We have chronicled many patents issued from the USPTO’s Green Technology Pilot Program as part of our analysis of that program and its relevance to the links between intellectual property (IP) and sustainable development. The program offered accelerated examination of applications meeting specific criteria filed from December 2009 through mid-February 2012 for “green” inventions; it accepted 3,520 applications. Patents issued from the program are heavily weighted toward energy-related inventions, with 67% of the 2,227 patents issued through December 10, 2013 falling within our patentECO Energy Index. The next two most prevalent invention categories are Industry and Transportation, which together account for about 29% of the grants.
In our continuing review of the results of this targeted program we found patents whose provision of ‘clean tech’ seem to have questionable value, and others that are clearly leading-edge innovations in the clean tech universe, with direct application to sustainable development.
Inventor Jeffery J. Bohl of Glendale, Arizona received one of the more innovative energy patents from the program. He founded Bohl Energy, LLC in Phoenix AZ in 2011 to “design, develop and deploy technologies to help make life more comfortable, less expensive and less impactful on the world around us,” according to the company’s web page. Bohl Energy, LLC is one of the young companies to participate in the Green Tech Program.
Heat to Electricity
Bohl’s invention, US 8,581,088, is titled “Thermoelectric power generation apparatus and method,” granted November 12, 2013.
Patents are to “teach” their art — that is, they must provide sufficient information for a “person having ordinary skill in the art” (‘POSITA’) to build it. This teaching includes background information that helps you understand the prior art and the problem the inventor desires to solve. Mr. Bohl teaches:
The sun radiates electromagnetic and thermal energy against the Earth continually, lighting and heating buildings, roads, sidewalks, pools, roofs, walls, and all manner of things in the world. These objects absorb thermal energy and later release it back into the environment. Heat that is not permanently absorbed, captured, or converted is lost. Efforts have been made to capture the thermal energy released by the sun, but the results have been less than satisfactory, either because of expense, maintenance, or inefficiency. Accordingly, there is a need for an improved system and method for capturing heat and converting it into energy.
One manner in which heat can be captured is through the conversion of a thermal energy gradient into electrical power. The thermoelectric effect is the transformation of a temperature or thermal energy difference into an electrical potential. This principle relies on the tendency of charged carriers to move from hot to cold. The Seebeck effect is the specific principle that a temperature difference will generate a voltage in a conductor.
Thermoelectric devices exploit the Seebeck effect. A thermoelectric device is typically a thin electrical assembly having a hot side, an opposed cold side, semiconducting materials spaced between the hot and cold sides, and leads extending from the device at which a voltage difference is established in response to the differences in temperature between the hot and cold sides. Thermoelectric devices are non mechanical, efficient, and reliable means of producing electricity from thermal energy, and there is a great need for power generated from renewable sources such as the heat radiated from the sun.
The abstract summarizes his innovation:
A thermoelectric power generation apparatus includes a thermoelectric device having a first surface, an opposed second surface, and a first thermal energy storage unit operatively coupled to the first surface of the thermoelectric device setting the first surface at a first temperature. The thermoelectric power generation apparatus also includes a second thermal energy storage unit having a second temperature, the second thermal energy unit for setting the second surface of the thermoelectric device at an operative temperature in response to a temperature difference between the first temperature of the first surface and the second temperature of the second thermal energy storage unit. The thermoelectric device generates power in response to a temperature differential between the first temperature of the first surface and the operative temperature of the second surface.
Inventor Bohl’s thermoelectric power generator uses a series of heat storage vessels buried at increasing depths in the ground to provide temperature differences to the ‘hot’ and ‘cold’ sides of thermoelectric devices, which in turn generate direct-current electricity that is converted to standard 120-volt, 60 cycle current.
Referring to the patent drawing, the thermoelectric power generation apparatus 20 includes a housing 21 buried at ground level 27 and heat sinks 22, 23, 24, and 25 buried below housing 21 in the ground 28.
The heat sinks are thermal energy storage units or thermal masses which absorb, store, and release thermal energy to and from the surrounding environment or ground. The ground typically has a low thermal conductivity coefficient, while those of the heat sinks are much higher. Heat sink 25 is a major (large) heat sink, the others are minor heat sinks.
The heat sinks are thermally connected; the connections are controlled by an onboard computer that senses temperatures throughout the unit, performs thermal load/electricity generation calculations, and controls switching of the thermal connections between and among the heat sinks.
A lens, covered by a transparent dome, is mounted at ground-level at the top of the unit to focus light onto the top plate bearing thermoelectric devices.
A plate contained within the housing marked ‘21’ in the drawing is a thermally-conductive thermal mass with thermoelectric devices attached to its underside. Mr. Bohl prefers that the plate is constructed of a material with a relatively high coefficient of thermal conductivity, such as aluminum. This allows efficient thermal energy transfer from the plate to the thermoelectric devices.
The thermoelectric devices produce a voltage in response to a temperature difference between their upper and lower surfaces. By coupling two circuits of ten thermoelectric devices each, the unit can produce a DC maximum voltage of 480 volts at 13 amps, for a power generation of 6.24 kilowatts. This voltage is supplied to the inverter and converted into an AC output of 120 volts at 60 hertz — normal US household current.
What magnitude temperature difference is required to produce electrical energy in this device? Voltage production in thermoelectric devices is proportional to the temperature difference, and the thermoelectric devices in Bohl’s invention operate within a temperature difference range of 0.1 degrees Celsius to 65 degrees Celsius, provided the temperature of the upper and lower surfaces of the devices does not exceed 125 degrees Celsius. The preferred operating range of the unit is between 6.2 degrees Celsius to 29.2 degrees Celsius — this range generates between 225 volts and 700 volts of DC electricity.
Only the switches that connect/disconnect the heat sinks from the thermoelectric devices, managed by the onboard controller. Low maintenance, and use of ambient and impinging thermal energy — definitely positives for sustainable development.
Way Better Patents asked Jeff Bohl about the inspiration or “aha!” moment that led him to conceive of this invention. He tells the story:
I was driving home from work in July 2011, a sweltering Arizona afternoon, something above 110F and looked at the sidewalk and wondered how hot that surface temperature was. My thoughts then jumped to my days of doing marble quarry surveys and the Danby Imperial Mine back in Vermont wherein we would literally drive a quarter mile or more into the mountain where the marble is mined and remembered how the survey equipment would 'sweat' with the temperature change. Then I considered that the ambient soil temperature just a few feet below that sidewalk would be much cooler than the surface temps. So it was just a passing thought for a couple more miles but I got to another intersection and as I turned west into the setting sun, I nearly drove off the road as it hit me. I threw my hands up to both sides of my head as if to keep the idea in until I could get to a stopping spot and semi-frantically called my girlfriend, ranting that oh my god I think I have something big here. See, I had looked into thermoelectrics for another idea a few months prior and just connected the dots for this application. Pulled over at the next intersection and scribbled a few notes to myself to mark the thoughts and let them expand. It was a fun few minutes.
We also asked Mr. Bohl about his vision for uses for his device.
I think the opportunities are wide and diverse at this time. My initial vision of a high efficiency deployment was to utilize my device in commercial parking lots. They are already innately heat islands, why not get something good from it. The structural capacity to accommodate vehicle traffic has been integrated in the prototype. From there I went to individual driveways and then roadways. I think all are viable but of course each install configuration presents it’s own unique constraints and opportunities. I believe the definitive component of this system is it’s flexibility, which allows us to harvest not only ambient thermal but also waste thermal from various additional sources. The multi-source capacity will also allow expansion to more moderate climates.
One item of note where I think my system has a significant advantage over conventional PV electric is in that by the very function of the system, yields are highest in the harshest of environmental conditions as opposed to the efficiency losses inherent in photo-PV when temperatures elevate. Of course, this design could also be applied to enhance PV yield through those more extreme periods by harvesting and removing the heat buildup from the PV panels, thereby raising their efficiency by bringing them back into better thermal operating ranges.
Additionally, the capability to yield power overnight is simply beautiful and without an answer from photo PV and instantly gives me a common sense advantage when comparing to PV based systems.
No. From the beginning of 2001 through the present (i.e., the 21st century), 338 US patents include “thermoelectric” in their title, 633 in the abstract, 1138 in the claims, and 4093 in the specification. Thermoelectric technology is not new, but it is advancing and being applied in innovative ways, as this patent demonstrates.
Software — Good or Bad?
The patent does not contain language regarding the software needed to operate the controller, other than
“Controller 51 is a computer preprogrammed with the operating parameters of thermoelectric devices … controller 51 determines … Having calculated a value for selected temperature T.sub.S, controller then performs a thermal systems analysis and sends control signals to switches …”
Clearly, however, software is involved in the operation of this clean tech device. Assume for a moment that inventor Bohl also patents the control software. Would that software be considered a viable invention by critics of the US patent system that believe either no software patents should be allowed, or only some (the boundaries of which they have not clearly articulated)? If software patents are ever disallowed by action of the US Supreme Court, where will the boundaries be set? What is “good” vs “bad” software? Is software in the service of clean tech, public health and safety, transportation, or industry good, and games, social media, banking and finance bad?
The study of electricity is centuries-old. One of the early pioneers was Luigi Galvani (1737–1798), an Italian physician who discovered the electrical nature of nerve impulses through his experiments on frog muscles. He hypothesized that animal tissue contained “animal electricity”, and that the brain secretes an “electric fluid” that flows through nerves to stimulate muscle fibers. Alessandro Volta, a physicist, disagreed and conducted experiments that showed that the electricity was generated by different metals (brass and iron in this case) in contact in a moist environment.
- Galvani’s name is found in the term “galvanic.”
- Volta’s name gives us the word “volt.”
- Science is never “settled”, and there is no such thing as “scientific consensus” in medicine, physics, climatology, or any other branch of science.
- Jeff Bohl’s patent attorney is Thomas W. Galvani.