Barcelona Subways Are Revolutionizing Energy Efficiency

The city's MetroCHARGE project uses the regenerative braking of subways to power trains, stations, and neighborhood EV chargers.

Hiya!

We all know how destructive fossil fuels are and what a mistake it was to become reliant on them as our primary energy source. Thankfully, we can own and learn from our mistakes and, in the process, invigorate our ingenuity.

Such creativity is already spreading worldwide as brilliant minds of all ages develop innovative ways to harness and use alternative energy sources. A great example is the MetroCHARGE project in Barcelona, Spain, which uses regenerative braking to power trains, stations, and local EV chargers.

Regenerative Braking

Any time a train slows to a stop, all that friction generates kinetic energy, which can be converted into electricity. This electricity can then be fed through inverters that distribute it elsewhere.

This process, known as regenerative braking, uses energy that would otherwise be lost as heat every time the train’s driver applies the brakes. Using the captured kinetic energy can significantly lower a transit system’s energy consumption.

It’s not just trains, either. Regenerative braking is already commonly used in hybrid and electric vehicles, but applying the method to trains can power far more than just the trains themselves.

In Barcelona, only a third of the regenerative power the subway trains produce is used to run them. The rest provides energy to the subway station amenities, like powering escalators, keeping the lights on, and fueling a growing network of electric vehicle (EV) chargers in nearby parking lots.

Barcelona is only one of a growing number of cities, including Philadelphia, São Paulo, and Vienna, to implement regenerative braking in some way. However, few use it as extensively as Barcelona’s MetroCHARGE project, which is also the first city to use it for public EV charging infrastructure.

The MetroCHARGE Project

Transitioning to using better, safer, renewable energy sources is vital in reducing global temperatures. At the 2023 United Nations (UN) climate talks, known as COP28, over 200 countries, including the Group of 20 industrialized and emerging-market nations, came together to demonstrate global solidarity by committing to doubling energy efficiency by the decade's end.

In his closing speech, UN Climate Change Executive Secretary Simon Stiell said:

“Whilst we didn’t turn the page on the fossil fuel era in Dubai, this outcome is the beginning of the end. Now all governments and businesses need to turn these pledges into real-economy outcomes, without delay.”

Barcelona didn’t waste time creating a package of clean energy technology options that could, among other things, help make its subway system greener with the MetroCHARGE program.

Making the subway greener may not seem like a big deal, but it is. On an average workday, approximately 2.3 million people use Barcelona’s metro, which consists of 8 lines, 165 stations, and 167 trains operating during peak times. Residents and tourists take over 440 million trips a year — and it requires a lotta energy to make all that happen.

Transports Metropolitans de Barcelona (TMB), a publicly owned transit agency, has installed three inverters at sixteen of Barcelona’s subway stations, with more in the works.

Once finished, the agency expects regenerative braking to provide 41 percent of the energy needed to power the trains and estimates that this transition will save around 3,885 metric tons of annual carbon dioxide (CO2) emissions.

Jordi Picas, project leader and Director of metro systems at TMB, told Natalie Donback of Grist that, thanks to the MetroCHARGE program, about 33 percent of the energy trains currently use comes from regenerative braking, enough to power 28 subway stations. He also explains that when subway systems don’t include regenerative braking technology,

“[T]here’s so much energy that’s not being used, and not only is it lost, it also generates heat that spreads inside the tunnels and increases the temperature.”

Increasing temperatures are already a problem on our planet, and we don’t need them rising in our subways, either. However, Picas says the temperature in Barcelona’s subway systems has decreased by 1.8 degrees Fahrenheit since implementing regenerative braking.

In 2023, electrified transport surpassed renewable energy as the largest category of energy transition investment worldwide, receiving about $634 billion globally (around 606 billion euros).

Implementing MetroCHARGE, which includes European Union funding, has already cost about $8.6 million (7.8 million euros), but TMB predicts that, between the energy savings and revenue from the EV charging stations (currently a rate of about 33 cents per kilowatt-hour), the program will return the investment within four to five years.

The Obstacles