The cost of delivering deep-sea-cold-water using pipes has always been notoriously high, and implementation terrifyingly complicated.
Particularly in the tropics, deep sea cold water is valuable; just a few litres per second is sufficient to help generate enough power for one household.
There are many more uses including very low-cost air-conditioning across the World.
We wanted to find a way to make it possible to use hoses to deliver Deep-sea-cold-water.
Hoses are an attractive prospect because they have numerous physical advantages that mean that they are less costly than pipes.
The turbo-pump comprises a hydro-turbine joined to a pump through a common shaft. The Turbo-pump uses two hoses. Water drives the turbine generating shaft power, and that power is transferred to the pump through the shaft.
The turbo-pump can operate in deep water without any sophisticated measures, hence the attraction.
We showed that this idea can work using a turbocharger, this is the same kind of machine in terms of basic principle.
We are now working on a method to convert ordinary pumps and turbines into commercial scale turbo-pumps.
Why use two water hoses and not a hydraulic pump?
One great advantage to using two hoses reveals itself wonderfully as the system gets bigger; the wastewater can balance the head on the system on or offshore because it is the driving fluid. This means vitally improved efficiency because the energy used to drive up the fluid created potential energy in the water, and this energy is recovered and used for the most part to drive the turbine side of the turbo-pump. Some extra power is required to overcome the pump and turbine efficiencies.
Now that’s sorted the remaining energy required to run the water-delivery system properly is the energy required to overcome the pressure drop due to friction in the hose; these values are far smaller than gravity head values. Depending on the location of the OTEC or SWAC heat exchangers for example, as much as 10% to 20 % of gross power output can be held onto as net power! In fact, in some locations this advantage might mean the difference between a system being viable at all, or not.
We demonstrated the ease with which 30 cm diameter hoses can be installed at Sea in a Budget Field Test.
30 cm diameter hoses are large enough to save millions of pounds in air conditioning expenses in just a few years! The advantages of hoses were obvious; hoses are flexible and can be coiled or folded. They are easy to transport. They are just as easy to recover as they are to install; now here, is a major difference. A simple maintenance job on deep-water pipes the size of the image just below has cost $millions.
Hoses can naturally find the most hydrodynamic position if they are allowed to. The fact that hoses can change shape makes them perfect for delivering the water; they work particularly well underwater where the weight of the water and the hose is negated. What with the lack of weight, hoses underwater are unlikely to puncture; and this we have found to be true from experience.
Low Pressure drops.
What with the low cost, and ease of installation, larger diameter hoses are much less costly than smaller diameter pipes.
Larger diameters mean lower pressure drops, and this is an exceedingly desirable outcome for power applications where efficiency is so important.