As long ago as 1773, the American statesman and scientist Benjamin Franklin wrote that: "I wish it were possible to invent a method of embalming drowned persons in such a manner that they might be recalled to life at any period, however distant; for having a very ardent desire to see and observe the state of America a hundred years hence. I should prefer to an ordinary death being immersed with a few friends in a cask of Madeira, until that time, then to be recalled to life by the solar warmth of my dear country."

Franklin was ahead of his time on many matters, and cryonics - the preservation of humans at low temperature for future revival - was just one of them. Since then, the subject has become a staple of science fiction, through the work of Arthur C Clarke, H G Wells and even George Bernard Shaw.

Cryonics is a concept adored by Hollywood, from semi-serious treatments in Alien or Mel Gibson's character in Forever Young, to comedies such as Woody Allen's Sleeper or Mike Myers's Austin Powers.

But this particular piece of science fiction - or the first part of the process - is now almost a reality. And Isle of Skye native D J MacLennan is a paid-up member of the international cryonics club. The 36-year-old, who still lives and works on Skye, has signed up with the US-based Alcor Life Extension Foundation in order to be cryonically preserved upon his death - or his brain will be, at least. "I've gone for neuropreservation only," he says. "I just think that wasting a lifetime of knowledge that might be stored in a structure - and I see the brain as a structure - is an incredibly wasteful thing to do.

"We don't waste organs anymore, so why do we waste brains? Why do we plant people in the ground to rot? Shouldn't we consider dealing with dead bodies in a different way?

"A good analogy is with a computer hard drive: people who know about computers, when they get a new machine, take the hard drive out of the old machine and transplant it into the new one, so the computer is evolving and the data is being preserved, it's not being dumped. So, in a way, we treat our Word documents, music files and other data with more respect than we do our minds."

Backing up a brain or body rather than a hard drive doesn't come cheap, however. Whole body preservation currently costs the equivalent of £75,000, so D J - who is a partner with the architects Dualchas - has gone for the brain-only option at £40,000. "One reason I went for neuropreservation is that it's cheaper but, also, if you accept the outside possibility that a human mind in suspended animation can be brought back to consciousness in some form, then you have to accept that anything else that's required will be possible as well," says MacLennan.

"There will be some way of regenerating a new body, or some way of transferring the consciousness on to another substrate and loading it in some way. If you can accept the principle that you can bring the consciousness back, then you're going to have to accept the fact that you have no body is not going to be a problem - they'll be able to regenerate a new substrate for that consciousness."

Alcor members usually opt for a life insurance policy to cover the cost of the service, as well as an annual fee of around £150. Like any other form of life insurance, the younger you are when you sign up, the less you'll have to fork out each month. In MacLennan's case, it's about £40.

For its part, Alcor is a non-profit organisation, and MacLennan sees his money - and one day, his brain - as helping scientific research. Signing up to be cryonically preserved was the easy part, but to qualify for his insurance policy, MacLennan had to undertake a detailed medical.

"The doctor said he hadn't had to do such a thorough examination in years, and he wondered what was going on, and I just told him it was complicated. But he kept asking me questions, so eventually I said to him cryonics'.

"It turned out he was a real science-fiction enthusiast and knew all about the theory of cryonics - and this was my local GP on Skye. So maybe there are more enthusiasts out there than we think."

Currently, however, the numbers involved are pretty small. Alcor, one of the few companies to offer the service, has just 842 members, with 78 "patients" already in cryopreservation.

MacLennan rejects the thought that signing up is an act of ego, self-importance or desperation. "People may think this is the self indulgence of wealthy people, but I wouldn't remotely call myself wealthy," he says.

"In terms of cryonics being the last refuge of someone desperately trying to hang onto life, if that is the state of your mind, that's terrible, but that's not what I've seen. The people I've come across are intensely practical and they have a particular way of looking at the world, an unromantic, unglamourised view."

Much like MacLennan himself. "I'm an atheist and I think about things in a mechanistic way," he says. "Because of my interest in computers I think more in terms of the mechanics of how things work. I'm a pretty unsentimental person altogether."

MacLennan's story has inspired a radio drama, written by Iain Findlay Macleod and due to be broadcast next week (April 14) on BBC Radio Scotland. In the drama version of events, a young islander, Neil, falls into his mother's grave just before her coffin is lowered on top of him. The sequence of events leads Neil to sign up to be cryonically preserved, which in turn leads to estrangement in his small community and the breakdown of his relationship with his wife and his colleagues.

MacLennan is quick to distance himself from the character of Neil. "My situation might have been the spark for the idea, but it's not about me and it has no real connection to my life," he says. "Science is of interest to me, but not the drama of it. My own wife supports my decision because she has seen the thought processes that have led me to this point.

"I think if she saw me decide to do something radical like this out of the blue then that would be difficult for her, but she can see what's brought me to this point, and has also read a lot of the material, so she understands what it's about."

If the preservation part of the process is a reality, the revival part is, of course, an unknown. Members such as MacLennan undertake the process only in the vague notion that, one day, science will catch up and be able to reanimate the brain, or at least transfer its data into another form. Even Alcor is at pains to point out that there is no "near-term technology" to complete the process.

And to even stand a chance of being properly preserved, the procedure should start within a minute or two of the heart stopping. In all seriousness, Alcor says the best thing a member can do is to relocate to the area of Phoenix, Arizona, which is home to the foundation's facility.

It is there the clients are stored in steel flasks at a temperature of -196C. It's a long way from the Isle of Skye, but MacLennan is undeterred.

"Alcor has stand-by teams made up from current members who are ready to start the process, athough the nearest ones are based in the south of England," he says. "But the movement is growing, so the facilities could either move closer to me or I'll move closer to the facilities.

"On the other hand, I could be around long enough that this will become so widespread that I won't even have to consider it."

MacLennan's preferred option, however, is not to have to use cryonics at all. "Obviously I don't want to die, and I think that with advances in technology people will live an awful lot longer and something like this will never have to happen to me," he says. "But if I'm going to die I'd like some effort made to preserve what I was.

"For me, this is not something that I want, it's a last resort above all else."

  • Frozen, by Iain Findlay Macleod, is on BBC Radio Scotland on April 14 at 3.30pm.