Page first featured October 22, 2009

Bruce Marshall proposes a hydrothermal system that would harness the vast energy available from deep sea hydrothermal vents in which water seeps into near-surface magma, where it is continuously heated and ejected through vents at around 750 degrees Fahrenheit (400 C) -- hot enough to melt lead. The hot water and minerals would be brought to the surface in a matter of about a dozen minutes through insulated pipes (resulting in minimal temperature drop), and the heated fluid would then be used to turn turbines.

The vent output is very consistent and energy dense and at very high volumes. For example, a 3m pipe would be cranking out this hot water at a rate of 21,000 liters (5,000 gallons) per second, which is like a small residential swimming pool of superheated water every second. Computer modeling has shown the heated water has a producible energy density of about 1 megawatt per 10 cm2 pipe area.

This is a brand new, previously untouched, energy source -- a discovery on the scale of man's harnessing nuclear power, but cleaner and potentially cheaper.

National Geographic estimates the power of just the known worldwide vents at around 17 million megawatts, with thousands of miles of ocean still unexplored. It's difficult to estimate the quality and number of vents that are convenient enough to be practical, but Marshall believes that several thousand gigawatts of power are recoverable worldwide-- the equivalent of perhaps 1,000 or more nuclear power plants.

As the hydrothermal fluid rises it carries with it some of the richest ores to be found anywhere, laden with just about every metal and mineral that we mine the surface for now, including iron, gold, silver, copper, zinc, cadmium, manganese, and sulfur, with significant amounts of methane gas mixed into the fluid. Halides, sulphates, chromates, molybdates and tungstates are also abundant. For this reason, the best surface mines are located over hydrothermal veins of the geologic past. Also, as the water component of the fluid flashes to steam it can be recovered as distilled water.

Marshall calculates that a pilot plant could be built for 75% the capital cost of a nuclear plant (around $4.5 billion), with approximately the same output of around 2 gigawatts. Eventually, a single plant with a 3-meter pipe, could power 20 million homes -- 5 times more than the largest nuclear plant. Though the capital costs would be high, the energy cost could compete with the cheapest power available today since there is no fuel to buy. However, because this is more than just an energy system, capital costs would likely be split among energy, mining, and water interests.

As for practical considerations, much of the engineering has yet to be worked out. But the oil industry has developed the off-shore platform technology to the point that would work for this application. To contain the heat and avoid corrosion, ceramics (e.g. by Directory:Ceramatec's Sodium Sulfur Battery of Salt Lake) lining the pipes could be used. Marshall has also filed a There was an error working with the wiki: Code[1] for a method of transmitting the power to land via light cables rather than electricity. Once developed, it promises to reduce the cost of the systems substantially by eliminating the need for extremely expensive undersea cables and replacing them with hollow steel pipes.

The reception by the scientific community has been very positive. The reception by business interests has been less enthusiastic, given the capital cost for a pilot plant for a yet-unproven methodology. No politicians have become advocates yet. There is no doubt this is a workable idea. It's just a question of cost and political will.