What's the greenest way to shave?

Illuminating answers to environmental questions.
Dec. 28 2010 12:09 PM

Trimming Your Carbon Footprint

What's the greenest way to shave?

Razor. Click image to expand.
Are all those disposable razors bad for the earth?

My friends are always arguing about the relative merits of electric and disposable razors. All the debate over closeness of shave, maintenance, and the ability to do one's grooming while stuck in traffic is wearing me out, so I'm putting my decision in Mother Earth's hands. Which kind of razor is better for the environment?

Ah, one of the great dude debates. Right up there with boxers vs. briefs and The Godfather vs. Billy Madison. Sure, grooming enthusiasts have a plethora of shaving options, from single-blade to safety razors, but for most men the choice comes down to disposables versus electric. After a column on menstruation and another declaring women the greener sex, it's about time the Lantern tackled a male-centric conundrum.

Here we face a classic environmental conundrum: Is it better to buy a more energy-intensive manufactured product that can provide years of reliable service or to keep replacing cheap, low-energy disposables. We've been in this territory before. Glasses or contacts? Books or an e-reader?

Let's start with the energy you'll use as a consumer. Most of the energy consumed while shaving with a disposable goes toward heating the water. Unless you're some kind of shaving Jedi, you'll probably use at least a quart of hot water for your daily grooming session. It takes approximately 0.04 kilowatt-hours to heat that much water from ground temperature to 123 degrees, a comfortable level for shaving, so your hot water would cost you 10.4 kilowatt-hours annually, if you shave five times per week. Electric shavers vary widely in their energy consumption, but they often run between five and six watts. That amounts to roughly 0.35 kilowatt-hours of electricity each year, if it takes you 15 minutes to dry-shave before work.

The electric shaver comes out on top by a 30-to-1 margin in terms of energy used by the consumer, but that's just one piece in the overall puzzle. You'd also want to consider the carbon dioxide generated during the product's design, manufacture, transport, and disposal. Unfortunately, none of the major electric shaver manufacturers have been forthcoming with this sort of information, so we'll have to make some assumptions and do some reverse-engineering.

According to a report (PDF) by WRAP, a U.K.-based sustainability advocacy organization, approximately 40 percent of an electric toothbrush's lifetime energy consumption comes during the consumer-use phase. An electric shaver likely has a similar profile, since the two products use approximately the same materials, in the same volumes, and require about the same amount of electricity during use. (The toothbrush runs a slightly higher wattage for a shorter time.) Most electric shavers come with a two-year warranty (PDF). Let's charitably assume that your unit will last twice that long. Over the course of four years, you'll burn through 1.4 kilowatt-hours of electricity. If that represents 40 percent of the shaver's energy consumption, that means design, manufacture, transport, and disposal will add on 2.1 kilowatt-hours, for a total four-year consumption of 3.5 kilowatt-hours. Generating kilowatt-hour of energy releases an average of 1.297 pounds of carbon dioxide, so keeping your face smooth electrically is responsible for roughly 1.13 pounds of CO2 per year.

So how does that compare with the disposable? It depends a little on which disposable you choose. BIC estimates that it takes 43 grams (PDF)—that's 0.095 pounds—of carbon dioxide to make one Ecolutions shaver, one of the few products for which a life-cycle assessment is available. Assuming you can squeeze 10 shaves out of a disposable, as BIC says you can (PDF), your razors would be responsible for 2.5 pounds of CO2 equivalents every year. Adding in the 13.5 pounds of carbon dioxide you needed to heat your water, that brings your total annual bill to 16 pounds of CO2.

Choosing a less-green disposable will magnify your razor's manufacturing impact, but it won't change the overall picture very much. BIC says its product beats out other models by 59 percent (PDF), which would place the average disposable's annual CO2 total at about 6.1 pounds. But that change would only represent a 22 percent increase in overall shaving impact, since the hot water really drives the equation.

After a healthy bit of conjecture, the electric shaver beats the more eco-friendly disposables by a margin of 14.9 pounds of carbon dioxide. So what does that annual difference represent? Driving your car for about 16 miles or running a compact fluorescent light bulb for 47 minutes. It would take more than 350 years of shaving with a disposable instead of an electric to account for the annual greenhouse gas emissions of a single cow. In other words, don't sweat it.

Electric shavers do trump disposables when it comes to the landfill. Every year, Americans toss out 2 billion disposable razors. That's a pretty big pile of metal and plastic entering the waste stream. Most of them can't be recycled, because they're dangerous to disassemble and no individual municipality produces enough of them to make collection cost efficient.

Electrics are usually powered by nickel-metal hydride batteries, which are recyclable in most places and are less toxic than lithium or nickel cadmium rechargeables. You'll still need to take them to a drop-off site, but—let's face it—you're probably heading to Home Depot, Target, or Wal-Mart sometime this month, anyhow.

While your choice of razor can make a slight environmental difference, the worst thing you can do is shave in the shower, a sin that can be committed with a disposable or a waterproof electric. Shaving for 10 minutes with a typical 2.5 gallons-per-minute shower head, you'd waste more than 24 gallons of hot water, 4.1 kilowatt-hours of electricity, and 5.3 pounds of carbon dioxide in your warm, misty tub. It would take less than three days of shaving to account for the energy you'd use by shaving in the sink for an entire year.

If 14.9 pounds of carbon dioxide keeps you up at night, but you don't want to break any world record for grooming delinquency, there are a couple of odd-ball antique products you might consider. Some clever manufacturers offer hand-cranked razors and units that work by rolling across your face, like a manual lawn mower. If you demand a closer shave than an electric—or a facial-lawn-mower—can provide, turn to the old-fashioned straight-blade razor. You'll still have to rely on water, but a good blade will last for years, and you can even get one secondhand. Plus, your nattering friends will bow to your barbershop cred.

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Brian Palmer writes about science, medicine, and the environment for Slate and the Natural Resources Defense Council. Email him at explainerbrian@gmail.com. Follow him on Twitter.

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