A new form of cellulose insulation could give plastic foams a run for their money.
We’re not called TreeHugger for nothing; we love wood and wood products and try to promote anything that reduces our use of fossil fuels, and have written many stories about cellulose insulation. But there is a new kid on the block, Nanowood, that a lot of blogs are gaga over. The Big Think titles its post Female inventor creates 'Nanowood' — a material that could (really) save the planet. The LA Times calls it “a new invention that could greatly reduce humanity's carbon footprint”. WOW!
So what’s the big deal? The inventor, post-doc student Tian Li, notes in a press release that “this can insulate better than most other current thermal insulators, including Styrofoam. It is extremely promising to be used as energy efficient building materials.”
Insulations are mostly air, and so is Nanowood. According to the research article, they take American Basswood and remove the lignin by boiling it in Sodium Hydroxide and Sodium Sulfite, then treat it with Hydrogen Peroxide and freeze-dry the pure cellulose that is left. To be blunt, there is nothing high tech and "nano" about it at all; they are boiling out the meat and leaving the bones. But there is nothing wrong with good marketing.
It still has the tubular structure of the wood so it has low thermal conductivity across the grain and higher conductivity parallel to it. With a thermal conductivity of 0.03 W/m·K it is not going to save the planet; it is about the same as plastic foams and slightly better than the cellulose insulations from Steico that we showed recently. (Thermal conductivity is a measure of the capacity of a material to conduct heat through its mass; the lower the better.) The tubular structure apparently also helps distribute the heat that does get through the stuff over a larger area, resulting in a cooler surface.
It is really strong compared to other insulations. Although only a third as strong as the wood it is made from, it might be strong enough that one could build walls out of it.
They say it is cheap ($7.44 per square meter, but they don’t say how thick it is). It can be made of any kind of wood; they suggest fast-growing species like balsa, which is a pretty good insulation all on its own.
It’s a shame that these developments get pitched as “saving the planet” (really!). It’s just insulation. But it is neat stuff that is as effective as extruded polystyrene (Styrofoam is a trade name, not a generic) without the carbon footprint.
Tian Li reports to Liangbing Hu, an associate professor in the department of materials science and engineering at the University of Maryland, who says “we are reinventing ways to use wood that could be useful in constructing energy efficient and environmentally friendly homes.” He has a startup called Inventwood which also markets Transparent Wood, another interesting idea. Imagine solid walls of Nanowood with transparent wood windows. We might soon see buildings that are truly TreeHugger approved.