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Last Updated: Monday, 29 September, 2003, 12:48 GMT 13:48 UK
Q and A: Power blackouts
Sunday's blackout in Italy was the latest in a series of major power cuts to affect national power grids across large areas of the developed world - coincidence or conspiracy? BBC News Online explains.

What caused the power cuts in Italy?

Italy does not have enough electricity generating capacity to satisfy Italians' demand for power. Its nuclear power programme was closed down after the Chernobyl disaster in the 1980s and it has been unable to build new fossil fuel plants because of objections from environmentalists.

As a result, Italy is highly dependent on electricity supplies from neighbouring countries.

The blackouts happened when storms over the Alps knocked out a transmission line carrying power from Switzerland, followed by the breakdown of another two supply lines in France. The power failure then spread rapidly to the whole of Italy, with the exception of the island of Sardinia.

Did the Italian power cuts have anything in common with the recent blackouts in London, North America, Sweden and Denmark?

London's blackout was traced to a badly-installed fuse at a power station, but the others all happened for similar reasons.

Throughout the developed world, demand for electricity is increasing as computer technology becomes more widespread. The recent heat wave in much of Europe also boosted sales of air conditioning units, putting more pressure on electricity generating stations and on the grids that carry power supplies.

Electricity cannot be stored, so managing big fluctuations in demand can be difficult. To overcome this, there is a growing trend for countries to club together and link their national grids into big regional networks.

This makes it possible for individual countries to manage peaks in demand without having to carry too much surplus capacity, but it makes them vulnerable to a domino effect when equipment breaks down.

Are there underlying problems or were these freak accidents?

Deregulation and privatisation have added to the problems faced by the electricity industry worldwide. Over the past 10 years, the cost of generating power has actually halved in many countries because of greater efficiency, but at the same time, it has become harder to make a profit from the business.

This makes firms reluctant to invest in the infrastructure, so power grids are not being modernised in line with the increased demand for electricity.

Conspiracy theories circulating via e-mail and the internet indicate that many people are inclined to blame terrorism or sabotage. What do the experts say?

The BBC's security correspondent, Frank Gardner, says he has seen no evidence to link any of the recent power failures to terrorism. He says the possibility was explored by the UK and US security services, but nothing that they have seen points in the direction of sabotage.

Are we likely to see more of this?

There have already been calls by French energy officials for the European Union to intervene and improve co-ordination of electricity production.

In the US, there is concern that liberalisation of the energy market may have been poorly handled, with some experts saying that it made a complicated system even more complex.

It seems likely that, unless the years of under-investment are reversed, the power grids of the developed world will remain vulnerable to breakdown.

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