When a test to link the electricity grids of Libya and Tunisia failed in November 2005, the architects of the project to create a synchronous electricity ring in the Mediterranean basin were sent back to the drawing board. Almost two years later, the technical problems encountered during the ill-fated test have still not been resolved.

Energy trading

The dream of linking all the electricity networks around the Mediterranean with a ring of alternating current (AC) connections to create one synchronous region is growing increasingly distant. Current thinking envisages the implementation of a compromise scenario, which will allow energy trading to take place while avoiding the problems associated with synchronisation.

The concept of a Mediterranean electricity ring (Medring) was first mooted in the early 1990s. Once interconnected, the sequence of national networks would form an elliptical ring that would be 4,000 kilometres east to west and 2,000 kilometres north to south. This began in August 1997 when a 400-kV AC submarine cable between Morocco and Spain was energised, and in May 1998 it was used for the commercial exchange of power for the first time.

Today, Europe is interconnected from Poland to Spain and two synchronous systems operate independently in the southern Mediterranean: the first includes Algeria, Tunisia and Morocco; the second runs from Libya to Syria through Egypt, Jordan and Lebanon. Turkey is an independent bloc, but aims to join the wider network.

‘Turkey is pushing hard to join the European system,’ says a source close to the Medring project. ‘It is a fact of life in Europe that electricians are always in advance of politicians. It is a strong symbol of going towards Europe.’

A connection between Libya and Tunisia is the missing link, but joining the two countries has already proved difficult. The 2005 test of a connection between the two was designed to run for three days, but failed within minutes after the capacity of power surging into the connection from Europe caused it to trip.

‘A wave of power from Europe caused the activation of protection in the Maghreb, tripping lines from Algeria to Morocco,’ says an industry source.

‘If the regulatory capacity is not the same speed [across the connections], you have an imbalance immediately and power comes in [to balance the system] from Spain. Europe has an installed capacity of 400 GW, while Algeria and Libya have 6 GW and 4 GW respectively. This means its ability to withstand fluctuations is much greater. The regulatory capacity of Europe is much stronger.’

Another weakness in the system is the interconnection between Libya and Egypt. The 220-kV double-circuit line linking the two systems has a capacity of only 120-140 MW. Plans include strengthening the interconnection by extending a 500-kV line from Marsa Matrouh to Tobruk. A 500-kV/400-kV transformer would be located in Libya, which would complete the upgrade of its electricity backbone to 400-kV by 2015.

One possible solution to the problems of synchronous interconnection was proposed at the meeting of the liaison committee of electricians around the Mediterranean Basin (Medelec) in April 2007. A direct current (DC) back-to-back link could be set up between Libya and Egypt.

With a peak load of approximately 20,000 MW, the Egyptian power system is the largest in the southern Mediterranean, and therefore subject to higher fluctuations. In a synchronous structure, these fluctuations would be transmitted throughout the system. ‘A back-to-back interconnection acts as a filter for normal power frequency fluctuations on either side,’ says Juan Manuel Rodriguez Garcia, head of network studies at Red Electrica de Espana.

Compromise solution

The new link would still allow energy exchange, however. ‘If you have 220-kV lines with 300-MW capacity, these fluctuations occupy 70 per cent of their capacity,’ says Garcia. ‘If you have a back-to-back connection, all the capacity will be available for commercial purposes; otherwise you reserve part of the capacity for these fluctuations.’

With much of the necessary infrastructure already in place, compromising the original idea of a synchronous Mediterranean ring by installing DC connections may be the only way forward. ‘If there are such big technical problems forcing a decrease in cross-border transfer capacity, why not use direct current?’ says the industry source.

Cost will be a key consideration when it comes to installing a DC link. ‘Each country will have to cope with the investment cost,’ says the industry source. ‘Having already spent on AC connections, they will now need Eur 150 million [$214 million} for DC.’

Whether investments to date have paid off is debatable. The volume of energy exchanged on a commercial basis is small, with two exceptions. In 2006, Spain exported approximately 1.9 TWh to Morocco. Trade between Egypt and Jordan is the second exception.

‘Two to three years ago, trading of energy was quite high,’ says the industry source. ‘It reached 1 TWh, but after some blackouts the trading of energy decreased slightly.’

Jordan consumes 8 TWh of electricity annually, with demand growing at 10 per cent a year. Apart from this, commercial exchange within the Maghreb and Mashreq is minimal, consisting mainly of Algeria exporting to Morocco and Tunisia, and Egypt exporting to Libya.

‘There is no trade, only spot exchange with remuneration in kind,’ says the industry source. ‘There is no electricity market yet. Trading is on the basis of long-term commercial agreements like in Europe in the 1970s and 1980s.’

Under this arrangement, neighbours agree to exchange specific quantities of energy on a quid pro quo basis. Where a price is agreed, competition is low. ‘Except in Egypt, where the hydro installed capacity is by far the highest, the generation mix is based on thermal power plants [fuel, natural gas and coal], so there are not many possibilities for competition,’ says Garcia.

In addition to the exchange or trading of energy around the Mediterranean system, several submarine connections are planned for the export of electricity from the Maghreb to the southern shores of Europe.

‘Medring is an idea launched in the 1990s,’ says the industry source. ‘It is one process that is going on, but it might be necessary to decouple the system. In 2000/01, new feasibility studies were launched aimed at building interconnection towards Europe.’

The link most likely to be implemented is a connection between Tunisia and Sicily, which will export 800 MW to the Italian island. This will involve the construction of a 1,200-MW power station at El-Haouaria in the north-east of Tunisia. Rome and Tunis have now given the go-ahead for the formation of a joint venture company to implement the scheme.

Sub-sea connections

Other projects include sub-sea cables linking Algeria and Europe - one to Spain and another through Sardinia to Italy. Feasibility studies have also been completed for a line between Libya and Sicily, with a possible connection to Malta.

For the time being, it is unlikely that another test to synchronise the Mediterranean system will be carried out. ‘There are no plans for a new test,’ says Francois Meslier, secretary-general of Medelec.

‘We will hold meetings before the end of 2007 to make a decision. In the first test, the normal fluctuations of the system were too high compared to the strength of the interconnections.’

At least until the countries in the southern Mediterranean complete the upgrade of their grids and the interconnections between them, a slightly less ambitious goal - an asynchronous system or open ring - will be a more realistic option.

TABLE: Planned Mediterranean power and water projects

Source: Observatoire Mediterraneen de l’Energie