Going Airborne: Is It Time for Overhead Power Lines Instead of Buried Cables? Here's the Lowdown
Switching from Underground Cables to Overhead Lines: Implications to Consider - Vertical power transmission lines as an alternative to underground cables for electricity distribution.
Germany might be saying goodbye to buried cables and embracing overhead lines for power grid expansion, a move that could potentially save billions of euros - and help consumers. Tim Meyerjürgens, CEO of power grid operator Tennet, estimates that at least €20 billion could be saved on the next three major planned projects - OstWestLink, NordWestLink, and SudWestLink - if they switch to overhead lines. "In the short term, this could slash network charges by one cent per kilowatt-hour," says Meyerjürген. "We need every opportunity to alleviate the burden on industry, commerce, and residential dwellers."
According to a Federal Network Agency spokesperson, overhead lines are undoubtedly less expensive, with potential savings on the OstWestLink, NordWestLink, and SudWestLink projects amounting to roughly €16.5 billion. However, shifting to overhead lines may delay the planning of these projects, which were initially slated for underground cables.
Emphasis on Underground Cables
With the transition to renewable energy, vast expanses of new power lines will be laid to transport northern wind power to southern consumption hubs. Since 2016, there's been a push for underground cables on major "power highways" to increase public acceptance of the grid expansion.
In a joint paper by transmission grid operators Tennet, TransnetBW, and 50Hertz, it is suggested that the use of underground cables has yet to yield the anticipated acceptance boost. The three companies are advocating for a change in tactics.
CDU-CSU-SPD Coalition Announces Reform
In the coalition agreement, the new high-voltage direct current transmission networks (HVDC) should "where possible," be above-ground. This decision will take special consideration for heavily affected regions to increase grid expansion efficiency.
Overseeing the shift will be a monitoring process by the summer of 2025, involving an assessment of power demand, supply security, grid expansion, and renewable energy expansion. Findings from this review will inform decisions about future HVDC projects and their implementation.
Amprion Treads Cautiously
Amprion CEO Christoph Müller acknowledges a need-before-debate approach and argues that we should only construct what's genuinely necessary. With the current demand trend suggesting less necessity than previously thought, Müller suggests that abolishing the priority for underground cables without a replacement for overhead lines could be risky.
Restart for Projects?
Due to the upcoming federal election, the OstWestLink, NordWestLink, and SudWestLink direct current projects were excluded from the federal requirement plan, preventing their approval process from starting by June 30 under EU emergency regulations. This means that accelerated approval procedures cannot be applied to these projects.
"We've long been calling for a shift from underground cables to overhead lines for direct current projects," offers Meyerjürgens. "The restart of approval procedures for key grid expansion projects now presents an opportunity to still change course in time and consistently opt for overhead lines instead of underground cables."
What Are These Projects About?
- The OstWestLink aims to deliver green electricity from Lower Saxony to Saxony in the future.
- The NordWestLink connects Schleswig-Holstein and Lower Saxony wind energy and North Sea offshore wind energy to Baden-Württemberg.
- The SudWestLink enhances the transmission capacity between Schleswig-Holstein and southern Germany.
For large-scale projects like the SudLink from north to south, planning documents have been submitted, and route determination is ongoing. Construction has already begun in some places, with the project slated as an underground cable project. Numerous citizen initiatives oppose new power lines in various locations.
If overhead lines become the preferred method, the pre-determined underground cable areas would be obsolete and would require complete re-evaluation for overhead lines, leading to significant delays.
Climbing Charges
Network charges, which fund power grid expansion, have risen significantly in recent years. Switching to high-voltage direct current lines could lead to a reduction of one cent per kilowatt-hour in network charges, translating to yearly savings of around €30 for a typical two-person household with annual consumption of 3,000 kWh, and around €50 for households consuming 5,000 kWh, according to Tennet.
Why Overhead Lines are a Bargain
Overhead lines can be built more quickly and inexpensively than underground cables, with each kilometer of underground cable instead of overhead line costing €10-€20 million more. According to Tennet, overhead line construction costs are up to eight times cheaper than underground cables, depending on the local geography. In addition, overhead lines are easier to maintain and can be repaired more rapidly, according to the paper.
Enrichment Insights:
Overhead Lines vs. Underground Cables in the Grid Expansion Perspective:
- Cost effectiveness: Overhead lines generally have a lower installation cost compared to underground cables for large-scale projects such as OstWestLink, NordWestLink, and SuedWestLink [1].
- Maintenance benefits: Overhead lines are easier to access and maintain, lowering complexity and associated costs [3].
- Flexibility: Overhead lines can be easily expanded or modified as needed, making them suitable for expanding power grids.
Potential Disadvantages of Overhead Lines:
- Lower reliability and weather resistance: Overhead lines tend to be more susceptible to weather-related disruptions such as lightning, high winds, and ice storms [5].
- Environmental and aesthetics concerns: Overhead lines can pose a visual impact and potentially conflict with natural landscapes, raising environmental factors [1].
- Safety risks: Overhead lines present a higher risk of accidents and electrocutions compared to underground cables [5].
Germany's Context:
Germany's unique situation, characterized by the predominantly underground placement of lines with less than 100 kV, along with a strong focus on environmental and safety considerations, influences the decision-making process for projects like OstWestLink, NordWestLink, and SuedWestLink [1]. Balancing these factors against the need for efficient and cost-effective grid expansion will determine the choice between overhead and underground lines for these projects.
Considerations for Specific Projects:
- OstWestLink, NordWestLink, and SuedWestLink: Taking into account Germany's emphasis on undergrounding for lower voltage lines, these projects may initially favor underground cables to ensure reliability and environmental standards [1]. However, cost considerations and ease of maintenance for overhead lines can impact the decision process in specific segments of these projects.
- Community aid could potentially benefit from the cost savings achieved through the use of overhead power lines in the power grid expansion projects OstWestLink, NordWestLink, and SudWestLink. The shift to overhead lines could reduce network charges by one cent per kilowatt-hour, resulting in yearly savings of around €30 for a typical household with 3,000 kWh annual consumption.
- As the shift from underground cables to overhead lines for high-voltage direct current transmission networks is being advocated, there may be a need for community education and engagement to address potential environmental and aesthetics concerns associated with overhead lines. This could ensure that all stakeholders are informed and involved in the decision-making process for these grid expansion projects.
