The SuperGrid refers the existing high voltage transmission grid in Great Britain that was constructed in the 1960s, and to various overseas parallels, including the concept, again in the British context, of increased connectivity to our neighbours. In the code that governs the British Grid, the Grid Code

, the Supergrid is defined as those parts of the British electricity transmission system that are connected at voltages in excess of 200 kV (200,000 volts).

The article below refers to a particular concept for a high voltage grid (or supergrid), which is novel in that it combines with the distribution of cryogenic hydrogen, to achieve superconductivity. This is not the usual use of the term "supergrid", and from this point onwards, this page may be viewed as an article about "possible future superconducting grids with hydrogen" :

A supergrid with hydrogen is an idea for combining very long distance electric power transmission

Electric power transmission

Electric-power transmission is the bulk transfer of electrical energy, from generating power plants to Electrical substations located near demand centers...

 with liquid hydrogen

Liquid hydrogen

Liquid hydrogen is the liquid state of the element hydrogen. Hydrogen is found naturally in the molecular H2 form.To exist as a liquid, H2 must be pressurized above and cooled below hydrogen's Critical point. However, for hydrogen to be in a full liquid state without boiling off, it needs to be...

 distribution. The hydrogen is both a distributed fuel and a cryogenic

Cryogenics

In physics, cryogenics is the study of the production of very low temperature and the behavior of materials at those temperatures. A person who studies elements under extremely cold temperature is called a cryogenicist. Rather than the relative temperature scales of Celsius and Fahrenheit,...

 coolant for the power lines, rendering them superconducting. The concept's advocates describe it as being in a "visionary" stage, for which no new scientific breakthrough is required, but requires major technological innovations before it could progress to a practical system. A system for the United States is projected to require "several decades" before it could be fully implemented. High-voltage direct current

High-voltage direct current

A high-voltage, direct current electric power transmission system uses direct current for the bulk transmission of electrical power, in contrast with the more common alternating current systems. For long-distance transmission, HVDC systems may be less expensive and suffer lower electrical losses...

 (HVDC) lines have the capability of transmitting similar voltages, for example a 5 gigawatt HVDC system is being constructed along the southern provinces of China without the use of superconducting cables.

1.5%
of the energy transmitted on the British AC Supergrid is lost (transformer, heating and capacitive losses), of which a little under two-thirds, or 1% on the British supergrid, represents "DC", resistive, heating type losses. With the use of superconductors, the capacitive and transformer losses, in the unlikely event the transmission lines were still overhead, AC lines, would remain the same. Overhead lines do not lend themselves at all well physically to the incorporation of cryogenic hydrogen piping

, due to the likely weight of the transmission medium and the considerable brittleness of supercooled materials. It would probably be necessary for a supercooled hydrogen-carrying transmission line to be subterranean, and this in turn means that for such a cable, if it were of any distance (e.g. over 60 km), the power would have to be converted to DC and transmitted as such, since otherwise the capacitive losses would be too high. The power electronic losses in the AC/DC converter substations to convert the AC power at either end of the cryogenic cable to/from DC, if the transmission line(s) itself were DC, would also remain exactly the same as they would have been without the use of a superconducting transmission line - but the DC type resistive losses in the transmission lines would be rendered even smaller than at present.

Even before comprehensive continental and (in the case of the proposed European Super Grid

Super grid

A super grid is a wide area transmission network that makes it possible to trade high volumes of electricity across great distances. It is sometimes also referred to as a "mega grid".-History:...

) intercontinental backbones of electrical transmission may be realized, such cables could be used to efficiently interconnect regional power grids of conventional design.

See also

• Superconducting cables
• High voltage direct current

External links

• SuperGrid Workshop at University of Illinois at Urbana-Champaign
  University of Illinois at Urbana-Champaign
  The University of Illinois at Urbana–Champaign is a large public research-intensive university in the state of Illinois, United States. It is the flagship campus of the University of Illinois system...