Below the streets of Stockholm, a remarkable engineering endeavor is underway. Deep within a narrow, humid tunnel, an enormous drill named Elektra relentlessly gnaws through layers of unyielding rock. Larger than a skyscraper, this mighty machine has tirelessly toiled for over three years and has now reached the halfway point of its momentous expedition.
Stockholm’s tunnel project, an integral part of a comprehensive plan to modernize the power transmission network, holds the key to propelling the city toward a sustainable, greener future.
A Steady Pace toward Sustainability
At an unwavering pace of 70 meters (230 feet) per week, Elektra is gradually carving a subterranean pathway that will revolutionize Stockholm’s aging electricity infrastructure.
This ambitious tunnel project, stretching 13.4 kilometers (8.3 miles) from the affluent suburb of Danderyd to the middle-class neighborhood of Hammarby Sjöstad, forms an integral part of a comprehensive 15 billion Swedish kronor ($1.37 billion) plan by the national grid to modernize and expand the power transmission network.
Overcoming Carbon Conundrums
The completion of this tunnel will address a pressing challenge faced not only by Stockholm but also by cities worldwide. As metropolises strive to reduce carbon emissions through electrification, their existing networks struggle to keep up with the surging demand. By the project’s completion in late 2028, the tunnel will serve as a crucial link in the city’s infrastructure overhaul, allowing the city to bid farewell to its outdated overhead powerlines and ushering in a new era of energy efficiency.
Powering Up for a Sustainable Future
Sweden, renowned for its abundant power generation and status as Europe’s largest electricity exporter in 2022, still faces a discrepancy in supplying Stockholm. While the nation’s power generation capacity is substantial, the network supporting the capital can only sustain approximately 3.5 gigawatts.
This becomes problematic during peak demand periods on the coldest days of the year and hampers the integration of new subway stations, commuter tunnels, and electric vehicle chargers, as well as the electrification of ports and ferries.
Bridging the Energy Gap
To mitigate the interim power deficit, local grid manager Ellevio AB secured an emergency supply agreement in 2019 with plant operator Stockholm Exergi AB, assuaging concerns during the coldest days. However, the urgency to upgrade the grid remains palpable.
The city’s ambitious goal of becoming completely fossil fuel-free by 2040, five years before demand is expected to surge to over a third of current levels, underscores the necessity for swift action.
A Wake-Up Call
The fragility of the existing infrastructure came into sharp focus on April 26, when a combination of human error and faulty equipment caused a power outage that paralyzed train and subway services during the morning rush hour, leaving tens of thousands of commuters stranded. Traffic lights faltered, and two nearby nuclear reactors had to be temporarily shut down.
Even Elektra, the stalwart machine entrusted with the grid’s renaissance, is not immune to power shortages. On a cold winter’s day in early December 2021, the colossal drill, consuming electricity equivalent to that of a small town, had to halt operations for approximately four hours as Stockholm residents ramped up their heaters.
An Ambitious Vision Takes Shape
The impetus to revamp the grid was set in motion nearly two decades ago, prompted by outages that affected the technology hub of Kista and the residential areas north of the capital. Initial proposals for a subsea cable encircling Stockholm’s archipelago were ultimately discarded due to concerns over cost and reliability. This paved the way for the underground tunnel as the sole viable option.
However, navigating through legal hurdles and red tape proved arduous, with the plan only receiving the green light in 2017. When complete, nine aluminum-based cables will run along the tunnel’s walls, facilitating the transfer of electricity from the national grid to the local network.
Descending into the Subterranean Marvel
Venturing into the tunnel entrance, concealed behind a substation occasionally subject to golf balls from a neighboring driving range, reveals the hidden marvel below. A surprisingly smooth, 5-meter-wide passage winds its way through the earth, occasionally patched with concrete where necessary. Tunnel boring machines, a relatively novel addition to Sweden’s engineering arsenal, have replaced the once-dominant dynamite.
At the tunnel’s ceiling, a conveyor belt diligently transports excavated rocks to the surface, destined for utilization in other essential infrastructure projects. Inside the tunnel, a control room houses personnel monitoring operations, while workers donning yellow protective gear and white overalls diligently carry out their tasks, undeterred by the arduous conditions.
Within a toolshed, project members gather to exchange notes and compare progress. This multinational team of 60 individuals, hailing from various European countries, operates on a rotational schedule, working in two-week shifts until their monumental mission reaches completion.
For officials and residents alike, this vision represents a radiant light at the end of the tunnel. Through the completion of the ambitious tunnel project and the subsequent grid enhancements, Stockholm will march toward a greener, more sustainable future, setting an inspiring example for cities worldwide.