Environmental impact
El impacto ambiental potencial de líneas de transmisión de energía eléctrica incluyen la red de transporte de energía eléctrica, el derecho de vía, las playas de distribución, las subestaciones y los caminos de acceso o mantenimiento. Las estructuras principales de la línea de transmisión son la línea misma, los conductores, las torres y los soportes.
Las líneas de transmisión pueden tener pocos, o cientos de kilómetros de longitud. El derecho de vía donde se construye la línea de transmisión puede variar de 20 a 500 metros de ancho, o más, dependiendo del tamaño de la línea, y el número de líneas de transmisión. Las líneas de transmisión son, principalmente, sistemas terrestres y pueden pasar sobre los humedales, arroyos, ríos y cerca de las orillas de los lagos, bahías, etc. Son técnicamente factibles, pero muy costosas, las líneas de transmisión subterráneas.
Las líneas de transmisión eléctrica son instalaciones lineales que afectan los recursos naturales y socioculturales.[3] Los efectos de las líneas cortas son locales; sin embargo, las más largas pueden tener efectos regionales. En general, mientras más larga sea la línea, mayores serán los impactos ambientales sobre los recursos naturales, sociales y culturales. Como se tratan de instalaciones lineales, los impactos de las líneas de transmisión ocurren, principalmente, dentro o cerca del derecho de vía. Cuando es mayor el voltaje de la línea, se aumenta la magnitud e importancia de los impactos, y se necesitan estructuras de soporte y derechos de vía cada vez más grandes. Se aumentan también los impactos operacionales. Por ejemplo, los efectos del campo electromagnético (EMF) son mucho mayores para las líneas de 1000 kV, que para las de 69 kV.
Los impactos ambientales negativos de las líneas de transmisión son causados por la construcción, operación y mantenimiento de las mismas. Las causas principales de los impactos que se relacionan con la construcción del sistema incluyen las siguientes:.
La operación y mantenimiento de la línea de transmisión incluye el control químico o mecánico de la vegetación dentro del derecho de vía y, de vez en cuando, la reparación y mantenimiento de la línea. Estas actividades, más la presencia física de la línea misma, pueden causar impactos ambientales.
En el lado positivo, al manejarlos adecuadamente, los derechos de vía de las líneas de transmisión pueden ser beneficiosos para la fauna. Las áreas desbrozadas pueden proporcionar sitios de reproducción y alimentación para las aves y los mamíferos. El efecto de "margen" está bien documentado en la literatura biológica; se trata del aumento de diversidad que resulta del contacto entre el derecho de vía y la vegetación existente. Las líneas y las estructuras pueden albergar los nidos y servir como perchas para muchas aves, especialmente las de rapiña.
Effects on fauna
Power lines can lead to electrocution of both birds and mammals when they touch two conductors or a conductor and part of the support. The most affected group are birds, of which thousands die annually when landing on supports. Among birds, the most affected are raptors, since they usually perch on supports to use them as vantage points to stalk their prey.
The design of the supports, the orography of the terrain, the meteorology or the habitat are some of the factors that determine the danger of the lines. Increasing the separation between the conductors or between conductors and the crosshead are some of the measures that reduce the risk of electrocution. Also, cover the conductors with insulating and weather-resistant materials in the areas of greatest risk of contact.
In addition to electrocution, electricity transmission lines also cause accidents to birds due to collisions with conductors. This problem is especially serious in areas with frequent fog, since in the fog the birds do not see the power lines and it is easier for them to collide with them. Different devices can be placed to increase the visibility of the cables, such as polypropylene spirals, balls of different materials, loops, reflective pieces, etc.
Effects on land use
The greatest impact of electric power transmission lines is on land resources. An exclusive right-of-way is required for the electric power transmission line. Grazing or agricultural use is not normally prohibited on rights-of-way, but other uses are generally incompatible. Although rights-of-way are not very wide, they can interrupt or fragment the established use of the land throughout their entire length. Long transmission lines will affect larger areas and cause more significant impacts.
Transmission lines can open up the most remote lands for human activities such as colonization, agriculture, hunting, recreation, etc. The occupation of space reserved for the right of way can cause the loss or fragmentation of the habitat, or the vegetation that is in its path. These effects can be significant if natural areas, such as wetlands or wildlands, are affected, or if the newly accessible lands are home to indigenous peoples.
Clearing and control of vegetation on rights of way
There are a variety of techniques to clear right-of-way vegetation and control the amount and type of new vegetation. From an environmental point of view, selective clearing using mechanical means or herbicides is preferable and should be analyzed in the project's environmental assessments.
Aerial spraying of herbicides should be avoided because it is non-selective and introduces large quantities of unnatural chemicals into the environment, and it is an imprecise application technique and can contaminate surface waters and terrestrial food chains, eliminating desirable species and poisoning wildlife.
Health and safety risks
Placing low lines or placing them close to areas with human activities (e.g., roads, buildings) increases the risk of electrocution. Technical standards normally reduce this danger. Towers and transmission lines can disrupt the flight path of aircraft near airports and endanger low-flying aircraft, especially those used for agricultural activities.
Electrical power transmission lines create electromagnetic fields. The power of the fields, both electric and magnetic, decreases with the increase in the distance of the transmission lines. The scientific community has not reached any consensus regarding specific biological responses to electromagnetic force, but emerging results in communities related to this physical influence suggest that there is a well-founded history of health risks associated with some types of cancer.[4].
Regulations have been promulgated in several states in the United States that regulate the electromagnetic force that is associated with high voltage transmission lines "Voltage (electricity)").
Although there are people who argue that high voltage lines could affect the environment and the people who live near transmission lines, the truth is that said electromagnetic pollution is mitigated by the economic benefits of transporting power at a high voltage. There are countries in which people who live under or in the vicinity of high voltage lines are subsidized, under the assumption that organic tissues could be damaged by the electromagnetic fields caused.
induced development
Depending on their location, transmission lines can induce development on or adjacent to rights-of-way, or on lands that have become more accessible. Where housing is scarce, rights-of-way are often attractive sites for building informal housing, and this, in turn, causes other environmental impacts and overloads local infrastructure and public services.