Who knows if a piece of land exists in Rome without ancient sculptures, vases, coins, weapons buried underground and ready to tell their millennia-old stories at the first pickaxe strike.
Every time the city digs, archaeological treasures sprout up from underneath, bringing to light artifacts and their personal tales from centuries of obscurity.
Beneath Rome the open-air museum lies Rome the hidden museum, remnants of the city’s glorious past some 30 metres below 21st-century life.
The soil in Rome features what geologists call an ‘incoherent structure’
For local authorities, cultural heritage in such abundance is both a blessing and a curse – what draws millions of people to the Italian capital every year is also what complicates its path to green mobility.
Rome’s metro line, for example: it covers a fraction of the city’s 1,285 square kilometres, and not just because transport engineers and archaeologists often end up working on the same site.
“The soil in Rome features what geologists call an ‘incoherent structure’. This means that some tiers have a particular texture, but as one keeps on digging the layers below have a different consistency,” says Stefano Brinchi, Director of Roma Servizi per la Mobilità, the body in charge of the city’s public and private mobility services. “This sometimes crumbly, sometimes rock-hard terrain is often at risk of collapse, requiring inserts of concrete and specialised works that cost time and money”, he adds.
How do you then move 5.9 million people in a clean, sustainable manner here? How do you wean that 63 per cent off the private cars that they drive for lack of better options?
If you can’t go underneath, strengthening the above-ground sustainable infrastructure is Roma Servizi per la Mobilità’s answer.
Supercapacitor-powered buses have better features than battery-powered ones
New electric buses, more trams, trolleybuses and cycling paths will increasingly compensate for the lack of a large subway infrastructure. They are part of the city’s sustainable mobility overhaul that in recent years has been helping Rome to align with EU environmental goals.
Buses are playing a starring role in this new scenario. Off with the old 1990s polluting and noisy 2,000-strong fleet; in with brand-new quieter models that will help to bring down a large share of public transport’s CO2 emissions.
Brinchi wants to take the plan even further: his ambition is to expand the electric fleet to include hydrogen and supercapacitor buses in addition to traditional battery models.
« I believe that supercapacitor-powered buses have better features than battery-powered ones,” Brinchi explains. “In supercapacitor buses, electricity is provided by a power storage system that gets recharged very quickly after each trip,” he adds.
Since October, the city has been putting a supercapacitor vehicle to the test not just on any route but on one of its most crowded lines, the 64 that shuttles passengers from the central train station to the Vatican.
“We installed a fast electric charging station at the terminus of bus 64 in St. Peter’s (near the Vatican). Once the vehicle arrives, it gets connected there for a few minutes to recharge the supercapacitor,” Brinchi explains.
This operation happens speedily while drivers are taking their mandatory three-five minutes break; once recharged, the supercapacitor is ready to power the bus again for its next ride.
The trial conducted so far is promising says Brinchi. “We’ve had a preliminary performance assessment and results are excellent.”
Why so special?
We’ve had a preliminary performance assessment and results are excellent.
Those few minutes that the bus 64 spends at the charging station are enough to power it for its next 16 kilometres ride, until its return to the terminus.
Compared to battery chargers, the supercapacitor is lighter so the bus can load some extra passengers along its route, a great advantage for vehicles serving busy central routes.
In addition, supercapacitors can recharge a bus some 100,000 times during their lifespan compared to batteries’ 7,000; once disposed of, every part of a supercapacitor can be recycled and put to different use (carbon fibres, for example, can be employed as bike components).
Then there’s the time factor: battery-powered buses are recharged together at the depot at the end of their daily service, an operation that usually takes an entire night; their supercapacitor-powered equivalents, on the other hand, can be powered independently multiple times a day at a simple charging station in the city.
One city, three options
In parallel to these two models, Roma Servizi per la Mobilità is planning to further diversify its fleet by introducing a third clean energy vehicle: hydrogen buses.
The idea, says Brinchi, is to install solar panels for the independent production of hydrogen. This ‘homemade’ hydrogen would then be distributed to the bus where, thanks to a chemical reaction with water, it will generate electricity to power the engine.
The Italian city of Bolzano is already employing 15 hydrogen buses and serving as a model that Rome intends to reproduce in the near future.
In the long run, Brinchi’s plan is to use each type of bus according to the area that it will serve; a fleet as complex as Rome’s can’t rely on a single bus model, he says.
“Battery-powered buses will work well for suburban areas because they usually have fewer passengers and make fewer journeys, so a single night charge will be enough for the entire day,” the director explains. Hydrogen-powered and supercapacitor-powered buses will be a more suitable option for crowded city centre lines that cover shorter distances and have a higher passenger load, Brinchi adds.
Unveiling a new face to the world
The coming years will be crucial for Rome’s green mobility. By 2025, buses serving all city centre areas will be almost exclusively electric and the new clean fleet will gradually replace all old models.
The Rome transport makeover will be particularly crucial as the city prepares to host international visitors for the 2025 Jubilee at the nearby Vatican.
Like St. Peter’s square columns hugging pilgrims in their wide embrace, Rome will open its doors to the world with a brand new look: cleaner, quieter, easier to live in.
In parallel to its investments in sustainable public transport, Rome is testing innovative charging solutions for electric cars, bikes and e-kick scooters through its participation in the USER-CHI project: www.userchi.eu