Small-scale heliostat

by Hansraj Agrawal | Jun 29, 2025 | Science

Scientists Adithyan TR, Prof Sreeram K Kalpathy and Prof Tiju Thomas of the Department of Metallurgical and Materials Engineering, Indian Institute of Technology (IIT), Madras, have designed and evaluated a tilt-roll two-axis tracking heliostat (solar concentrator) that is economically viable for small-scale applications.

In this heliostat, the design eliminates the need for a commercially available solar tracking system, so it can be deployed in areas with limited installation space. The solar positioning system is capable of operating independently, without the need for a powerful microcontroller or microprocessor.

“The combination of the tilt-roll dual-axis tracking system achieves a heliostat design that could be easily deployed for small-scale usage and experimental purposes in households and academia,” says an article in IIT-M Tech-Talk.

“The results have been demonstrated on a rooftop at IIT-Madras. The heliostat prototype could reflect the sun’s radiation to the desired target. The dual-axis heliostat design used here provides an effective way to track the sun’s movement for maximum solar energy capture by combining tilt and roll mechanisms,” the article says.

Future work will focus on developing and testing advanced heliostat drive devices, such as heliostat with induction motors, and linear drives to reduce operation power losses. Future work may also focus on making the system robust under dynamic wind-loading conditions.

Dr Ajay Chandak, an innovator, developer and entrepreneur in sustainability and a global advisor of Solar Cookers International (SCI), says in the article that the use of heliostats for power generation is obsolete due to the low cost of solar PV.

However, such smaller heliostats can be useful in solar thermal applications.

Solar-to-hydrogen energy

Scientists at the Centre for Nano and Soft Matter Sciences (CeNS), Bengaluru, have developed a next-generation device that produces green hydrogen by splitting water molecules using only solar energy and earth-abundant materials, without relying on fossil fuels or other expensive resources.

The team designed a silicon-based photoanode using an innovative n-i-p heterojunction architecture, consisting of stacked n-type titanium dioxide, intrinsic (undoped) silicon and p-type nickel oxide semiconductor layers, which work together to enhance charge separation and transport efficiency. The materials were deposited using magnetron sputtering, a scalable and industry-ready technique that ensures precision and efficiency. This engineering approach allowed better light absorption, faster charge transport and reduced recombination loss — key ingredients for efficient solar-to-hydrogen conversion.

“The device is highly effective at generating hydrogen under solar energy,” says a press release. It also showcases “exceptional long-term stability, operating continuously for over 10 hours in alkaline conditions with only a 4 per cent performance drop, a rare feat in Si-based photoelectrochemical systems,” the release says.

This new device is attractive for several reasons, including high efficiency, low energy input, robust durability and cost-effective materials, all in one package. It even demonstrated successful performance at a large scale, with a 25 sq cm photoanode delivering excellent solar water-splitting results.

“By selecting smart materials and combining them into a heterostructure, we have created a device that not only boosts performance but can also be produced on a large scale,” says Dr Ashutosh Singh, who led the research. “This brings us one step closer to affordable, largescale solar-to-hydrogen energy systems,” Singh says in the release.

More Like This

Published on June 29, 2025

Source link

Demagnetising the Chinese monopoly

by Hansraj Agrawal | Jun 29, 2025 | Science

Two home-grown engine makers devise ways to wriggle out of China’s stranglehold on rare earth minerals

Source link

How machines are learning to recommend the right crop season

by Hansraj Agrawal | Jun 29, 2025 | Science

Agricultural productivity in India is lower than in some other countries. Wheat yield, for instance, is roughly 2.7 tonnes a hectare in India, compared with 6 tonnes in China.

Technological aids such as drones and sensors are helping step up agricultural output, but artificial intelligence (machine learning) can prove to be an even bigger game changer, especially in determining which crops to grow next for improved yields and profits.

‘ML-based crop recommendation systems’ is the next big thing in agriculture today. With over 145 million small farms in India, most under 1.1 hectares, farmers need clear, data-based guidance to choose the right crops for better income and resilience against climate change.

In this, two independent researches have concluded that the ‘random forest’ ML model has the highest prediction accuracy. The ‘random forest’ model combines multiple ‘decision trees’ — ML algorithms that use tree-like structures to make predictions.

The first study is by scientists Steven Sam and Silima Marshal D’Abreo of the Brunel University, London. They examined 12,389 data points of 19 crops in 15 Indian States during 2011-14.

“We combined environmental and economic input parameters to develop and evaluate the accuracy of two machine-learning models (‘random forest’ and ‘support vector machines’) for recommending high-yield and profitable crops to farmers,” the authors say in a yet-to-be-peer-reviewed paper.

They concluded that ‘random forest based on lag variables’ (past values of a data point used to predict the future) is the most accurate.

Diverse conditions

The researchers tested two computer-based models to see how well they could suggest the right crops. One method showed high accuracy but wasn’t realistic because it didn’t consider how crop conditions change over time.

To balance accuracy with real-world usefulness, the researchers introduced ‘lag variables’, which improved the model’s performance. In the end, the model using the random forest method with the time-aware approach worked best for crop recommendations in India.

The study highlights that an examination of both market and environmental factors produces better advice for farmers. It also suggests that future improvements should include more data like market demand, prices and returns, to make the recommendations even more suited to India’s diverse farming conditions.

Another research paper, titled ‘Crop recommendation system using machine learning’, by researchers at the Prakasam Engineering College in Kandukur, Andhra Pradesh, has also concluded that the random forest model is the best, with accuracy of 99.3 per cent.

“The system successfully recommends optimal crops across 22 different crop categories, contributing to improved agricultural productivity and sustainable farming practices,” say the authors of the paper, Dr M Lakshma Rao and his student Soprala Naveena.

“The crop recommendation system represents a successful integration of machine learning technology with agricultural science, creating a tool that bridges the gap between sophisticated analytical capabilities and practical agricultural applications,” they say, adding that the system “serves as a proof of concept for the broader potential of artificial intelligence and machine learning to support sustainable, productive and equitable agricultural systems”.

More Like This

Published on June 29, 2025

Source link

Pale blue-green dot

by Hansraj Agrawal | Jun 15, 2025 | Science

Astronomer Carl Sagan famously had Voyager-1 turn briefly and snap a picture of the earth — a ‘pale blue dot — from 3.7 billion miles away.

Back in the Archean eon (3.8-1.9 billion years ago), that image would have been a ‘pale green dot’ — there was little or no atmosphere on earth, and the oceans were green, as a group of Japanese scientists have deduced.

There were only single-celled organisms in the oceans, making food from the iron dissolved in the water — a process that released oxygen and led to ‘the great oxidation event’ about 2.4 billion years ago.

Iron deposits from this period, known as banded iron formations, show layers of oxidised and unoxidised iron, recording this key environmental shift.

Japanese researchers studying the greenish waters around the volcanic island of Iwo Jima found similarities to ancient oceans. The green of the water is due to oxidised iron and supports blue-green algae — primitive bacteria that can use both green and white light for photosynthesis.

In the future, sulphur from volcanic activity could see purple bacteria proliferating. And if oxidised iron enters the oceans, you may have rolling waves of red.

An unprepossessing sight, for sure!

More Like This

Published on June 15, 2025

Source link

Chemistry for everyone

by Hansraj Agrawal | Jun 15, 2025 | Science

The 75th edition of the Yusuf Hamied Chemistry Camp at IIT-Bombay was designed specifically for visually impaired students

Indian Institute of Technology, Bombay, recently hosted the 75th edition of the Yusuf Hamied Chemistry Camp, designed specifically for 59 visually impaired students from government schools in Mumbai, Nashik, Pune and Solapur. The landmark event reaffirmed a powerful message: chemistry is for everyone.

Supported by the Royal Society of Chemistry (RSC) and funded by Dr Yusuf Hamied, the camp provided a first-of-its-kind, hands-on opportunity for blind students to explore the wonders of chemistry through the senses of touch and smell. This year’s camp — developed under the leadership of Dr Swetavalli Raghavan, Head of Innovation Strategy and Government Affairs at RSC — featured a brand new module developed by Prof C Subramaniam of IIT-Bombay.

“Given that chemistry is about colour and visual perception, designing the experiments to convey concepts with clarity was intellectually stimulating and provided a unique peek into the day-to-day lives of these children,” says Subramaniam.

The camp focused on fun, sensory-based experiments — tactile molecular models, scent-based chemical identification, concepts in physical chemistry such as levitating magnets, and safe experiments that allowed students to feel textures and temperature changes during reactions, says a press release from IIT-Bombay.