Based on the article, it sounds like initial applications are possibly worn devices or other small devices that use rechargeable batteries. The mechanics of being worn, or possibly even creating air convection by lining a heat sink with this stuff, might allow it to access sufficient airflow.
That said, it'd be interesting to find larger structures that could take advantage of natural convection where wind turbines or solar panels might not be terribly suitable, but that's probably a bit of a pipe dream; I doubt this stuff can both work and be exposed to challenging environmental conditions (dust, snow, freeze / thaw cycles, rain, animals scurrying around on it, etc).
A watch battery has 1.55V and 40mAh. That's 1.5 * 40 / 1000 * 3600 J = 216 J. How long does they last? 1 year? That's 216/365/24/3600 W = 0.0000068 W ~= 0.000007 W, i.e. 1/2000000 of my lamp.
The lamp needs 40000000 liters of air per second, so a watch needs 2 liters of air per second. (That's half a gallon.) One person breath like 1 liter each time, 15 times per minute, so blowing your wrist you get only .5 liters per second. To get 2 litters per second you must be running or moving your arms like crazy. And still I guess you will not have enough air flow.
That said, it'd be interesting to find larger structures that could take advantage of natural convection where wind turbines or solar panels might not be terribly suitable, but that's probably a bit of a pipe dream; I doubt this stuff can both work and be exposed to challenging environmental conditions (dust, snow, freeze / thaw cycles, rain, animals scurrying around on it, etc).