There's nothing better than a cold, delicious pint of beer — except maybe a cold, delicious pint of organic beer made in a solar-powered brewery. Since green beer first appeared on store shelves in the 1990s, the selection has exploded with varieties ranging from smooth pale ales to dark, chocolaty stouts. Green beer is now being produced all over the world — so, more often than not, you can find one that's local, too.

What exactly makes a beer green? Any beer that's either made with organic ingredients, brewed using environmentally friendly processes or both fits the bill. To qualify as organic, ingredients must be free of chemical pesticides, herbicides, fertilizers and genetically modified organisms. The popularity of organic beers has had the benefit of allowing American farmers to begin growing more organic hops, supporting small family farms that have long been squeezed by their bigger competitors.

The biggest name in organic beer is Anheuser-Busch, partly due to its sheer overall size, since it was bought in 2008 by the world's largest beer company, Belgium-based InBev. Anheuser-Busch had entered the organic market two years earlier and offers two organic selections: Wild Hop Lager and Stone Mill Pale Ale. Neither is clearly marked as being made by Budweiser, instead bearing the names of "Green Valley Brewing Company" and "Crooked Creek Brewing Company," respectively. Anheuser-Busch also announced plans to power its breweries with at least 15 percent renewable energy by 2010. 

While they don’t currently have any organic offerings, MillerCoors is also stepping up sustainability efforts, operating some of the most efficient breweries in the world. MillerCoors has committed itself to water stewardship, reducing its energy and carbon footprint, driving packaging sustainability, moving toward zero waste operations and reducing the environmental footprint of its supply chain.

For example, MillerCoors recycles approximately 98% of all brewery waste, including glass, paper, board, plastics, metals and byproducts and reuses plastic from barrels used in the brewing process, shredding them for use in garden and lawn applications.

Of course, "Big Beer" isn't the greenest way to go, and there are plenty of craft breweries with certified organic selections distributing nationally. Among them are Wolaver's, Goose Island Brewery, Eel River Brewing Co., Butte Creek Brewing Co., Deschutes Brewery, Lakefront Brewery and Peak Organic. Lots more are available regionally, for those who'd like to keep it local (and that's the greenest beer of all).

You might be surprised to learn that not all beer is vegan. A substance called "isinglass," which is a collagen made from animal bladders, is sometimes used as a clarifying agent. If you'd rather enjoy libations that don't have traces of animal products in them, seek out vegan beers — there are plenty out there. Check out a list at Vegan Connection (which also includes nonorganic, nongreen beer).

Anheuser-Busch is far from the only beer company turning toward clean, green energy to keep its breweries running. The number of breweries implementing sustainability into their practices is multiplying by the day. Sierra Nevada, maker of one of America's most well-known and beloved pale ales, reuses treated industrial water to irrigate hops fields and draws energy from rooftop solar panels. Brooklyn Brewery was the first company in New York to run entirely on wind power, purchased from a wind farm upstate.

New Belgium Brewery in Fort Collins, Colo., has gotten even more creative with conservation and energy efficiency. About 70 percent of the company's operations are powered by wind, with the other 30 percent coming from a unique form of biodegradable recycling: After the brewing process, bacteria are added to the spent grains, releasing methane gas that's then used to power generators.

Green beer isn't just found at health-food stores anymore. As its popularity continues to grow, organic and sustainably produced beer can be found at grocery stores, gas stations — even Walmart. If you've got a local green brewery, see if it offers refillable half-gallon glass jugs called growlers.

Naturally, the greenest way to drink green beer is to get it on draft at your local pub, as reusable glasses can be used instead of bottles or cans. Just be sure to call yourself a taxi, since it's hard to resist drinking more than one.