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Illustration Umweltpolitische Digitalagenda

More and more people are using eco-friendly modes of transport or technologies. Yet energy consumption and CO2 emissions have not decreased. This is due to rebound effects triggered by changes in behaviour. These setbacks are particularly evident in mobility. The city of Bremen has shown how rebound effects can be curbed using digital technologies.

It is raining on this November morning in 2019. The thought of cycling through the city is not particularly inviting on a day like today, as Bremen begins a new chapter in its transport history. The first e-scooter rental company began operations overnight. Around 700 electric scooters can now be rented via app: to commute to work, to buy groceries or to get from point A to point B.

While the rental companies are celebrating the scooters as a technical revolution, they caused some debates in the city: about crowded footpaths in the city centre, for example, about possible electronic waste dumped into the Weser River or the advantages of scooters in a city that already has more bicycles than inhabitants. Stories people had heard from other cities like Berlin or Hamburg. The controversial issue wound up on desk of Michael Glotz-Richter, policy officer for sustainable mobility in Bremen. "I think that e-scooters can be a viable part of environmentally friendly mobility in cities," he says today. "We just have to be careful not to end up with too many unwanted effects."

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Researchers have found these unwanted effects in practically all areas where more efficient technologies converge with old behaviours and lifestyles. Rebound effects are said to occur when a new technology fails to meet its original goals – or even completely reverses a positive outcome. Although the share of renewable energy in Germany has doubled in the last ten years, the heating requirements in private households have decreased by one third since 1999 and more than 100,000 electric cars are now registered: energy demand and CO2 emissions in Germany are falling more slowly than the potential technological savings would lead us to expect. How is this possible?

"New technologies trigger all sorts of changes in behaviour," says Reinhard Madlener, professor for energy economics at RWTH Aachen University. Increased energy efficiency makes energy services cheaper. And, new technology can often make people’s everyday lives easier, ultimately leaving them with more time and money. "This creates an enormous incentive to consume more." If you spend less money on car maintenance, you might just spend the money you saved on a flight for a weekend away. If you switch to energy-saving LED lights, you may be tempted to buy an entire lighting system and leave it on longer. The Federal Environment Agency (UBA) estimates that rebound effects cancel out around 10 to 30 percent of potential savings from energy-efficient technologies.

How e-scooters create more traffic

The Bremen mobility planner Michael Glotz-Richter also deals on a daily basis with the effects that lead to increased demand for transport. These effects are particularly pronounced in the mobility sector, all the more so as systems based on digital innovations and artificial intelligence are becoming increasingly common in this sector. Glotz-Richter is familiar with studies showing that car sharing primarily appeals to people who used to get around by public transport or bicycle. He knows that self-driving and electric cars tempt people to get behind the wheel instead of taking the tram. He took note of the first surveys on e-scooters in San Francisco and Paris. Three-quarters of users would have walked, cycled, taken the bus or stayed at home had it not been for the new scooters. The scooters also lead to more traffic on the road because they have to be collected, charged and serviced every night. Researchers also suspect that carelessly parked scooters displace bicycle and pedestrian traffic. 

Where clear rules support the transport concept

These studies are not a "plea to ban new technologies in urban transport," says Glotz-Richter. "Instead, they encourage us to consider all aspects of traffic flows and management. For the e-scooters, this means: clear rules for e-scooter rental companies, more cycle paths and the use of artificial intelligence. For example, parks are off-limits to e-scooters in Bremen. The providers' app automatically prevents users from parking e-scooters in these no-go zones, saving the local authorities from daily checks. Glotz-Richter: "I would love to see something like this for cars parked carelessly on footpaths and cycle paths. They are by far the biggest obstacle to traffic in the city."

Initial evaluations suggest that Bremen's plan is working. Many people in this city on the banks of the Weser River use the e-scooters as they should be used: to supplement local public transport and their own bicycles. The Swedish e-scooter sharing service Voi recorded more than 50,000 trips in the first two months alone. One hotspot is the area around the train station. The city's outer districts will be connected in the coming months. Claus Unterkircher, General Manager of Voi for the German market, regards the scooters as serious competition for cars. "What's important is that they are integrated into existing transport infrastructures as seamlessly as possible, for instance, in local mobility apps." And, it is essential that more cycle paths are built. "Bicycles and e-scooters sharing the roads with cars is not an attractive option for anyone."

When e-scooters will start to compete with cars

This is also how Glotz-Richter sees it. Bremen benefited from being one of the most bike-friendly cities in Europe when the e-scooters were launched. "There is no way that anyone here would get rid of their bicycle in favour of an e-scooter. They're also much too expensive for this." However, the inhabitants of Bremen would certainly reconsider owning a private car given the right alternative. For more than ten years, the city has been developing a car sharing system with large and small vehicles ranging from two-seaters to vans. Of the 20,000 people who use the service, 6,000 have given up their own cars. "The ultimate goal in an urban area like Bremen is for it to be no longer worthwhile to own a car," says Glotz-Richter. He adds that the better coordinated and more widely available car sharing, local transport, bicycles and e-scooters are, the easier it will be to prevent rebound effects and achieve the ultimate goal. One factor that should not be underestimated is how much fun e-scooters are to ride. "One reason people drive so much is because they enjoy it. It can only be a good thing if there are emotional alternatives."

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