Gulfstream MegaPower tower (kilometric high sealed heat pipe)
Sky-high tower of power may ride the waves
What is over 7 kilometres tall and dangles into the North Sea? According to researchers in the Netherlands, it could be MegaPower -- an enormous power station which they claim may one day be a major source of pollution-free energy.
Design and operation of a mega-power power plant in the sea / DER SPIEGEL / Frank HOOS
While the scheme may sound crazy, the working cycle that the tower would use to generate electricity is similar to the cycle that underlies hydroelectric power.
Figure 1: Butane / NH3 process cycle, the liquid in the sea water evaporates and at high altitudes it condenses, the pressure and flow of the liquid column are converted into energy
The turbines in a hydroelectric power station harness the potential energy of water as it falls from a lake or reservoir towards the sea. But this is only half the story. The water gained potential energy when it evaporated from the ocean and rose into the clouds where it cooled down and condensed to form rain that replenished the lakes.
MegaPower would enclose the system inside a giant tower and replace the water used for hydroelectric power with another fluid. At the top the fluid would condense in the cold of the upper atmosphere. From there it will fall through a turbine to the upper atmosphere to the bottom of the tower where energy from the sea would evaporate the fluid and start the cycle again. It is claimed that the cost of the scheme will be ‘within the costs of providing equivalent conventional generating capacity’.
Figure 2: Average water temperature in North Sea
Figure 3: Temperature at 5500 m
One MegaPower installation would have a capacity of 7000 MW. The largest conventional power station in Britain, at Drax in North Yorkshire, is rated 4000 MW.
In its simplest form, the MagaPower design envisages an enclosing tower 50 metres in diameter with 5 kilometres above the sea. It uses a chemical like ammonia as a working fluid. The base of the structure would be held in place by three 8-kilometres cables attached to the seabed. Iron or steel cables would break under their own weight, but new materials should be able to cope. To minimise the weight of the tower, it would be built from plastic sandwiched between two skins of aluminium. It would weight over 400000 tonnes.
Figure 4: There are two versions (Fig. 4, 5 and 6)
Figure 5 : pipe with flotation
The potential benefits may, one day, offset the development and capital costs and make the project commercially viable.
Currently this seems unlikely given the relatively low cost of conventional energy sources and generating methods. Alan Carter, a structural engineer with Amec Process and Energy, was more sceptical, the scheme for Megapower would not, in his opinion, be economic until hydrocarbon fuels have been exhausted.
Figure 6: floating bodies integrated in pipe
29.01.1996 DER SPIEGEL 5/1996
Ing. R.M. van Ginkel, Frank Hoos, Ir. R.M. Krom, Drs.ir. P. van Summeren
Ing. van Ginkel en ir. Krom zijn work at Hoogovens Groep BV.
Frank Hoos, creator of the mega-power idea, works at Seatec Ltd and Dr ir Van Summeren is a freelance project manager.