After that it could become a new type of carpeting. After that yet another product or perhaps finally deposited in a landfill. (Bioplastics in a landfill might not yet be the end of the line. Waste bioplastics stored and managed carefully underground could be a source of hydrocarbon fuel for some future generation.)
Recycling is key to century-or-longer sequestration of carbon in bioplastic building materials. Already the construction industry has a good history (and getting better) of recycling. Materials from demolished buildings take up considerable space in landfill operations so demolition companies are encouraged to recycle and discouraged from wholesale dumping by high tipping fees at landfills. Further, demolished building materials have value. Wood is sometimes recycled into other products as is concrete, brick and stone. Fixtures are reused. Metals are quick to be pulled aside from the waste pile for their value. Bioplastic construction materials could be added to the recycling list at demolition time for continued carbon sequestration.
A typical wood frame house of 2400 square feet has roughly 28.5 tons of sequestered atmospheric carbon dioxide. How much more would there be if all the plastic materials in the home were carbon storing bioplastics?
Homes are just tip of the iceberg for the potential for sequestering carbon dioxide in the materials they are made of. Start thinking about industrial and commercial buildings as well as infrastructure. They are all part of our built environment that could be put to work pulling carbon dioxide out of the air and sequestering it for centuries.