Engineer's transistor can play crucial role in fighting climate change

What do fluorescent lamps, air-conditioning units and portable defibrillators have in common?

They were all made possible through the use of a little-known device called an insulated-gate bipolar transistor (IGBT) semiconductor.

Invented in 1979 by Professor B. Jayant Baliga, an electrical engineer in India, IGBTs are commonly used as switching devices to convert direct current (DC) to alternating current (AC), and also to drive motors of various sizes.

Prof Baliga will speak for the first time at this year's Global Young Scientists Summit, a gathering in Singapore of young scientists and researchers from all over the world.

The summit will take place virtually from today to Friday, and is organised by the National Research Foundation, a department within the Prime Minister's Office.

Speaking to The Straits Times, Prof Baliga said: "Young scientists of this day are more entrepreneurial than when I was at their age as they have more opportunities for starting companies now compared with the 1980s."

But he also called on young scientists to be passionate about their ideas and "to pursue them with benefits to humanity in mind rather than purely for personal financial gain".

Prof Baliga was working for American manufacturer General Electric to help create a variable-frequency motor which could operate at different speeds in order to be more energy-efficient.

The IGBT was conceived in the process, by combining the features of two other existing devices: metal-oxide-semiconductor field-effect transistors and bipolar power transistors.

In turn, IGBTs have paved the way for many other devices, which have helped save more than 100,000 terawatt-hours (TWh) of electricity over the past 30 years, said Prof Baliga.

For comparison, Singapore consumed about 50TWh of electricity in 2020.

Prof Baliga said: "One-fifth of electricity is used for lighting. Over 20 billion fluorescent lamps are now in use around the world.

"Each lamp saves 75 per cent of electricity usage compared with traditional incandescent lamps and has a relatively long life of over 10 years."

The semiconductor can also be found in the adjustable speed drives of air-conditioning units.

The adjustable drives were first introduced in the early 1980s, according to Prof Baliga, and are 40 per cent more efficient than the previous motors used.

Prof Baliga noted that IGBTs would be integral in the fight against climate change.

By his estimates, his invention has amassed nearly 50 billion tonnes of carbon savings just by making more products energy-efficient.

He said: "The IGBT is an essential component in all renewable energy generation systems.

"It is used in the inverters for conversion of the DC power produced by all installed solar panels and for conversion of the variablefrequency AC power produced by wind turbines to the well-regulated AC power delivered to homes and factories."

Prof Baliga added that inverters are also used for all other forms of renewable energy such as tidal power, wave power and hydroelectric power.

Electric and hybrid cars similarly use the semiconductor to convert the power from their electric batteries from DC to AC.

For his work, Prof Baliga won numerous awards, including the Institute of Electrical and Electronics Engineers' Medal of Honour in 2014, the highest accolade given out by the institute in the United States.