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

From the air it looks like a road, starting and finishing nowhere… on one side is a beach with waves breaking, but the other side also has no land, just a vast, calm stretch of sea.
“That’s the OHX” advises your pilot “it’s 5kms long and 300m wide, except for the central node which is 500m wide”

It soon is obvious why… the node has an accommodation block with a helipad on top. On the lee side, several ships are moored and there is a marina for small boats. Along the full length is a series of huge wheels mounted across the structure. As you approach you can see them turning slowly. “Cross Wheels” you are told “fifty in total”

After the helicopter engine stops there is a stunning silence… As the door is opened, even the breakers seem mysteriously hushed.
Soon you are seated in the Station Manager’s office. His name, Shagga, hints at a Samoan origin, which he is proud to confirm.
"Yes" He continues “you’ve chose a fairly quiet day to visit. Sometimes in the winter the waves are crashing onto the beach and there’s spray everywhere. We can be confined to barracks for several days running. But what can I tell you about this wonderful machine that we live on?”

Well, if you don’t mind, just assume I know nothing and start with the big picture.

He leans back in his chair and takes a deep breath…
“OK. You are now aboard the Ocean Heat Exchanger Albert, one of about 400 such machines which spend their time enhancing ocean circulation to counter the effects of Global Warming.
As the atmosphere warms, it heats up the ‘mixed zone’, the upper 100 metres say, of the ocean. Below that level, temperatures drop progressively (the Thermocline) until you reach the deep ocean at say 500 metres which is generally between 0 and 4°C. Now water is a poor conductor of heat, so the only effective way for the lower ocean to warm up is through the great ocean currents which carry heat down at ‘down-welling’ points.”

Yes, that’s why they call the ocean “the earth’s thermostat”.

“Correct… and indeed, given time, they would mop up all the excess heat which we are currently generating. The only problem is that the system works very slowly by humanity’s reckoning; scientists estimate that it will take 100,000 years for the heat we are accumulating up here to mix. In the meantime the surface swelters.”

But I thought the ocean currents moved vast amounts of water?

“They do, but in order to sink naturally, the surface water has to become very dense, which means very cold. Thus it has shed almost all its heat load by the time it goes down.
In contrast, we are located at a point there the surface water is hot and salty, and there is no way it would sink unaided; however we have way of helping it.”

OK, so you’re moving relatively modest amounts of water, but through big temperature differences, is that right?

“Spot on! This machine moves say 4 cubic kilometres of water per week through about 20°C, meaning that it buries an average of 670 Gigawatts which is equivalent to the total power and waste heat emitted by well over 100 central power stations running flat out.”

So how do you do it?

“We use wave power, as you can see” he points out of the window, “it’s a simple principle called over-topping. Basically we let the waves run up a ramp (the beach) which converts their kinetic energy into potential energy. In practice that means the waves fill up a reservoir (the pond) which has a mean water level several metres above sea level.”

Doesn’t that vary with the weather?

“Of course, when the sea is rough, we de-ballast the whole machine so the pond is anything up to 8 metres above sea level. On quiet days, we struggle to get 3 metres.”

What is the minimum?

“We need enough to force the lighter surface water down and the denser deep water up. This varies dependant on surface temperature, but the minimum is 2.1 metres. On the few days when it is calmer than that, we take advantage of the situation and get our routine maintenance done.”

And how does the water get from the pond to the ocean depths?

“There are large vertical pipes under the pond, and the excess head height is enough to drive the hot water down into the cold deep.”

How far down do you take it?

“Just below the Thermocline, that’s about 500 metres down just here and the temperature is about 5°C. Any deeper and you get a poor return for the extra energy expended… for example going down to 800 metres would take double the energy and only increase heat burial by 10%... it’s all to do with the head loss due to density difference”

And where do the wheels come in?

“You can see them outside like huge fairground ferris wheels, except that they have a rope running over them with discs attached every so often.

“As well as sinking hot water, we also lift cold water... it’s a bit more complicated, but there are several good reasons for it.” He raises three fingers.

1. The cold water directly cools the ocean surface. That affects the weather; the rain for half the western U.S. is generated in this region, and higher surface temperature have been causing a drought. Where we are located is a ‘sweet spot’ which has been found to counter the effect nicely.
2. Deep water is where most decomposition occurs, and it arrives charged with nutrients. That stimulates plankton growth which locks up CO₂ – lots of it! It also helps prevent anoxic conditions in deep water, which is another symptom of reduced ocean circulation resulting from global warming.
3. The energy needed for Cold Lift is not as great as Hot Sink. We can pump water up from 2kms down for less energy than hot sinking to 500metres, saving an overall 30% efficiency.”

OK, I can appreciate it’s worth the effort, but how do you actually achieve it

“Right, look at this diagram…The driving force, of course, is the elevated hot water in the pond, which descends in the down-tube under its own weight. By putting pistons in the tube, we harness some of this energy via a continuous loop of cable which pulls the pistons up the riser pipe, bringing cold water with them.”

So that cable goes down 2 kilometres?

“A bit more actually, it makes quite a lazy turn at the bottom. The total rope length is 4¼ kilometres with pistons every 85 metres. That’s 2,500 pistons in the whole installation!”

He seems pretty impressed with this piece of information! Quite a complex operation!

“Yes, we’ve borrowed a lot of the technology from the mining industry, and the low speeds that we use means that components last well. We only have to replace 2 or 3 pistons per year and cables almost never… thank the Gods, because it’s a heavy task”

How do you prevent the hot water from coming up again?

“Ah yes.. the hot water discharges under a horizontal shelf called a diffuser.” he points at the diagram “This keeps it down while it mixes into the subsea current. We do the same trick with the cold water riser as it emerges on top of the upper diffuser at -20 metres”

That’s still a long way down! Why don’t you bring it to the surface?

“The deep water is slightly CO₂ rich and bringing it to the surface might release some greenhouse gas. At -20m the pressure is 3 times atmospheric and the CO₂ is stable. Furthermore, despite the diffuser, the cold water descends to about -40m before it is completely diluted. However, it is still well within the mixed zone and the nutrients are accessible to the plankton at those depths.”

Tell me about the plankton, please.

“Many types of marine organisms benefit from the nutrients in these waters, which is why the fishing is so good! However, the native species which thrive under hot summer conditions when the light is good, die off in the winter, which results in vast amounts of CO₂ being released. So we are experimenting with releasing Arctic varieties during the winter.”

Isn’t it hazardous introducing non-native species?

“Well, it certainly needs extreme caution, which is why we’re engaged in a 20-year experiment. But if you would like to know more about this, why don’t we take a break now and stroll down to the Diatom Farm? I’m overdue for a visit anyway.”

You descend to the ground floor where you are issued with an ID card, and then past a security guard to the ‘Basement’.

Why the Security in this remote place? you want to know.

“It’s just a basic precaution in case of misguided saboteurs. There’s nothing secret here; everything we do is published on the net and available for public scrutiny. Wouldn’t have it otherwise!”
He knocks on the door marked ‘Prof. Ongo’ and we are invited in. Prof Muriel Ongo is in her late thirties and apart from the trainers and the lab coat hanging nearby, looks like any other well-groomed executive. Ritual greeting are exchanged.

“Our friend here is interested in your protégé’s, Muriel, as am I, of course. Do you have time to give us an overview and update?”
“Only too pleased” says the Professor “Public Awareness is an important part of the job! How much do you know about marine organisms, diatoms in particular?”

Not an awful lot! you have to admit.

“Ah, well they are interesting animal, which come in a huge variety of shapes and sizes” She points at some of the pictures on the wall.

courtesy of New Scientist

“Which is marvellous from our point of view, because cross-breeding is relatively easy. We have been selecting them to: tolerate the cold; thrive in low-light conditions; grow shells with certain pore sizes and shapes; grow extra shell.”

So this is bio-engineering?

“It’s applied natural selection. Cross-breeding of naturally occurring organisms is what farmers have done for years. You don’t run the risk of creating a totally novel, and hence unpredictable life forms, as you do with bio-engineering. We started with Arctic diatoms selected for a small pore size suitable for locking up carbon dioxide. Then we bred them in a high-CO₂ environment, where the ability of the empty shell to filter out carbon dioxide was pivotal to their existence. Then we bred Arctic zoo-plankton to predate them. It took 8 years and countless generations to achieve what we have today, Navicula Megacauda, Meg for short.”
She points at another series of pictures. “Spot the difference!”

This one’s got a tail!

“It has indeed; a totally unexpected development which only nature could contrive. The tail grows continuously and is, as far as we can tell, totally useless except that it mops up CO₂, becoming progressively heavier until a section breaks off. The broken segment, complete with gas load, then sinks to the base of the tank, or seabed.”

Don’t sea-shells dissolved in deep water?

“Carbonate shells do. However diatoms make their skeletons from silica which they extract from seawater. This is a complex reaction which also reduces the bicarbonate content, and thus lowers ocean acidity which is a side effect of global warming.”

So you win in several ways here?

“Meg locks up CO₂ directly, reduces bicarbonate, lowers acidity, takes carbon down when she dies, stimulates zoo-plankton growth and the subsequent food chain.. Yes, we think she is a winner!”

How do you ensure they don’t become a nuisance?

“With experimental types we inserted a gene which acts as a biological counter, and prevents cell division above a certain figure. In effect this means the organism dies out after a certain number of generations. This IS bio-engineering, of course, but being used as a safety belt. Our final babies will not have, nor need, this feature. On a large scale, we have found that once summer conditions prevail, the native species out-perform Meg on every front. She is, by nature, slow-growing for a diatom, and the tail makes her noticeable and vulnerable to the fast-moving summer predators. We are expecting to have to re-introduce her every autumn from stock reared here.”

Does every OHX do this?

“There were 3 experimental bio-stations, now down to 2, of which ours is the most promising in terms of CO₂ lock-up, which is of course the current priority. We’re hoping to go to full-scale production in 2 years time.”

Why take the chance when the OHX functions without the bio aspect?

The Station Manager answers you. “The OHX and similar machines are just a temporary fix. We can’t go on burying heat in the ocean. Although a century of burial only results in a one quarter degree temperature rise, if spread evenly, it’s still unsustainable in the long term.
In contrast, these humble animals take CO₂ out of the system permanently (by human standards). We, and the rest of the biosphere, need them.”

So what does the future hold? you ask the Professor

“Our research will continue for the next few years, every season is an opportunity to improve the stock. This porous tail-growing characteristic only emerged two years ago, and we have no idea what the limits are. We are looking forward to being able to actively reduce CO₂ content in the ocean and hence in the atmosphere. That is, of course, if others succeed in limiting emissions!”

That seems to be her final statement. You thank the Professor for her time and take your leave.

The Station Manager leads the way to the coffee room, where a small alcove lends a certain privacy.

You know, many people would consider the diatom work as ‘interfering with nature’.

“Yes” says Shagga “but it’s really a bit late to come up with that argument. Humanity has been inadvertently ‘interfering with nature’ for hundreds of years now, if not thousands. OK, our ancestors may not have been aware of what they were doing, but we no longer have that excuse. We have, like it or not, become the (temporary) custodians of the earth, and, accepting that we have not made much of a job of it to date, we still have the opportunity to succeed. Imagine if a gardener, seeing some of the mistakes he made in earlier years, just walked out of the gate and let the garden go wild!
No, the earth is a beautiful place, and could be all the more so with humanity living in balance and accepting the responsibility of looking after it.”
Then, with an abrupt change of subject, “Fancy a walk outside?”

You do, and after finishing your coffee and putting on protective gear, you make you way through a pair of heavy doors, onto an elevated observation platform.

“So here we have the so-called Esplanade, and as you can see there is a Wheel every 100 metres, we call them Cross-Wheels for obvious reasons.”

Indeed, the wheels each form a giant ‘X’ shape, being round with four bites taken out.

“The Beach, as you can see from here, is not flat; there are subtle chutes in it designed to focus the waves at times of low sea activity. The green colour is caused by a seaweed which we encourage to grow, it has been found to lower the friction of the beach surface by 25%”

Why do the waves seem to run along the beach?

“The whole machine is angled slightly to the waves; this has three effects: firstly it reduces the wave hammer, secondly it prevents the pond from over-flooding and accompanying wastage, and thirdly it produces a secondary wave in the pond which runs up the ramp and gives another foot or so of head”

He points to the point in the pond where the top of the Downpipe can clearly be seen.

How do you keep the OHX orientated relative to the waves?

“Well, the first thing you have to appreciate is that a long structure like this tends to align itself across the wavefront. This works to the disadvantage of stranded oil tankers, but helps us considerably! So our only concern is the small angle which we keep offset to the waves, and that is achieved by Dynamic Positioning, basically water jets which rotate the whole machine.”

You mentioned de-ballasting before, how is that achieved on such a huge structure? Does it not need enormous amounts of energy?

“We have bow and stern flotation tanks. If it becomes necessary to de-ballast, it’s because the sea is getting rougher, which by definition means there is excess compressed air being generated by our ‘wave machine’ sectors; this air is used to pressurise the flotation tanks. Of course, when things calm down, we release this compressed air and recover over 50% of the energy:”

So how many days per year do you operate?

“Since the installation of the Wave Focuser we rarely have a quiet day… I would estimate we function effectively for 360 days per year…”

He reacts to your raised eyebrows by pointing at the far horizon.

“You can’t quite see it from here, but upwave from us about 12kms away is a floating structure we call the RWF or Remote Wave Focuser. During heavy weather the waves just proceed over the top, but in light weather it has the effect of slightly diffracting the wave front and focussing more energy on our profile; up to 30% under marginal conditions; a worthwhile bonus in financial terms.”

And that structure has to move also?

“Indeed, it is also dynamically positioned, although much more crudely than we are. But time for a walk along the Esplanade, I think”

Your route takes you down two flights of steps to the rough concrete top of the main spine. The water level in the ‘pond’ seems a long way down.

“Yes,” says Shagga “even though we are ballasted down at present, the rear of the pond has to provide for waves which crash over the crest of the beach… we are currently 5 metres above Crest Level, and the Crest is at the moment..” He peers at a marker board.. “3.2 meters above sea level, with average Pond Level half a metre lower than that, ie 2.7 metres above sea level”

And that is sufficient drive to power the cycle?

“Certainly; the fact that the Wheels are rotating tells you that we are pumping heat… about 300 gigawatts I would estimate at the moment, equivalent to some 50 central power stations.”

That’s a staggering amount of heat… Can we have a closer look at the Wheels?

“Yes, the Cross-Wheels are impressive, aren’t they?” He leads the way. Facing across the line of the main structure, the wheels rotate slowly towards the beach. Each one pulls a rope up from the rear, feeding it down at the front. Every so often a disk-shaped ‘piston’ appears out of the ocean, supported at its centre point by the rope and shedding water as it emerges. As the cross-wheels rotate, the piston fits neatly into one of the indentations, is carried over the top then descends into the pond where the outline of the down-pipe can just be discerned. Up close the scale of the thing is apparent, each piston being bigger than the wing of a jumbo jet, while the rope is as thick as a man.

“Six thousand tons,” says the Station Manager “Six thousand tons of load on each wheel, one rotation every six minutes, carbon fibre pistons, Kevlar rope, stainless steel structure, cast iron shoes, whole thing designed to last two hundred years.”
He obviously loves his machine!

So this is really just a giant water pump, but what is that?

You are pointing at a much smaller secondary wheel driving a rope which disappears into a concrete ‘house’ near the base of the wheel.
“Alternator. Each wheel has its own power generation, which we can also use to moderate the speed and even stop the wheel if needs be. Solid state electronics converts the output to a standard 50 cycles for use around the OHX.”

And is this your only source of power?

“No, as I mentioned before, 10% of the bow edge is dedicated to a standard wave machine which generates compressed air to drive our big power users, being Dynamic Positioning and De-ballasting. Then as back-up we have wind generators, one per sector, and flow batteries.”

Flow batteries?

“Yes, we have a 20-megawatt-hour vanadium flow battery, the electrolyte is stored in that tank behind the office block. It was installed as an alternative to a backup diesel generator, and intended to keep us running for a week of flat calm. However, apart from an annual maintenance run, we never use it... but it’s there!”
He pauses to answer his mobile phone and grunts an affirmative..
“I gather you are going whale-watching on your way home. Time for us to make our way to the harbour.”

As you walk along, there is time for a last couple of questions.

So what is the overall impact of your machine, and how does that pay?

“You have seen most of it, but it amounts to five basics:

1. We bury a lot of heat, both directly by pumping surface water down and indirectly by lifting cold water. We are paid for this by the World Carbon Trading Bank.
2. The cold water directly cools the ocean surface and affects the weather. This we are not paid for, but receive research funds from the US on a ‘quid-pro-quo’ basis.
   It’s also kind of satisfying when you’re stuck out here for a month to realise that you’re probably providing the rain which keeps the folks at home going.
3. The cold water plume is charged with nutrients which stimulates plankton growth and locks up CO₂. We are paid for this by the WCTB.
4. The plankton provides food for fish and the rest of the chain. We receive support from the WWF for our part in ocean conservation.
5. We circulate oxygen to the deep water, this we receive no money for, but its part of the service!

and when the diatoms come on line, we’ll be able to add another 3 items

1. A tripling of quantity of CO₂ absorbed.
2. Significant reduction of ocean acidity
3. A 50% increase in marine food chain.

Which we estimate will nearly double our profits.

So when you consider that the original machine paid for itself in six years, you can see that the shareholders in this baby should have no reason to complain!”

And how many other machines are there like this?

“Ah, now you have me… I used to keep an exact tally but have lost count now; they’re launching about two per month at present.
In round numbers, if you include the Hot Water Column machines which they tend to use in shallow seas, you have:

HWC machines in shallower seas (oxygenation, surface cooling)	50
OHX machines off East coast Africa (rain making)	10
OHX machines in Pacific – US west coast (rain making)	20
OHX machines East Caribbean (Hurricane calming)	40
OHX machines East of Japan (Hurricane calming)	30
OHX machines East of Brazil (Hurricane calming)	10
OHX machines East of China (Hurricane calming)	10
Others	20
Total:	190

Between us we bury 35% of the world’s excess heat and 20% of its CO₂ emissions.
In ten years time, those figures will be more like 110% and 150%”

You mean the world will have started to cool again?

“Yes, and we’ll have the capacity to take the historical CO₂ out of the biosphere. If you add to that the advancement in efficiency of power generation, hydrate mining, renewable energy and all the other tricks that the boys are getting up to these days, I predict that by 2050 we’ll be well on the way to getting Global Temperatures back to normal”

With those reassuring words ringing in your ears, you take your leave of the Ocean Heat Exchanger and head off with the boatman to see if you can spot the whales which are now common in these productive waters.

Roger  Clark
STEP 2000