My invention

Frank Scruggs Practical solar

An

SBIR White paper

Many people believe their way of life is at an end: that they cannot have their prosperity without destroying the planet. There is a way to create jobs and reduce the deleterious effects of fossil fuel usage. In the 21^st-century a couple phrases may be very important. They are Practical Solar and the Franklin Cycle. Practical Solar will be an inexpensive heating, air-conditioning, and electric generation system. To truly understand Practical Solar; one must first understand the Franklin Cycle.

The Franklin Cycle is a method of pulling energy out of thin air. Since we can’t create energy we have to convert it from another form. The Franklin Cycle converts thermal energy into electrical energy by tapping the difference in temperature of day and night, summer and winter. Creating energy from temperature fluctuations is very similar to creating money from stock market fluctuations. In the stock market, one buys stock at a low price and holds onto it to sell it for a high price. With thermal energy, engineers do the opposite. They collect heat at a high temperature, store it and radiate it to a low temperature.

A simple Franklin Cycle can be demonstrated with the use of thermocouples. If hundreds of iron and constantan wires are connected in series and one end is buried three feet in the ground, then an electrical generator is created, it could be called a Franklin Cycle thermal pile. Three feet underground the earth stays a relatively constant 50°F in Michigan. On a 70° day, each thermocouple in this thermal pile would register the 20°F difference in temperature between the buried end and the end at the surface. This would generate one half of a millivolt in each junction, generating a positive voltage. During a winter’s day of 30°F the device would create a negative voltage because now the ground would be warmer than the air.

To make a larger scale Franklin Cycle work large-scale thermal storage is needed. A way to create large-scale thermal storage was accidentally discovered when work was being done on Radio Carbon Free Foods. The RC Free Foods project required an industrial greenhouse to be air-conditioned. To cool this building a Morley water cooling tower was purchased and placed in the building; a two horse water pump from Sears was used to pump 30 gallons per minute from a hand dug well, this provided 300,000 BTU an hour of cooling, an amount equivalent to 10 home air conditioners for only $100 a month electric usage. The water was returned to the ground through a drain field under the greenhouse. After months of satisfactory operation, water from the well started to get warmer by 2° per month. By the end of the summer, the water was coming out of the well at 60°F and no longer able to adequately cool the greenhouse. After pondering how to solve this problem, the inventor had an epiphany. It seems the ground does not stay at 50° exclusively, but it will stay at whatever temperature it is placed. If the inventor wanted to cool down the well, he could spray water on the roof of the greenhouse in the winter to melt off any snow. In combination with the evaporation of the roof spray system the water returned to the drain field could be cooled to 35°F. By this method the inventor could lower the temperature of the cold storage system to below 40°F.

The inventor could build himself another well and drain field to store 70°F hot water from a roof spray in the summer. He would then have the ability store summer’s heat and winters cold. With one billion BTU available the inventors Franklin Cycle was now big enough to meet the electric needs of a house. It would be far too expensive to make a Franklin Cycle with thermocouples. The inventors first thought was to design a backward air-conditioner that used 70°F water to boil 250psi refrigerant to drive a turbine and use the 40°F water to condense the refrigerant at 190psi. His bench top experiments with this system proved it too inefficient for this application. The next thing the inventor wants to try is a high throughput Sterling engine. One wonders if the Franklin Cycle will ever be practical as a stand alone technology.

Now that you have heard the story of the Franklin Cycle, how it relates to Practical Solar will become clear. In 1979, Frank Scruggs was sales manager at a brand-new solar company called Sole-Source. Then as now, solar power was overpriced for the market. With few sales the job did not last long, but its impression on Frank did. For years, he pondered how to make less expensive solar collectors and how to break the thermal energy storage problem. This quest was thought of as the search for Practical Solar. To be called Practical Solar, it has to last more than ten years and pay itself off in less than three years. To make inexpensive and durable collectors, it’s all about the materials. Frank was introduced to Tedlar while at Sole-Source. Tedlar is that plastic that covers the screen of your new electronic devices and also covers the outside of vinyl house siding. Tedlar is ten times more transparent than glass and would make the perfect solar glazing, except it is too stretchy. Frank plans to conquer this problem by making it into bubble packaging and bonding it directly to the collector surface. To test bubble wrap as the glazing material, Frank once heated food to 140°F in a solar oven made of bubble wrap. Sealed Air Corporation makes a flat plate collector based on polypropylene. These collectors would make a good test platform for Franks Tedlar bubble wrap glassing. By adding solar collectors capable of heating water to 200°F, Frank adds wonderful new capabilities to his Franklin Cycle. The first capability would be to heat his hot well to 150°F. This provides for on-demand home heating. Any time his house needs heat, the thermostat just turns on and the well pumps hot water all winter long. The cold well provides air conditioning all summer long. When the factory on the other side of town starts its big machinery, the Power Company will be able to ask my Franklin cycle to help meet that need.

Seasonal thermal storage becomes practical when pre-existing geology is exploited with minimally invasive techniques. In the book Green Building ( Kusuda et al) many thousands of dollars are spent trucking in sand and pouring it into it concrete foundation and more is spent on insulation board creating artificial thermal storage geology. But Frank plans to take what he learned from the RC free foods project and apply it to the work of Charles F. Meyer and David K. Todd Wood. (In volume seven of the 1973 environmental science technology page 251) and without moving any soil or in laying any insulation many thousands of tones of rock and soil can be used as thermal storage by simply drilling wells. The soil surrounding that, through which hot water pa****, becomes the insulating medium.

In a time where modern technologies failed us it may be wise to remember our long forgotten technologies. Due to low sun angles short cold days and diminished thermal collector efficiencies solar space heating in the winter has been deemed impractical. To solve this problem we look to cavemen. Ancient man discovered that if he built a large fire in his cave in the morning as the family was leaving to go hunting and gathering; that his home would be bug free smoke-free rodent free and cozy warm all night long. This caveman was using in-ground thermal heat storage. 200 years ago refrigeration was achieved by the melting of ice. This ice had been harvested from the local lakes in the middle of winter and stored underground. It appears they also recognize the value of in-ground thermal storage. The current most common use for in-ground thermal storage is to protect foundations against frost heaving. Tradesmen are taught that the ground stays a constant temperature and if you dig your footings deep enough that you will reach this constant temperature and be protected from frost. This incorrect constant temperature paradigm has been carried over into the modern geothermal heat pump industry. The cavemen knew what I’m trying to reassert that the Earth stays at whatever temperature you put it. With this background one can now see that in-ground thermal storage provides a large enough heat sink or solar thermal collectors to work at the optimum throughout the year. It is now obvious that fewer collectors are needed in this type system making solar thermal space heat practical for the first time.

There are certain advantages to having your car parking lot covered with a solar awning. Like son protection and snow removal. A retiring couple covers their entire property to derive income from the property. By intentionally putting the in-ground thermal storage near the surface you can automatically melt snow and ice from sidewalks or driveways. The high throughput Sterling engine will be a wonderful spinoff for bottom cycling most existing boilers. With hot and cold wells on tap it is easy to envision on demand heating, cooling, and low delta T. electricity generation.

At the time of his writing and two my knowledge no one has stored 200 degrees water in the ground in this manner and there are a few things we do not know for sure. We can predict most of the thermal dynamics with high degree of certainty the effects of water migration bacteria growth and plant root kill are not as well known. As a first phase SBIR project Frank plans on demonstrating injection and retrieval of one million BTU of thermal energy from subterranean pre-existing geology. Detect and arrest through site subservice water migration. Observed thermodynamic losses and compare them to the computer predicted losses. Success in this endeavor will be teased by the accuracy of compliance with computer predictions.

system. In his first attempt he assumed a constant three-foot thermal insulation layer with R36 and a constant ∆t of 150°F but these first heat loss numbers were nonsense Frank discovered that the thermal insulation layer grew everyday and the local ∆t shrank everyday. This problem would have to be solved cubic foot by cubic foot and day by day

This chart is a main part of the argument for long term in-ground thermal storage. How Frank came up with this chart will require some explanation. To simplify the calculations frank only calculated one half of the thermal storage area starting from the center to the right most extreme. To give the model three-dimensional depth he treated each linear foot to the right as the radius of the sphere. For this he used the formula ¾ πr^3. Frank would calculate each new sphere volume to the right and subtract the one he previously calculated; this would yield the volume of the sphere shall equal to 1 ft. thick and the radius is the distance from the center of the heat storage area. Using this volume Frank multiplied by the specific heat capacity of 10% sand and water mixture of 42.25 BTU/FT^3 F° (given by C&P Handbook D-47) He now has the heat quantity of each sphere at any given temperature. Frank now calculates the heat transfer though each sphere for each day Using the formula Q = u ∙ a ∙∆t (given by C&P Handbook pD98) where Q is the daily heat loss, u is the thermal conductivity of sand (THERMAL COMDUCITIVY p14), a is the surface aria between the two sphere shells in question, and ∆t is the temperature difference between two adjacent shells sphere and the next. The first day had a heat loss of 1,862,400 BTU this was rather a shocking, at this rate of all the heat storage would be gone in six months. This shocking condition did not last long however by the end of the eighth day the heat lost dropped below one million BTU a day. Now that Frank was satisfied that his calculations probably reflected reality he wrote a program on Excel spreadsheet incorporating all the aforementioned formulas plus a few additional transferring heat in now using water. To show the results of this program that he named Q. Sim Frank had the program printout, to a separate sheet, the results in 50 day blocks showing each spherical layers temperature by color. Red is above 150°F yellow is 90°F to 150°F clear is 60°F to 90°F and blue is all rings below 60F°. That is what is illustrated in fig 3 by the 12 vertical colored stripes. Of particular interest is the growing white section this is the thermal insulation band.

If we observe short-term compliance with the computer simulation then we will feel confident that our longer-term projections may also be correct. There are many key features that make this technology affordable and practical. Depending on the depth of the Wells this could completely eliminate thermal losses to the surface. Using high-tech polymers our advanced models will be much less expensive to produce, with grater efficiency and achieve long-term durability. I do expect to break a three-year payback barrier with the early production models. Some specialty components will have to be developed such as a high temperature will pump. These techniques are all well within the current state-of-the-art for component design.

Research on the Franklin Cycle, Practical Solar, and a high throughput Sterling engine; precisely match the mandate Congress gave the Department of Energy. The DOE is charged with funding promising innovative ideas, the creation of jobs, and stabilizing our future energy prospects. I call for a study of in-ground heat storage subservice water migration and low delta T. electric energy generation grant solicitations.

WORKES CITED

Guanapo Sharp Sand, India, January 2005 (author unknown).

Handbook of Chemistry and Physics, 62^nd Edition, CRC Press, Inc., Florida: 1981.

Kusuda, E, Greenbuilding, Wisconsin: USA, 2006.

Meyers, Charles F. and David Todd, Environmental Science and Technology, Volume Seven, New York: 1973, Page 512.

US Patent 3931851, Liquid Aquifer Energy Storage Method, Patent Issued January 13, 1976.