Among backyard grill masters, the fuel-of-choice question can stir a level of debate usually reserved for discussions about hometown sports teams, favorite beers, or hot-sauce brands. Some swear by the taste of charcoal grilling; others tout the even cooking delivered by gas, or the convenience of electricity. But which of these options is best for the environment?

As it turns out, natural-gas and liquid-propane grills release the fewest air pollutants per grilling hour, with natural gas burning the cleanest. Grilling with natural gas emits about 4.1 pounds of carbon dioxide per hour, while a liquid-propane grill emits roughly 5.6 pounds of carbon dioxide in the same amount of time.

By comparison, similar use of a charcoal grill results in approximately 11 pounds of carbon dioxide emissions, along with several other not-so-savory compounds. Charcoal grills ignited with lighter fluid release volatile organic compounds, nitrous oxides, and toxic particles, and contribute to ground-level ozone. (How’s that for a side with your wieners and brats?) Some of these emissions are from the evaporation of the lighter fluid, but most are due to the burning charcoal.

Although electric grills produce little pollution on their own, the emissions from generating the energy to power them can be significant. If the energy comes from a coal-fired power plant, total emissions can easily exceed those of the charcoal grill—about 15 pounds of carbon dioxide per hour of grilling.

Besides its other benefits, gas cooks faster and more evenly, reducing the time the grill is fired up. Sure, it costs more to buy a gas grill, but the cost per grilling hour is much less than for grilling with charcoal.

If you live in one of the more than 80 million U.S. households that already own a grill, you can tuck this information away for when the time comes to replace it. But if you’re planning to buy one of the 17 million new grills that will be sold this year, keep the planet in mind when you make that choice—and there will be one more good reason for your guests to kiss the cook.