New generator creates electricity directly from heat

Scientists from Germany and the U.S have recently developed a thermionic generator which is capable of converting heat and light into electrical energy. This new invention is said to overcome the so called ‘space-charge predicament’ that stood as a barrier with previous developments of such devices.
The newly developed generator is far more efficient (at least four times) compared to its contemporaries, and is equipped with state of the art technology, that can convert solar power and heat generated from combusting the waste materials, into electrical energy.

Working Principle

Thermionic generators are capable of generating electrical energy directly from the heat or light using the temperature difference between the two metallic plates installed inside the device, and separated by the vacuum.
When direct sunlight or induced heat (thermal conduction) turns one plate hot, the electrons tend to evaporate from the surface of the hot metal plate and settle on the surface of the other metal plate which is cold.
As a result, a charge difference or potential difference (in electrical terms) is created between the two metal plates, generating usable electricity.

The Space-Charge Predicament

Constructing generators that can convert heat into electricity is under development since early 1950’s. Over all these years, development of such devices was seriously hampered due to space-charge problem.
In general, the metallic plates used in thermionic generator are separated by 3 to 5 μm. This distance used to act as a barrier for the charge (electrons) to move from the hot plate to the cold plate effectively, making the flow of the charge very slow.



The reason behind this is, as one of the metal plates is heated, the evaporating electrons form a cloud like barrier while travelling towards the cold plate. In other words, electrons get slower as they travel longer distances, and at one stage they almost become standstill, thus forming an electron wall. More electrons coming from the heated metal plate reach this wall and get repelled. This repulsion continuous to take place till the so called electron cloud (wall) settles down on to the cold plate, which takes a lot of time to happen. Thus these devices were very ineffective.
Scientists have tried to reduce the gap between the metal plates to less than 3 μm, but found out that it is almost impossible to construct a generator with such a less space between the electrodes, and to operate high temperatures.

How Does The New Thermionic Generator Solve This Problem?

The newly invented thermionic generator is able to overcome this problem by generating an electric field between the two plates. Once the electric field is activated, the electrons released from the hot metal are forced to accelerate towards the cold metal. As they approach the cold metal, the electric field is deactivated and the electrons are slowed down to settle on the cold plate.
This is achieved by introducing a honeycomb shaped gate into the generator that has hexagonal openings in it. The electrons are driven through these openings with the help of the induced electric field. As a result, there is no electron cloud formation and there are no electron-electron repulsions. This has increased the efficiency of the new device by four times when compared to its contemporaries.

Advantages

• Since thermionic conductors can generate electricity directly from the heat, they have a great potential in practical applications. For example, if they are used in thermal power stations, thermionic generators can prove to be very powerful compared to steam turbines.


• They could also be used to generate electricity from the solar energy for household as well as industrial purposes.


• Electricity crisis in developing nations can come to an end.


• Wastage can be effectively recycled to produce valuable electricity.


• This could be the most cost-effective process of producing electricity compared to hydel and thermal electricity.

Conclusion

Hence, in the near future, when thermionic generators become even more efficient and cheap, every common household will be able to purchase one, and save money on their electricity bills.

Producing electricity using thermionic generators will also help us save valuable and scarce natural resources such as water and coal. Moreover, this will also help reduce global warming as well as green house emissions that are threatening our mother nature.