Monthly Archives: March 2018

JNCASR’s novel material to convert waste heat into electricity

Records, All, Science & Technology
Ongoing effort : We are now trying to increase the efficiency, says Kanishka Biswas (left) .
Ongoing effort : We are now trying to increase the efficiency, says Kanishka Biswas (left) .

With nearly 65% of utilized energy wasted, the focus is on materials to mitigate this

A novel compound that exhibits poor thermal conductivity in the 25-425 degree C range but shows good electrical conductivity has been developed by a team of researchers led by Dr Kanishka Biswas from Bengaluru’s Jawaharlal Nehru Centre for Advanced Scientific Research (JNCASR). The compound, silver copper telluride (AgCuTe), shows promise as a thermoelectric material for converting waste heat into electricity.

Since nearly 65% of utilized energy is wasted as heat, the focus is on developing materials that exhibit good thermoelectric property with both glass- and metal-like properties. Potential applications of the thermoelectric technology are in automobile industry, chemical, thermal and steel power plants where large quantities of heat are wasted.

Due to the low thermal conductivity of the material developed by JNCASR, one end of the 8 mm-long rod that is contact with waste heat remains hot while the other end maintains cold temperature. The temperature difference is essential for the generation of electrical voltage. At the same time, the material exhibits good electrical conductivity like metal. The results were published in the journal Angewandte Chemie.

In the AgCuTe material, the silver atoms (cation) are weakly bound, giving rise to poor thermal conductivity due to the slow vibration of the lattice (soft lattice). At high temperatures, copper in the material further lowers the thermal conductivity along with silver. “Since the silver lattice vibrates slowly, it provides record low thermal conduction of 0.35 W per metre per kelvin, which is actually close to the glass,” Dr Biswas says.

“Both cations [silver and copper] contribute to low thermal conductivity but silver contributes more. Over 170 degree C, both silver and copper ions flow like liquid within the rigid tellurium sublattice, thereby reducing the thermal conductivity to the level of glass without affecting the hole (electrical carrier) transport,” says Subhajit Roychowdhury from JNCASR and first author of the paper.

Tellurium lattice

In contrast, the tellurium atoms (anion) are strongly bound and the lattice is very rigid. The strongly bound tellurium provides a conduction channel for holes thus rendering good electrical conductivity as seen in metals.

“By combining silver and copper with tellurium we have made our material as a combination of glass and metal — poor thermal conductivity and good electrical conductivity,” Dr Biswas says.

“Silver telluride does not have good thermoelectric property because it has higher thermal conductivity than our material,” says Roychowdhury.

It is a challenging task to have glassy and metallic properties in a single material, which is the fundamental challenge in the field of thermoelectrics. “We addressed this challenge through structural chemistry by creating a bonding hierarchy in the material,” Dr Biswas says.

The calculated efficiency to convert heat into electricity is 14% for the new material developed by JNCASR researchers. The lead telluride (PbTe) has higher efficiency of 18%. “But unlike lead telluride that contains lead, which is toxic, our material is lead-free,” he adds. The theoretical calculation to know the electronic structure was done in collaboration with Prof. Umesh V. Waghmare of JNCASR and coauthor of the paper. “We are trying to increase the efficiency by doping with different cations and anions,” Dr Biswas says.

source: http://www.thehindu.com / The Hindu / Home> Science / by R. Prasad / Bengaluru – March 03rd, 2018

This Anglo-Indian settlement was football’s birthplace in Bengaluru

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Austin Town has changed. As in many erstwhile British Cantonment and Anglo-Indian localities, the early settlers have sold off property to migrate elsewhere. Colonial homes with monkey-tops and tiled roofs have made way for more ‘practical’ buildings.

For 50-year-old engineer, Kevin Vieyra, the biggest drawback of these changes is the fragmentation of the community. Vieyra’s grandmother Enid Wilson, an Irish woman was the sergeant of the locality in the 1900s, was one of the earliest residents of the Anglo-Indian quarters. She was the go-to person for anyone with a problem that needed solving. “Even when I was growing up, Austin Town was a close-knit community where it did not really make a difference which home you belonged to,” Vieyra recalled.

Austin Town was built in the early 1920s when the British authorities decided to re-settle workers and lower-income residents in the aftermath of the bubonic plague of 1898. The locality was made up of small cottages. Original settlers included the Anglo-Indian community and a large Tamil population that traced its ancestry to the soldiers and workers brought to the Cantonment by the British after the fall of Tipu Sultan in the Fourth Anglo-Mysore War in 1799.

According to Mansoor Ali, founder of Bengaluru By Foot, “The locality is named after Sir James Austin Bourdillon who was born in Madras in 1848 and was educated at Marlborough, England. He held multiple official posts in Bengal and Patna before becoming the Resident of Mysore between 1903 and 1905.”

The sanitary works in Austin Town were designed by WH Murphy, an engineer in the British cantonment, after whom Murphy Town is named. While James Austin himself enjoyed cricket and rifle shooting, the locality named after him is known to be the birthplace of football in Bengaluru.

 It is said that the Italian prisoners of war, held here during World War II, passed the game on to the locals. Among the first Olympians from India (in the Games of 1948 and 1952) were footballers Anthony, Kanniah, Raman and T Shanmugam — all of who were from Austin Town. So were other football greats Ulaganathan and former India football captain Carlton Chapman.

Even today, the children of the locality practise football with as much fervour as they play cricket. Twenty years ago, the locality was renamed as F Kittel Nagar, after 18th century German missionary Rev Ferdinand Kittel.

source: http://www.economictimes.indiatimes.com / The Economic Times / Home> News> Sports / by Divya Shekhar, ET Bureau / March 01st, 2018

CM inaugurates first phase of Pavagada Solar Park

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Chief Minister Siddaramaiah inaugurated the first phase of Pavagada Solar Park at Thirumani in Pavagada taluk of Tumakuru district on Thursday.

Addressing a large gathering, Mr. Siddaramaiah termed the solar park as the “eighth wonder of the world.” He said that “we are thankful to all those farmers who have leased out their land to the government for the project.”

In the first phase, the solar park will produce 600 MW. A total of 2,300 farmers of Pavagada have leased out 13,000 acres of land at Rs.21,000 per acre per annum. This will help to boost the economic activities in the most backward taluk. Before the solar park was established, the land rates were around Rs. 25,000 per acre but now they have risen to Rs. 4-5 lakh.

Energy Minister D.K. Shivakumar said that Karnataka will become self-reliant in the production of power and there will be no need to depend on other States. Pavagada Solar Park will be completed by December 2018 and will generate 2000 MW of power, he added.

District-in-charge Minister T.B. Jayachandra, MP Chandrappa, MLA Thimmarayappa, former Minister Venkataramanappa and others were present.

source: http://www.thehindu.com / The Hindu / Home> News> States> Karnataka / by Staff Reporter / Tumakuru – March 01st, 2018