Mr Denis O'Brien's career has not been marked by failure, but his decision to close ePower indicates he saw no reasonable prospect of success in the electricity business.

The move to abandon a market in which the company had secured 117 industrial customers was in stark contrast to the company's entry 18 months ago, when ePower's management spoke of breaking the ESB's monopoly.

It is a very negative development in an industry whose structure has been described by the EU Competition Commissioner, Mr Mario Monti, as "not favourable to competition".

Whereas liberalisation is designed to foster competition, the Irish market has seen off competitors rather than attract them.

EPower is the fourth company with significant investment plans to leave the market and those remaining complain that prices will have to rise to make their businesses viable.

Little surprise then that the chief executive of Huntstown Power, a competitor of ePower owned by the Northern Ireland firm Viridian, described ePower's departure as "sobering". Mr David de Casseres said: "Sooner or later, the people making policy in this area need to wake up to the fact that they're frightening people off."

It did not take long for Mr O'Brien and ePower's chairman, Mr Leslie Buckley, to learn that triumph in telecoms does not mean success in electricity is automatic.

Their company, which employed 15 people earlier this year, lost #6 million. For a multimillionaire such as Mr O'Brien, who absorbed significant losses at Esat, it was a relatively modest sum. But it was too much.

The bulk of the losses are probably attributable to its failure to sell all the power secured in an auction of virtual capacity last year.

It gained rights to sell 240 megawatts (MW) of power wholesale in that auction, which was designed to introduce competition to the market before new generation plants came on stream.

However, it could sell only 160 MW to industrial customers and had to pay a reserve fee to the ESB for the unused power.

EPower had also alleged that a wholly-owned subsidiary of the ESB was engaged in anti-competitive behaviour in the liberalised section of the market. The State company denied that and accused ePower of "whingeing". However, the electricity regulator, Mr Tom Reeves, issued a direction to the company compelling the ESB subsidiary to withdraw from certain activities.

Elsewhere, power plants in which ePower had an interest encountered planning barriers and regulatory difficulty surrounding connections to the national grid.

Under pressure from Mr Monti, Mr Reeves has also sought to change the system for allocating connections to the National Grid. Such a change, Mr Buckley said, was "too little, too late".