By Simon Gompertz
Business Correspondent, BBC Working Lunch
I am standing on a buoy off the US Atlantic coast, wondering if I have taken a step too far by leaving the safety of our boat behind.
The UK government wants to generate 10% of electricity from renewable sources by 2010
Below me, a thin, floating structure stretching 10m underwater, then a much greater depth of ocean down to a seabed littered with clams.
Normally, only the clam boats venture out here. A few days ago a clam fisherman fell overboard and expired in the icy sea after only three minutes.
It's a buoy with a difference, because it generates power from the waves. But it is still a buoy, five miles out from Atlantic City and regularly engulfed with water.
The boat standing by is the American equivalent of a lifeboat.
Plus, there is an experienced rescuer on hand, dressed in a survival suit. All the same, I'm nervous.
Luckily, the swell isn't too high. Also there is a point to being here: what we are showing is truly pioneering work.
It might help to close the power gap that we face, now that gas, coal and oil have copped the blame for global warming.
Clinging on to the back of the buoy while Hugh, our cameraman, proceeds to film, is Joe Troutman, rocket scientist.
After spending years designing satellites, now he is using his expertise in batteries and controls to perfect the technology inside the buoy, or "boo-ee", as he calls it.
Joe says that the waves today are little more than ripples, which is comforting. I have seen a few six-footers.
He wants them two or three times as high to generate a decent amount of electric power.
Briefly, the buoy has a central column which stays pretty well immobile, even in heavy seas.
Wide discs under the water restrict its movement. But around it is a float, which bobs up and down, lifting rods in and out of the centre of the column. The rods drive a generator.
Our wave watching started a few days ago, in swirling snow, on the Isle of Lewis.
Wave technology could prove a boost for coastal economies
For a few months this is the lair of a giant metal sea snake, named by its creators, Pelamis.
Climbing inside it feels like boarding a submarine: it is a tube 5m wide; it has a hatch on top; and, when finished, it will be 140m long.
We saw three of these huge structures being built on Arnish Point just outside Stornoway.
They are another species of wave machine, destined for Portugal.
Rocket-sized tubes are manoeuvred around the fabrication yard on motorised carriers with dozens of independently controlled wheels.
There was only one word I could think of to describe the scene when I saw it: Thunderbirds.
The Pelamis looks like a snake and it moves like a snake. In a finished machine, the long sections are joined by shorter "knuckles". These are the power modules where the generating work is done.
In the sea, the bigger tubes pull hydraulic rams in and out of the power modules, as the whole structure twists in the waves. That's how wave power is converted to electric power.
Earlier, in the former Kvaerner yard on the Fife coast, I had crouched inside one of the power modules with Richard Yemm, the engineer who dreamed up the idea.
He talked of hundreds of these imposing structures dotting the coastline, and thousands across Europe.
Some green groups claim wave power could produce all the UK's electricity
A few days later, I am standing on a narrow ladder, several metres above a swirling sea current and wreathed in mist. The water is sliding along at five knots.
It is a river in the sea, a favoured route for the tide ebbing out in the Bristol Channel.
The concentrated power of this moving mass of water is astonishing.
But what is occupying me is that I am out of sight of land, clinging on my own to a steel pile driven into the sea bed, staring one moment up a further 10m of ladder to a small platform and the next down to the menacing rapids around the pile.
From the safety of the rib, the small rubber-sided speedboat we came out in, I had hatched a plan to climb to the top to be filmed.
On the ladder, this gung-ho mood is falling away with the tide.
I do my recording half way up, then scramble off, leaping from the bottom rung to the rib, my foot clipping the waves.
"If you fell out," warns Gus, the coxswain, "you'd be over the other side of the bay in 10 minutes and heading out to sea."
"There'd be no point in trying to swim," he adds, grimly.
The point of this expedition is to visit SeaFlow, a few kilometres out of Lynmouth in North Devon.
It is an electricity generator powered by the tide, rather like a windmill underwater. The water turns a rotor, which powers a turbine.
The apparatus can be lifted out for inspection and when it surfaces you begin to picture how we might be able to use the tide to help solve our electricity problem.
These blades are 11m across. The next version will have twin blades of 18m each.
There are plans to install an array of 12 tide mills here in a few years time.
The company behind this technology, Marine Current Turbines, expects the Lynmouth array would provide enough electricity for 5,500 homes, as long as the tide is on the move.
I imagine mills like this all around our western coasts. That's where the tides are strongest, some of them double the speed of Lynmouth's.
But the most striking thing is that the tide mills are on the brink of commercial exploitation.
Cameraman Hugh Fairs and producer Nigel Gooing brave the weather on the Isle of Lewis
The next to go in, on Strangford Lough in Northern Ireland, will be connected to the grid and churning out power.
Are we on the brink of a power revolution? We could be.
The wave and tide machines I have seen are working technologies which soon will be delivering electricity to thousands of people in different sites across Europe.
In future, catching sight of one could be less remarkable than seeing a boat on the water.
You can watch Simon's films again in broadband quality...
VIDEO: Film One - Sea Snake
VIDEO: Film Two - PowerBuoy
VIDEO: Film Three - Tidal Power
VIDEO: Film Four - Comparing The Costs
VIDEO: Your Questions on Renewable Energy