Heard the one about the two Irishmen who say they can produce limitless amounts of clean, free energy? Plenty of scientists have - but few are taking them seriously. Steve Boggan investigates

Do you remember that awful feeling as a child on Christmas Day when Santa left you the toy you wanted . . . without any batteries? This feeling comes to me as I meet Sean McCarthy and Richard Walshe, two men making the claim that they are about to change the world - for ever.

These dynamic and personable businessmen from Dublin insist that they have found a way of producing free, clean and limitless energy out of thin air. And they are so confident that they have thrown down the gauntlet to the scientific community in a bid to prove that they have rewritten the laws of physics. Last week, frustrated that they couldn't persuade scientists to take their work seriously, McCarthy, Walshe and the other 28 shareholders of Steorn, a privately owned technology research company, took out a full-page advertisement in the Economist. In it, they called upon scientists to form a 12-member jury to decide whether their free-energy system is real, hoaxed, imagined or incorrectly well-intentioned.

So, as they prepare to demonstrate this wonder of science to me at their modest offices near the Liffey, I feel all the excitement of Christmas Day. There is a test rig with wheels and cogs and four magnets meticulously aligned so as to create the maximum tension between their fields and one other magnet fixed to a point opposite. A motor rotates the wheel bearing the magnets and a computer takes 28,000 measurements a second. The magnets, naturally, act upon one another. And when it is all over, the computer tells us that almost three times the amount of energy has come out of the system as went in. In fact, this piece of equipment is 285% efficient.

That's a lot of "free energy" and, supposedly, a slap in the face for one of physics' most basic laws, the principle of conservation of energy: in an isolated system (the planet, say), energy can be neither created nor destroyed; it can only be converted from one form into another.

"We couldn't believe it at first, either," says McCarthy, chief executive of the company. He is a 40-year-old engineer born in Birmingham but brought up in Dublin. After a couple of decades in the oil industry, McCarthy, Walshe and two others set up Steorn as a technology and intellectual-property development company. "We did difficult things. If someone had an idea that they wanted to make work, we'd work on it with them, help them recruit staff and get them through to their first product."

Then, by chance, came their "discovery". They were called upon by the police to help gain forensic evidence against "skimmers" who cloned the cards of people using ATMs. Subsequently, when banks approached asking how they could prevent such fraud, Steorn advised that the best way was to catch the small number of people committing most of the crime. They came up with a system of 16 tiny CCTV cameras that could guarantee recording the identities of the perpetrators.

"We wanted the cameras to be independently powered, so we tried out small solar and ambient wind generators," says McCarthy. "We wanted to improve the performance of the wind generators - they were only about 60-70% efficient - so we experimented with certain generator configurations and then one day one of our guys [co-founder Mike Daly] came in and said: 'We have a problem. We appear to be getting out more than we're putting in.'"

That was three years ago. Since then, McCarthy says, the company has spent £2.7m developing the technology. Steorn has also gone into partnership with a European micro-generator company to develop prototypes.

In Steorn's theory, fixed magnets could act upon a moving magnet in such a way as to make it a virtual perpetual motion generator. In an electrical appliance - a computer, kettle, mobile phone or toy - that would provide all the power for its lifetime. Of course, free-energy cars, power plants and water-pumping systems could follow. A better world indeed.

But then that Christmas Day feeling kicks in; doubts about the power source. According to McCarthy and Walshe, the marketing manager, there have been no fewer than eight independent validations of their work conducted by electrical engineers and academics "with multiple PhDs" from world-class universities. But none of them will talk to me, even off the record. I am promised a diagram explaining how the system works, but then Steorn holds it back, saying its lawyers are concerned about intellectual property rights. And that European partner, the one with the moving, almost perpetual, prototypes? It won't talk to me either and Steorn has undertaken not to name it.

"It's the Pons-Fleischmann factor," says McCarthy, and he and Walshe look at each other darkly. Stanley Pons and Martin Fleischmann were the last experts to excite the scientific community with free-energy claims when, in 1989, they reported producing a nuclear-fusion reaction at room temperature - what happens in the sun at millions of degrees centigrade. The subsequent controversy resulted in the scientists being pilloried, even though the scientific community remains divided to this day over claims of "low-energy nuclear reactions".

"No one in the scientific community wants to become embroiled in the kind of controversy that Pons and Fleishmann faced," says McCarthy. "With our challenge, we're hoping to provide a respectable public platform for serious evaluation of the technology. Then, perhaps, scientists will feel confident enough to challenge the conventional view."

Certainly, the Steorn team seems genuine and well-intentioned. Walshe says that if the technology is accepted it will be licensed to manufacturers, but given away to electrical and water projects in developing countries. And, until their claims have been assessed by the jury, McCarthy says they won't be accepting any investor offers. So if this is a hoax, it would appear not to be a money-making scheme; Walshe says the Economist ad alone cost £75,000.

"Before we went public, we realised that if we're wrong it could have a very adverse effect on our business, so we're not doing this lightly," says McCarthy. "We expected stick, and we're getting it already. We've had a lot of abusive emails and telephone calls -people telling us to watch our backs, that sort of thing. Someone even published my home address on a website."

The conspiracy theorists are, indeed, having a field day in a forum section set up by the company on its website, www.steorn.com.

"We've been accused of being a publicity stunt for the next Microsoft Xbox gaming system because some of the artwork on our website was similar to theirs," says Walshe. "Some people have said our offices don't exist and one accused us of simply being a call centre in Australia because one of our telephonists has an Australian accent. My favourite is the one that says we are a CIA or oil-industry front intended to discredit research into free and clean energy. In other words, our claims are deliberately false and when they are found out to be, it will be a blow for all free and clean research."

Steorn says it has seven patents pending on its technology, though it is difficult to see what can be patented; magnets already exist and so do the 360 degrees of a circle. Yet it is the positioning of the magnets that seems to be at the heart of this "new" energy. And, as McCarthy points out, the Patent Office rejects inventions that fly in the face of such fundamental principles as, say, the conservation of energy. Nevertheless, as of yesterday, almost 3,000 people claiming to be scientists had expressed an interest in sitting on the Steorn jury. The 12 best will be chosen at the end of the month and then testing will begin.

"We've been advised it could take between a week and 10 years," says McCarthy. "We don't have any doubts. We've conducted meticulous research and we're getting such phenomenal results - up to 400% efficiency - that small glitches and errors in testing can be ruled out. We really believe we've found something that can change the world."

The rest of us can only wait and see. In the meantime, I ask Martin Fleischmann, the cold-fusion scientist, now 79 and retired, what he thought of the Steorn project.

"I am actually a conventional scientist," he says, "but I do accept that the existing [quantum electro-dynamic] paradigm is not adequate. If what these men are saying turns out to be true, that would be proof that the paradigm was inadequate and we would have to come up with some new theory. But I don't think their claims are credible. No, I cannot see how the position of magnetic fields allows one to create energy."

With great charm, Dr Fleischmann wishes the Steorn team luck. And if their "free" energy can light up a developing-world village or the eyes of a child with a toy, then perhaps we all should.