Refrigeration – Structural installation – Geographic – e.g. – subterranean feature
Reexamination Certificate
2002-08-01
2004-02-10
Tapolcai, William E. (Department: 3744)
Refrigeration
Structural installation
Geographic, e.g., subterranean feature
C062S238700, C137S563000, C165S045000
Reexamination Certificate
active
06688129
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention is a very low cost method to insert and extract heat energy to and from potable water using a single pre-existing underground water service pipe, without either consuming or degrading the potable water. Extremely efficient geothermal heat pump space-conditioning installations are made possible without the high cost of excavation or insertion of underground heat exchanger equipment. When combined with on-site fuel cell electrical power and co-generation waste heat, the present geothermal invention becomes even more efficient, consuming only a small fraction of the energy required by prior art systems.
GEOTHERMAL BACKGROUND
The high energy efficiency of geothermal heat pump (GHP) air conditioning is well known. Geothermal renewable energy is dilute, in terms of energy density, but it is still the world's most abundant and most reliable form of stored terrestrial clean energy. The dilute thermal energy density at the surface of the earth compared to many other high energy density sources (such as fossil fuels) makes the immense geodetic heat sink difficult and expensive to access. Despite its dilute energy density, the earth contains far more stored energy than all other conventional energy sources combined. Hence, the pursuit of geodetic clean energy remains a high priority and is completely justified. Unfortunately, its current use hardly registers on the global energy-usage scale for the following reasons. Prior art GHP installations are too expensive; GHP installation-payback is not cost efficient for many years. Prior art GHP systems are also not universally appropriate for all ground conditions such as poor thermal conduction, soil hardness (rock), lack of moisture, and high population density zones (high-rises for example) which do not offer high acreage to tap ground heat. Deep boring and/or long trenching costs represent about half the total cost in a typical geothermal installation, but excavation costs can be much greater in many locations. Geothermal publications abound with sophisticated schemes to drill deep geothermal holes for the insertion of closed fluid loops, back-filled with improved thermal conduction grouting materials. Likewise, the literature overflows with techniques for filling long deep trenches with various thermally conductive loop backfill materials. Even navigationally guided horizontal loop-drilling technology has been developed to drill very long curved loops, where tubing can be pulled into and around a horizontal drilled loop. Furthermore, numerous techniques have been developed to tap the geothermal energy of lakes, rivers, and oceans. Single well (open loop) and multiple well (closed loop) ground water sources have also been exploited, but the use of such geothermal bodies of water still imposes high installation and excavation costs, or longevity shortcomings such as dirt and/or debris filtration problems, and a long list of similar objections.
In other attempts to bring geothermal costs down, elaborate compound geothermal heat exchange systems are being employed. For example, noisy evaporative cooling water towers have been combined with cool ground waters. The cost can be high in large commercial applications, but energy savings are also high. Another high cost example of commercial size geothermal installations—typically in excess of 100-1000 tons (1,200,000 to 12,000,000 BTU/hr)—involves major excavation to access municipal water mains at distant points. Major municipal water flow is interrupted and then diverted with two large pipes directed too and from a large heat exchanger device, forming a large underground ioop within a municipal water system. This type of costly installation requires large earth moving machines for significant earth (and even paved road) excavation, followed by land and road restoration and, of course, the costly permits to interrupt large commercial water mains. Such prior art heat exchange systems claim to be cost effective only in large multi-dwelling housing developments of 40 or more adjacent homes, or in large commercial buildings. The amount of excavation for this special type of geothermal application is high, but can be less costly than excavating many thousands of feet of individual underground heat exchange closed loops for an entire housing development. Such community geothermal installations have additional complex and expensive considerations, such as measuring and metering the thermal usage billed to each dwelling or office connected to the common municipal water system. The many limitations of massive evacuation for heat exchange loops in municipal water mains makes the cost of such complex geothermal methods prohibitive for single residences.
Nonetheless, the availability of effectively inexhaustible stored geothermal energy, the low pollution associated with it, and the low energy cost of using it, continues to beckon us to adopt this largest-of-all renewable clean energy sources—especially if installation costs can be greatly reduced, as disclosed in the present invention.
There is no question that “renewable” geothermal energy is extremely clean, incredibly abundant, essentially free, energy-efficient, and exceptionally reliable 24 hours a day (unlike wind, tide, or solar energy). The temperature of the few hundred outermost feet of the earth—that which is accessed for GHP—is largely governed by years of stored solar energy. In fact, more sunlight energy intersects this planet in one year than all the energy used by mankind throughout history. In that respect, GHP is really just a convenient form of stored solar energy, just as wind and rain energy are byproducts of intercepted solar energy. Geothermally stored solar energy is simply a much more direct solar absorption and heat storage mechanism. High temperature heat energy from deep within the earth's core conducts through the earth's crust and is ultimately liberated from the surface of the earth at a rate of only 15.9 BTUs per hour per square foot. Solar energy heating the earth exceeds 100 watts/ft
2
, or more than 341 BTUs per hour per square foot, so that incoming solar energy far exceeds the heat losses from the earth's core. The earth's crust has reached an equilibrium average temperature resulting from daily solar exposures and seasonal variations, so “geothermal energy” is better referred to as “geo-solar energy”. When that stored solar energy is tapped by geothermal heat pumps, the stored solar energy store is temporarily borrowed in the winter months and is pumped back in the summer months. The highest core temperature of the earth—“genuine geothermal energy”, is typically extracted for steam powered electric generators in western territories of the U.S. Unlike other clean renewable solar energy systems (e.g. solar photoelectric arrays), which require massive and very costly man-made energy storage systems when no sunlight is present, “geothermal stored solar energy” is cost free and essentially unlimited year round. Until now, the main obstacle has been that of their high costs of excavation for heat exchange loops.
The principle obstacles to the global adoption of prior art GHP have been the high installation cost and the accompanying long energy-savings payback period. The U.S. government's Department of Energy (DOE) endorses the adoption of various geothermal energy systems and has a goal of increasing geothermal installations to only 2 million by 2005. The DOE also endorses renewable solar energy installations with a similar low target of only 1 million roofs with solar panels by 2010. However, both of these very modest goals reveal how reluctant Americans are to adopt the costly prior art clean energy saving technologies. If geothermal installation costs could be greatly reduced immediately (as with the present invention), and if the ground itself were more universally conducive to geothermal deployment (as achieved by the present invention), then geothermal energy would likely become a much more popular clean energy source far sooner than autho
Jones, Tulllar & Cooper, PC
Tapolcai William E.
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