Power systems utilizing at least two heat source streams with substantially different initial temperatures, where the systems include a simple vaporization, separation, and energy extraction subsystem, a recycle subsystem, and a condensation and pressurization subsystem and methods for making and using same.

A geothermal installation for collecting heat for the generation of electricity is provided. The installation includes a fluid transport system comprising at least one fluid injection bore extending from a thermoelectric generator located at or near the Earth's surface to a depth below the Earth's surface sufficient such that energy collected can produce electricity. In particular, a depth of at least 500 m, preferably at least 1500 m, and more preferably at least 3000 m is sufficient to see benefits. The fluid injection bore is connected at the said depth, respectively to a plurality of micro-tunnels which extend outwardly substantially horizontally or diagonally downwardly from a horizontal plane passing through the said depth, preferably interconnected in at least one array. The micro-tunnels in turn are connected with fluid return bores which return a heat transfer fluid to the thermoelectric generator. The fluid transport system is adapted for the flow therethrough to and from the thermoelectric generator of the heat transfer fluid.

A hybrid geothermal power system is discussed. The system includes a geothermal system including power plant (101) and pumping station (102) and a nuclear plant (103). Pumping station (102) is used to inject fluid from reservoir (104) through an injection well (105) into the bedrock (106) (also referred to as the hot dry rock HDR zone) and extracted via a secondary bore (extraction well) usually coupled to the power plant (101). In the present example however the injection well is linked to the extraction well (107). As fluid is injected into the bedrock a drop in temperature occurs due to heat transfer to the fluid. Nuclear plant (103) is utilized to combat this drop, the plant (103) has the fissionable components (1091, 1092, 1093) of the reactor positioned within bores (1081, 1082, 1083) within the HDR zone.

A rotary shutter valve 500 is used for geothermal reservoir stimulation. The valve 500 includes a pressure chamber 520 for holding a working fluid (F) under pressure. A rotatable shutter 532 is turned with a powering device 544 to periodically align one or more windows 534 with one or more apertures 526 in a bulkhead 524. When aligned, the pressurized working fluid (F) flows through the bulkhead 524 and enters a pulse cavity 522, where it is discharged from the pulse cavity 522 as pressure waves 200. The pressure wave propagation 200 and eventual collapse of the bubbles 202 can be transmitted to a target rock surface 204 either in the form of a shock wave 206, or by micro jets 208, depending on the bubble-surface distance. Once cavitation at the rock face begins, fractures are initiated in the rock to create a network of micro-fissures for enhanced heat transfer.

A geothermal energy system comprising a plurality of borehole heat exchangers, each borehole heat exchanger containing a working fluid and comprising an elongate tube having a closed bottom end and first and second adjacent elongate conduits interconnected at the bottom end, a manifold for the working fluid to which the plurality of borehole heat exchangers is connected, and a plurality of valves connected between the plurality of borehole heat exchangers and the manifold, whereby the first and second conduits of the plurality of borehole heat exchangers are selectively connectable to the manifold by operation of the valves.

A geothermal loop in-ground heat exchanger for energy extraction including an outer tubular casing and an inner tubular portion spaced from the outer tubular casing to define an injection space wherein a working fluid is injected into the injection space at a first temperature, T.sub.1 while the heat exchanger is located in a geothermal heat reservoir and the working fluid exits through the inner tubular portion at a second temperature, T.sub.2 which is greater than T.sub.1.

A borehole is bored to a borehole target depth in a site and a geothermal heat exchanger is inserted into and then secured in the borehole at the desired depth. Once the heat exchanger has been secured in the borehole, the heat exchanger has a closed distal end and an open proximal end and has at least one fluid path between the closed distal end and the open proximal end, with installation fluid disposed in the fluid path(s). After securing the heat exchanger in the borehole and before excavation of a portion of the site immediately surrounding the borehole, the heat exchanger is temporarily sealed by installing, through the open proximal end, at least one respective internal seal in each fluid path. For each fluid path, the internal seal(s) will be disposed below a respective notional subgrade depth and excavation of the site immediately surrounding the borehole can proceed.