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WHAT IS A POWER CHIP ?

Introduction

"Hot" and "cold" are words we use to describe the presence (or absence) of heat. Heat is best described as energy contained within something else. So a cup of hot coffee has more energy than that same cup an hour later, after much of the heat has dissipated. The energy which makes up "heat" is the kinetic energy of the atoms. So if the atoms in the cup of coffee are moving around very fast, the coffee is "hot". When the atoms slow down, the coffee becomes "cold". And if the atoms get cold enough so that they are no longer moving around rapidly, the coffee freezes into a solid.

While the atoms in a solid tend to be relatively immobile, the electrons within them are always moving. At any temperature above absolute zero (-273° C), electrons are constantly in motion, rapidly swapping places with the electrons of surrounding atoms, especially in metals.

Depending on the temperature, electrons have higher or lower energy. The low energy electrons are 'cold', while the high energy electrons are 'hot' and move around much faster. Generating power with electrons involves supplying heat to create energetic electrons, encouraging the high-energy electrons to move in one direction, and bringing in low energy electrons to replace them in a complete circuit.

What makes Power Chips different?

There are other well-known technologies, which use electron migration to generate power. These fall under the rubric of "thermoelectrics", and have been studied since the discovery of the Peltier Effect in 1834. These technologies all use special materials and geometries to encourage high-energy electrons to migrate in one direction, creating an electric current. The biggest problem with thermoelectrics is that while electrons carry their energy in one direction, the material itself returns most of that energy through conducted heat.

Thermo-electric device
 
  Power Chip
 
Heat Source (Cathode -)  Heat Source (Cathode -)
 
Heat Sink (Anode +)  Heat Sink (Anode +)

Conventional thermo-electric devices allow conducted heat (red arrows) to spread throughout the device, greatly reducing the efficiency: most heat is transferred without driving electron current (yellow arrows)
 
By introducing a gap the path for conducted heat (red arrows) is broken, making Power Chips extremely efficient: only electrons can cross the gap and generate a current. The heat itself remains behind.

Power Chips are different because the electrons must move across a gap, which provides excellent thermal insulation. As a result, Power Chips are expected to have extremely high operating efficiencies, as much as an order of magnitude higher than thermoelectrics.

How do the electrons move across the gap?

The difficulty in getting lots of electrons to flow across a gap is that electrons do not easily leave their place to go into a new space. There are two mechanisms that can move electrons across a gap: "Tunneling" and "Thermionic Emission". Tunneling, a quantum physical effect, only works over very short distances, in the order of 1 - 10 nanometers, which is impractical for medium to high temperature devices.

Thermionic emission works best with gap widths of 1 - 3 μm which are easier to maintain. The amount of electrons capable of leaving the surface depends mainly on the temperature and the material properties of the electrode. These properties define a 'Work Function' (wf), i.e the amount of work needed to free an electron and move it off the surface so it can go somewhere else. Work function has been discussed in the scientific and engineering literature for a century, and it has daily practical significance in most fields of modern technology. Typically, most metals have a work function of 3 - 5 eV (electron volts). This would necessitate a temperature of over 1,000° C on the hot side to obtain a sizeable electric current.

Power Chips plc has developed and patented a method to reduce the work function. This method, called the Avto Effect™, allows us to change the electronic properties of a material by etching a unique surface pattern using standard nanotechnology methods. The Avto Effect is demonstrated by putting a thin film of conductive material onto an insulator and then etching a specific corrugated nanoscale pattern onto it. This pattern reduces the material's electron work function, making it easier for electrons to be evaporated from a source surface and enter an opposing surface - thereby producing an electrical current.

A reduced work function means that a material can emit electrons at lower temperatures and/or with a lower applied voltage. This means that Power Chips can be used to harvest heat from a broad range of commercial, industrial, residential and natural heat sources. Power Chips then convert this heat energy to an electric current by taking advantage of our ability to move electrons easily out of the heated side of a Power Chip and into the collector side. This will enable electricity generation using a simple, solid-state, highefficiency and non-mechanical generating system.

Technology Benefits

The Power Chips technology has many significant advantages over conventional internal combustion or turbine systems. Generators based on conventional systems are massive, complex, and require frequent maintenance. Those technologies have been around for over 100 years, and dominate the marketplace simply because there has been, as yet, no viable alternative for most applications.

From a technical perspective, Power Chips offer many advantages over existing systems. The Power Chips technology will offer the market a core technology that is light, modular, silent, highly efficient and virtually free of harmful emissions. In addition, power generation solutions based on the Power Chips technology should, in mass production, cost significantly less to manufacture than existing solutions. Compared to other thermionic devices, Power Chips will provide a new dimension of power density, efficiency and flexibility. Being robust, solid-state devices, Power Chips will be installable in physically demanding and even extreme environments - for applications that require power but presently have no practical way to generate it. Power Chips prototypes are small electronic devices similar in appearance to a computer chip. When a source of heat is applied to one side, the electric current is generated on the other as energetic electrons move across a 1-to-3 micrometer gap separating the two sides. We expect to produce currents of about 20 Amps of electrical current per squarecm of active surface area. This translates to about 10 W/cm2 power generation1.

What will Power Chips Enable?

A better question might be, what won't Power Chips enable. Enormous quantities of heat energy are being emitted and dissipated by industrial processes and modern machines at every moment. They have been for over a century. Power Chips will provide the only low-cost, flexible, high-efficiency technology to begin recovering this waste heat and convert it into valuable electricity.

As solid-state devices Power Chips will be placed in the most rugged and demanding environments, without worrying about mechanical breakdown or intensive maintenance. Eventually Power Chips will generate power by recovering human body heat and providing the electricity to any device that may need it: a cellphone charger, an emergency radio or night-vision goggles to pick a few obvious examples. From the inside of a jet engine nacelle to a combat soldier's 'Power Vest', Power Chips will stand ready to produce energy everywhere that heat flows. Power Chips technology is about to cause a paradigm shift in the ways that human beings produce, use and think about power.

In summary, the Power Chips technology has the following attractive attributes:

  • Efficiency: Power Chips can achieve in excess of 50% of Carnot (ideal) efficiency2, compared to a maximum of 36% for single stage power plants, 50-60% in conventional two stage power systems, and 5-8% for thermoelectric devices.
  • Weight: The low weight of the chips enables mobility and easy installation.
  • Size: Power Chips are extremely compact allowing for high power in a small package.
  • Simplicity: Power Chips have no moving parts, and have no current surge or lag at startup.
  • Ruggedness: As solid-state devices, Power Chips are highly resilient in mechanically and thermally demanding environments.
  • Modularity: Devices can be swapped with ease. Likewise, because larger applications will be designed to use an array of many individually replaceable Power Chips, catastrophic failure becomes far less likely than in conventional power generation systems that have a single point of failure.
  • Integration Costs: The technology design allows for a single basic unit to be applied and used in numerous different end use applications. Application of the Power Chip Technology will vary only by the operating temperature range, the number of Power Chips installed in a system, and the watts of power generation capacity of each individual chip.
  • Environmental Benefits: Power Chips can use almost any fuel source, and produce no noise or vibration. They are designed to be environmentally friendly because as an add-on recovering waste heat, no additional heat source is required to significantly increase the output of existing facilities.

1 WE expect the output voltage of each Power Chip around 0.5 Volts. At a 20 A current, the power output is 20 A * 0.5 V = 10 W for every cm2 of Power Chips.
2 THE Carnot cycle describes the most perfect heat pump allowed by physical laws. Actual efficiency will vary depending on the temperature conditions present, but the Carnot equation will always show the maximum efficiency that is theoretically achievable given those conditions.



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