Superconductor Geothermal 

Power (SGP),

or ‘Hot Wire’ plants

Geothermal power is one of the tried and established technologies that supported the federation races before contact, with advances in drilling technology, this technology provides a major stopgap, between ‘dirty’ methods of power production, fossil fuels, fission etc, and ‘clean’ power generation, geothermal, wind, solar, and advanced fusion. This article concerns a particular type of geothermal power production, which is still greatly in use in the modern federation because it relatively easy to install, very low maintenance, and provides sizable amounts of power.

Old geothermal plants utilized steam of supercritical water heated by subsurface rocks to drive turbines, these turbines would then drive the generators which produced the electricity. The design for these plants is relatively simple, one or more bore holes is driven down through the crust, up to several kilometres, depending on the available heat. Water is introduced which is turned into steam by the hot rocks, and the steam coming up one of the boreholes under pressure drives the turbines. In some cases a natural subsurface water supply can be used, removing the necessity of pumping water down, and reducing the reliance on a water supply, other plants generate supercritical fluid, which has a greater heat density than steam, though has its own problems.

This type of plants were relatively simple in design, and for the little maintenance and initial construction cost, produce several megawatts over many decades. However the lifetime of this kind of plant is limited, mineral precipitates form in the boreholes, which eventually fur them up, so that the bore holes have to be re-drilled, or new bores sunk. This is where the advantage of hotwire plants comes in, they are not dependent subsurface heat carrying fluids.

In a hot wire plant, the same deep boreholes are sunk, but instead of passing water down these pipes, a thick superconducting cable is passed down instead, this cable replaces the need to send water subsurface. Cables can also be sunk by super heating them, and rather drilling a hole for the cable, the wire melts its way through the rock, this method also ensures that the surface of the cable are also in contact with the heated rock surfaces. Superconducting cable has the property of being the same temperature anywhere along its length, this means that heat far below ground is transmitted to the surface with very little loss (though the cable also transfers heat to the cooler rocks near the surface).

Power generation can happen at the surface, using the top of the heated cable as the heat source, the same water-steam method used in the early geothermal plants is still used in the federation, simply because of its simplicity. Other liquids can also be used, such as ammonia, but these systems tend to be closed, to prevent loss of working fluid to the environment (and therefore driving fluid does not need to be replaced). The more advanced method is to distribute the generated heat through a lattice of superconducting cables, the heat is then transferred through efficient thermopiles into a second cooler superconducting lattice. This method of power generation is completely solid state, and requires almost no maintenance as a result. Several thermopile stacks can be used, progressively reaching temperatures approaching external environment, and extracting nearly all the thermal energy.

As well as providing for conventional power generation on land, similar systems can also be sunk into the sea-bed, this has the advantage of removing the station and its equipment from the visible landscape, while also providing an ideal cooling solution, for the solid state generator, as circulated sea water carries away the heat from radiator fins.

Hot wires are also used in non-power generating applications, especially in terraforming. The hot wires ability to tap internal geothermal heat and bring it to the surface is useful for heating the atmosphere of cool planets, with a few adaptations to the cable’s surface head, such as the installment of a heat dissipation complex, a series of such stations can heat the atmosphere with very little extra work. The principle can also be used in reverse, surface heat can be sent deep under ground, or into oceans, although this does not actually remove heat from the system as a whole, it does facilitate its movement, which is useful say if you wanted to even out particular temperature regions.