While technological advances have improved the efficiency of the United States’ transmission system, about 5% of electricity is lost through transmission and distribution. Ohmic loss refers to Joule heating loss when electricity encounters resistance in transmission line conductors. Since losses scale with the square of a wire’s current, keeping voltage high (and current low) helps reduce losses.
The more efficient high-voltage transmission lines are used for moving electricity long distances. At substations, the high voltage electricity is stepped down so that it can be distributed on lower voltage power lines. These less efficient distribution lines result in higher electricity losses.
Strategies for Reducing Transmission Loss
Many possibilities exist for improving the efficiency of the grid’s transmission system. However, market and policy restraints make some solutions more practical than others.
Superconducting materials can conduct electricity with little to no resistance, but require cooling to nearly absolute zero. These cooling requirements typically make superconducting materials too expensive to be considered for transmission lines.
However, advances in higher temperature superconducting technology have reduced cooling requirements, also reducing their cost of operation. The city of Essen, Germany, installed a liquid nitrogen-cooled 0.6 mile superconducting cable (the longest in the world at the time it was installed in 2014) that connects two large transformers.
In addition to nearly eliminating electricity loss, the cable can transport five times more power. Superconducting cables could also eliminate the need to amp up transmission voltages and make expensive equipment such as transformers no longer necessary, according to Extreme Tech.
High voltage direct current transmission lines offer greater efficiencies over the more typical alternating current (AC) lines. However, the relatively high cost of this approach makes it most practical for long distance transmission.
Flexible AC Transmission Systems, or FACTS, can help increase the efficiency of existing power distribution systems by maintaining acceptable voltage limits. This technology adjusts the amount of power injected into or absorbed by the power system.
FACTS allow AC lines to be loaded more heavily, increase reliability of the transmission system and mitigate power oscillations. These systems require new control technologies, but do not require any change to the distribution system materials.
Beta Engineering has designed and built numerous high voltage projects across the country. We specialize in EPC services for gas insulated substations (GIS), switchyards and substations, FACTS and high voltage transmission lines. Take a look at selected projects from our portfolio to find out more about the EPC solutions Beta can provide for you.