Solar Energy

NTU Singapore scientists design ‘smart’ device to harvest daylight

Published

4 years ago

April 1, 2021

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NTU Singapore scientists design ‘smart’ device to harvest daylight

A team of Nanyang Technological University, Singapore (NTU Singapore) researchers has designed a ‘smart’ device to harvest daylight and relay it to underground spaces, reducing the need to draw on traditional energy sources for lighting.

In Singapore, authorities are looking at the feasibility of digging deeper underground to create new space for infrastructure, storage, and utilities. Demand for round-the-clock underground lighting is therefore expected to rise in the future.

To develop a daylight harvesting device that can sustainably meet this need, the NTU team drew inspiration from the magnifying glass, which can be used to focus sunlight into one point.

They used an off-the-shelf acrylic ball, a single plastic optical fibre – a type of cable that carries a beam of light from one end to another – and computer chip-assisted motors.

The device sits above ground and just like the lens of a magnifying glass, the acrylic ball acts as the solar concentrator, enabling parallel rays of sunlight to form a sharp focus at its opposite side. The focused sunlight is then collected into one end of a fibre cable and transported along it to the end that is deployed underground. Light is then emitted via the end of the fibre cable directly.

At the same time, small motors – assisted by computer chips – automatically adjust the position of the fibre’s collecting end, to optimise the amount of sunlight that can be received and transported as the sun moves across the sky.

Developed by Assistant Professor Yoo Seongwoo from the School of Electrical and Electronics Engineering and Dr Charu Goel, Principal Research Fellow at NTU’s The Photonics Institute, the innovation was reported in the peer-reviewed scientific journal Solar Energy early this month.

The device overcomes several limitations of current solar harvesting technology. In conventional solar concentrators, large, curved mirrors are moved by heavy-duty motors to align the mirror dish to the sun. The components in those systems are also exposed to environmental factors like moisture, increasing maintenance requirements.

The NTU device, however, is designed to use the round shape of the acrylic ball, ridding the system of heavy-duty motors to align with the sun, and making it compact.

The prototype designed by the researchers’ weighs 10 kg and has a total height of 50 cm. To protect the acrylic ball from environmental conditions (ultraviolet light, dust etc.), the researchers also built a 3mm thick, transparent dome-shaped cover using polycarbonate.

Device compact enough to be mounted as a lamp post

Asst Prof Yoo, lead author of the study said, “Our innovation comprises commercially available off-the-shelf materials, making it potentially very easy to fabricate at scale. Due to space constraints in densely populated cities, we have intentionally designed the daylight harvesting system to be lightweight and compact. This would make it convenient for our device to be incorporated into existing infrastructure in the urban environment.”

The NTU team believes the device is ideally suited to be mounted as a conventional lamp post above ground. This would enable the innovation to be used in two ways: a device to harvest sunlight in the day to light up underground spaces, and a streetlamp to illuminate above ground at night using electricity.

The research by the NTU scientists is an example of NTU’s Smart Campus vision that aims to develop technologically advanced solutions for a sustainable future.

Smart’ automatic positioning to harvest maximum sunlight

As the sun moves across the sky throughout the day, so will the position of the focused sunlight inside the acrylic ball. To ensure that maximum sunlight is being collected and transported down the fibre cable throughout the day, the system uses a computer chip-based mechanism to track the sun rays.

The Global Positioning System (GPS) coordinates of the device location are pre-loaded into the system, allowing it to determine the spot where maximum sunlight should be focused at any given time. Two small motors are then used to automatically adjust the position of the ?bre to catch and transport sunlight from the focused spot at one-minute intervals.

To guarantee the device’s automatic positioning capability, pairs of sensors that measure light brightness are also placed around the sunlight collecting end of the fibre cable. Whenever the sensors detect inconsistencies in the light measurements, the small motors automatically activate to adjust the cable’s position until the values on the sensors are the same. This indicates that the fibre is catching the maximum amount of sunlight possible.

During rain or overcast skies when there is inadequate sunlight to be collected and transported underground, an LED bulb powered by electricity installed right next to the emitting end of the fibre cable, will automatically light up. This ensures that the device can illuminate underground spaces throughout the day without interruption.

Performs better than LED bulbs

In experiments in a pitch-black storeroom (to simulate an underground environment), the NTU researchers found the device’s luminous efficacy – the measure of how well a light source produces visible light using 1 Watt of electrical power- to be at 230 lumens/Watt.

This far exceeds those recorded by commercially available LED bulbs, which have a typical output of 90 lumens/Watt. The quality of the light output of the NTU smart device is also comparable with current commercially available daylight harvesting systems which are far more costly.

Dr Charu, who is the first author of the study, said, “The luminous efficacy of our low-cost device proves that it is well-suited for low-level lighting applications, like car parks, lifts, and underground walkways in dense cities. It is also easily scalable. Since the light capturing capacity of the ball lens is proportional to its size, we can customise the device to a desired output optical power by replacing it with a bigger or smaller ball.”

Michael Chia, Managing Director at Technolite, a Singapore-based design focused agency specialising in lighting, and the industry collaborator of the research study said, “It is our privilege and honour to take this innovation journey with NTU. While we have the commercial and application knowledge, NTU in-depth knowhow from a technical perspective has taken the execution of the project to the next level that is beyond our expectations.””

Moving forward, the lighting company is exploring ways to potentially incorporate the smart device or its related concepts into its industrial projects for improved efficiency and sustainability.

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Solar Energy

Battery boom drives Bangladesh lead poisoning epidemic

Published

1 day ago

April 1, 2025

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Battery boom drives Bangladesh lead poisoning epidemic

By Philippe ALFROY

Mirzapur, Bangladesh (AFP) April 1, 2025

Bangladeshi Junayed Akter is 12 years old but the toxic lead coursing through his veins has left him with the diminutive stature of someone several years younger.

Akter is one of 35 million children — around 60 percent of all children in the South Asian nation — who have dangerously high levels of lead exposure.

The causes are varied, but his mother blames his maladies on a since-shuttered factory that hastily scrapped and recycled old vehicle batteries for profit, in the process poisoning the air and the earth of his small village.

“It would start at night, and the whole area would be filled with smoke. You could smell this particular odour when you breathed,” Bithi Akter told AFP.

“The fruit no longer grew during the season. One day, we even found two dead cows at my aunt’s house.”

Medical tests showed Junayed’s blood had twice the level of lead deemed by the World Health Organization to cause serious, and likely irreversible, mental impairment in young children.

“From the second grade onward, he didn’t want to listen to us anymore, he didn’t want to go to school,” Bithi said, as her son sat next to her while gazing blankly out at the courtyard of their home.

“He cried all the time too.”

Lead poisoning is not a new phenomenon in Bangladesh, and the causes are manifold.

They include the heavy metal’s widespread and continued use in paint, in defiance of a government ban, and its use as an adulterant in turmeric spice powder to improve its colour and perceived quality.

A great many cases are blamed on informal battery recycling factories that have proliferated around the country in response to rising demand.

Children exposed to dangerous levels of lead risk decreased intelligence and cognitive performance, anaemia, stunted growth and lifelong neurological disorders.

The factory in the Akter family’s village closed after sustained complaints from the community.

But environmental watchdog Pure Earth believes there could be 265 such sites elsewhere in the country.

“They break down old batteries, remove the lead and melt it down to make new ones,” Pure Earth’s Mitali Das told AFP.

“They do all this in the open air,” she added. “The toxic fumes and acidic water produced during the operation pollute the air, soil and water.”

– ‘They’ve killed our village’ –

In Fulbaria, a village that sits a few hours’ drive north of the capital Dhaka, operations at another battery recycling factory owned by a Chinese company are in full swing.

On one side are verdant paddy fields. On the other, a pipe spews murky water into a brackish pool bordered by dead lands, caked with thick orange mud.

“As a child, I used to bring food to my father when he was in the fields. The landscape was magnificent, green, the water was clear,” engineer and local resident Rakib Hasan, 34, told AFP.

“You see what it looks like now. It’s dead, forever,” he added. “They’ve killed our village.”

Hasan complained about the factory’s pollution, prompting a judge to declare it illegal and order the power be shut off — a decision later reversed by the country’s supreme court.

“The factory bought off the local authorities,” Hasan said. “Our country is poor, many people are corrupt.”

Neither the company nor the Chinese embassy in Dhaka responded to AFP’s requests for comment on the factory’s operations.

Syeda Rizwana Hasan, who helms Bangladesh’s environment ministry, declined to comment on the case because it was still before the courts.

“We regularly conduct operations against the illegal production and recycling of electric batteries,” she said.

“But these efforts are often insufficient given the scale of the phenomenon.”

– ‘Unaware of the dangers’ –

Informal battery recycling is a booming business in Bangladesh.

It is driven largely by the mass electrification of rickshaws — a formerly pedal-powered means of conveyance popular in both big cities and rural towns.

More than four million rickshaws are found on Bangladeshi roads and authorities estimate the market for fitting them all with electric motors and batteries at around $870 million.

“It’s the downside of going all-electric,” said Maya Vandenant of the UN children’s agency, which is pushing a strategy to clean up the industry with tighter regulations and tax incentives.

“Most people are unaware of the dangers,” she said, adding that the public health impacts are forecast to be a 6.9 percent dent to the national economy.

Muhammad Anwar Sadat of Bangladesh’s health ministry warned that the country could not afford to ignore the scale of the problem.

“If we do nothing,” he told AFP, “the number of people affected will multiply three or fourfold in the next two years.”

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Solar Energy

Modi to kick off construction of India-Sri Lanka solar plant

Published

3 days ago

March 30, 2025

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Modi to kick off construction of India-Sri Lanka solar plant

by AFP Staff Writers

New Delhi (AFP) Mar 28, 2025

Indian Prime Minister Narendra Modi will launch the construction of a long-delayed solar power project during his upcoming visit to Sri Lanka, an official said on Friday.

Vikram Misri, the secretary of India’s foreign ministry, said Modi and Sri Lankan President Anura Kumara Dissanayake will witness a virtual groundbreaking ceremony for their joint-venture solar power project in the island’s northeast on April 5.

The proposed 120-megawatt venture in the northeastern coastal district of Trincomalee has stalled for years, but New Delhi backed it as a joint project between the neighbouring nations.

“This, in many senses, is going to be a milestone in the bilateral partnership,” Misri told reporters in New Delhi.

“They will together dedicate several projects that are being built with Indian assistance in Sri Lanka and will also witness the exchange of several MoUs pertaining to energy connectivity, digitisation, defence, health, and multisectoral grant assistance.”

The pair will watch the virtual groundbreaking from Sri Lankan capital Colombo. The costs of the project were not immediately available.

The groundbreaking, a day before Modi concludes his two-night visit to Sri Lanka, comes as Colombo grapples with the competing interests of its powerful northern neighbour and China, its largest lender.

Modi will be the first foreign head of government to visit the island nation under the new administration of leftist Dissanayake. He flies into Colombo on April 4 after attending a regional conference in Thailand.

Dissanayake’s first foreign visit after his election last year was to New Delhi in December.

Sri Lankan officials in Colombo said Modi and Dissanayake will travel to the northern Buddhist pilgrimage city of Anuradhapura on April 6.

Dissanayake travelled to Beijing in January, underscoring Sri Lanka’s delicate balancing act in maintaining ties with the two regional rivals.

New Delhi has been concerned about China’s growing influence in Sri Lanka, which it considers to be within its sphere of geopolitical influence.

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Solar Energy

Optical advances offer boost to next-generation solar module designs

Published

3 days ago

March 30, 2025

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Optical advances offer boost to next-generation solar module designs

by Robert Schreiber

Berlin, Germany (SPX) Mar 30, 2025

In 2023, solar photovoltaic (PV) systems accounted for over 5 percent of global electricity output, with installed capacity doubling roughly every two to three years. Optical technologies are now emerging as key enablers to further enhance module efficiency and enable new applications, including aesthetically tailored solar panels for building facades. A new expert-driven report, coordinated by Helmholtz-Zentrum Berlin (HZB) scientists Prof. Christiane Becker and Dr. Klaus Jager, offers a detailed analysis of the most promising innovations in this area.

Solar photovoltaics have become one of the most affordable sources of electricity worldwide. As of November 2024, global PV installations surpassed two terawatts, underscoring the rapid pace of expansion and cost decline.

Contributions from 22 leading research institutions

“At a recent workshop, we discussed how the optics community can contribute to the further growth of photovoltaics,” said Prof. Christiane Becker, who leads the Solar Energy Optics Department at HZB. Along with Dr. Klaus Jager, she brought together a team of 27 experts from 22 institutions across nine countries to produce a wide-ranging review of emerging PV and optical technologies.

Breakthrough optical concepts

Beginning with a comprehensive look at current terawatt-scale PV deployment, the report identifies critical areas where optical strategies can make significant contributions. “We have also identified a number of optical concepts that are currently only on the threshold of economic viability, but which hold the most promise for advancing PV technology,” said Becker. Key areas include multi-junction solar cells, which offer the highest efficiencies among all PV technologies and could help reduce the levelized cost of energy.

Sustainability and aesthetics

The review also emphasizes the importance of environmentally responsible manufacturing and the reduced use of scarce materials through eco-design approaches. Another highlighted innovation is the development of colored PV modules suitable for integration into building architecture. “Especially in cities, we need to use facades and other surfaces too for solar energy conversion, and of course, it does matter how the PV modules look. Such innovative solar modules allow sophisticated aesthetic solutions,” said Becker.

Becker and Jager believe the review will serve not only as a valuable resource for researchers but also for funding bodies and policy strategists seeking to accelerate the deployment of advanced solar technologies.

Research Report:Optics for Terawatt-Scale Photovoltaics: Review and Perspectives