The main worldwide patent positions on elpipes are based on this international patent application:
Roger Faulkner and Ron Todd, PCT patent appl. PCT/US2010/048719 “Underground Modular High-Voltage Direct Current Electric Power Transmission System,” September 14, 2010.
This patent (now pending or issued in many countries) is based on four earlier US provisional patent applications, and covers a lot of ground in its 130 pages and 84 claims. Here is the full text of this international patent application. This PCT patent describes several different inventions; one that is particularly important is a way to thin the insulation of an elpipe compared to a cable, by using a spirally-wrapped insulation that is not feasible for a cable (which must be flexible). This invention is also addressed in this paper that was presented at the IEEE Dielectrics and Insulation Society's Electrical Insulation Conference, June 5-8, 2011.
The core of the patent is the idea of hybridizing a powerline, a pipeline, and a train. The train-like features decouple installation of the pipeline from insertion of the elpipe, allowing all the critical electrical joints to be made in a clean room environment at the point of insertion of the elpipe into the conduit (which is essentially identical to a gas pipeline). The moveable nature of the elpipe also enables repairs without having to dig the elpipe up, because the fault can be positioned in a maintenance vault.
In addition to this main patent position, I have also filed several patent applications for my HVDC circuit breaker concept, which is described in this abstract.
