Very high voltage cables are increasingly used to carry electricity over long distances. But the more you increase the voltage, the less effective is the insulation of the wires. Swedish researchers have discovered an additive that reduces conductivity by three, which would significantly reduce the weight of the cables.
In 2020, renewable energy represented 28% of electricity production in the world. The problem is that very often the place of production does not correspond at all to the place of consumption. In Germany, for example, wind turbines are mainly installed in the northern coastal regionsWhile the large industrial basins, large consumers of electricity, are located rather in the south, towards Bavaria. Likewise, in China, the large hydraulic installations are located in the northeast of the country, while the population is concentrated on the southeast coasts.
Increasingly heavy cables
To transport electricity over long distances, ultra-high voltage cables are used, some of which can carry up to 800,000 volts. But the more the voltage increases, the lower theisolation of the cable is effective. Therefore, it is necessary to lay a very thick insulation layer, which makes them considerably heavier. Therefore, certain 400 or 500 kV high voltage cables weigh up to 100 kg / meter for diameters between 20 and 30 cm! Therefore, scientists have been working for many years on insulators more efficient, reducing limitations.
Reinforce cable insulation
At present, the material used for the insulation of HVDC cables (DC high voltage) is mainly low-density polyethylene (LDPE). To increase the conductivity of the latter, additives are added in the the plastic, What high density polyethylene (HDPE), nanoparticles Metal oxide, allotropes carbon or various molecules aromatic. These additives “trap” electrical charges and reduce their mobility, which helps reduce electrical conductivity.
A team from the Chalmers University of Technology in Sweden has just gone a step further by introducing a new material that is up to three times less conductive, a discovery that could revolutionize long-distance electric transport. The base of the insulation is still polyethylene, but the researchers added a very small amount of a polymer called poly (3-hexylthiophene) (P3HT), to the tune of 0.0005% by weight of plastic. They then observed a reduction in conductivity of up to 6,000% by weight. ” that far exceeds the efficacy of any other compound studied to date “They congratulate themselves on their study published in the magazine Advanced materials. By reducing the conductivity, we can use less plastic and therefore lighten the cable.
Promising new materials
Conjugated polymers like P3HT are nothing new – they were used in the past in electronics as semiconductors to manufacture flexible printed circuits or photovoltaic panels. But this is the first time they have been considered insulators. ” This discovery could open a new field of research in the design and optimization of plastics with advanced electrical properties for energy transport and storage. », Assures Christian Müller, professor of the Department of chemistry and Chemical Engineering from Chalmers University of Technology and co-author of the study.
Ceramic insulator for more conductive cables
Additional article published on 05/10/2003
A new insulating material used for coaxial cables has just been developed that would improve performance by more than 25%. speed data transfer.
Tri Chemical Laboratories and Osaka University Professor Hiroshi Nakayama jointly developed the product and hope to be able to commercialize it in 2-3 years. The material consists of a alloy carbon silicon and it would serve to fill the space between the different layers that make up the cable. His constant dielectric is 3.01 versus 3.9 for the silicon oxide layer, which means that it would facilitate the transfer of the electrical signal through the wire. To make the film, the research team used a catalytic chemical vapor deposition (CVD) method. Previously, the CVD plasma method was used at a temperature of 800 ° C, which caused damage to the substratum.
The catalytic CVD method is used at 400 ° C, which reduces the possibility of damage. Also, the speed of lamination it is only 0.4 µm / min, 10 times faster than conventional methods. Researchers are currently working on developing an insulating film with a lower electrical constant.
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