Pictures: Seven Energy-Smart Zoos and Aquariums

San Diego Zoo: Local Advantages

Photograph from Alaska Stock/Corbis

The San Diego Zoo's resident polar bears are a counterintuitive sight in southern California—and also in a zoo that mostly houses exotic species already at home in San Diego's balmy climate.

Spokesperson Christina Simmons said the San Diego Zoo has adopted LEED-certified buildings, and houses a small solar power plant in the parking lot operated by San Diego Gas & Electric. But much of the zoo doesn't actually use large amounts of electricity, she noted. That's largely because many of the zoo's animals already feel at home in San Diego's mild climate.

"That's the way were were created and developed," Simmons said, "to take advantage of the climate we have here." And while many of the zoo's animals are well suited to their locale, others who are not—like these polar bears—have taken to the weather like many human transplants to southern California.

"The polar bears we have were orphaned," she explained, "and we brought them here very young, before they had a chance to build up all that blubber. "We can hardly get them to go into the water if it's less than 60 degrees (15.6°C)."

Published May 23, 2013

National Zoo: Green Elephants

Photograph by Mehgan Murphy

Elephant Trails, the new home for Asian elephants at the Smithsonian's National Zoo in Washington, D.C., now has four residents (one of whom is pictured above), with the arrival this week of a new elephant, Bozie, transferred from Baton Rouge Zoo. The new facility in the nation's capital is built to accommodate an eventual herd of eight to ten adults and their young; Bozie was moved here because her companion elephant in Louisiana died and it is not healthy for elephants to live alone. Also important: Keeping the elephants comfortable through Washington's steamy summers and frigid winters.

The zoo's elephants retire to a "barn" quite unlike its typical farm counterpart: the state-of-the-art LEED Gold-certified building uses 40 geothermal wells to maintain constant temperatures. Operable skylights provide natural lighting, cutting electricity use; and "shade cloths" help cooling air circulate through open doors, allowing rising heat to escape through the roof, which slashes air-conditioning demands.

Outside, the barn's roof is greener still—literally, because it is planted with insulating vegetation that makes the building more energy-efficient, soaks up rainwater, and creates a hospitable living space for local plants, birds, and butterflies. The exhibit's outdoor spaces employ recycled materials for construction, further reducing its energy footprint, and include an on-site system of efficient pool-water filtration and reuse that reduces the strain on the city's water infrastructure.

Published May 23, 2013

Georgia Aquarium: Stemming the Tide

Photograph by Joel Sartore, National Geographic

Aquariums typically replace 10 percent of their water volume per week to maintain proper chemistry for their residents. But because the Georgia Aquarium in Atlanta (above) is the world's largest, containing more than 10 million gallons of water, that option wasn't economically or logistically feasible, said Eric Hall, the facility's director of life-support systems.

"Faced with that, we use infrastructure to reclaim and reuse the majority of our water—about 99.5 percent of our total volume," Hall said. The incredible savings are achieved with a suite of innovative techniques, many of which are borrowed from Mother Nature. "Lots of our filtration processes are designed to mimic naturally occurring processes that take care of pollution," Hall said. "We have collection tanks and settlement basins. We have the same kind of sand you'd find on a beach catching particulate matter in filters. We mimic waves crashing on a beach, with a protein skimmer, to generate that familiar foam of dissolved organic carbon or waste."

The aquarium sterilizes water with UV light, and disinfects by injecting it with ozone gas. It also employs a process called sulfur-driven autotrophic denitrification to clean up the messes made by so many marine animals. "It's taking primary waste from animals and converting all the way to a nitrogen gas the way nature does using plants. We use bacteria to do it right here," Hall said.

The aggressive and comprehensive array of water-saving technologies has earned the aquarium numerous awards, and more importantly, reduced its potential water discharge from 1 million gallons a week to 25,000 gallons.

Published May 23, 2013

Shedd Aquarium: A Sea Change

Photograph by Michael S. Lewis, National Geographic

A trainer works with a dolphin at Shedd Aquarium in Chicago, where perhaps 45 percent of the aquarium's sizable energy load goes to cooling the pools that keep marine animals comfortable, according to Aquarium Vice President of Facilities Bob Wengel. "We have a beluga whale collection, and we're keeping those guys' [water temperatures] at 58 degrees (14.4°C) year-round," he said. Those efforts are aided by efficient equipment and ingenious green solutions, including winter systems that allow engineers cool water through a tower on the chilly Chicago rooftop instead of using power-hungry chillers.

Aquarium denizens also need proper underwater lighting to aid their sensation of depth. "Historically with aquariums, the solution to drive light into the bottom of tanks has been 400- to 1,000-watt fixtures, and lots of them," Wengel explained. "We found 85-watt LEDs that produce the same light but save a ton of energy. Plus, you don't have as much heat buildup to later remove from the building, and you only have to send someone up and out over the water to change it once a decade, rather than every year." The zoo even farms some shrimp and snails for sustainable foodstuffs on site. All this innovation is good for the bottom line, and part of the aquarium's overall plan to cut total energy use in half by 2020 as part of a larger mission.

"What's good for the animals in our collection, in this case, is also good for the animals outside our collection," Wengel said. "That's the connection we try to make, and that's why we're here, to make people appreciate the wild species and care about what's going on around them."

Published May 23, 2013

Denver Zoo: Waste Power

Photograph by Andy Cross, Denver Post/Getty Images

Bodhi, an eight-year-old Asian elephant, enjoys a cooling spray at the Denver's Zoo's new Toyota Elephant Passage. Opened in June 2012, the space is also home to greater one-horned rhinos, gibbons, clouded leopards, and fishing cats. Starting this summer, it will be entirely powered by elephant poop and other zoo waste.

The elephant exhibit burns 15 to 20 percent of the zoo's power, mostly because of all the water required by pachyderms and the rhinos. But if the permitting process continues as planned, the zoo will soon use a new gasification system for energy. "We're taking 90 percent of our total waste stream, including animal waste and visitor trash, and converting it into a viable fuel product, using gasification, to produce about 20 percent of the zoo's total energy needs," said the zoo's sustainability manager, Jennifer Hale.

"The elephant waste has a good heating value to it, so we have that advantage," Hale said, adding that gasification produces not only fuel for electric power but also residual heat that will boost boilers and be used to create warm pools for "elephant hot tubs."

"We're excited. It's definitely not something that has been built on this scale, and so it's exciting for the zoo to have this chance to drive innovation and develop something that could not only be feasible for other zoos but for campuses, small companies, and other types of facilities as well," Hale said.

Published May 23, 2013

Saint Louis Zoo: Efficient Sea Lion Oasis

Photograph by Mark Schuver

Saint Louis Zoo's new Sea Lion Sound exhibit, which opened in June 2012, is the most energy-intensive part of the zoo. But it's also the focus of the zoo's greatest sustainability effort yet, which began from the ground up. The exhibit is composed of 650 tons of recycled material, equivalent to the weight of three blue whales, which was used to cut the demands of material production.

Sea Lion Sound boasts sunbathing beaches, a transparent walk-through tunnel for visitors (seen above), and year-round outdoor pools of varying depths filled with some 250,000 gallons (946,000 liters) of saltwater. Sustainable management tools such as bio-filtration swales (vegetated channels), save enough water to supply the annual household needs of every zoo employee—a staggering 11 million gallons (41.7 million liters) a year. By using ozone to disinfect those pools, the zoo has also cut chlorine use by 80 percent.

High-tech advances also have helped the zoo save electricity. Exhibit pump filters used to run full power at all times and were controlled by valves which could open and close to restrict flows as necessary. The new exhibit powers the pumps with variable-frequency drives that ramp the motors themselves up and down, doing the same job with drastic reductions in power use.

Published May 23, 2013

Next: Centralia Mine Fire, at 50, Still Burns With Meaning

Photograph by Don Emmert, AFP/Getty Images

Published May 23, 2013