Costs and Development Strategies

Component costs are not likely to be excessive. The thin pipe in early, relatively small-scale megapumps would be made from spoolable insulated pipe which is widely used in the offshore oil industry. It is readily available from a number of manufacturers, e.g. WDS Flexible Pipe (Germany), Aspen Aerogels(US). Either the ocean floor would be drilled and plugged or a funnel shaped cowling would be used to cover an existing HTV.

The fat pipe is fully submerged and is subject to only small lateral pressure differences. Its early embodiments might therefore be made from a light flexible material such as polypropylene. A buoyant collar would be required at the upper end. A heavier metal collar may be needed to stabilize the lower end and to provide anchor points for incoming thin pipe. Mooring lines and anchors would also form part of the material costs, at least initially.

In the early stages, prototypes would be fitted with sensors which would be connected via an umbilical to a separately moored buoy which would transmit data via satellite. Instrumentation and telemetry will need to be included in initial costs.

Excluding instrumentation, early stage component costs are expected to be in the low hundreds of thousands of dollars range.

The greatest cost components are likely to lie in exploration and deployment. Specialist vessels such as those used in the offshore oil and gas industry will need to be chartered for exploration and deployment. Suitable HydroThermal Vents (HTVs), indeed whole HTV fields, will need to be identified, mapped and monitored. This will involve keeping such vessels at sea for long periods.

Deployment will require ROVs (Remotely Operated Vehicles) rated for depths of 3000m or so. These too are expensive to charter. In fact new types of specialist, dedicated ROVs may need to be designed and built for this new technology.

Because these upfront costs are so high compared with component costs it may prove to be more economical to deploy a number of Nutrient Megapumps rather than a single one in small-scale deployments. A number of thin pipes, each one servicing its own HTV, could be brought together and fed into a single fat pipe.

There is another good reason for doing this: there are "economies of scale" relating to the physics - as the plume gets bigger, energy losses due to heat loss and foam collapse are proportionally smaller, as suggested in Section 4.

Deploying a number of Nutrient Megapumps distributed contiguously over a region of ocean has three further advantages:

1. Their individual nutrient plumes will merge into a single large plume, and

2. A larger area plume will tend to be more confined by coriolis force into a single large eddy. This has advantages from a fisheries management perspective.

At the time of writing it was too early for any detailed costing to be carried out. The offshore oil and gas industry has extensive knowledge and expertise in this area, particularly regarding thin pipe risers and interfacing the thin pipes to the ocean floor. Only the fat pipe technology is really new. Fat pipe technology is more closely related to fish cage manufacturing techniques.

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