The word “digital” joins a long line of adjectives too exciting for their own good. Look back in the history of hype and you find its ancestors: “electropathic”, “atomic”, “computerised”, “turbo” or just “state-of-the art”. With Lord Carter of Barnes's report on Digital Britain, overstimulation peaked.

Starting from Gordon Brown's startling assertion that only this technology can “unlock our imagination”, it plunged with boyish glee into arias about “seamless connectivity”, converging platforms, twitter, wiki, blogs, telepresence and “e-healthcare”. Fine. We are used to phones that double as movie cameras, music libraries, tellies, games, calculators, diaries, maps and guidebooks. We are grateful for Lord Carter's confirmation that broadband is essential. However, in the general brouhaha about top-slicing the licence fee and taxing granny's landline, the most preposterous plan of all has not had the raspberry it richly deserves. If any other report proposed an arrogant, wasteful, environmentally damaging assault on daily life - a copper-bottomed vote-loser, a V-sign to the vulnerable - there would be an outcry. But veiled as it is in glittery stuff about computers, we almost didn't notice.

The assault is on radio. Baldly, the report proposes a surprise acceleration of the plan (still not widely grasped) to turn off FM and AM transmission of all national stations. They must “migrate” to DAB - which requires new digital sets. Your existing wirelesses - the bedside one from which Humphrys or Wogan talks you into sentient life, the old Roberts on the bathroom windowsill, the wind-up Freeplay in the garage, the jogging one with a clip, the flash stereo for listening to Radio 3's Haydn season, the pocket one that consoles you on the freezing railway platform, the one in your car...all could be useless after 2015. Which is an eye-blink away - less than half new Labour's tenure, or a secondary school career. That ramshackle collection of radios, perfectly functional despite the odd bent aerial or melted chocolate on the £5 tranny in the schoolbag, could in less than six years be deaf to Radio 1, 2, 3, 4, 5, Classic or Absolute. Finis: a century after Reith, a massive disenfranchisement of the listener.

Of course, the networks would still be on your computer, TV and a few cellphones. Lord Carter loves this, cheerfully saying that the “diverse and flexible nature of the medium places it at the forefront of device and platform convergence”. But because radio is “intimate and ambient” he concedes it must also be delivered through portable devices. And with a startling leap of logic he says this cannot be done without a “dedicated digital medium - DAB”.

That radio has a perfectly adequate medium already, from transmitters that even the report concedes have many years life left, seems not to matter. Our version of DAB - rejected, remember, by everyone else in Europe except Denmark and Norway - is the only option. He recommends that when coverage reaches 90 per cent of the population (hard luck on remote communities) and when digital listening reaches a mere 50 per cent, it should trigger a two-year notice of full analog switch-off. He proudly says that “nine million DAB sets already exist in homes and cars”.

Yeah, right. And hundreds of millions of non-digital radios exist alongside them. DAB sales have been 50 per cent lower than forecast: check the industry websites for details, but the most optimistic prediction I can find is that by 2011, 12-15 per cent of radio devices might be DAB. There are reasons for this, even where transmission works. Music buffs complain about sound quality. The sets are expensive (Lord Carter reckons they will be brought under £20, but analog radios can be picked up for a fiver, and plenty of us have 1970s sets working perfectly). Moreover, the cost of replacing or converting car radios will be astronomical on a national scale and painful on a personal one.

And - here's the elephant in the room - we are all supposed to be thinking green, but digital radios use more than four times the energy (8.5 watts) of analog (average 2 watts). The industry is working on this, but the most optimistic forecast is 3.5 watts. More importantly, unless you switch them off at the wall, they are computers on permanent standby - like leaving a light on full-time. Portables gobble batteries six times faster. I suppose wind-up technology could help, but we will all develop massive biceps from flinging ourselves on them every four minutes to see if Jonathan Dimbleby has got to the end of his question yet. The conflict between green pieties and the rush to digital has never been addressed properly.

But then, it hasn't in the wider sphere either. I hear chattering-class podcasters dismissing the “steam valve mentality” with the blithe line that “distributing audio and video via the web is where we're heading”. What such people never admit is that video-streaming and iPlayering and online entertainment is massively heavy on power - not just domestically, but at vast data centres. Googling and downloading are becoming as carbon-guilty as flying and driving. A data centre uses 20 times the power of a normal office block. In the United States, local politicians are banning them from city centres because they drain more power than can be generated.

Two years ago worldwide carbon emissions from data centres topped 170 million tonnes; by 2020 the figure will have quadrupled, outstripping airlines. Work is being done on reducing it - Google plans to float offshore centres to provide cheap cooling - but the unwelcome fact remains that whenever you or I view or listen through a computer we use fuel far faster than on our old kit. Kit that will be poking its sad old aerials through heaps of landfill by 2016, unless we choose to listen to “ultra-local community stations”: a proposal by Lord Carter that is obviously not just a figleaf for the possibility of flogging the bandwidth to phone companies. Perish the thought.

Well, think about it. And if you are from a commercial outfit promoting analog switch-off because it will create a level playing field for non-BBC stations, don't sneer that I write this for fear of competition. Know, brothers, that everyone on dear old Radio 4 simply longs for it to be healthily challenged by speech competitors. We were furious when poncey Channel 4 bought and cruelly closed down the excellent Oneword. This is not about Luddism or competition: it is about saving the most portable, economical, mentally liberating and humbly useful of media from an ill-conceived ideological purge.

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