Power trip – Are there alternatives to overhead transmission lines?

Transmitting electricity over long distances faces growing challenges

Let’s face it: Overhead transmission lines are not always accepted by the public. For various reasons, many people do not really like these highways of electricity.

For one, they are not the prettiest of sights on the horizon. As they march across mountains, pile across prairies, dash through deserts – all in the service of transmitting power from generating stations to users – most people don’t find them particularly pleasing to look at. When they come close to populated areas, people then tend not to like them as neighbors, either. They worry about electromagnetic radiation, and sometimes about the potential hazard of so much power concentrated in so little space. Homeowners fret that nearby power lines knock value off of their hard-earned houses.

Power transmission? Today, more than ever!

But the fact is, we need transmission lines – today, more than ever. On the one hand our need for energy is increasing, due to economic and population growth. On the other hand the urgent prerogative to reduce the carbon footprint of electricity generation encourages us to tap into a multitude of renewable sources. These resources are not always close to the consumer or load center. Transmission lines allow us to access energy from wind offshore parks or hydro power plants in the mountains. Overhead lines with pylons are for sure the most simple, reliable and affordable solution for this.

Nevertheless, Siemens is working on ways to do it without pylons – at least some of the time. We’ve already demonstrated alternative solutions, and we’re busy finding further refinements.

Pick and mix

Broadly speaking, there are two technology options for long-distance transport of electricity:

• AC or DC? – the big plus for alternating current (AC), the kind coming out of an ordinary outlet, is that its voltage can be transformed up and down, which is particularly useful in local distribution. Direct current (DC), on the other hand, can travel long distances with much lower losses.

The next question is how to build transmission lines:

• Above ground or underground? – the above ground option includes the pylons we know and not-so-much love, which actually have a number of advantages over underground solutions that are more costly and complicated to build and operate.

But if you go underground, there are two possible solutions:

• Conventional cables or gas-insulated lines? - an alternative to high-voltage cables that carry electricity underground are gas-insulated-lines (GILs) that allow large capacities of power to move right alongside humans.

Solutions based on GIL can be operated as AC transmission, whereas GIL with DC transmission is still work-in-progress. Siemens is driving this development forward.

In the coming series of blog posts, we aim to introduce these further, and to discuss their pros and cons. Please stay tuned!