US20100154216A1 - Methods of Modifying Surface Coverings to Embed Conduits Therein - Google Patents

Abstract

Methods of modifying surface coverings to embed conduits therein to collect solar heat energy including grinding away a portion of the surface covering, installing a network of conduits in the recess and filling the recess to cover the conduits with a material capable of transferring heat from solar radiation to the conduits and a method for modifying a surface covering to embed conduits therein to collect solar heat energy including softening the surface covering, forming a channel in the softened surface covering, pressing a conduit into the channel and filling the channel with thermal conductive material to cover the conduit.

Description

CROSS-REFERENCE TO RELATED PATENT APPLICATION
• This application claims priority from prior provisional patent application Ser. No. 61/138,143 filed Dec. 17, 2008, the entire disclosure of which is incorporated herein by reference.
BACKGROUND OF THE INVENTION
• 1. Field of the Invention
• The present invention pertains to obtaining and using power/energy from man-made structures including manufactured (paved) surfaces and, more particularly, modifying pre-existing surface coverings to create power/energy in the form of heat obtained from solar radiation for use in the operation of energy conversion equipment, such as chillers, hot water supplies, heat pumps, organic Rankine cycle engines for mechanically generating electricity, water purification and distillation for buildings and/or other facilities.
• 2. Brief Discussion of the Related Art
• Surfaces and structures are heated by solar radiation during the course of a typical sunny day. A typical asphalt or concrete surface has good heat-absorbing properties, and the heat energy from such structures is normally wasted and not utilized to its potential. Greater use of solar energy is an environmental friendly way of meeting increasing energy needs. In recent years, it has become increasingly evident that fossil fuels used to generate energy are finite and that their use is harmful to the environment. Large paved surfaces increase surface temperatures. The National Oceanic and Atmospheric Administration's National Geophysical Data Center relative to highways, streets, buildings, parking lots and other solid structures, notes that the total paved surface area of the 48 contiguous states of the United States of America and the District of Columbia is approximately 43,480 square miles (112,610 km²). This same study further describes that 1.05% of the United States of America land area is constructed, impervious surface (83,337 km²) and 0.43% of the world's land surface (579,703 km²) is constructed, impervious surface. China has more impervious surface area than any other country (87,182 km²) but has only 67 m²of impervious surface area per person, compared to 297 m²per person in the United States of America. Asphalt, concrete, bituminous roofs and other hard-paved surfaces absorb heat making it unpleasant to walk on a sidewalk in hot weather and increasing the strain on the air conditioning systems of buildings. Since hot air rises, the hot air traps airborne pollutants, such as auto exhaust, close to the ground adding to complications for pedestrians. The Portland Cement Association estimates that the “heat island effect” of concentrated areas of paved surfaces impervious to water increases the temperature of the paved areas by average of three to eight degrees. The most extreme increases take place in heavily paved areas, areas without shade, and areas paved with materials that don't reflect substantial light, such as asphalt. The heat island effect occurs in both small-town and urban commercial areas.
• The organic Rankine cycle engine uses an organic, high molecular mass fluid with a liquid-vapor phase change, or boiling point, occurring at a lower temperature than the water-steam phase change. Accordingly, Rankine cycle heat recovery can be obtained from lower temperature sources such as industrial waste heat, geothermal heat, solar ponds and the like. Typically, the lower temperature heat is converted into useful work that can itself be converted into electricity.
• Waste heat recovery is the most important development field for the organic Rankine cycle engine, as well as for absorption/adsorption chillers. Waste heat can be applied to heat and power plants (for example a small scale cogeneration plant for a domestic water heater) and also can be applied to industrial and farming processes such as organic products fermentation, hot exhausts from ovens or furnaces, flue gas condensation, exhaust gases from vehicles, inter-cooling of a compressor, and condenser of a power cycle.
• As identified by the United States Environmental Protection Agency, developing urban areas modify their landscape. For example, solid and impermeable buildings, roads, and other infrastructure replace permeable and moist fields and vegetation. These changes cause urban regions to become warmer than their rural surroundings, forming an “island” of higher temperatures in the landscape. These heat islands occur on the surface and in the atmosphere. On a hot, sunny summer day, the sun can heat dry, exposed urban surfaces, such as roofs and pavement, to temperatures 50-90° F. (27-50° C.) hotter than the ambient air, while shaded or moist surfaces—often in more rural surroundings—remain closely aligned to ambient temperatures. Surface urban heat islands are typically present day and night, but tend to be strongest during the day when the sun is shining. The EPA states that these elevated temperatures from urban heat islands, particularly during the summer, can affect a community's environment and quality of life; the majority negative. These impacts include:
• (1) Increased energy demand for cooling. Research shows that electricity demand for cooling increases 1.5-2.0% for every 1° F. (0.6° C.) increase in air temperature, starting from 68 to 77° F. (20 to 25° C.), suggesting that 5-10% of community-wide demand for electricity is used to compensate for the heat island effect. Peak electricity demand, instigated by the urban heat island, inevitably occurs on hot summer weekday afternoons when offices and homes are running cooling systems, lights, and appliances. The resulting demand for cooling can overload systems and require a utility to institute controlled, rolling brownouts or blackouts to avoid power outages.
  (2) Elevated Emissions of Air Pollutants and Greenhouse Gases. Increasing energy demand generally results in greater emissions of air pollutants and greenhouse gas emissions from power plants. Higher air temperatures also promote the formation of ground-level ozone.
  (3) Compromised Human Health and Comfort. Increased daytime temperatures, reduced nighttime cooling, and higher air pollution levels associated with urban heat islands can affect human health by contributing to respiratory difficulties, heat exhaustion, non-fatal heat stroke, and heat-related mortality. Excessive heat events, or abrupt and dramatic temperature increases, are particularly dangerous and can result in above-average rates of mortality. The Centers for Disease Control and Prevention estimates that from 1979-2003, excessive heat exposure contributed to more than 8,000 premature deaths in the United States. This figure exceeds the number of mortalities resulting from hurricanes, lightning, tornadoes, floods, and earthquakes combined.
  (4) Impaired Water Quality. High pavement and rooftop surface temperatures can heat storm-water runoff. Tests have shown that pavements that are 100° F. (38° C.) can elevate initial rainwater temperature from roughly 70° F. (21° C.) to over 95° F. (35° C.). This heated storm-water generally becomes runoff, which drains into storm sewers and raises water temperatures as it is released into streams, rivers, ponds, and lakes. Water temperature affects all aspects of aquatic life, especially the metabolism and reproduction of many aquatic species. Rapid temperature changes in aquatic ecosystems resulting from warm storm-water runoff can be particularly stressful, even fatal, to aquatic life.
• There are four current strategies to mitigate the urban heat island effect:
• (1) Increasing tree and vegetative cover over the general landscape;
• (2) Creating rooftop gardens;
• (3) Installing reflective roofs; and
• (4) Employing cool pavement technologies (aggregate make-up).
• Heat island mitigation is part of a community's energy, air quality, water, or sustainability effort. These activities may range from voluntary initiatives to policy actions, such as requiring cool roofs via building codes. Most mitigation activities have multiple benefits, including cleaner air, improved human health and comfort, reduced energy costs and lower greenhouse gas emissions.
• As an alternative to powering vehicles using the internal combustion engine, designers have experimented with batteries, fuel cells, and solar panels. These experiments have been motivated, in large part, by a concern that gases emitted by internal combustion engines could harm humans by adversely affecting their environment. Motivated by these concerns, lawmakers have passed laws governing vehicle emissions. Accordingly, there is an ongoing need for sources of power that can supplement or replace the internal combustion engine as a source of power for vehicles. For similar reasons, there is a need for alternative stationary sources of power that reduce harmful environmental effects associated with the combustion of fossil fuels.
• With a growing concern over global climate change, scientists, lawmakers, and entrepreneurs are all seeking solutions. At the forefront of this debate are new sources of power. These could provide an alternative to fossil fuels, which release harmful greenhouse gases.
• Similarly, in addition to clean energy sources, it is important not to overlook methods to reduce the effects of global warming. Paving over vegetation allows more heat to be absorbed by the Earth's surface, and later reradiated into the atmosphere. This is particularly true in areas with heavy populations, roads and travel, where the necessity for paving is largest. This gives way to the Urban Heat Island effect, which has increased the needs of air conditioning in cities like Los Angles by over 40% during the summer months.
SUMMARY OF THE INVENTION
• Systems utilizing modified surface coverings formed in accordance with the present invention use the heat absorbed by surfaces from incident solar radiation to produce energy in various forms. The systems can use embedded thermally conductive materials or fluid carrying pipes/conduits in pavement as a structure to transfer heat for multiple uses. A heated fluid will first be moved to a heat exchanger. The heat produced can be used for hot water for hotels, laundromats, car washes, pre-heating of boilers, or chemical/industrial processes to name a few. The systems can also produce electrical power through a low temperature generator such as one powered by an organic Rankine cycle engine. Heat from the systems can drive an absorptive or adsorptive chiller to produce an air conditioning or cooling system. The systems can be used in conjunction with or in series with another source, such as a Concentrated Solar Power system, to produce higher temperatures for more efficient power generation. Designs to improve efficiencies of the system include the use of thermally conductive roadway aggregates, low emissivity coatings, and use of guardrails, bridges and other thermally conductive structures as a heat source or heat transfer method. The system heat source can be used for pasteurization, distillation and the like therefore permitting use for water purification.
• The system can use the aggregate itself as the conductive material instead of another thermally conductive material that would not normally be part of the HMA (hot mix asphalt). If thermally conductive materials are not available locally, they can be purchased and transported from non-local sources. A conductive layer can be put down within the surface to reduce the costs of what may be a more expensive aggregate material. This serves to increase the heat travel to essential regions for practical conversion. The heat collected from such systems can be used to run a thermal cycle engine (e.g., an organic Rankine cycle engine), a heat pump, or a chiller. The heat energy is used to heat a fluid such as water or refrigerant that is used in such equipment. This provides a means of converting raw heat into more tangible or useful applications. A network of pipes/conduits can lead from the source (manufactured surface covering, such as a paved surface or structure) to the drain (energy conversion unit or heat exchanger). The pipes/conduits can be installed in a number of ways and can be made of various materials and geometries. Regardless of how they are installed, the commonality is the intention of removing heat from the pipes/conduits. The system can be used in conjunction with other energy sources, namely geothermal, photovoltaic, and biofuel. Additional uses include the use of these systems as a means to purify, decontaminate, desalinate, and clean water. Heat can be derived from buildings and roadway structures.
• A low temperature source such as geothermal, flat plate or paved surface, (roadway power system) can have its temperatures bolstered by a supplementary heating source. This source could be solar driven, e.g. concentrated solar power (CSP), parabolic, dish or a combustion engine, using gas, oil, or another incendiary source. These elevated temperatures allow use for agriculture, water purification and desalinization, biofuels, hydrogen generation and increased efficiencies with existing methods of energy conversion.
• When using the system to generate electricity, it will relieve part of the dependency on ‘dirty’ power by bringing a new source of ‘green’ electricity generation. It will also help reduce loads on the electrical transmission systems since it will act as distributed generation on-site.
• One aspect of the present invention is to provide a method for modifying or retrofitting an existing surface covering to embed conduits therein providing a heat recovery structure.
• In another aspect, the method of the present invention permits modification or retrofitting of a man-made covering on the earth's surface to have fluid carrying conduits embedded therein with a purpose of delivering solar heated fluid to an energy conversion device. The covering can be any existing surface such as a paved surface, a roadway, a road shoulder, a parking lot, a sidewalk, a path, a track, a racetrack, a sports field, a roadway divider, a railroad track, a patio, a roof, shingle or siding for buildings, tarmac, and the like.
• In another aspect, the present invention permits the use of existing structures and surface coverings for collection by modifying or retrofitting such structures and surface coverings, particularly pavement and synthetic turf by embedding a conduit network therein to collect solar heat energy.
• A method according to the present invention for modifying a surface covering to embed conduits therein to collect solar heat energy includes the steps of grinding away a portion of the surface covering to form a recess therein, installing a network of conduits for carrying heated fluid in the recess and filling the recess to cover the conduits with a material capable of transferring heat from solar radiation to the conduits to heat the fluids.
• The present invention also relates to a method for modifying a surface covering to embed conduits therein to collect solar heat energy including the steps of softening the surface covering, forming a channel in the softened surface covering, passing a conduit into the channel and filling the channel with thermal conductive material to cover the conduit.
• Various aspects, advantages and benefits of the present invention will become apparent from the following description taken in conjunction with the drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
• FIG. 1 is a perspective view of a surface covering, with parts cut away, with a network of conduits disposed in the recess in accordance with the present invention.
• FIG. 2 is a schematic representation of a device for removing a top layer of a surface covering by grinding.
• FIG. 3 is a schematic drawing of a piece of equipment for heating a surface covering forming a channel in the surface covering, passing a conduit into the channel and filling the channel to cover the conduit.
• FIG. 4 is a schematic representation of the shape of wheels for pressing the conduit into the channel.
• FIGS. 5 and 6 are sectional views of surface coverings after modification or retrofitting in accordance with the method of the present invention.
• FIG. 7 is a schematic drawing showing conduits being placed in channels formed in a surface covering in accordance with the present invention.
• FIG. 8 is a sectional schematic drawing of conduits placed in channels in a surface covering with a top layer covering the conduits and the high conductive layer at which the conduits are placed.
• FIGS. 9 and 10 are schematic drawings of a surface covering having channels formed in the underside thereof with conduits placed in the channels.
• FIG. 11 is a schematic drawing showing conduits embedded in a surface covering after modifying or retrofitting of the surface covering.
• FIG. 12 is a schematic drawing showing a guardrail with a base thermally coupled with a roadway.
• FIG. 12A is a sectional schematic drawing of a guardrail having a thermal insulated outer coating to retain heat.
• FIGS. 13,14 and15 are schematic/block diagrams of a system utilizing a surface covering retrofitted or modified in accordance with the present invention.
DETAILED DESCRIPTION OF THE INVENTION
• FIG. 1 is a schematic drawing of a retrofitted/modified surface covering for use of solar heat energy formed in accordance with the present invention. The surface covering has a top layer2 and alower layer4 and in order to form the surface covering, the top layer and middle layer are ground away such that a network ofconduits50 can be installed in the recess formed by grinding. The network ofconduits50 carry fluid to be heated and the network is installed in, on, under or in contact with all or a portion of the surface covering, preferably in the layer4 (or14 as shown inFIGS. 5 and 6) which are high thermal conductivity layers.
• The method of modifying an existing surface covering to embed conduits therein to collect solar heat is shown inFIG. 2 where an existing surface covering7 is removed with agrinder6 which can be part of a piece of equipment, such as equipment moved by avehicle5. The equipment can be driven by an operator or could be a hand-driven piece of equipment. Thegrinder6 removes a portion of the existing surface covering7 or the entire surface covering can be removed thereby forming a recess shown by the curved lines inFIG. 2 and the cut away portion inFIG. 1. Once the surface covering has been ground away, thenetwork50 of fluid carrying conduits can be installed in the recess and part of a resurfacing operation for the surface covering.
• As shown inFIG. 3, a method for modifying a surface covering includes the step of softening the existing surface covering, for example by use of aheater8, forming a channel in the softened surface covering, for example by use of awheel9, pressing aconduit11 into the channel, for example with use of awheel13 having shaped peripheries as shown inFIG. 4 which illustrate U-shaped and V-shaped wheel peripheries and filling the channel with thermal conductive material to cover the conduit, for example by means of arotating spreader15. The filler can be obtained from the surface covering or can be another thermal conductive layer of material.
• As shown inFIG. 5, the resulting structure includesfluid carrying conduits11 embedded in the surface covering. The fluid carrying conduits can be embedded at different lengths within the covering with varying spacing, and the fluid carrying conduits can be formed as a single loop, for example running down the side of a driveway road or sidewalk or multiple loops covering the entire area of a surface. The fluid carrying conduits are referenced as “heat exchanger pipes” in the drawings and are shown disposed in a highthermal conductivity layer14. An example of a high thermal conductivity layer is an asphalt binder with high thermal conductivity aggregate therein increasing the efficiency of the surface covering in capturing heat from incident solar radiation on the covering. The high thermal conductive layer can be at any depth within the covering so as to be in the top low thermalconductive layer16 and the bottom low thermalconductive layer18. The high thermal conductive aggregate can be created by additives such as metal particles, wire, rods, rebar, conductive films or tapes as well as conductive aggregate (rock) materials such as in the class of quartzite and sandstone.
• As shown inFIG. 6, the surface covering can have a top visible transmitting and infrared/heat blocking layer on a low thermal conductive layer and thefluid carrying conduits11 can be disposed between layers ofasphalt16 and18 constituting low thermal conductive layers. The surface covering can be created with a visible wavelength light transmitting and infrared heat blocking top layer with embedded fluid carrying conduits but with no conductive layer and no lower heat insulating layer. Alternatively, the surface covering can be made with no visible wavelength light transmitting, infrared heat blocking top layer but with a thermal conductive layer and lower heat insulating layer. The purpose of the arrangement of the layers is to increase the efficiency of the system by allowing an increased percentage of heat energy to be captured by fluid in the conduits from the incident solar radiation on the surface covering. The top layer creates the “greenhouse effect” within the surface covering to allow light from the sun to enter the surface covering while trapping heat therein whereby more heat can be transferred to the fluid in theconduits11 to drive a more efficient system. The top layer can be of a material type such as glass, ceramic, rock type materials, film, tape, a spray-on layer and liquid that hardens, for example.
• FIG. 7 shows conduits28 (11 inFIGS. 3-6) laid inchannels30 in a surface covering. Once the conduits are installed, the conduits can be left as is covered with another layer or the channels can be filled with a solid, liquid or malleable material that subsequently hardens. The fill material can be a high thermal conductivity material.
• FIG. 8 showsconduits28 inchannels30 in a surface covering where the surface covering has a top layer of covering with an optionalmiddle layer14 of higher thermal conductivity materials.
• FIG. 9 shows positioning of the channels on the underside of a surface of thechannels30 on the underside of a surface covering with conduits in the channels. This arrangement is particularly useful for roofing materials, such as shingles.
• FIG. 10 showsconduits28 inchannels30 on the underside of a surface covering in the form of amat32 that can absorb solar radiation but could also absorb heat from a surface supporting the mat. Sloped edges of the mat allow it to be used in an area where pedestrians or vehicles might pass such as on a roadway or parking lot. The ability to perform a mat can provide cost savings over more permanent installed systems.
• FIG. 11 showsconduits28 embedded in surface covering32 where the mat could be formed by extrusion with channels and separate conduits. The ability of mats and conduits to interlock in a leak-free seal increases flexibility in system design. The bottom surface of the mat can be either a thermal conductor to take heat from the surface supporting the mat or a thermal insulator to prevent heat from escaping to the surface below.
• FIG. 12 shows aroadside guardrail36 having a base34 extending into the surface covering or roadway for better thermal contact with the surface covering. Fluid carrying conduits can also be embedded or formed in the guardrail to increase heat transfer. The guardrail is normally formed of a metal-based thermal conductor and can be used to capture and transport solar generated heat either with the fluid carrying conduits or without the conduits. The concept of utilizing roadside heat collectors can be extended to other common roadway structures such as dividers, Jersey walls and the like.
• FIG. 12bshows theguardrail36 being surrounded with a thermal insulated outer layer to retain heat. Other roadway metal structures can be similarly insulated to assist in the capture and transport of solar thermal energy for example, bridges, overpasses, pipes and railroad tracks.
• FIGS. 13,14 and15 show systems for operating energy conversion equipment, utilizing the heat and energy produced by surface coverings modified or retrofitted in accordance with the present invention. InFIG. 13, heat from conduits in a surface coating is supplemented by a concentrated solar power system (CSP) and can also be used to store the CSP heated fluids at night to maintain higher temperatures. The system is shown operating asteam cycle turbine26. InFIG. 14, fluid carried by conduits in a surface covering20 obtained from solar radiation incident on the covering is supplied via aheat exchanger24 to anauxiliary heater32 to raise the temperature before supplied to an energy conversion device (ECD) to convert the heat into a useful form of energy. The use of heat exchangers permits multiple circulating fluid loops to control temperatures, pressures and flow rates, and separate fluid storage tanks can be maintained. An optionalcold source44 can create a higher temperature differential for the ECD.FIG. 15 shows use of heat from solar radiation on a surface covering20 with aheat exchanger24 andauxiliary heater32 as shown inFIG. 14 for operating energy conversion devices including hot water supply, chiller, heat pump, ORC (organic Rankine cycle), water purification and/or distillation units. Additionally,conduits30 can communicate with the surface covering20 to supply a fluid with increased heat through the surface covering for melting of precipitation such as snow or ice. For this use,separate conduits30 can be used or the conduits from the main system can be run with the flow reversed. Multiple auxiliary heaters, such assolar concentrators28, can also be used in the system.
• As described above, high heat conductive aggregate in an asphalt binder improves the heat transfer in a pavement or structure and, thus, using more conductive rocks, aggregate, can improve heat transfer in the system. Use of thermally conductive additives to a pavement or hot asphalt mix (HMA) could have a negative impact on binding and structure. In addition, the high cost of certain metal-type additives could make them prohibitive as a conductive additive. Accordingly, the use of aggregate itself as the conductive material instead of another thermally conductive material that would not normally be part of the HMA or pavement is desirable.
• As explained above, the surface covering has a high thermal conductive layer disposed within the surface between low thermal conductive layers and can reduce the cost of what may be a more expensive aggregate material. This layer will also make it possible to increase efficiency as the asphalt will conduct more heat through the layer and less energy will tend to be conducted inwards where it cannot be used.
• The heat source from the surface covering can be used in conjunction with a system to produce cooling or air conditioning. Specifically the low temperature heat source can be attached to an adsorptive chiller, absorptive chiller, heat pump or other systems that use a refrigerant, desiccant, or the like via a heat exchanger. A chilling system that uses expanding gases to create a cooling effect can be fueled by heat. These systems, including adsorptive and absorptive chillers, are designed specifically to make use of low temperature heat sources and are often used for large scale cooling requirements. The heat that can be generated from paved surfaces, buildings and rooftops, with average temperatures of 120-150 F are perfectly matched for these chiller systems. The heat is used to heat a fluid such as water or refrigerant that is used in such systems.
• Flexible pipes (conduits) can be used for collection of heat from construction fixtures and buildings. Use of modern flexible piping materials allows lower cost of installation and more durable systems. The pipe/conduit itself is used for heat transfer. The pipes are extruded in geometries favorable to heat transfer with the outside media. Pipes extruded in different geometries such as with fins, oval, stars and the like promote better surface area and contact with the media. Having a pipe cross section with more surface area towards the horizontal plane will promote heat transfer since the top and bottom of the pavement are cooler than the center. That is, where an oval pipe cross section is used, the longer leg is preferably disposed vertically.
• An alternate method to embedding the pipe prior to paving is to install the pipes in pavement prior to hardening of the pavement. Then the pipes are left exposed or are covered with an additional material. That is, the pipe gets pressed into the asphalt when it is still not hardened. This can be on a top layer or a middle layer. An asphalt roadway machine can be designed to press the hose into the still soft asphalt.
• A grinding/milling machine can be used to mill a pipe channel into a surface to create channels or grooves wherein the pipe can be laid. The pipe is pressed into the channel, left exposed or covered with an additional roadway layer, as required. This arrangement is particularly effective in low energy demand projects, like home heating and cooling and/or pool heating.
• Solar thermal energy can be harvested without embedding pipes below the surface. Materials are produced with internal pipes or channels to create a similar result. One design resembles a rubber speed bump with embedded grooves for the tubes, or a closed bladder, holding fluid above the surface, facilitating the easy placement and removal of the heating technology. Similar designs with internal fluid carrying channels can be used in roofing materials (shingles), siding materials, and surfacing materials such as driveway or patio bricks or in surface composites (e.g. Trex, or Timberteck). Thermally conductive materials, low emissivity coatings and interlocking channels are design features dependent upon use conditions. In the simpler version, the fluid carrying channels are not within the materials, but grooves or channels are manufactured into the front or underside of the surface. Then a flexible hose or pipe is pressed into the channel. An advantage of this design is to limit the number of connections between panels, thus lowering the chance of a leak.
• The system can collect heat from structures and buildings. The heat conductive materials used in municipal and traffic structures as well as buildings provide a source to capture, store and transport heat energy. Existing heat-conductive structures in bridges, overpasses, guardrails, railroad tracks, and the like, can be used to collect and transport heat. The structures themselves gain heat from incident radiation and they also act as a heat exchanger to pull heat from the paved surfaces and structures they are in contact with. Because of the thermal conductivity of these metal based structures, heat can be transported. A fluid based heat exchanger can be placed along the back of a guardrail or at periodic intervals. These structures include, but are not limited to, metal guardrails, metal utility poles, road signs, bridges, overpasses, and railroad tracks. A design to promote heat exchange between the surfaces and the metal structures and to enhance thermal transfer can include elongated footings added to guardrails to extend further into the roadway material. They provide additional contact area with the adjacent paved surface which will promote heat transfer. In another design, the structures are thermally insulated to hold the heat within and allow it to transport within the body to the heat exchanger. In the design using a metal guardrail, elongated fins or feet can extract heat from the paved surface while the plastic or rubber coated guardrail transports the heat within its metal structure to a heat exchanger.
• The fluid carrying conduit of the system can be designed in a closed loop, where a heat exchanger is used to extract the heat. The heat exchanger is used to transfer heat from the fluid to a second fluid for use in various systems, i.e., to have two independent fluid loops so that the fluid that is used to collect the heat is kept separate from the working fluid used in the target system. Alternatively, the heat exchanger could be a radiator or similar structure to heat buildings (e.g., homes, hotels/motels, office buildings, etc.)
• A heat exchanger between systems has several advantages including, but not limited to, fluids made up of different materials and are managed for different contaminants to add a longer life to the systems and allow for easier maintenance.
• The heating source described herein can be used to produce, or assist in producing, clean or fresh water (desalination) and to reclaim and recycle wastewater. Certain purification processes are achieved from low temperature heating of the water. Low grade waters are used for irrigation systems for crops and the like. Pasteurization temperatures of 70° C. are achieved by the system. Clean water is becoming a scarce resource in some regions of the country and world. These systems will be used by governments or private property owners. In the Pacific southwest of the US, there are already shortages and rationing. Fighting for the limited sources between agriculture, towns and cities is underway. Meanwhile, this is still one of the fastest growing areas for population and construction of commercial and residential properties. Farms, lawns, golf courses and the like all have requirements for water. There are differences in water quality: potable, drinkable, for lawns, ponds, other uses. Further, desalination as a technology is important in areas of the world where fresh water is in short supply. The present heat source can be used for water purification and desalinization in membrane based purification systems. The higher temperature water contains atoms/molecules in an excited state which allows for easier separation of the undesirable elements at the membrane filter. Easier separation results in lower energy costs to push the fluid through the membrane. A further benefit is to keep the filters cleaner, preventing clogging, which allow a longer membrane filter life, lower energy costs and lower (less frequent) replacement costs.
• Inasmuch as the present invention is subject to many variations, modifications and changes in detail, it is intended that all subject matter discussed above or shown in the accompanying drawings be interpreted as illustrative only and not be taken in a limiting sense.

Claims (6)

1. A method for modifying a surface covering to embed conduits therein to collect solar heat energy comprising the steps of

grinding away a portion of the surface covering to form a recess therein;

installing a network of conduits for carrying heated fluid in the recess; and

filling the recess to cover the conduits with a material capable of transferring heat from solar radiation to the conduits to heat the fluid.

2. The method for modifying a surface covering to embed conduits as recited inclaim 1 wherein the surface covering is pavement and said filling step includes filling the recess with ground pavement.

3. A method for modifying a surface covering to embed conduits therein to collect solar heat energy comprising the steps of

forming a channel in the softened surface covering;

pressing a conduit into the channel; and

filling the channel with thermal conductive material to cover the conduit.

4. The method for modifying a surface covering to embed conduits as recited inclaim 3 wherein the thermal conductive material is obtained from the surface covering.

5. The method for modifying a surface covering to embed conduits therein as recited inclaim 4 wherein said softening step includes heating the surface covering.

6. The method for modifying a surface covering to embed conduits therein as recited inclaim 5 wherein said softening step, said step of forming a channel, said pressing step and said filling step are all accomplished by a piece of equipment moved along the surface.

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