But the environmental practices adopted at stadiums are voluntary, since the stadiums are privately owned and only rented by FIFA for the World Cup.
Organizers are heavily promoting public transportation as part of a program it calls "Green Goal."
Fans buying tickets for matches in the 12 World Cup venues can use them to travel for free on trains and buses on match days.
The estimated 6,000 journalists covering the event are given monthlong rail passes.
"We aim to have every second fan come to the games by public transport," Hackbarth said.
So far, that goal has been surpassed. For the opening game between Germany and Costa Rica, 40,000 of the 66,000 fans traveled by public transportation.
But littering could be a big problem. At the stadiums drinking cups are reusable and recyclable, and German bratwursts are served without plates.
But with thousands of fans congregating in the city centers before and after the games, public squares and streets have been virtually blanketed by beer cans and other trash in the first few days of the tournament.
Watering the Fields
All energy for the World Cup is derived from renewable sources, including hydroelectric plants in Switzerland.
Three large solar-power facilities have been built in Dortmund, Kaiserslautern, and Nürnberg (see a map of Germany).
Overall, the amount of solar power produced for the World Cup is two and a half times greater than that produced for the Sydney Olympics in 2000.
One of the biggest issues is water use. The 1.4 million cubic feet (40,000 cubic meters) of water used to water the soccer fields during the games is equivalent to the monthly water use of 12,000 single-person households.
Several stadiums will be watered from a new rainwater-harvesting system.
Four huge tanks collecting rainwater were built for the World Cup. The largest, at Berlin's Olympiastadion, is about 70 feet (21 meters) wide and 35 feet (10.6 meters) deep, making it one of the largest water cisterns in Europe.
A number of stadiums have installed dry urinals, which operate entirely without water.
Parking lots have been surfaced with latticed mats made from recycled plastics, which have been filled with soil and sand, allowing grass to grow on top.
"This way, rain water can seep into the ground naturally," Hackbarth said.
Hothfeld, the environmental scientist, says a mega-event like the World Cup can never be perfectly green.
"But we hope to make it as environmentally friendly as possible," he said.
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