We’re all about saving energy at ecovent, but there are a few times a year when it makes sense to let loose. In the U.S., the Fourth of July is one of those times. Between the barbecues, the parades, the pool parties, and the little extra A/C that kicks on when the weather’s nice, it takes a lot of juice to celebrate Independence Day.
But what about the energy created by July 4th’s main event—the fireworks?
Fireworks give off energy in three forms: light, sound, and heat. Depending on the chemical reaction created, fireworks emit different wavelengths of light: blue/violet for higher-energy reactants; red and orange for lower, for example. When a firework detonates, it also causes the air around it to expand faster than the speed of sound. This produces a shock wave, otherwise known as a sonic boom. Pretty cool.
So that takes care of the light and sound part. But what about heat? Fortunately, we’re never close enough to feel the heat from a firework’s explosion. That’s a good thing because fireworks burn at incredibly high temperatures. For example, the sparkling, crackling aluminum-based fireworks you see in July 4th fireworks displays burn at temperatures up to 5,400 degrees F.
So how much energy do fireworks generate on the Fourth of July?
The American Pyrotechnics Association estimates that more than 14,000 public fireworks displays light up U.S. skies ever year on July 4th. And last year, U.S. towns and cities set off approximately 23 million pounds of fireworks. Although we can’t know exactly which explosives go into every public fireworks display, we can at least estimate how much energy come out of them.
Display-quality fireworks contain more than 2.5 ounces of explosive “flash powder,” which has an energy density of about 9200 Joules/gram. If we assume that the powder represents 25 percent of the fireworks’ overall weight—pyrotechnicians please check our math here—and that all that explosive power could be magically turned into electricity, then U.S. towns and cities detonate enough explosive material on July 4th to generate 6.6 million kilowatt-hours of electricity. That’s enough to power more than 550 U.S. homes for a year.