German and Japanese scholars insist on using electric poles, thinking that the maintenance cost of underground cables is too expensive; China, however, widely uses underground cables, thinking that electric poles are ugly and backward. Which transmission method is better?
At present, it is clear that most large cities in developed countries are replacing electric poles with underground cables. According to statistics, the penetration rate of underground transmission methods in some modern cities in the world, such as Berlin, Tokyo, Osaka, Copenhagen, etc., has exceeded 70%.
The same is true in China. Beijing has proposed a goal of reaching a 94% penetration rate in the core area by 2020. For this reason, there are no electric poles in the city center of China now, and they are all replaced by underground cables.
In contrast to the speed of underground cable popularization in China, old developed countries seem to have doubts about this, and only replace electric poles in the center of more important capital cities. For example, the penetration rate of underground cables in Japan in 2015 was only 15%.
Why don’t you dare to lay underground cables at will? In fact, laying underground cables is not as simple as we think. It is enough to just buy cables. It also involves many problems.
First of all, because air is an insulator and the ground is a conductor. Therefore, it is more conspicuous to use poles to erect wires, and ordinary people will not approach them casually. As long as there is no leakage accident, it is very safe.
However, if the cable is buried underground, if there is leakage, it is easy to cause electric shock accidents, especially for some small animals close to the cable. Of course, the most important thing is that the current will not go far after the leakage, which may cause power outages in nearby buildings.
Therefore, in order to prevent leakage, underground cables must be covered with thick insulating shells. Ordinary cables can be buried underground in this way, but there is no effective insulating shell for ultra-high voltage transmission lines with higher voltages, so they can only be erected in the air with iron towers.
Then, underground cables have higher technical requirements than poles, because underground cables are not just a matter of installing cables, but also need to be combined with urban road construction to improve line plans according to power supply needs.
In addition, engineers also need to determine the construction route and construction site based on local geological conditions, sewer distribution and weather conditions.
The reason why Japan has not rapidly popularized underground cables is mainly because the cost and maintenance costs are too expensive, and it is really unaffordable. Of course, some people speculate that this may be related to the frequent earthquakes in Japan, because earthquakes can damage the bottom layer, and cables are prone to breakage and exposure to the surface, which is very dangerous.
In fact, there is another key factor, that is, most old capitalist countries are very stingy about infrastructure construction and are unwilling to spend a lot of effort and cost to upgrade.
For example, the electric poles we see are basically made of cement, but the United States has retained a lot of wooden electric poles, even in big cities such as Los Angeles, New York, and Washington.
This is because most of the infrastructure in the United States was built in the 1950s. If you want to upgrade the entire US power grid system, it will cost at least 50-100 billion US dollars, which is a huge expense.
Some railways are privately operated, and they are even more unwilling to rebuild the crooked railways, resulting in constant train derailment accidents every year.
In short, underground cable technology is definitely more advanced and more suitable for the development of modern cities, but due to funding, technology and policy limitations, it is unrealistic to completely replace telephone poles for a long time in the future.