The USA is going to be building a lot more transmission lines. Utilities are going to invest billions of dollars in new T & D infrastructure. Society has become much more sensitive to questions of ecosystem damage: will the new assets have a lower impact on the environment?
This infrastructure development is being driven by several factors, including the need to rebuild lines following severe weather, efforts to protect existing electric infrastructure against severe weather, and bringing significant quantities of renewable electricity from sometimes remote areas or offshore where it is generated, to customers in urban conglomerations. The decisions to where to site the lines and pylons is based on numerous factors, including affordability, reliability and also severe weather events like floods and wildfires.
Building transmission lines across forested areas is a challenge. Nobody wants to cut down trees unnecessarily. However as laying cable underground is usually too expensive – often 10 times the cost of conventional pylons – so will not be possible in many cases. Normally this means cutting down trees on either side of the line, to preserve Right of Way (ROW) and avoid wildfires.
ATCO Electric, a Alberta, Canada-based utility, deployed a 69 kV line in Jasper National Park,with a 25-kV under-build, with both lines using an aerial covered conductor in a tree wire configuration, to minimize the danger of wildfires while also reducing ROW clearance. This meant that the fewest trees were felled, reducing the clearance from 15 meters to 10 meters. By using covered wires, which were more expensive than uncovered ones, but hugely cheaper than running them underground, the forest was preserved as much as possible.
This shows that by paying attention to the ecosystem, new transmission assets can be deployed, while causing the minimum of ecosystem disruption.