By Sam Wilson
BBC News, Dortmund
The environment has played an important part in planning
Borussia Dortmund's football ground, as well as being one of the biggest and most formidable in Germany, is one of the centrepieces of the country's strategy to run an ecological World Cup.
The venue for six matches, including a potential Germany semi-final, is bristling with solar panels that generate 550,000 kilowatt-hours of energy a year.
For these days, hosting the world's premier tournament entails more than just a chance to showcase one's nation and to roll in the tourist euros.
Now there is guilt too - the guilt of knowing that for all the fun that is being generated, the world is paying a price.
The World Cup organisers estimate the tournament will generate some 100,000 tonnes of greenhouse gas emissions.
But this admission is made not sheepishly, but with a hint of pride.
For not only have they gone to great lengths to keep down emissions, they say, but they vow that every molecule created in Germany will be neutralised by projects they are funding elsewhere.
It will, in short, be "the first climate neutral World Cup".
The organisers say the stadia used for the event have all been refurbished and offer state-of-the-art environmental features.
The ground in Munich, for instance, harvests rainwater from the stadium site, storing it in underground reservoirs.
All energy used at the stadia during the World Cup is being imported from hydroelectric plants in Switzerland.
There are also incentives for fans to use buses and trains rather than planes and cars.
Supporters with football tickets get free match-day transport, while a pass offering unlimited travel on the rail network for the month-long tournament costs 349 euros (£255).
At every stage - from the upgrading of stadia, to the hours of floodlighting provided for each match - the cost in greenhouse gas emissions has been calculated.
Cow dung-to-biogas projects will help neutralise CO2 emissions
The World Cup team say unprecedented efforts are being made to compensate for this pollution, through programmes in the developing world.
The main project takes place in the Indian state of Tamil Nadu - parts of which were devastated by the tsunami of 2004.
Half a billion euros are being invested in facilities to turn cow dung into biogas, which will be channelled through new pipes into homes which have previously relied on wood and kerosene to fuel cooking stoves.
The exercise will not just claw back carbon emissions - it could have a dramatic health benefit in a poor part of the world, where huge numbers of people die from respiratory infections caused by cooking on open fires.
Klaus Toepfer, former executive director of the UN Environment Programme, was drafted in to help with the World Cup's "green goal". He calls it "one of the widest-ranging programmes seeking to minimise the negative impact of a mass sports event on the environment".
But, as the organisers admit when pressed, there are holes in the plan.
The biggest is what it does not account for.
The largest contribution of greenhouse gases will have been made by hundreds of thousands of fans taking journeys by plane into Germany.
Thomas Hackbarth, a spokesman for World Cup organising committee, says negating the effect of emissions "outside Germany" was never part of the plan.
That would have meant making up for another 100-150,000 tonnes of greenhouse gases, he said.
The authorities say tourists are swarming onto public transport
There are other questions over the commitment to ecological standards.
Could each group not have been played out in a single city, to avoid fans travelling across the country? Do floodlights really need to be operated during daylight games, just to eliminate shadows for television viewers?
Is it right that Franz Beckenbauer, the head of Germany 2006, has been shuttling between virtually every game in a private helicopter? Or travelled to all the participating countries before the World Cup kicked off?
Mike Childs, of environmental campaign group Friends of the Earth, says Germany's efforts are "commendable".
"But transport is one of the greatest areas of concern - that's where they need to go the extra mile," he adds.
Many fans would have made the trip to Germany on cheap flights, because rail services were too expensive, he said.
"This needs bigger changes that governments and societies need to bring about - like schemes to make rail travel more affordable."
"Making sure that Beckenbauer doesn't zip around in a gas-guzzling helicopter" would also help, he said.
Mr Hackbarth defends the decision to play group games in different cities, saying it is "very good for the football fans", giving them a chance to move around the country.
Nuremberg's solar panels make it one of the most advanced venues
"Granted, [using the same city] would have been more ecological, but this is the world's biggest tournament, and you have to take care of the fans."
Mr Beckenbauer's trips to see all the countries play, he added, were "greatly appreciated by the nations".
These were "decisions that had to be made" for the good of the tournament, he said.
But Germany had made great efforts to minimise the effect on the environment, and had laid down a marker for future events, he said.
"This is an important first step for football, and hopefully the ball will now be passed on."
Mr Childs agrees. "The fact that the Germans have made this much effort makes you think 'why don't they do this much at every major sporting event?' "