"The commercially successful machine were hybrids, amalgams of concepts, symbionts of overlaid technologies.
What they had in common was… they were BIG!”

It's an exciting day with an exciting start… you have never been on an ocean-going outrigger before. The crew of three seem little more than boys, yet they handle their boat with casual ease. Soon you are skimming across the wave-tops, and the Pacific island which seemed so substantial is disappearing over the horizon!
In a little over an hour, the captain points casually; more land is evident ahead. Soon, several other outriggers are visible, their occupants busy fishing. As your boat approaches, you can see what appears to be an atoll with a central island, but it's different. The palm trees on the outer atoll are dwarfed by tall towers, each topped with a huge conical 'Wind Sock'. There are no breakers on the beach; as you get closer you see why. The edge of the island overhangs the sea, and the waves disappear under this low 'cliff' with barely a murmur. The outrigger passes through a gap in the atoll into totally calm water.
The lagoon is about 2kms across and the central island about 500m diameter, a few boats are on their way from the island to the atoll. "Rise is starting" says the captain. He pulls in to a small harbour on the inside face of the atoll. "Welcome to our home", he says "the Chief will meet you in a few minutes"

Sitting on the beach under the shade of a palm tree, enjoying a drink served by girls in traditional grass skirts, it is difficult to appreciate that this is a man-made structure.
"Yes", the Chief reassures you, "We are actually living on a huge machine, however, although the concrete structure was built in India, all the 'landscaping' was done locally in true Polynesian style. The result is a pleasant place to live, overlying a technical wonder, and if you look at the island again, you will see the evidence."
Yes, the island does look different; now it has cliffs at the side and the palm trees on top are much higher against the horizon.
"That's right", says the Chief "the Rise is well on its way now. The island is actually a Rig consisting of a number of huge concrete tanks (7 large ones and sixteen smaller ones), and the atoll is a wave machine (WM), producing compressed air at a modest pressure. As the air generated by the WM is piped across to the Rig, it rises, ultimately to a height of 300m above sea level."

So why the different names, you wonder.

"Well, it's because of the combination of habitat and machine… if you're thinking habitat, it's the Island and the Atoll, whereas the underlying machines are the Rig and the Wave Machine, together making up the Cold Water Miner. It's easy when you get used to it!"

OK, you can handle that; How long will the 'rise' take?

"Oh, that depends on the sea. on a day like today I would imagine about an hour and a half. Then another half an hour for the fall. On rougher days it will rise in maybe 20 minutes, but that's as fast as we allow it to move. During storms, we often have excess power so it is diverted to the electrolysis plant for turning seawater into hydrogen, oxygen and minor gases. Some of the hydrogen we use here to fuel our boats, the rest of the gases are sold on the neighbouring land. Yes, thanks to us, the islands around here are basically a hydrogen economy", he adds, "with the help of solar, of course. Oxygen is sold to the diving industry and the rest is exported."

"But our main income is from Cold Water Mining and CO 2 Sequestration", he claims.

"Beneath the Rig is a Riser, a huge concrete pipe 30m in diameter, descending more than 2km into the ocean. As air is vented, the Rig sinks under its own weight and cold water enters the tanks via the riser. Once full of cold water, and with only 10m of freeboard, the Rig rises as the process is reversed. Only this time, the water cannot escape down the riser, because there is a huge check (one-way) valve in the base of the rig. Instead it is distributed just below sea level by enormous pipes and discharges under the WM, at the same time imparting a tangential thrust to the WM structure."

So the Rig cycles up and down, each time filling with cold water from deep down and ejecting it at the surface?

"Yes, that's basically the idea, a huge reciprocating pump, driven by compressed air which is supplied by the Wave Machine."

and what is the tangential thrust for, you want to know.

"Oh, that's just a minor technical detail to keep our mooring lines tight. You see, the Rig is anchored (by catenary anchors) to the seabed 4 km below us, which allows enough movement for its Rise and Fall but keeps us on location. The WM is connected to the Rig by spiral lines, to allow for changing geometry as the Rig rises (actually all the pipes are spirals as well). The spirals are kept tight by the Rig rotating clockwise as it vents air (going down) and the WM rotating anticlockwise during cold water discharge (going up). Simple really, but a bit disorientating when you first live here as the sun seems to move somewhat erratically. Overall it ensures we stay in the same place and centralised."

What is the big picture then?

"On average, we lift more than 11 cubic kms of cold (4 deg C) water per month, which is 11,000 million tons, and although it's small compared with the ocean itself, we and the other 750 odd rigs in the same business manage to counter the major effects of Global Warming."

How does that work?

"Well, you're a bit outside my area of expertise, but basically you have to realise that the ocean is an enormous heat sink; for example 3m of ocean has the same heat capacity as the whole atmosphere. So there is plenty of capacity to soak up the excess heat, without affecting the ocean much."

OK, but surely that's only a short-term solution?

"Yes, in geological terms, very short-term. If we continue like this for a hundred years, average ocean temperatures will rise by almost half a degree Centigrade." He smiles. "However, it is only intended as a stop-gap while the industrial sector sorts itself out. thank the Gods that they have finally realised that this polluting cannot continue. But, of course, you can't turn the clock back (or the electricity off), and new technology can't be invented overnight. What's more, developing countries just can't afford the more sophisticated plant, and have to continue to burn fossil fuels for some time to come. The Cold Water Miner has a design life of 200 years, and we sincerely hope it will not be necessary to build a replacement", he pauses "Yes, this one will do for the rest of my days and probably my grandson's."