The true picture (2)

I refer to the recent correspondence in The Sunday Times on interconnecting the Maltese electricity network to the European Grid.

Enemalta Corporation fully supports this proposal and is committed to developing it into a viable project which will enhance security of supply locally. It is also prepared to support schemes to exploit renewable energy, whatever the source. Readers are referred to the Enemalta Generation Plan 2006-2015, particularly sections 2.2.4 and 3.6. This report may be downloaded from www.enemalta.com.mt, and was approved by the Government in July 2006 and represents the official policy direction given to the corporation.

All electro-mechanical systems require periods of outage, either planned for maintenance or unplanned as a result of a fault. In the case of electricity supply, it is Enemalta's policy to build a level of redundancy into its systems to minimise the effect of such unplanned outages.

For example, if a particular distribution centre requires two cables to meet the projected load, Enemalta will install three cables, so that in the event of a fault on any one cable, the remaining cables can safely be switched to take the load until the required repairs are carried out. This is commonly described as 'N-1' redundancy.

Enemalta agrees that the large interconnected European grids are generally very reliable, and interconnection presents several significant benefits to an isolated system such as ours.

However it would be foolhardy to ignore the potential risks of system failure, as was amply demonstrated during the extensive outages which occurred in several European states during the heatwave of summer 2003, and the widespread outages affecting about a third of all consumers in Europe, during the winter of 2006 (caused by overloading and not the sudden fall of wind energy in Germany, as erroneously claimed), not to mention the recurrent problems caused by interruption of supply of gas from such unreliable sources as the ex-Soviet Union. This is a quote from the official Swiss report on the failures which led to the 18-hour Italian nationwide blackout of 2003.

"The underlying causes of the incident that occurred on September 28, 2003, are the unresolved conflicts between the trading interests of the involved countries and operators and the technical requirements of the existing transnational electricity system. Present-day standards and legal instruments are lagging well behind economic realities."

Following the 2006 outage, the EU Commission has proposed regulations to better control the grid and to develop better levels of co-operation between the transmission system operators. However, given Malta's location on the periphery of Europe, an interconnector between Malta and Sicily could potentially suffer from the consequences of congestion and overloading of the transmission system anywhere in the supply chain.

Apart from this, the interconnector or its shore installations may fail, and in such a situation, the lack of redundancy in the source of supply could lead to prolonged outages, particularly as repairs to a submarine cable could be expected to take several weeks.

To adopt Prof. Cilia-Vincenti's analogy, a car owner has several readily available alternatives if his car is unavailable due to maintenance or fault, but unfortunately while large MW-class generating units are available internationally for hire, they are not generally available at a few hours' notice. In the event of an unplanned outage of an interconnector, the lack of a reserve local generating plant would imply prolonged electricity supply failure and economic disruption.