Md Saquib Maqsood

ID No: RA1412011010001

M.Tech (PED)

SRM University, Chennai

INTRODUCTION

• Present electricity generation system is not very efficient in terms of energy transfer.

• 20 to 30% energy is lost during the distribution of the electricity.

• Scientists are working on the projects to improve the ultimate electricity supply.

• Looking for alternate and efficient technologies to provide 100% electricity transfer.

• Wireless transmission of electricity is also on move.

Wireless Electricity Transmission (WET)

Takes place in any type of system in which electrical current is conveyed from a power source to an electrical load.

No usage of any type of wiring to connect the system to a source of power.

Transmits electricity with the help of microwaves. Three approaches which can be developed.

Continued…

1. Short range (Induction) o Ranges few centimetres e.g. transformer in which transfer

takes place due to mutual induction. 2. Moderate range (Adaptive Inductive Coupling) o AIC wireless power transfer technology can be used to charge

the electronic objects automatically. o Works on the principle of using coupled resonant objects for

the transference of electricity to objects without the use of any wire.

1. Power from mains to antenna. 2. Antenna resonates at a frequency of about 10MHz, producing electromagnetic waves 3. Tails’ of energy from antenna ‘tunnel’ up to 2m . 4. Electricity picked up by laptop’s antenna, which must also be resonating at 10MHz. 5. Energy not transferred to laptop re-absorbed by source antenna.

Continued…

3. Long range

o Moving electricity over a span of miles.

o Long distance wireless power is the technology of sending power to earth.

o Many new techniques but we use only two here. By using Solar Power Satellite (SPS) By using WET Technology (Without SPS)

By using Solar Power Satellite (SPS)

o Satellite converts the sunlight into energy; this energy is composed of microwaves.

o Microwave signals are transmitted to an antenna on ground/Main grid station (MGS).

o From MGS these waves are transferred to BGS (Base grid station) so called rectenna which convert microwaves into DC electricity.

Without using SPS

o Produce electricity at MGS by (hydropower, Thermal ,Wind, Solar ) and convert this electricity into microwaves by using Microwave generator.

o Transfer it to base grid station (BGS) so called RECTENNA through transmitting Antennas and from here electricity is transmitted to home wirelessly.

o There will be energy receiver box or energy router in each home.

o The information of the electricity or power required for each home will be available with the grid station.

Component detail of WET using SPS system

Microwaves Solar Power Satellites Microwave Generator Transmitting antenna Rectennas

Microwaves

• Wavelengths- 1 meter to 1 milimeter

• Frequency- 300 MHz and 300 GHz

• For wireless power transfer- high power microwaves 1-10GHz radio-waves.

• Used for point-to-point communication. • This allows nearby microwave equipment to use the same

frequencies without interfering with each other, as lower frequency radio waves do.

Solar Power Satellites

o Concept of collecting solar power in space for use on Earth. It has been in research since the early 1970s.

o Mainly consists of three segments. Solar energy collector DC to microwave converter (Microwave tube system and /semiconductor

system). Transmitting Antenna

• Tubes such as Magnetron and Klystron have been proposed for the SPS.

• The power conversion efficiency is reasonably high more than 70 % at low cost.

Microwave Generator

• Most popular type of transmitting antenna- Slotted wave guide antenna, micro strip patch antenna, and parabolic dish antenna

• The slotted waveguide antenna - high aperture efficiency

(> 95%) and high power handling capability.

• Assembled by a number of array antenna panels.

• To form a microwave beam precisely focused at the ground station, the phase of microwave from each panel needs to be adjusted between the panels.

Transmitting antenna

Rectenna

• Rectifying antenna- directly convert microwave energy into DC electricity.

• A simple rectenna element consists of a dipole antenna with a Schottky diode placed across the dipole elements.

• Schottky diode- low forward bias volt.(< 0.6V) , faster , low noise index, less power consumption.

• In laboratory environments, efficiencies of over 85% have been observed.

• The efficiency of first Rectenna in 1963 was 50% at output 4W DC.

LPF is required to suppress harmonics to improve system performance and prevent harmonics interference.

Input filter also transforms the input impedance of the antenna to the input impedance of the rectifier.

The output filter is used to effectively block the RF energy and to pass the DC power to a load or battery.

The chip capacitor is also used to maximize the diode's conversion efficiency.

Inductance tunes the capacitance reactance of the diode. Its resonance is needed to maximize the diode efficiency.

• First Ground-to-Ground MPT Experiment in 1975 in US using JPL 26m dish antenna and 3.4 m x 7.2 m rectenna located 1 mile apart from the transmitter.

• Microwave of 2.388GHz and 450 kW transmitted from klystron and the achieved rectified DC power was 30 kW DC with 82.5% rectifying efficiency.

• MINIX rocket experiment in 1983 by Japanese scientists carried out in space

• In the MINIX experiment, they used cooker type 800W-2.45GHz magnetron for microwave transmitter.

• Currently Japanese scientists are set to test the largest wireless electricity transmission ever attempted.

• The test is designed to transfer about 1200 watts of power at a range of 100 feet (could reach 300 feet)

• SPS Project is in Development in Japan • Goal is to build a low cost

demonstration model by 2025 • 8 Countries along the equator have

agreed to be the site of a rectenna.

Advantages

Remove physical infrastructure “Grids and Towers” . Cost effective (Remove cost of towers and cables). During rain and after natural disaster it is often hard to

manage cables and towers so it removes this. Microwaves (electricity) are more environments friendly. It

does not involve emission of carbon gases. Zero fuel cost.

Conclusions

More reliable than ground based solar power. Fossil fuel electric power plants generate greenhouse gases

which are responsible for global warming. WET can overcome these problems well.

In order for SPS to become a reality it several things have to happen: Government support Cheaper launch prices Involvement of the private sector