Patent Publication Number: US-11655680-B2

Title: Tunneling for underground power and pipelines

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation of U.S. patent application Ser. No. 16/813,214 filed on 9 Mar. 2020 and entitled “Tunneling for Underground Power and Pipelines,” which is a continuation of U.S. Pat. No. 10,584,585, filed 15 Nov. 2017 and entitled “Tunneling for Underground Power and Pipelines,” which claims priority to U.S. Provisional Patent Application No. 62/422,539, filed 15 Nov. 2016, the contents of all of which are incorporated herein in their entirety. 
    
    
     FIELD 
     The present technology relates to tunneling, and more particularly to using plasma for tunneling underground. 
     BACKGROUND 
     The cost of renewable energy is now equal to or less than the cost of fossil fuel generated electricity. Electricity to run vehicles is cheaper than gas even in the case where gas is less than $1.00 per gallon. Wind and solar are booming industries, adding tens of billions of dollars per year of newly installed projects at a 30%+average compound annual growth rate. Studies show significant benefits to the US economy due to clean power, including new jobs (e.g., wind turbine technician was the fastest growing job in the USA in 2015), efficiency gains, reduced health costs due to cleaner water and air and reduction of the rapidly increasing costs to the economy of climate change. 
     Wind &amp; solar power plants now provide electricity that&#39;s cheaper than new or existing fossil fuel power plants. However, much of this potential clean, affordable resource remains unavailable to most people due to the lack of suitable transmission lines. One solution for providing transmission lines is running them underground. However, building this type of infrastructure to transmit and store power can be slow and expensive using existing technology. 
     For example, Bertha is one of the world&#39;s largest tunnel boring machines. The speed of Bertha is about 10 m per day. It is also huge, at 17.5 m wide and nearly 100 m long, requiring assembly at each job site and then disassembly to move it to the next location, as well as needing large slurry pipes and a 2.7 km long conveyor belt to move soil out of the way by injecting water and chemicals in the broken soil until it runs into a soft paste slurry. Furthermore, such tunnel boring machines are expensive to operate. Bertha uses 18.6 MW of power and 25 people to keep it operating. Bertha stalled in December 2013 and required substantial repairs, delaying a tunnel project in Seattle, Wash. by about 3 years. 
     Accordingly, there is a need for new tunneling technology to facilitate quickly and cost effectively boring tunnels. Cost effective tunnels can be used for power transmission lines, transportation, energy storage, and the like. 
    
    
     
       BRIEF DESCRIPTION OF THE FIGURES 
       The present technology is illustrated by way of example, and not by way of limitation, in the figures of the accompanying drawings and in which like reference numerals refer to similar elements and in which: 
         FIG.  1    is a system diagram showing the various elements of the system. 
         FIGS.  2 A- 2 E  are illustrations of one embodiment of the rapid burrowing robot (RBR). 
         FIG.  3    illustrates one embodiment of an RBR with an attached mother rig. 
         FIGS.  4 A- 4 E  illustrate various views of one embodiment of a mother rig. 
         FIGS.  5 A- 5 D  illustrate various views of one embodiment of an RBR with a mother rig and a father rig. 
         FIGS.  6 A- 6 E  illustrate various views of one embodiment of a father rig. 
         FIGS.  7 A- 7 G  illustrate various views of one embodiment of a pull cart and supply cable management system. 
         FIGS.  8 A- 8 D  illustrate various views of one embodiment of a rotating plasma torch element of the RBR. 
         FIG.  9    is a block diagram of one embodiment of the RBR system. 
         FIG.  10    is a diagram of one embodiment of a system with a pull cart based cable management mechanism. 
         FIG.  11    is a diagram of one embodiment of a system with a wheeled cable management mechanism. 
     
    
    
     DETAILED DESCRIPTION 
     The present application describes a rapid burrowing robot (RBR) that can dig tunnels using ultra high temperature rotating plasma torches. In one embodiment, the RBR can be used for placement of new high voltage transmission cables 10 to 55 times faster at 20% of the cost of conventional tunneling. New transmission lines networked into a new Energy Superhighway—or a Super-grid—can be installed quickly by the RBR deep underground where it won&#39;t bother people, and can move cheap, clean wind energy from the Great Plains and solar power from the desert Southwest. Being able to easily bring renewable energy to our biggest cities where it&#39;s needed will increase renewable energy use, and decrease its cost. The RBR gasifies and/or melts rocks underground to create a sealed tunnel. In one embodiment, the sealed tunnel can act as an airtight tube to store compressed air, as a battery. Moving away from coal, gas and oil to cheaper, more predictable wind, solar and other clean power sources means lower energy bills for consumers and businesses, cleaner air, cleaner water, and a reduction of CO2 induced climate change. 
     The RBR uses innovative plasma and robotic technologies to tunnel quickly underground through rock and soil. The RBR primarily does this without mechanical drilling, or with reduced mechanical drilling. Using the RBR, it is possible to build subterranean tunnels which can then be lined with super high voltage transmission lines. In one embodiment, those tunnels could form a self-healing neural network of smart grid transmission lines that would be nearly impervious to vandalism, terrorist attacks or natural disasters, hardening and backing up our existing electrical and power system. In one embodiment, the tunnels could also double as batteries to store vast quantities of clean renewable energy, smoothing out availability. All this could be done without the need to spend decades to get the permits needed for dozens of new overhead transmission lines, at tunneling speeds many times faster than conventional boring drill rigs and at a fraction of the cost. Furthermore, by moving such lines underground, the potential damage and risk from adverse weather events and third-party attack is reduced. 
     The following detailed description of embodiments of the disclosed technology makes reference to the accompanying drawings in which like references indicate similar elements, showing by way of illustration specific embodiments of practicing the technology. Description of these embodiments is in sufficient detail to enable those skilled in the art to practice the technology. One skilled in the art understands that other embodiments may be utilized and that logical, mechanical, electrical, functional and other changes may be made without departing from the scope of the present technology. The following detailed description is, therefore, not to be taken in a limiting sense, and the scope of the present invention is defined only by the appended claims. 
       FIG.  1    illustrates a simplified high-level diagram of the system. The tunnel system  160  is drilled by the RBR  100 , for energy management, in one embodiment. The RBR  100  is controlled by RBR operator system  110 . In one embodiment, the operator system  110  provides instructions to the RBR  100  underground. In one embodiment, the operator system  11   o  may be a wired or wireless controller, which directs the RBR, and addresses any issues. In one embodiment, the RBR  100  may be partially or fully autonomous when no issues are encountered. 
     In one embodiment, the RBR  100  is powered using energy management system  120 , which receives energy from various alternative energy sources. In one embodiment, this means that the energy management system  120  receives power from one or more of the solar energy grid  130 , wind energy grid  140 , and other alternative energy sources  150 . The alternative energy sources  150  may be other renewable energy sources such as geothermal energy, hydroelectricity, tidal power, wave power, biofuel, etc. The specific forms of energy used depends on the availability and cost. In one embodiment, energy management system  120  may also use power from the electrical grid or other sources that may not use renewable sources. In one embodiment, the system preferentially uses energy during low use times, such as at night for wind power, or mid-morning for solar power. 
     In one embodiment, the system of tunnels  160  built by the RBR  100  can be used as part of energy management system  120 . For example, in one embodiment sealed tunnel segments may be used as batteries for storing some power. 
       FIGS.  2 A- 2 E  illustrate one embodiment of the rapid burrowing robot (RBR)  200 . The RBR  200  is a robotic boring machine that can bore (tunnel) quickly through rock, dirt and other subterranean material with few moving parts using electricity as its energy source. In one embodiment, it is equipped with a center pulse laser  202  and multiple plasma torches  204  operating at an adjustable angle relative to the center laser. The RBR uses intense heat to “drill” through rock and soil. 
     The energy for the RBR is DC (direct current), in one embodiment. The RBR is powered, in one embodiment, through a connection with the DC output of a wind farm, solar farm, or other renewable energy source. In one embodiment, the system may include energy storage. In one embodiment, the system may further have a backup connection to the grid with a high-powered AC to DC inverter to ensure a consistent power supply in the event that solar or wind energy is unavailable or insufficient. 
     In one embodiment, the centrally located pulse laser  202  creates an initial guidance bore. In one embodiment, the guidance bore is at the center of the intended tunnel. For some tunneling applications where the rock melting point is below the maximum, the laser can be replaced with a center mounted plasma torch. 
     A series of plasma torches  204  operating at very high temperatures of up to 28,000° C. are arranged in a circular design. In one embodiment, a rotating torch element  210  includes the torches, their support structure, and a shaft  212 . In one embodiment, the torches are non-transferable plasma torches which do not touch the material to be gasified, but rather complete the circuit between the cathode and anode of the torch, and use compressed air to provide a larger plume size. In one embodiment, the torches are transferable plasma torches which use a clamp attached to the material to be gasified. In one embodiment, the plasma torches are cooled using water or another coolant, circulating through the system. 
     In one embodiment, the torches are arranged in a Fibonacci spiral design, as shown in  FIG.  2 A . A Fibonacci spiral is created by drawing circular arcs connecting the opposite corners of squares in the Fibonacci tiling comprised of squares sized according to the Fibonacci sequence of numbers. 
     The torches are, in one embodiment, mounted on a support structure  210  which includes disks (e.g., disks  214 / 216 ) or partial discs (e.g., disks  218 / 222 ) made of a tungsten alloy (or Hf—Ta—C alloy or another material with high melting temperature such as titanium). These rotating discs are mounted to a shaft  212  that spins slowly in the center point, in one embodiment. The torches gasify the material (rock, dirt, ore, etc. collectively the “material”). 
     In one embodiment, the discs are arranged in the spiral pattern, with each disc separated by a small axial distance along shaft  212 . In one embodiment, the separation is 5 cm with ˜22 torch nozzles on the first disc  214  and additional torches or torch pairs on each subsequent disc or disc ring segment (collectively referred to as the “Spiral Rig”). In some embodiments, pairs of torches are used at each location to increase the rate of penetration. In one embodiment, the base unit (“Base RBR”) contains 72 torches and bores a tunnel of 1 meter in diameter (see  FIGS.  8 A- 8 D ). In some embodiments, on each disc the torches are staged such that some are toward the front and another set of torches are in the back to cut out a wider area. 
     In one embodiment, RBR&#39;s rotating torch element  210  is coupled to a cart enclosure  220 , and propulsion system  230  which may include a continuous track  232 , wheels  234 , or other elements. In some embodiments, the wheels  234  can be driven with hydraulic or electric motors (not shown) or other actuators. In one embodiment, the cart enclosure  220  is shielded with a class of refractory ceramics called ultra-high-temperature ceramics (UHTCs). UHTCs offer excellent stability at temperatures exceeding 2000° C. The enclosure contains the circuitry, processors, electric motors, and communications equipment needed for the RBR to operate semi-autonomously. In one embodiment, the power management equipment is primarily located at the staging area, with some power management in the enclosures of the first two carts. In one embodiment, the water or other coolant used to cool the plasma torches are circulated from the staging area as well. In one embodiment, the water is recirculated. In one embodiment, the recirculated water may be cooled at the staging area. In one embodiment, the compressed air to increase plume size is also provided. In one embodiment, the air supply may be 1500 cubic feet/minute. 
     In one embodiment, high-powered LED lights  240  are mounted on the RBR and a series of High Definition video cameras  242  are located on the first disc  214  and near the back of the RBR enclosure  220  to monitor progress, as can be seen in  FIG.  2 E . In one embodiment, the video cameras have pan, tilt and zoom capability, and may be remotely controlled. In one embodiment, the lenses are coated with a nano-coating that significantly mitigates accumulation of dust or other particles. In one embodiment, the RBR also may include sensors, such as temperature and air quality sensors. In one embodiment, the supply line also provides a communication line, which may be a fiber optic communication line, to send back data from the video cameras and sensors. 
     In one embodiment, the RBR uses continuous tracks or treads  232  made of UHTCs. In one embodiment, the tracks  232  may be embedded with high temperature alloy spikes (for traction). The roller wheels  234  within the continuous tracks  232  may include multiple cooling slots designed to disperse the heat. In another embodiment, the water used to cool the plasma torches can be circulated within the RBR housing  220  and track rollers  232  to remove heat. In one embodiment, the roller wheels  234  are power by individual water cooled and insulated variable speed DC electric motors. 
     In one embodiment, the minimum power requirement of each plasma torch is 500 kilowatts (0.5 mW) per torch. In one embodiment, the Base RBR, which bores a tunnel with a 1-meter diameter, has a minimum power requirement of approximately 40 megawatts (MW), 72 torches at 0.5 MW=36 MW plus 4 MW (about 10% of the aggregate capacity of the plasma torches) for propulsion and other auxiliary systems. In one embodiment, each non-transferable torch can accommodate up to 1.5 MW of power, or three times (3×) its minimum rated capacity. At three times the power, the temperature and corresponding gasification capacity increases by approximately three times as well. Thus, the theoretical maximum power input is between 40 MW to 120 MW for a 1-meter diameter tunnel. If less power is available, the RBR moves more slowly by optimizing the available power to fewer torches (such as 2 out of every 3 torches, or every other torch). In one embodiment, the RBR may alternately bore a smaller radius tunnel, when there is less power available by focusing the torches in a more constrained area. In one embodiment, some portion of the torches may be modified to be either transferable or non-transferable plasma torches. 
     The RBR can be equipped with an optional Stage 2 “Mother Rig”  300  immediately behind the primary RBR  200 , which contains a secondary spiral rig or platform  310  of disc ring segments which can expand the tunnel diameter to up to 3 meters.  FIG.  3    shows one embodiment of a mother rig  300  attached to an RBR  200 .  FIGS.  4 A- 4 E  show various views the mother rig  300 . 
     A Stage 3 “Father Rig”  400  of the same design—but with larger ring segments—can be inserted behind the Stage 2 rig  300  for even larger tunnels, as needed. In one embodiment, the Father Rig  400  could bore tunnels of up to 10 meters in diameter.  FIG.  5 A- 5 D  illustrate various views of one embodiment of a father rig  400  attached to an RBR  200  and mother rig  300 .  FIGS.  6 A- 6 E  show various views of one embodiment of the father rig  400 . These additional rigs, if all plasma torches on each of their ring segments are fully utilized, have an estimated minimum power requirement of 120 MW and 300 MW respectively, with maximum power capacity of 360 MW and 900 MW respectively. 
     The speed of the rotation is related to a combination of the power available to the RBR and the density and composition of the material through which the RBR is tunneling. In one embodiment, the minimum speed is 2 revolutions per minute (RPM). The RPM can be increased as the power increases. In one embodiment, for every 10% increase in power, the RPM can increase by between 5-10% depending on the composition of the material the RBR is drilling through. In one embodiment, 6 RPM is the maximum rotation speed, using one embodiment of the torch design. However, it may be possible to increase the maximum speed beyond RPM, and the present application is not intending to limit the maximum RPM. In some embodiments, the shaft and discs rotate in a clockwise direction. 
     To increase RPM, in one embodiment, the RBR may utilize plasma torches that have a higher energy capacity (from 1.5 MW to up to 5 MW each) which could increase the potential maximum RPM by up to 10×. Additionally, the addition of optional plasma torches on a mother rig or a father rig, which would be turned on as more power is added to triple the gasification potential may be used to increase the RPM. In one embodiment, the design shown in  FIG.  3    could increase the maximum RPM by 3×. 
     In one embodiment, the Mother Rig and Father Rig, having more space to insert additional ring segments, could add additional torches to increase capacity by at least 5× and 10× respectively for larger tunnels, subject to power availability and geology. 
     The adjustable nature of the RBR allows for flexible tunnel sizes, ranging from about 0.5 meters to 2 meters in diameter. Larger versions with extra rigs carrying additional rings of torches behind the initial rig can bore tunnels of 10 meters in diameter or larger. 
     The forward tunneling speed of the RBR is determined by how quickly the material it is moving through gasifies. In one embodiment, the RBR gently pushes into the material, applying a constant pressure and moves forward as the material in front of it gives way to gasification or ash. In other words, the speed is variable based on how quickly the RBR gasifies the material. This depends on the material and the energy output of the torches. In one embodiment, the RBR may push into the material slowly, and pause to allow the temperature to decrease before moving forward into space that was previously occupied by the removed material. 
     The power supply cables and consumables supply lines to the RBR are connected to the back end of the RBR, in one embodiment.  FIGS.  7 A- 7 G  illustrate various views of one embodiment of a pull cart  500  and cable management system  510 . In one embodiment, the pull cart  500  provides a cable management system including tungsten or titanium wheels with modest on-board electric propulsion to eliminate drag on the RBR. In one embodiment, carts  500  contain expanding/collapsing connection rods  520 , which are each between 2-5 meters long and connect a series of carts. The connection rods  520  provide protection for the cable, which extends from the pull cart to the base station outside the tunnel. The supply conduits lead power (electricity), coolant (water), plume dispersant (compressed air), and communication cabling (fiber optic cable) to the rigs. In one embodiment, the carts contain sensors that monitor the temperature of the tunnel floor as they pass over it. Although  FIGS.  7 A- 7 G  and  FIGS.  10  and  11    illustrate a single conduit, the system may include separate conduits. In one embodiment, the separate conduits are encased in a single temperature managed cable enclosure, for protection from the heat and dust. 
     In one embodiment, carts are approximately 0.5 meters by 0.5 meters by 0.5 meters. Each Cart follows the preceding cart by 3 meters when the supported interlocking jointed arm (“Arm”) is fully extended, in one embodiment. When the Arms are fully collapsed the Carts compress together into a length that is roughly 6 times shorter than their fully extended length to allow for easier transport. In one embodiment, the RBR is designed to accommodate at least no Carts, so it can tunnel at least 1 kilometer from any staging point where the Carts have been staged in a compressed arrangement.  FIG.  10    illustrates one embodiment of the staging point, with carts  500 ( 4 - 8 ) in close proximity, and showing the sequence of carts  500 ( 1 - 3 ) that are strung along to provide cable management and reduce drag on the system.  FIG.  10    is not to scale, since the expected spacing between carts is between 2 meters and 10 meters. Although only a few carts are illustrated, in a real implementation, the system may include over 100 carts. 
     In another embodiment, the power, supply &amp; communications cables may be rolled up in a protective tube  540  (in one embodiment made with a refractive liner) lined on the outside with wheels  542 , as illustrated in one embodiment in  FIG.  11   . In one embodiment, the wheels may be small (such as roller blade sized) made of tungsten or titanium with tungsten or titanium ball bearings. The wheels are spaced approximately every 20 cm. In one embodiment, there are wheels all the way around the circumference of the tube every 20 cm. The tube could simply be pulled behind the RBR  200  and/or Mother/Father Rig  300 / 400 , without a separate pull cart. In one embodiment, the first 20-30 meters or so would be heavier, with stronger refractive protection since that&#39;s the portion that would be exposed to the most heat until the tunnel walls cool enough to eliminate the need for any protection 
     In one embodiment, a backup RBR with the spiral rig/torches removed (or pull cart) could be placed periodically to create additional torque for the cables if needed. In one embodiment, the backup torque carts may be placed every 200-500 meters. The cable tube could be wound up on large spools for preparation for each tunneling job. The ends of the cable tube on each wheel have modular connectors, in one embodiment. 
     The RBR is designed to create a safe, usable tunnel without concrete liners due to the thick liquefied/vitrified rock tunnel walls created by the RBR process. Of course, the wall thickness and strength are fully dependent on the composition of the material, so robotic inspection and constant sampling of the gases by the RBR help to inform the operators whether concrete tunnel liners are necessary. In one embodiment, sensors on each of the carts monitor temperature and mineral content of the material being melted or vaporized, and some carts are equipped with additional sensors and video cameras to provide additional data to the operators. Robots can enter tunnels after the Material is sufficiently cool, if needed, for further inspection and/or to begin installing HVDC power cables, pipelines, or other uses. 
     The outer portions of the Material that is not fully gasified due to lower temperatures would be liquefied and as it cools under pressure would naturally form a glass-like wall lining the tube, similar to a lava tube, for some materials. In one embodiment, up to 60% of the Material encountered in the tunnel could be vitrified and/or compressed into the tunnel walls. Removal of the Material that does not become part of the tunnel walls is removed. In one embodiment, the Material is removed through the use of a vacuum created behind the RBR, to pull the gasified Material back to the surface, including any Material that precipitates into sand or silt as it cools. In one embodiment, a vacuum system is at the staging area, and suction is created in the entire tunnel to remove the gasified and particulate material. 
     In general, the Material would be small chunks of rock, sand and/or silt. In one embodiment, such Material could be sold for use in construction applications. In one embodiment, the Material is melted rather than vaporized and removed using a conveyor system, although this application would be utilized only in the unlikely event where either geology requires melting rather than vaporization, or where sufficient power is unavailable for Material vaporization. (giant vacuum at the staging area) (air compressor/water cooling &amp; recycling system) 
     The variable speed feature of the RBR allows for a very high peak power limit, to tunnel very rapidly under the right geological and electricity cost conditions. Initial engineering suggests that tunneling through limestone (melting temperature of 825° C. with its calcium carbonate component having a melting temperature of 1,339° C. and limestone gasification temperature of 1500° C.) and soil with the RBR could be up to 250 meters per day for large 3 to 10-meter diameter tunnels, or 10 times faster than Martina Tunnel Boring Machine by Herrenknecht AG. Smaller diameter 1-2-meter tunnels for a HVDC cable could be carved out at even higher speeds: preliminary engineering estimates tunneling speeds of 1 kilometer per day when connected to a 100 MW wind or solar farm with an above average capacity factor. 
     The rate (speed) of tunneling is directly proportionate to the level of power (current) from the DC input, making it flexible and variable speed depending on the composition of the material being gasified at the time. Therefore, the tunneling speed can be reduced during times when electricity is expensive, and increased during times when electric rates are cheap. This gives great flexibility in managing tunneling cost, since energy consumption would otherwise be the largest variable operating cost. 
     In one embodiment, the RBR is able to bore tunnels at speeds of 10 to 55 times faster, or greater, than conventional tunneling techniques using low cost 100% renewable energy while helping to mitigate curtailment of wind and solar energy during “over-production” periods—all while eliminating the need to solve the development timelines delays of up to 10 years for above-ground transmission projects. This leads to significant cost savings. 
     One of the sources of cost savings is that the “drilling” function uses heat, rather than mechanically spinning drill, rotors or cutters. There are very few moving parts, with none of the moving parts perform any of the work need to bore the tunnel. Therefore, the friction-based wear and tear of conventional drilling is eliminated, lowering parts and mechanical related operating costs substantially. Note that plasma torches have consumables that need replacement, including the electrode, nozzle and shield. The cost &amp; frequency of replacement of these consumables is much lower than conventional drilling parts. 
     Due to the vastly reduced mechanical and parts related costs, and the fact that the RBR can be 100% robotic, the labor usually needed to regularly replace, lubricate and maintain these parts is eliminated, whether on the surface for horizontal drilling of small diameter boring over short distances or within larger tunnels with manned rigs. This further reduces operating costs substantially by eliminating most labor costs. 
     The temperature of the plasma torches is a direct function of the current of electricity. In one embodiment, therefore, the RBR can increase the temperature to gasify hard rock like granite or dolomite in mountain ranges as needed. This not only eliminates the heavy wear &amp; tear on conventional boring heads and saves costs, but also allows a consistent rate of tunneling per hour by simply increasing the current to the torches avoiding costs associated with prolonged delays of the tunneling project. In one embodiment, water is used for cooling of the plasma torches, and the volume of water circulating within the water supply and return hoses can be increased or decreased as needed based on geology, RBR tunneling speed, power being delivered to the RBR, and other factors. In one embodiment, the RBR software control systems shall automatically adjust water flow rates, electric current, RBR propulsion speed, compressed air flow to the plasma torches, and other control systems based on input from the sensors incorporated into the RBR. 
     In one embodiment, the energy to the RBR can be scaled up during times when the value of the solar/wind energy is cheapest (such as off-peak nighttime hours or highly sunny days when the local grid cannot absorb all the solar energy). In many cases, the DC energy will be free or negative priced (the RBR would earn income simply by operating, similar to a “tipping fee”) during those times when the grid operator declares a curtailment event at the wind/solar farm due to severe congestion on the grid. This leads to very low energy costs to operate the RBR, in one embodiment. 
     Due to the vitrification of the rock at the edges of the tube, a seal is created that provides for:
         1. Structural integrity of the tube (which could be reinforced with concrete or other methods);   2. Prevention or reduction of liquids entering the tunnel such as water;   3. Prevention of reduction gases (radon, methane, CO, etc.) entering the tunnel; and   4. Ability to store compressed air in the tunnel for the purposes of:
           i. Energy storage potential (via compressors that run in reverse to capture the stored energy of compressed air like the techniques developed by Lightsail and others;   ii. To create a pressurized environment to mitigate entry into the tunnel of unwanted gases and/or liquids; and   iii. To create pressure that acts as a catalyst for the RBR to improve its efficiency in gasifying &amp; liquefying material.   
           5. Depending on the geologic composition, some portions of the tunnel(s) (where people or vehicles won&#39;t be present) is likely to eliminate the need to install concrete tunnel liners due to this glassification, saving additional money and time.       

     In one embodiment, since RGB utilizes the gasification of the rock and minerals, a gaseous spectral method (gas chromatography-mass spectrometry) can be used to identify high value minerals such as rare earths for potential extraction. This would further offset the costs of tunneling by recovering some portion of the high value materials displaced. 
     Initial engineering estimates of tunnel boring costs suggest that the RBR could reduce costs by up to 80% over conventional methods, even at a rate of boring up to ten times faster (excluding recovery of high value minerals). As renewable energy becomes increasingly less expensive than conventional fossil fuels—and as more renewable energy on the system causes even greater curtailment and “over-generation” periods—the cost to operate the RBR will continue to decline over time since the single largest cost is electricity. There may even be some locations of the world where the tunneling cost approaches zero due to optimization of “over-generation” periods to tunnel for “free.” This is the opposite thesis of conventional tunneling techniques which will increase with cost over time as materials and labor costs increase. 
     One of the things that RBR may be able to address is the aging infrastructure. RBR may provide rapid deployment of new transmission structures. Conventional transmission takes 6-10 years to obtain all the necessary permits and rights of way. The RBR could bore transmission tunnels at rates of 250 meters to 1 kilometer per day, under existing rights of way owned by transmission companies, utilities or railroads, without the need to obtain any above ground rights of way. Only subsurface rights of way from cooperative government, utility or private landowners are needed, and the permitting process would be greatly simplified. The RBR could save years of development time and up to 70% of the development cost of such projects. The RBR can help replace outdated transmission (and medium voltage distribution) lines, build new transmission lines equipped with smart grid electronics, and build out regional and ultimately global Super-grids. The tunnels created using the RBR can be a part of a neural self-healing network of super high voltage DC smart transmission segments. Such tunnels connect: Remote renewable energy resources, Weak points in the existing transmission system, Population load centers, Countries, and Continents. 
     The tunnels created using RBR can also be part of a super-grid backbone overlaid (underlain) by the RBR onto key nodes of the existing transmission system. The backbone could re-route energy in the event of natural disasters or other events that cause an interruption in the normal operations of the conventional electric grid. 
     Using the connections between heavily built-out wind and solar regions, curtailment is eliminated as the “over-production” negative or low energy pricing periods simply mean that any “excess” clean energy can now be sent to other regions for consumption. Portions of this excess energy can also be utilized by the RBR to bore more tunnels, or bore them faster by stepping up the current to the RBR during these times. 
     During evening peak periods on the East Coast, the sun is still shining in the West. Similarly, during evening peak on the West Coast, the wind is already blowing strongly in the Midwest. The RBR could connect the east and west coast together with the Midwest to move large quantities of renewable energy in remote areas to the big cities. The sun is always shining and the wind is always blowing somewhere, so connecting large regions together increases the percentage of intermittent renewable energy that can be affordably integrated into the electric grid. 
     In one embodiment, the melted rock will form airtight tunnels. With seals on two ends, glassy walls of the tunnel can be used to form an air-tight tube which can be pressurized with compressed air, for energy storage purposes. The length of many of these tunnels should facilitate a very large vessel for storing large quantities of compressed air for recapturing in the form of electricity by running the compressors backwards when the compressed air is released later when needed. This allows storage of days, weeks or even months&#39; worth of low cost renewable energy (produced during “off-peak” times such as weekends and night-time after 11 pm) to drastically increase the level of potential renewable energy penetration in the electric system. Such long-term energy storage would render gas peaking plants nearly or fully obsolete, as well as inflexible baseload coal or nuclear power stations. 
     Both large wind and solar plants as well as distributed generation (like rooftop solar, battery energy storage, geothermal, micro hydro-electric turbines, and other localized distributed energy resources) could scale up with immediate and massive deployment once the timeframe is known for nearby Super-grid nodes to be activated. 
       FIG.  9    is a more detailed illustration of one embodiment of the elements of the system. The rapid burrowing robot  910  includes, in one embodiment, a plasma/laser system  915 , and a coolant  917  and compressed air or other plume enhancement mechanism  919 . In one embodiment, the coolant is water, which is circulated from the controller/staging area  940 . In one embodiment, the rapid burrowing robot  910  further includes lights/cameras/sensors  920 , a cable management system  925 , and an engine  930 . In one embodiment, the rapid burrowing robot  910  also includes a self-driving guidance system, which enables the RBR  910  to be self-propelled without external controls. As noted above, the sensors  920  may include a camera, as well as air quality sensors, and heat sensors. The cable management system  925  may include one or more pull carts to manage the cables, or wheels or other mechanisms to enable the pulling of the cable. The cable couples the rapid burrowing robot (RBR)  910  to the RBR controller  940 . 
     The RBR controller/staging area  940  may include a data analysis system, from the RBR. The data analysis system  945  takes data from the cameras and sensors  920  of the RBR  910 , and provides analysis on the optimal speed, and mechanism for burrowing. For example, for dense rock that&#39;s highly conductive a smaller surface area hotter plasma may be used, compared to a more porous rock that liquefies easily. 
     Controller  950  controls the RBR  910 . In one embodiment, the controller  950  receives data from the RBR  910 . In one embodiment, the controller  950  controls the RBR  910  by sending it the appropriate level of power, coolant, and air supply  955 . In one embodiment, the controller/staging area  940  further includes a water cooler  959 , to cool the water circulating to the RBR&#39;s plasma torches  915 . In one embodiment, a vacuum system  960  is used to remove gasified material and/or debris from the tunnel. In one embodiment, an air compressor  957  is used to supply compressed gas to air supply  955 . 
     In one embodiment, RBR controller  940  may be controlled by a human “driver,” who provides instructions to the RBR  910  in real-time. In another embodiment, the driver may utilize the RBR controller  940  to set up a planned path/routine/energy usage pattern for the RBR  910  and allow the self-driving guidance system  935  to provide real-time controls. 
     The speed/power controls  955  provide the propulsion to the RBR  910 . In one embodiment, they are coupled to the controller  950 . Thus, the speed of the RBR  910  may be set based on the available power (via speed/power controls  955  and the type of material that the RBR  910  is encountering. The speed/power controls  955  interface with energy management system  970 . 
     The energy management system  970  provides a tap into the alternate energy grid  975 . Alternate energy refers to renewable energy sources, such as solar, hydropower, wind power, etc. In one embodiment, the RBR  910  is optimized to use renewable energy and to adjust its power consumption to minimize cost. In one embodiment, the RBR  910  may be run purely on alternative energy, whether dedicated or obtained from the grid. 
     Cost-benefit calculator  980  utilizes the data from the energy grid, or alternative energy supply  970 , to determine the optimal speed for the RBR  910 . In one embodiment, the cost-benefit calculator  980  may take into account all the available factors, including the urgency of completing the tunnel being bored. 
     In one embodiment, the output of the energy management system  970  is coupled to RBR controller  940  via power control  985 . Administration  987  provides the payment for the energy. In one embodiment, the administration  987  may interface with a plurality of energy providers, to obtain the best priced energy resources for the RBR  910 . 
     In one embodiment, the RBR  910  creates a self-closing tunnel. This tunnel may be utilized for a variety of reasons. Tunnel controls  990  provide some exemplary uses of such tunnels. In one embodiment, the tunnel may be used as part of a wiring system  992 . Wires, such as gas, electricity, fiber, and copper need to lead to every home and business, to provide the basic utilities. The tunnel system may be used with wiring systems  992  to provide a location for such wiring. Wiring, in this context includes plumbing, such as water supply and sewer system. 
     In one embodiment, the tunnel may be used as a battery  994 . The battery may consist of stored compressed air. High pressure compressed air is a safe, reasonably cheap, and simple way of storing energy. In one embodiment, the tunnel battery  994  may be used by the RBR  910  to fuel further burrowing. 
     In one embodiment, the tunnel may provide energy superhighway controls  996 . The “energy superhighway” in this example is a connected grid of tunnels that may be used to lead fiber the last mile, and to provide a safe and secure power grid. 
     In one embodiment, the tunnels may be used as part of a mapping system  998 , to map out an area and create a pathway. In some other embodiments, the tunnels created may be used for transportation, secure storage, and other purposes. 
     In a representative embodiment, a tunnel boring machine can comprise a propulsion system, a torch support structure carried by the propulsion system, and a plurality of plasma torches carried by the torch support structure. In some embodiments, the plurality of plasma torches can be arranged on the torch support structure in a spiral pattern. In some embodiments, the spiral pattern is in the form of a Fibonacci spiral. In some embodiments, the torch support structure comprises a disc mounted on a rotatable shaft carried by the propulsion system, and wherein at least selected ones of the plurality of plasma torches are mounted to the disc. In some embodiments, the torch support structure further comprises at least one partial disc spaced apart from the disc and mounted on the rotatable shaft, and wherein at least selected other ones of the plurality of plasma torches are mounted to the at least one partial disc. In some embodiments, the plurality of plasma torches are arranged on the torch support structure in a Fibonacci spiral. In some embodiments, the machine can further comprise a laser positioned proximate the center of the disc. In some embodiments, at least selected ones of the plurality of plasma torches can comprise non-transferred are plasma torches. In some embodiments, at least selected ones of the plurality of plasma torches comprise transferred are plasma torches. 
     In a representative embodiment, a tunnel boring machine can comprise a propulsion system, an enclosure carried by the propulsion system, and a torch support structure carried by the enclosure. In some embodiments, the torch support structure can comprise a primary disc mounted on a rotatable shaft carried by the enclosure, a first plurality of plasma torches mounted to the primary disc, and a power supply cable coupled to the enclosure and adapted to supply power to the boring machine from one or more power sources. In some embodiments, the machine can further comprise a control system configured to select the one or more power sources from among multiple available power sources based on a corresponding cost and a corresponding availability of each of the multiple available power sources. In some embodiments, the multiple available power sources can comprise at least two of solar power, wind power, geothermal power, hydro power, tidal power, wave power, power derived from biofuel, or power derived from fossil fuel. In some embodiments, the torch support structure further comprises at least one secondary disc spaced apart from the primary disc and mounted on the rotatable shaft, and further comprising a second plurality of plasma torches mounted to the at least one secondary disc. In some embodiments, at least selected ones of the first and second pluralities of plasma torches are arranged on the torch support structure in a Fibonacci spiral. In some embodiments, the machine can further comprise a laser positioned proximate the center of the disc. In some embodiments, at least selected ones of the plurality of plasma torches comprise non-transferred are plasma torches. In some embodiments, at least selected ones of the plurality of plasma torches comprise transferred are plasma torches. 
     In a representative embodiment, a tunnel boring system can comprise a first tunnel boring machine and a second tunnel boring machine. The first tunnel boring machine can comprise a first propulsion system, a first enclosure carried by the first propulsion system, a first torch support structure carried by the first enclosure, wherein the first torch support structure comprises a first disc mounted on a first rotatable shaft carried by the first enclosure, and wherein the first disc has a first diameter, and a first plurality of plasma torches mounted to the first disc. The second tunnel boring machine can comprise a second propulsion system, a second enclosure carried by the second propulsion system, a second torch support structure carried by the second enclosure, wherein the second torch support structure comprises a second disc mounted on a second rotatable shaft carried by the second enclosure and wherein the second disc has a second diameter larger than the first diameter, and a second plurality of plasma torches mounted to the second disc. In some embodiments, a first supply cable extends from the first enclosure to the second rotatable shaft. In some embodiments, the system can further comprise a power supply cable coupled to the second enclosure and adapted to supply power to the boring system from one or more power sources. In some embodiments, the system can further comprise a control system configured to select the one or more power sources from among multiple available power sources based on a corresponding cost and a corresponding availability of each of the multiple available power sources. In some embodiments, the system can further comprise a third tunnel boring machine. The third tunnel boring machine can comprise a third propulsion system, a third enclosure carried by the third propulsion system, a third torch support structure carried by the third enclosure, wherein the third torch support structure comprises a third disc mounted on a third rotatable shaft carried by the third enclosure and wherein the third disc has a third diameter larger than the second diameter, and a third plurality of plasma torches mounted to the third disc. In some embodiments, a second supply cable extends from the second enclosure to the third rotatable shaft. In some embodiments, the system can further comprise one or more push-carts connected to the third tunnel boring machine. 
     In the foregoing specification, the technology has been described with reference to specific exemplary embodiments thereof. It will, however, be evident that various modifications and changes may be made thereto without departing from the broader spirit and scope of the invention as set forth in the appended claims. The specification and drawings are, accordingly, to be regarded in an illustrative rather than a restrictive sense.