Power grids and pipelines

During solar storms, the solar wind subjects the Earth's magnetic field to severe fluctuations, and potential differences in voltage are induced between grounding points in electric grids much as at the extremities of transatlantic cables. The resulting currents may cause saturation of transformers and shorten their operational life, and disrupt the operation of relays and circuit breakers leading to systems shut-down.23 The risks are enhanced where, as in northern North America, much of the electrical grid is near the North magnetic pole and the 'auroral electrojet current', an oval zone around the North pole in which flow currents attaining several million amperes. The predominance of igneous rock, which commonly has high electrical resistance, encourages any geomagnetically induced currents to flow in the transmission lines rather than through the ground.24

A solar storm thus disrupted electricity supplies in parts of the USA and Canada in 1940. In 1972 a 230,000 V transformer at the British Columbia Hydro and Power Authority exploded. In 1958 there was a power failure in the Toronto area during which the only light was provided by the aurora.25 In March 1989 a solar storm led to a blackout in Quebec which lasted 9 h and affected more than 6 million customers.

These events cannot match in scale a blackout in 1965, which affected 25 million people for up to 12 h over Ontario and the northeastern USA, the 1999 blackouts that left 90 million people without power for several hours in Brazil and 8.5 million consumers in Taiwan, or the 2003 blackouts that again affected about 50 million people in Ontario and parts of northeastern and midwestern USA. All, so far as we know, were due to hurricanes, landslides, human error and other terrestrial agencies. Al Qaeda claimed responsibility for the North American 2003 event but a report released in 2004 blamed the failure on contact between overloaded high-voltage power lines and trees which had been inadequately trimmed,26 and the consensus now favours a simple case of overload. But all the above demonstrate how failure can cascade through extensive networks. The 800,000 km of bulk transmission lines in the USA and 12,000 major substations offer numerous entry points for geomagnetically induced currents, and power grids operate with little spare capacity. The giant power grids being proposed for the Mediterranean and North Africa and discussed in Chapter 8 offer even more scope for induced mayhem.

The impact of storms on power systems can be mitigated by reducing current flow with series capacitors in transmission lines or in the earth wires of transformers. Several such have been put in place in Quebec since 1989 but they are expensive and their installation is not straightforward. In the short term, effective forecasting might allow timely reduction in loading of the system to introduce more leeway and in other ways ensure that operators have emergency procedures in place.27 But restoring power after an extensive blackout is perhaps more problematic especially as demand can then be six times the normal level. Equipment is damaged, delaying restoration further. Large transformers can cost over $10 million each and may take over a year to replace. The cost of a major blackout in France lasting 4 h was put at a billion dollars; a major blackout in the northeastern USA would now result in losses measured in several billions of dollars; extrapolation to the flare of 1859 suggests that the related blackout could affect half the population of the USA, with losses estimated in trillions of dollars.

The issue is not simply one of industrial and domestic power, and the delay its restoration entails, but also of the many services whose disruption can have serious consequences, such as water supply, sewage treatment and disposal, refrigeration, public transport, airline management, and banking.28 Induced currents are hosted by long, metallic, grounded water, oil and gas pipelines, especially those that extend into auroral regions and their periphery.29 A power gas pipeline explosion in June 1989 caused by leakage from a corroded section engulfed two trains on the Trans-Siberian railroad, with hundreds of deaths. By 1977 the Alaska pipeline already measured 1,300 km from 62° to 69° N within the most active part of the electrojet current mentioned above; modelling of the induced fields during several solar cycles showed that half the time the induced currents would be less than 1 A but during high solar activity surges could exceed 500 A.30

The currents enhance corrosion by a process analogous to the deterioration in the zinc casing of a dry cell. They flow from anodic areas on the pipeline to cathodic areas through the soil, which acts as an electrolyte, and corrosion occurs at the anodic area. Damage can therefore be reduced by coating the pipe with electrically insulating material, by maintaining the pipe at a negative electrical potential relative to the ground to inhibit oxidation of the pipeline, or both, simple but expensive expedients.

A more complex version of the cathodic technique follows the discovery in 1824 by Humphry Davy, inventor of the miner's safety lamp, that the corrosion of ships'

copper hulls was reduced if lumps of iron were attached to the ship below the waterline. The essence of the technique is to make the surface of the pipe serve as cathode of an electrochemical (galvanic) circuit and, as in Davy's prototype, to introduce a 'sacrificial' metal. It is widely used for well casings as well as pipelines of all kinds in a wide range of environments.

The erratic nature of the field fluctuations during a magnetic storm could undermine any such electrical protective measures by creating surges that exceed the limits of cathodic protection. Moreover, according to some authorities, modern pipe coatings make things worse by creating greater pipe-to-soil potentials than in the past so that any defects in the coating can increase the risk of corrosion.31 The most effective (and expensive) solution remains to insulate the pipe more thoroughly from the ground whether below the surface or above it.

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Solar Panel Basics

Solar Panel Basics

Global warming is a huge problem which will significantly affect every country in the world. Many people all over the world are trying to do whatever they can to help combat the effects of global warming. One of the ways that people can fight global warming is to reduce their dependence on non-renewable energy sources like oil and petroleum based products.

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