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Treated refinery wastewater flowing through sand, cleans itself further with pollutant-eating bacteria, finds study

pro — Tue, 10 Sep 2024 09:15:30 +0000

Treated refinery wastewater flowing through sand, cleans itself further with pollutant-eating bacteria, finds study pro Tue, 09/10/2024 - 14:45

Refinery wastewater flowing through sand produced biofilms of pollutant-eating bacteria which inturn removed the harmful compounds from the water

? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ?Representative image from Rawpexel

Refineries, which transform crude oil into useful products like gasoline and diesel, generate large amounts of wastewater. This water, which has been used for activities like steam generation and heat transfer, often contains harmful organic and inorganic pollutants, including nitrogen-containing compounds. The wastewater then undergoes several steps of treatment to remove most of these contaminants before it can be safely discharged into the environment. Scientists have been exploring alternative additional treatment steps that are both environmentally safe and economically viable.

A recent study by researchers at the Indian Institute of Technology Bombay (IIT Bombay) on biofilters, which are water filters that use microorganisms, like bacteria, to remove pollutants, has led to an interesting observation- partially treated wastewater from refineries already carry bacteria that can remove the organic contaminants from the wastewater. The researchers only had to provide a substratum- in this case, a column of pure quartz sand - onto which the bacteria could cling to get to work.

For their study, the researchers investigated the properties of sand as a biofilter. “Sand was chosen since it is commonly used in deep bed filters used for water and wastewater treatment,” remarks Prof. Suparna Mukherji, from the Department of Environmental Science and Engineering, IIT Bombay, who led this study.

The researchers designed a biofilter made of an acrylic cylinder measuring 45 cm in length and 2 cm in diameter. They filled it with pure quartz sand to a depth of 15 cm. The filtration process begins by allowing secondary treated refinery wastewater, which has undergone the removal of toxic chemicals, to flow through the biofilter at a controlled rate of 1 to 10 mL per minute. The wastewater flowing through the sand leads to the formation of a biofilm, made of several different types of bacteria enmeshed in extracellular polymeric substances secreted by the bacteria, on the grains of sand.

Schematic of sand biofiltration, photo of Sand biofilters made of acrylic, and microscopic images of the sand with and without the biofilm. (Credits: Authors of the study)

“As the water flows through the sand bed, bacteria present in the water/wastewater get adsorbed onto the sand. Subsequently, the attached bacteria replicate and secrete extracellular polymeric substances to form a biofilm on the surface of the sand grains. Bacteria grow using dissolved oxygen, organic carbon, and other nutrients from the water flowing through the sand bed,” explains Prof. Mukherji. This biofilm in turn eats away at the organic contaminants in the water. Degradation of organic compounds containing nitrogen releases inorganic nitrogen in the form of ammonium, which is further converted to nitrate. Although some removal of nitrate may have occurred, build-up of nitrate was observed after biofiltration.

The team analysed the Chemical Oxygen Demand (COD), Total Organic Carbon (TOC), and Assimilable Organic Carbon (AOC), which are measures of the various organic compounds in the water. Analysis of COD and TOC allows researchers to estimate the concentration of organic contaminants in the water. Remarkably, they observed a significant reduction in COD, TOC, and AOC after just two recirculations of the wastewater through the biofilter.

The team also used a technique called GCxGC TOF MS, which stands for Gas chromatography Time of Flight Mass spectrometry, to detect and quantify specific organic compounds in the water. “Recirculating the wastewater up to 12 times resulted in maximum reduction in COD and TOC of 62% and 55%, (by more than half) respectively. GCxGC-TOF-MS revealed that several of the identified target (harmful) compounds could not be detected in the wastewater after 12 recirculations, suggesting 100% removal,” adds Dr. Prashant Sinha, an author of the study, who was pursuing his PhD from IIT Bombay at the time of the study.

The nitrates produced by the bacteria during filtration, through conversion of other forms of nitrogen, caused a build-up of nitrates in the treated water. “The build-up of nitrates observed is not desirable. However, refineries commonly employ reverse osmosis (RO) as the final treatment step. This process can reduce the level of nitrates in the final effluent,” says Prof. Mukherji. Biofiltration can also reduce the deposition and accumulation of unwanted material on the RO membranes by reducing AOC.

The study also delved into the biofilter’s microbial community. It turned out that the predominant bacteria belonged to a group called Proteobacteria. The group is known for their ability to break down complex organic compounds like polynuclear aromatic hydrocarbons (PAHs), which are harmful to living organisms. The Proteobacteria group includes helpful bacteria like Sphingomonadales, Burkholderiales, Rhodobacterales, and Rhodospirillales, all recognized for their role in cleaning up hazardous pollutants.

Sand biofiltration method stands out for its simplicity, meaning it could be an accessible solution for many industrial plants worldwide. It could significantly reduce the environmental footprint of oil refineries. With pure quartz sand being easily available, the overall cost of building and maintaining such a biofilter at large scales remains very low, making the filtration economical. Prof. Mukherji, however, is already planning her next steps, saying, “We would like to explore this process further using other types of media and with different types of water/ wastewater”.

Article written by:? ? ? ? ? ?Dennis C. Joy
Image/ Graphic Credit: ?Lead image: Rawpexel
? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ?Inline Image: Authors of the study
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Efficient treatment of secondary treated refinery wastewater using sand biofilt…

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Tue, 09/10/2024 - 12:00

Robots Mimic Animal Homing: Scientists uncover how animals find their way back home

pro — Tue, 27 Aug 2024 08:26:19 +0000

Robots Mimic Animal Homing: Scientists uncover how animals find their way back home pro Tue, 08/27/2024 - 13:56

IIT Bombay researchers use a robot that mimics animal movements to study how homing animals efficiently return home without getting lost or being late.

? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ?Path taken by the homing robot and a magnified view of the robot.
? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ?Credit: Dr. Nitin Kumar

Many members of the animal kingdom possess an incredible ability to find their way home from unfamiliar places, a skill known as homing. Whether it's birds flying thousands of miles during migration or ants finding their way back to their colonies after foraging, homing is crucial for their survival. Humans have even harnessed this ability of the birds to train homing pigeons to deliver messages over long distances. But how do these animals always find their way home and how do they do it so efficiently? These and many other questions about this intriguing ability remain unanswered.

Researchers at the Indian Institute of Technology Bombay are using robots to unravel the mystery behind this fascinating phenomenon. “The primary goal of our research group is to understand the physics of active and living systems. We achieve this by performing experiments on centimetres-sized self-propelled programmable robots. In simple words, we model these robots to mimic the dynamics of living organisms, both at the individual and collective levels,” remarks Dr. Nitin Kumar an Assistant Professor at the Department of Physics at IIT Bombay.

Dr. Kumar’s team has now developed a robot that mimics the foraging and homing behaviour seen in animals. This robot is designed to move on its own, much like an animal finding food
(foraging), and then to use light as a guide to return home (homing). In a new study, they have used this foraging and homing robot to study the underlying principles of homing.

The foraging robot is programmed to move in a semi-random manner, similar to how animals might wander around looking for food. This type of movement is called active Brownian (AB) motion, a computer model that mimics living dynamics. The robot's direction changes frequently due to something called rotational diffusion, which introduces a certain level of randomness to its path. When the robot needs to return home, it shifts to a different mode. The researchers shine the robot with a light gradient (a gradual change in light intensity) which the robot is programmed to follow to find its way back. This mimics how some animals might use the sun or other environmental cues to navigate. “The homing motion is similar to the AB model, except the robot undergoes frequent course corrections whenever it deviates significantly from its intended homing direction, as expected in actual living organisms” explains Dr. Kumar.

For their study, the team wanted to determine the time it took for the robot to return home, with increasing amounts of deviations from its homing path. Ironically, they observed that the reorientation rate, which is the frequency at which the robot (or an animal) should adjust its direction for successful homing, originated from the degree of randomness in its path. They discovered an 'optimal reorientation rate' for a particular value of randomness beyond which the adverse effects of increased randomness are negated by more frequent reorientations, ultimately ensuring successful homing. This suggests that animals might have evolved to reorient themselves at an optimal rate to efficiently find their way home, regardless of the noise or unpredictability in their environment.

Talking about the findings, Dr. Kumar exclaims, “The observation of a finite upper limit on return times indicates that the homing motion is inherently efficient. Our results demonstrated that if animals are always aware of the direction of their home and always correct their course whenever they deviate from the intended direction, they will surely get home within a finite time.”

To back up their findings, the researchers built a theoretical model based on the concept of ‘first-passage time’. Simply put, this model helps predict how long it will take for the robot to reach home depending on its behaviour. The model was not only able to explain the robot's experimental outcomes but also captured specific features of its homing paths, like how its orientation changes over time. The model could highlight the importance of reorientation as a strategy, showing that frequent course corrections are vital for efficient navigation.

Apart from physical experiments, the team also ran computer simulations where the robot's movement mimicked animals. This virtual robot combined active Brownian motion with occasional resets to its orientation to correct its course back towards home. These simulations matched the experimental results, reinforcing the idea that randomness and reorientation work hand-in-hand to optimise homing. “When we applied this model to the trajectories of a real biological system of a flock of homing pigeons, it showed a good agreement with our
theory, validating our hypothesis of enhanced efficiency due to frequent course corrections,” adds Dr. Kumar.

By mimicking the homing behaviours of animals, scientists have taken a significant step toward understanding the underlying principles. This study not only sheds light on how animals efficiently find their way home but also paves the way for technological advancements in robotics. Real-world navigation, however, involves more than just following a simple cue—it might include responding to changing landscapes, social interactions, and other environmental factors. “In real and more complex systems, the homing cues might be more complicated than a simple uniform gradient towards home, as modelled in our experiment. In our future research, we aim to model these scenarios in our experiment by using a combination of spatiotemporal variations in light intensity and physical obstacles,” concludes Dr. Kumar about the future direction of the research.

Article written by:	Dennis C. Joy
Image/ Graphic Credit:	Prof Nitin Kumar
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Uncovering Universal Characteristics of Homing Paths using Foraging Robots

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Tue, 08/27/2024 - 12:00

Unravelling the Sands of Time: Exploring the Mesozoic Sands of Saurashtra Basin

pro — Wed, 31 Jul 2024 10:17:03 +0000

Unravelling the Sands of Time: Exploring the Mesozoic Sands of Saurashtra Basin pro Wed, 07/31/2024 - 15:47

A new study of the Saurashtra Basin dates the minerals found in the sediments, revealing the paths of ancient rivers and the geological history of the Indian subcontinent.

Map of Western India with study area highlighted.
Credits: Roy, A.B. and Jakhar, S.R., 2002. Geology of Rajasthan (Northwest India) Precambrian to recent.?Scientific Publishers.

In Western India, spanning western Gujarat and the North of Mumbai coastline, lies the Saurashtra Basin which is an expanse of 2,40,000 SqKm area spanning sea and land. Much of the landscape here remains buried in volcanic rocks called Deccan Traps, created by volcanic eruptions at the Western Ghats during the Cretaceous period, 66 million years ago. However, the sediment beneath the volcanic ash and rocks hides the extraordinary journey of the Indian subcontinent over the millenia.

A compelling study of the sediments of the Saurashtra Basin by the Indian Institute of Technology Bombay (IIT Bombay) and National Centre for Earth Science Studies, Thiruvananthapuram is helping us piece together the region’s paleogeography—a historical study that tells us what the parts of the earth looked like in the past. The study reveals some secrets of the history of India and the ancient supercontinent configurations, providing insights into how continents were formed and have moved over time.

“Saurashtra Basin was formed by the separation of India from Madagascar about 100 million years ago. Before the separation, India, Madagascar, and the Seychelles were joined together. After the separation, the western margin of India became lowlands, while the north and north-eastern parts of the study area acted as highlands,” remarks Dr. Pawan Kumar Rajak from the Department of Earth Sciences, IIT Bombay and the lead author of the study.
Rivers flowing from the highlands of the north and eastern regions of the subcontinent brought along with them the sediments from these regions, depositing them in the low-lying Saurashtra basin. “The eruption of Deccan volcanism (which happened later) covered a vast area of the Saurashtra Basin, making it difficult to study the sediments. Today, only the mountains/hills, river sections and road-cuts expose the sediments of that time,” adds Dr. Rajak.

The study focuses on the ‘Mesozoic’ era sandstones in the Saurashtra Basin. The Mesozoic era, known as the age of the dinosaurs, spans from about 252 to 66 million years ago. By examining the mineral content and employing cutting-edge dating techniques on these sandstones, the study pieces together the source and routes of the materials leading to their current location in the basin. The team used two techniques: electron probe microanalysis (EPMA) and laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS). Talking about the uses of these techniques, Dr. Rajak explains, “The high precision and low detection limits of LA-ICP-MS allow us to know the minerals' composition and ages on a small scale. The EPMA can determine the composition of minerals as well as the Uranium-Thorium (U-Th) age of a mineral, such as monazite, and helps identify the possible sources.”

The team focused on zircon and monazite, minerals known for preserving geological data remarkably well. “Both are rare earth elements-bearing minerals and contain a significant amount of U and Th in their crystal lattice. Decaying U or Th into lead (Pb) is used as a geological clock. So studying these minerals helps us gain information about important geological events in the past,” explains Dr. Rajak

To the northeastern part of the Saurashtra Basin is a region with 600 metres of thick sediment, called the Dhrangdara Group, from the late Jurassic-early Cretaceous period. The new study showed that the sandstones in the Dhrangdara Group primarily originated from two primary ‘Precambrian’ sources. The Precambrian is the earliest part of Earth's history, covering most of our planet's timeline. Researchers found that the Neoproterozoic rocks (about 1 billion to 540 million years ago) and Archean rocks (dating back from 4.5 billion to 2.5 billion years ago) are the primary sources of the sediments in the Saurashtra Basin.

The study also hints at revelations about paleo-drainage patterns— the ancient river systems. These findings are crucial for understanding how landscapes evolved and reshaped over time due to geological forces. Future studies could use the knowledge gained from this study to shed light on the paths of ancient river systems.

An analysis of minerals, like rutile and tourmaline, in the sandstones indicated a varied derivation from multiple geologic sources such as granites, metapelites (metamorphosed clay-rich sediments), and tourmalinites. Their chemical characteristics helped trace the rocks back to their origins in older terrains like the Aravalli and Delhi supergroup of rocks—major regional features known for their long-standing geological history. “The analysis of the
samples shows multiple sources contributing to sediments. Initially, it was thought that the Aravalli-Delhi Fold Belt (source region) was the only contributor to the sediments in the basin,” says Dr. Rajak.

Graphical representation of sediment flow into the Saurashtra basin.
Credits: Pawan Kumar Rajak

Geochemical analysis and dating give us a sneak peek into significant global events. The study of the zircon minerals suggested a predominant contribution from formations dating back to 3.5 billion to 539 million years ago. These timelines correlate with ancient supercontinent cycles such as the formation and breakup of Columbia, Rodinia, and Gondwana. These are names given to massive landmasses that once contained most or all of the Earth's continents but eventually split and drifted apart to form the continents as we see them today.

“During the supercontinents Columbia (1800 Ma) and Rodinia (1200 Ma), all the continents of the current globe were part of a single mass. The geological ages we obtained in our study indicate that the source rocks (mountains) formed during those time cycles,” explains Prof. Santanu Banerjee, a Professor at the Department of Earth Sciences at IIT Bombay.

These findings are important not just for academic curiosity but also to offer practical insights into regional geology and resources. The Saurashtra Basin, along with nearby basins like Cambay, Kutch, and Narmada, forms a part of India's western margins, which have been identified as potential sites for hydrocarbon resources. Knowing the origin of these sediments can, therefore, assist in exploration efforts and better management of these resources.

Moreover, the study also touches on larger geological phenomena, such as significant orogenies—mountain-building events—and tectonic configurations that shaped the earth’s crust. The sands from the Mesozoic era in Saurashtra capture a historical narrative of the
Bhilwara, Aravalli, and South Delhi orogenies. These events represent significant periods where the earth’s crust was dynamically altered due to tectonic activities, leading to the formation of mountains and other geological structures.

The team behind the study is looking to explore the minerals of the basin further to improve our understanding of the geological history of the region. “The next plan is to work in the same area to refine our understanding of the source areas and paleogeographic changes of that time. We must check whether the sediments were also sourced from Madagascar and Seychelles. We plan to contact ONGC to get seismic data for the study area to determine the basin configuration and trace sediments across the Arabian Sea,” shares Prof. Banerjee about future plans to continue the research.

Article written by:

Dennis C. Joy

Image/ Graphic Credit:

Lead image: Roy, A.B. and Jakhar, S.R., 2002. Geology of Rajasthan (Northwest India) Precambrian to recent. Scientific Publishers.

Inline image: PawanKumar Rajak

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Wed, 07/31/2024 - 12:00

Super-emitters on the road- A need for a comprehensive review of vehicular regulations

pro — Wed, 24 Jul 2024 10:13:54 +0000

Super-emitters on the road- A need for a comprehensive review of vehicular regulations pro Wed, 07/24/2024 - 15:43

Researchers from IIT Bombay study heavy polluters on the Mumbai-Pune Expressway and suggest the need for stringent policies to restrict vehicular pollution.

? ? ? ? ? ? ? ? ? ? ? ? ?Few identified super-emitters from the study. Credit: Authors of the study

The year 2023 shocked the globe as the hottest year in recorded history. The last 12 months have experienced the highest monthly temperatures ever recorded, and it looks like it is only going to get worse from here. With every passing year, the realities of climate change are being experienced globally, and the need for comprehensive climate action has never been greater. Air pollution, particularly airborne particles, contributes to climate and is associated with adverse health effects. According to the Global Burden of Disease Study (GBD, 2021), 16.7 lakh deaths have been attributed to air pollution in India.

Emissions from motor vehicles are major contributors to urban air pollution in India. Rapid urbanisation, leading to an increase in the number of vehicles on the road, is a cause for concern. Congestion increases the time spent on the road, leading to large amounts of fuel being burned, thus resulting in more pollution. However, the polluting characteristics of all vehicles are not the same. Some vehicles release disproportionately higher amounts of pollutants. A recent study from the Indian Institute of Technology, Bombay (IIT Bombay) investigates the factors determining the polluting characteristics of such high-emitting vehicles or super-emitters.

“Until now, there has been no study in India that has examined the share of super-emitters in real-world vehicular fleets. The previous studies assumed their share based on literature from other countries or secondary data. The motivation was to reduce uncertainty in the emission estimation from real-world vehicular fleets,” says Ms Sohana Debbarma, a researcher from the study who worked under the guidance of Prof Harish Phuleria and Prof Chandra Venkataraman.

Super-emitters are vehicles that are either old, poorly maintained, over-loaded heavy-duty vehicles or all of them. They release significantly higher amounts of pollutants compared to the other vehicles in the fleet. According to the IIT Bombay study, for light-duty vehicles (vehicles that weigh less than 3,500 kg such as cars, two-wheelers, three-wheelers, and light commercial goods vehicles), the age of the vehicles and the maintenance of the engine potentially determines whether the vehicle is a super-emitter. In the case of heavy-duty vehicles (vehicles that weigh more than 3,500 kg, such as buses and trucks), the overloading condition, along with the age and maintenance of the vehicles, contribute to the disproportionately high pollutant emissions.

Roadway tunnels offer ideal conditions for this study because of the confined space within the tunnel, which effectively traps the emissions from the vehicles, barring the influence of other ambient sources. It also has the added advantage of being able to collect data from a large vehicle fleet in a real-world scenario, as opposed to measuring emissions from a limited number of individual vehicles in a controlled environment in testing laboratories.

To conduct the study, the researchers set up their pollutant-measuring equipment at the entry and exit of the Kamshet-I tunnel located on the Mumbai-Pune Expressway. Along with exhaust emissions (resulting from incomplete combustion of fossil fuels), non-exhaust emissions (resulting from brake wear, tyre wear, road surface wear, and resuspension of road dust) were also collected. The traffic data was collected using high-definition video cameras and the vehicle registration numbers data (collected manually). The study collected data over two weeks.

The researchers identified super-emitters through manual inspection based on the video surveillance records of the traffic passing through the tunnel. Vehicles that emitted a visible plume of smoke or appeared to be overloaded were identified as super-emitters. It was also validated using the information on the age of the vehicles and type of emission technology: Bharat Stages (BS) - II, III, and IV (the study was conducted in 2019 when there were no BS VI vehicles) and the type of fuel (petrol, diesel, and CNG).

Monitoring equipment at the study location. Credit: Authors of the study

The researchers observed that the pollutant levels at the exit of the tunnel were significantly higher than those at the entry, and the tunnel exit captured the true signature of the vehicular emissions. While the traffic flow was the major determinant of pollutants at the exit, other surrounding factors influenced the pollutant levels at the entry, such as biomass burning from the neighbouring village. However, determining the difference in pollutant levels between the entry and the exit helped to effectively capture the impact of the traffic flow on the measured pollutant levels.

The IIT Bombay researchers estimated that super-emitters constituted an average of 21%(±3%) of the total vehicle fleet in the Kamshet-I tunnel, where 10%(±2%) of the fleet had a visible plume of smoke and 11%(±2%) were overloaded freight vehicles. The team developed a mathematical model to predict the share of super-emitters in any given real-world traffic in India by factoring in the shares of heavy-duty vehicles and light-duty vehicles, their respective ages, and fuel composition.

Old vehicles with engines that don’t comply with modern emission technologies and poor maintenance of relatively new vehicles could lead them to become potential super-emitters. Overloaded vehicles, especially heavy-duty vehicles, require additional fuel to power the vehicle,?leading to the release of higher pollutant emissions. Additionally, overloaded vehicles also cause higher non-exhaust emissions due to the higher road surface friction while moving. The Vehicle scrappage policy in India focuses on the scrapping of private and commercial petrol vehicles more than 15 years old and diesel vehicles more than 10 years old. However, the researchers did not find strict enforcement of these policies. Moreover, some of the relatively newer vehicles, likely due to poor maintenance, can lead to disproportionate pollution from a significant portion of vehicles in India.

The IIT Bombay study has highlighted the importance of enforcing strict regulations along with strengthening vehicle inspection and maintenance programs on India’s vehicle fleet with respect to super-emitters and their disproportionate release of pollutants. With over one-fifth of the vehicles in India being estimated to be potential super-emitters, it is high time the authorities take action. According to the Voluntary Vehicle Fleet Modernization Program (VVMP) published by the Ministry of Road Transport and Highways, the replacement of vehicles at the end of their lives will reduce vehicular pollution by 15-20%. However, this alone will not be sufficient because even a relatively new heavy-duty vehicle can be a super-emitter if loaded beyond its capacity or poorly maintained.

Recently, Nitin Gadkari, the Union Minister for Road Transport and Highways, has expressed an intention to completely phase out petrol and diesel vehicles and adopt alternatives, such as electric vehicles (EVs). The Union Government has created multiple incentives for both industries and consumers to promote the adoption of EVs in India.

“While the exhaust emissions can be controlled with the introduction of EVs, the non-exhaust emissions will still be of concern. There are still no emission standards for non-exhaust emissions in India,” concluded Ms Debbarma.

Article written by:	Balaram Vishnu Subramani
Image/ Graphic Credit:	Authors of the study
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Impact of real-world traffic and super-emitters on vehicular emissions under in…

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Wed, 07/24/2024 - 12:00

IIT Bombay develops a method for finding the optimum size for Fuel Cell Electric Vehicle components

pro — Tue, 23 Jul 2024 04:55:56 +0000

IIT Bombay develops a method for finding the optimum size for Fuel Cell Electric Vehicle components pro Tue, 07/23/2024 - 10:25

The proposed method optimises the weight, cost and range of FCEVs by determining the optimally required radiator size in the vehicles

Representative Image: Dennis Joy

A novel optimization methodology developed by Prof. Prakash C. Ghosh and Nadiya Philip, a Prime Minister’s Research Fellow (PMRF), from the Department of Energy Science and Engineering, Indian Institute of Technology Bombay (IIT Bombay), can recommend the ideal weight and size distribution for the components of a fuel cell electric vehicle, increasing their efficiency and helping expedite commercialisation.

Electric vehicles have gained massive popularity recently and are seen as the future of green mobility and a cleaner alternative to fossil fuels. Tesla, one of the most recognizable electric car brands, is already outselling many internal combustion engine cars globally. In India, the electric vehicle market share saw an increase of 41% in 2024, according to data from the government Vahan portal, with the majority of the sales being two-wheelers.

An electric vehicle can be of two types: Battery electric vehicles (BEVs) or Fuel Cell Electric vehicles (FCEVs), apart from hybrid vehicles that use a combination of any two types of engines. While a BEV uses batteries that need to be charged, FCEV uses fuel cells to power the vehicle. Fuel cells are electrochemical cells that use chemical energy to produce electricity. Hydrogen fuel cells are preferred in vehicles, and they combine stored hydrogen and oxygen from the atmosphere to produce energy. FCEVs are often referred to as zero-emission vehicles?because the only byproduct from the engine is water vapour. And?unlike BEVs, FCEVs do not need to be charged but refilled with hydrogen, much like filling fuel in a vehicle powered by an internal combustion engine.

FCEVs, however, are not without drawbacks. One of the downsides is the excess heat generated by a fuel cell. Because of the poor energy conversion of fuel cells, it produces as much heat as its power output. The excess accumulated heat reduces the performance of the vehicle and can even endanger the vehicle and its hydrogen storage tanks. This necessitates the use of massive radiators to cool the fuel cells which increases the weight and size of the vehicle.

Prof. Ghosh and Nadiya Philip from IIT Bombay have proposed a new thermal management system comprising a compact radiator and a thermal energy storage (TES) unit to address the issue of ‘oversized radiators’. The team has also developed a generic methodology for recommending the ideal sizes for the radiator and TES unit for optimal performance.

According to Nadiya, “the use of TES provides two main advantages: one, it stores some quantity of the thermal energy generated by the fuel cell stack, thus allowing a reduction in radiator size, and two, it maintains a constant temperature for the coolant (used to cool the fuel cell) entering back into the fuel cell. Additionally, the thermal energy stored in the TES system can be utilised for different applications like a cold startup, cabin heating, or preheating reactant gases (hydrogen and oxygen) for use in fuel cells.” Earlier studies by the same group have also found that by using paraffin wax as phase change material (PCM), similar to the material used in cold packs, the minimum required radiator area in light-duty vehicles like cars can be reduced drastically. So far, manufacturers of FCEVs have not considered the usage of a TES unit to reduce the size of their cooling systems.

Most FCEVs use an electrical energy storage (EES) system, which includes batteries or supercapacitors to store some of the energy generated by the fuel cell to complement that from the fuel cell alone. “The inclusion of EES systems in fuel cell vehicles helps to reduce the size of the fuel cell system by taking care of the dynamic load demands,” explains Nadiya. When accelerating the vehicle, while most of the power comes from the fuel cell, the EES provides the peak power, rescuing the power drawn from the fuel cell alone and allowing a smaller-sized fuel cell system.

The new IIT Bombay study is the first to consider the combined use of EES and TES to calculate the ideal sizes of each component, namely, the radiator, fuel cell, EES, and TES systems. The team used a mathematical technique called pinch analysis to determine the ideal sizes for these components. “Pinch Analysis is an algebraic optimisation technique that aims to meet the demands with minimum resources. Two pinch analysis optimizations have been used in the current study, (one) to size the power sources (fuel cell and battery) and (other) to size the thermal management system components (radiator and PCM),” explains Nadiya. The study integrates these components, fitting them together like puzzle pieces to create optimal energy storage and cooling systems.

Typically, the large-sized fuel cells account for a majority of the total mass of the power sources. As for the volume, out of the considered components, the radiator takes up the most space, while the battery takes up the least. In terms of cost, the fuel cell is significantly more expensive compared to the batteries. The results of this study for sizing also have implications for optimising the weight, volume, cost, and range of the vehicle. “If lowering cost is the primary objective, then the sizing combination with the lowest fuel cell size should be chosen. However, if cost is not a major concern, it is always better to go for higher fuel cell sizes to improve the fuel cell performance and to reduce the radiator size,” remarks Nadiya.

The researchers have estimated that the proposed method can allow a reduction of the radiator size in heavy-duty vehicles like trucks by almost 2.5 times lower than normal by simply optimising the sizes of the parts. This method can potentially direct how to optimally integrate different energy sources and thermal systems in fuel cell vehicles based on the manufacturer's preferences. Whether they want a low-cost vehicle with minimal range and power or a high-cost vehicle with higher range and power, the IIT Bombay method can help them choose the best solution possible. This research can aid in the design of more efficient and cost-effective cooling systems in such automobiles.

“Our next step would be a lab-scale experiment to study the effectiveness of the proposed thermal management system. Simultaneously the methodology will be tested with different drive cycles (different driving conditions) of longer durations, for a wide variety of operating conditions. Following this, we aim for real-time testing in vehicles,” concludes Nadiya about the future of the research.

Article written by:	Dennis Joy
Image/ Graphic Credit:	Dennis Joy
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Tue, 07/23/2024 - 12:00

Researchers from IIT Bombay harness the power of Silicon Nitride to optimize photonic technology

pro — Mon, 08 Jul 2024 12:06:12 +0000

Researchers from IIT Bombay harness the power of Silicon Nitride to optimize photonic technology pro Mon, 07/08/2024 - 17:36

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The researchers have developed a novel method of using silicon nitride to enhance the efficiency of photonic elements, promising faster, more secure, and energy-efficient technologies for communication and information processing.

Photonic technology manipulates photons (particles of light) in a similar way as electronic devices handle electrons. This emerging field promises faster, more secure and energy-efficient technologies. In a recent study, researchers from the Indian Institute of Technology Bombay (IIT Bombay) and Tata Institute of Fundamental Research (TIFR) have developed an innovative method using silicon nitride (SiN) to enhance the efficiency of photonic elements, which are the future of communication and information processing technology.

Typically, creating photonic elements involves complex fabrication and encounters certain challenges, such as poor stability and optical losses leading to low-efficiency performance. One of the main complications arises because the light source (emitters) and photonic elements consist of different materials. This poses a challenge known as poor "coupling efficiency" which means that the light from the source is not perfectly guided into the photonic element, leading to losses and degraded performance.

To address this, researchers have been exploring ways to use the same material for both the emitters and the photonic elements, a concept known as "monolithic integration". In this study, the team of researchers turned to silicon nitride (SiN), a material that has shown potential as a good single-photon emitter at room temperature. Silicon nitride has the added benefit of being compatible with current widespread semiconductor production techniques, known as CMOS technology.

Prof Anshuman Kumar Srivastava from IIT Bombay explains, “Silicon nitride stands as a pioneering material in the realm of nanophotonics, boasting well-established prowess in the construction of integrated photonics circuits. The prominence of this work stems from the innate emitters inherent within SiN.” By managing the manipulation and enhancement of these intrinsic emissions, scientists can unlock a vast array of solutions for integrated photonics applications. “This can help harness existing capabilities of SiN and pioneer novel avenues in photonics integration, promising groundbreaking advancements in optical technologies,” adds Prof Srivastava.

The latest research revolves around a SiN structure called a microring resonator, which serves as a "microcavity" where light can bounce around, effectively being trapped to stimulate its emission. This microcavity is engineered to host these so-called "whispering gallery modes" (WGMs), which are specific type of light pathways that go around the circumference of the microcavity.

“In simple terms, a whispering gallery mode is a phenomenon where sound or light waves travel around the inside of a curved surface, like the walls of a circular room or a sphere, without much loss in intensity. This creates a kind of "whispering gallery" effect, where whispers or light signals can be heard or detected from far away on the opposite side of the curve,” elaborates Mr Anuj Kumar Singh, the PhD student who co-led this work. This is similar to the case when one whispers close to one side of a curved wall, and someone far away on the other side can hear it clearly due to the way the sound waves bounce around the curve.

“In optics, light waves can travel along the curved surface, bouncing off the walls repeatedly, leading to highly confined and long-lived light paths, which can be useful in various applications like optical resonators, sensors, and lasers,” adds Mr. Kishor Kumar Mandal, the co-lead author of this work.

However, it is challenging to introduce and extract light from whispering gallery modes. The research team addressed this by creating a small notch in the microring. This notch functions as an entry point, facilitating the effective transfer of light in and out of the cavity. Using this approach, the scientists demonstrated an efficient coupling of these light emitters into the whispering gallery modes of the silicon nitride microring cavity. This breakthrough uncovered?new and effective means of extracting the trapped light, which had previously encountered significant challenges.

Schematic layout of coupled excitation and detection of cavity mode.?
Image credit: Authors of the study

Practically, this new method could mean that we may eventually be able to manufacture on-chip emitting devices for many photonic and quantum technologies without worrying about losses or instability. Like most electronic devices, this can lead to emitting devices also being integrated on a chip. The study has demonstrated the potential of silicon nitride to serve as a platform that can efficiently manipulate light on a very small scale.

Sharing insights on the research findings, Mr. Anuj Kumar Singh says that, “this work holds promise for several real-world applications in the near future like quantum computing, secure communications, and quantum sensing. While some applications may require additional research and development for practical implementation, others could be realized sooner.” Overall, the findings of this research present SiN as a key player in photonic technologies.

The manufacturing process using SiN comes with its drawbacks/errors, which can limit the performance of this novel technique. The researchers believe that improvements are possible in the material growth techniques and cavity design, leading to enhanced performance.

“Our research contributes significantly, by enabling efficient light-matter interaction, controlled quantum emission, enhanced photonic devices, simplified integration, and the potential for quantum computing in quantum photonics. These advancements pave the way for groundbreaking applications in secure communication, ultra-fast computing, and other transformative technologies that will shape the future of science and technology,” adds Mr. Kishor Kumar Mandal.

In simpler words, a high-speed, secure, and energy-efficient digital future might be closer than we think!

Article written by:	Sudhira HS
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Mon, 07/08/2024 - 12:00

A much needed analytical study for a more sustainable waste disposal in the healthcare sector in India

pro — Tue, 25 Jun 2024 05:25:47 +0000

A much needed analytical study for a more sustainable waste disposal in the healthcare sector in India pro Tue, 06/25/2024 - 10:55

New study at IIT Bombay identifies factors essential for successful adoption of a circular economy model for healthcare waste management in India.

Image Courtesy: Generated using Wepik AI image generator

In 2020, India produced 774 tons of biomedical waste per day. Additionally, large amounts of used, unused and infected medications, instruments, safety gear, and packaging materials are disposed of by individuals and healthcare centres. Safe disposal of healthcare waste is a concern as the special methods and technologies needed for it are not easily available. Public awareness and professional training regarding healthcare waste disposal is inadequate and funds for proper planning and implementation of effective waste management systems are not enough.

A ‘reduce-reuse-recycle’ approach, termed as circular economy model, helps avoid and mitigate pollution and environment damage which a ‘take-make-dispose’ approach is likely to cause. Though the effectiveness of the circular economy model is well-proven for efficient waste management and minimisation in the non-healthcare sector, it is not explored enough in the healthcare sector. Implementing it for healthcare waste management has its own challenges.

Dr. Anuj Dixit and Prof. Pankaj Dutta from the Shailesh J. Mehta School of Management, Indian Institute of Technology Bombay (IIT Bombay) carried out a study to identify the key factors for effective implementation of the circular economy model for healthcare waste management. Their research was published in the journal Clean Technologies and Environmental Policy.

The IIT Bombay researchers studied prior research related to the practices, factors and barriers in adopting circular economy models at different global locations in industries such as healthcare, medical devices, stainless-steel surgical instruments, plastic healthcare products and biomedical waste. Most of these were qualitative studies. “Various existing qualitative studies recommended the need for quantitative research within the healthcare sector to gain more insights into adopting circular economy in the domain,” explained Dr. Anuj Dixit while highlighting the need for analytical studies.

The researchers collected data about how the participants of the survey rate the importance of various factors such as awareness and training about waste management, budget, use of technology, waste segregation/collection, responsibilities of various stakeholders among others. This data was gathered through an objective questionnaire survey from medical practitioners and other professionals from 54 healthcare organisations in India. The organisations included hospitals, nursing homes, healthcare waste recycling units, pathological laboratories, and pharmaceutical companies in the private and public sectors operational for a minimum ten years with a minimum annual revenue of ?100 million, indicating growing organisations. “Our major challenge was to select appropriate health organisations according to their type and nature of healthcare waste,” Prof. Pankaj Dutta reported.

The researchers used a combination of well-established statistical techniques called ANOVA, F- DEMATEL and ISM, which gave qualitative as well as quantitative insights. Combination of these methods help prioritise contributing factors in a system, provide actionable insights and help decision-making in the face of uncertainty. The researchers believe that the conclusions drawn from this study offer a deeper, more structured, and analytically rigorous understanding of complex systems compared to simple surveys.

They identified 17 relevant and adequate factors called ‘critical success factors’ (CSFs) under five broad areas of impact—research and development, education and social behaviour, economic facets, responsibility, and tracking mechanism—called ‘implication dimensions’, critical to success of a circular economy model in healthcare waste management. The CSFs denote the actual activities to which the efforts can be allocated, and they include factors related to estimation, design, training, awareness, budget, responsibility and transparency to name a few.

Based on their analysis, the researchers further categorised the CSFs as causal and effect factors to offer better direction in planning for the implementation. Twelve CSFs were identified in the causal group, while the remaining five were in the effect group. The identified factors were also ranked depending on their impact intensity which can help in prioritising effort allocation during policy making.

Factors such as ‘government's responsibility’ and ‘stakeholders' participation’ were found to have the highest driving potential, whereas ‘segregation and collection’, though considered critical, were found to depend on other causal CSFs. ‘Information visibility and transparency’, ‘manufacturer/corporate responsibility’, ‘training and empowerment’ and ‘budget allocation’ were the factors found to impact healthcare waste management most.

Considering case-specific implication dimensions based on the goals of the policies, the efforts can be focused on the required factors. The research findings can help policymakers and Government bodies to create practical and feasible plans to enhance the success of the ongoing efforts for sustainable healthcare waste management.

The researchers believe that although the results obtained are specific to India, they can be useful for other developing economies as well. Including more experts and policy makers in the survey can broaden and strengthen the results.

“It is also important that when the circular economy model reaches a satisfactory level of success, the critical success factors must be re-evaluated,” concludes Prof. Pankaj Dutta.

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A 'Cooler' Alternative to Cool Supercomputers

pro — Tue, 11 Jun 2024 11:58:30 +0000

A 'Cooler' Alternative to Cool Supercomputers pro Tue, 06/11/2024 - 17:28

Researchers have developed ceramic-based cold plates that could replace copper cold plates used to cool computers and allow smaller and compact packing of circuit boards

?Credits: Image by Parikshit Badhe, edited by Scientifickly

Heat is an inevitable factor in the operation of any computing device, a familiar experience for all who have interacted with laptops, smartphones, or similar gadgets. The prolonged use or engagement in demanding tasks, such as gaming, often exacerbates this issue, leading to significant heat generation. Along with causing inconvenience to the user, this thermal build-up poses various risks to the device, ranging from performance degradation to potential hardware failures.

Every element within an electronic device, be it an integrated circuit, a resistor, or a capacitor, contributes to this thermal output, and necessitates maintaining an ideal operating temperature for optimal functionality. Exceeding this optimal temperature threshold jeopardises not only the individual components but also the overall device performance. Removing any excess heat is paramount to maintaining device performance and longevity.

Conventionally, smaller systems like laptops and mobile devices use small fans that circulate air through the system to remove any excess heat. Larger and more complex systems, like High-Performance Computing systems (HPCs) or supercomputers, resort to cooling using liquid coolants and cold plates that dissipate heat. In a recent study, a team of researchers from the Indian Institute of Technology, Bombay (IIT Bombay) and the Centre for Materials for Electronics Technology (C-MET), Pune have proposed using Low-Temperature Co-fired?Ceramic (LTCC) as an efficient alternative to the conventionally used copper for making cold plates.

In liquid-cooled devices, liquid coolants like deionised water (water without any electrical charge) are circulated through the system to remove the excess heat. Cold plates are used like a heat sink transferring the heat from the circuit components into the coolant liquid. Copper is the preferred material for manufacturing cold plates, due to its low cost and high thermal conductivity. “Copper cold plates are extensively utilised for cooling in HPCs owing to their high thermal conductivity. However, there are limitations associated with copper, such as its weight, susceptibility to corrosion, and challenges in intricate design implementations,'' explains Parikshit Badhe, Senior project associate and a student at the Department of Mechanical Engineering at IIT Bombay who worked under the guidance of Prof. Shankar Krishnan and Prof. Milind Atrey from IIT Bombay.

LTCC is a technology used to manufacture ceramic substrates for circuits. Substrates are materials on which electrical interconnections are printed and other components like resistors, inductors and capacitors are mounted. PCB (Printed circuit boards) is the most commonly used substrate in our daily life electronic devices. LTCC Technology allows compact three-dimensional packing of the circuit, making them smaller and more efficient compared to conventional PCBs. “LTCC technology is already an established manufacturing method for ceramic printed circuit boards. LTCC substrates are extensively used in electronic equipment expected to endure high temperatures, such as automotive and defence equipment,” remarks Parikshit.

This new study demonstrates that microfluidic channels (micrometre-sized tiny channels that allow flow of a liquid through it) can be created in an LTCC package to form a cold plate. Thermal testing of these cold plates has shown that they can effectively cool microprocessor chips in supercomputers, successfully restricting temperatures below the safety limits, just as copper cold plates do. This proof-of-concept demonstration is a breakthrough finding that paves the way for integrating cooling solutions directly into the chip package. Essentially, this research validates the concept that if a chip is made using LTCC technology, microfluidic channels can be incorporated into the same package, enabling localised cooling of hot regions by allowing the coolant to penetrate deep into the chip package.

LTCC, though, has a big challenge - its thermal conductivity is poorer (100 times less) compared to copper. This means it is relatively less efficient at conducting heat, which is the key function in cooling systems. The researchers have overcome this hurdle by drilling tiny holes filled with metal, called thermal vias, into the LTCC cooling plate. A team of researchers headed by Dr Shany Joseph from CMET-Pune was instrumental in fabricating these cold plates in their lab. According to Parikshit “thermal vias are strategically incorporated into the bottom layer of cold plates to facilitate efficient heat transfer from the chip to the coolant via the microchannels embedded within the cold plate”. Owing to the thermal vias, the LTCC's thermal conductivity improved and the thermal resistance dropped by a whopping 43%.

Another challenge of using LTCC cold plates is their tendency for cracking and fracturing. “LTCC, being a ceramic material, is prone to cracking under uneven tensile loading. To address this issue, a novel clamping mechanism was developed to ensure that the cold plates remain intact without experiencing uneven cracking while fully loading the cold plates on live boards,” says Parikshit.

The team tested the performance of the LTCC cold plates on an Intel? Xeon? Gold 6154 CPU with deionised water as the coolant and compared its performance to that of the copper cold plates. The team also tested two flow patterns - called JI and MC, which determine how the liquid enters and flows through the LTCC cold plates. “In the MC flow arrangement, the coolant enters from an inlet on one side and exits from the outlet at the other side. In the JI flow arrangement, the fluid enters from the inlet at the centre and leaves from the two outlets at the sides,” explains Parikshit. While the MC arrangement allows the coolant to flow the entire length of the cold plate, the JI arrangement allows for localised cooling of a hotspot. LTCC cold plates successfully restricted the temperature of the processor below the safety limit at full processor power with both flow patterns.

MC and JI Flow arrangements on an LTCC cold plate. Credits: Parikshit Badhe.

Going forward, the team is looking at further improving the design and functionality of the LTCC cold plates. “Presently, the designed cold plates are tailored for a 200 W processor range. However, exploring the potential of electroplating at the base of the cold plate to enhance heat spreading can be investigated. This would allow the cold plates to accommodate higher heat inputs effectively,” remarks Prof. Atrey about the future direction of their work. If commercialised successfully, LTCC-based integrated cold plate technology has the potential to replace conventional cooling systems and chip packaging that are used today. More importantly, demonstrating the use of LTCC cold plates for existing supercomputer chips marks a significant breakthrough in the ongoing research on 3D Integrated Circuits.

Article written by:	Dennis Joy
Image/ Graphics Credit:	Parikshit Badhe and Scientifickly
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New IIT Bombay study could help improve cooperation amongst robots

pro — Thu, 02 May 2024 04:26:15 +0000

New IIT Bombay study could help improve cooperation amongst robots pro Thu, 05/02/2024 - 09:56

Novel algorithms allow real-time monitoring and dynamic task allocation to significantly improve cooperation among autonomous robots

Humans have built mechanical devices to overcome their limitations since the dawn of civilization. From the simple water wheels that were used to harness the power of flowing water, to weapons of war like the trebuchet or mangonel, that used mechanical power to hurl large boulders at enemies, humans have always resorted to machines. The Industrial Revolution and the advent of assembly line production saw robots replacing humans in various tasks in manufacturing and defence. Today, automated robots have become ubiquitous, performing tasks that may be mundane, tricky or dangerous for a human - from cleaning our dishes and building cars to clearing land mines and even exploring the cosmos.

As the complexity of tasks is increasing, multiple robots with the same features or each with a unique set of features are often deployed to perform a single task. In such tasks involving cooperation, various robots involved in performing them are required to coordinate their moves efficiently. Keshab Patra at the Indian Institute of Technology Bombay (IIT Bombay), under the guidance of Prof. Anirban Guha and Prof. Arpita Sinha, has been studying such cooperative robots. In a recently published study, Keshab and team have developed a novel technique that improves the efficiency of such robots, by helping them communicate with each other in a more efficient manner than earlier.

In their new study, the IIT Bombay team proposes three novel algorithms that help robots determine their task capability in real-time, allowing them to dynamically allocate tasks based on their individual strengths and limitations. “Imagine two similar robots carrying an object.
Sometimes because of small changes in the environment, like an uneven floor or the shape of the object, one robot may have a better grip on the object than the other. Our algorithms help identify these changes and make real-time adjustments to improve performance,” explains Keshab. The algorithm identifies less capable robots, thereby enabling task reallocation or determining the number of required robots for efficient utilisation of the robot group.

The algorithms, residing on the robots and a central monitoring computer, collect data from each of the robots in the group in real-time to make decisions. The first algorithm, called TaskCapability, assesses each of the robots in the group and determines various parameters, like grip strength and stability, and assigns a value to them. Next, the second algorithm, called Online Task Capability, compares the parameters with other robots to determine which of the robots are underperforming. Finally, the third algorithm named Online Task Allocator, uses the information from the other two algorithms to determine how many robots are needed and what task each should perform.

The set of three algorithms ensures a balanced workflow where each robot contributes according to its ability, leading to an overall boost in productivity. Moreover, the real-time communication between various robots also helps to minimise the chance of errors and robot collisions, enhancing their cooperative work. Conventional algorithms, on the other hand, generally use pre-programmed robots, wherein the path and performance of the robot are programmed even before it starts the task, with very few real-time manipulations. The algorithms that do allow for dynamic task allocation also rely on complex calculations, increasing their computation time.

The team tested their new method on two well-known industrial robots - UR5 and Franka-Emika Panda. They demonstrated that the new algorithm was much faster at performing tasks than conventionally used algorithms, like Skuric and Sasaki. “Our algorithms performed 15 times faster than Skuric and 8 times faster than Sasaki when performing the same task,” exclaims Keshab. The team verified the efficiency of their algorithm with four robots in the group. An increase in the number of robots in a group could affect the performance of the third algorithm, which resides on a central computer, because communication between the robots and the computer might be delayed. However, according to Keshab, “The computational data from our four robots group study indicates we can scale it to 2-3 times without any changes in the algorithms and real-time performances.”

The new algorithm also significantly reduced the computation time of the robots by 85%, enabling real-time adjustments in cooperative operation. “Our algorithms are truly innovative compared to conventionally used ones because those (conventional) are much more computationally intensive. This makes our method much faster and more efficient in task allocation in response to real-time changes,” remarks Prof. Guha.

The new algorithms, if implemented, could significantly boost the performance of cooperative robots by speeding up the task and removing inefficient and redundant robots from the task. Imagine this in a context such as a car assembly line manufacturing, where robots work
meticulously together to assemble parts of a vehicle. Each robot has unique capabilities, and to maximise efficiency it is essential to smartly distribute tasks, optimising each robot's unique abilities.

Utilising an innovative real-time algorithm like the one proposed in the study, robots can determine and adapt their task executions according to live changes in the circumstances. Providing robots with the capability to dynamically determine their task capabilities and allocate tasks accordingly could revolutionise how tasks are assigned and performed in complex automated machines and systems.

Article written by:	Dennis C Joy
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IIT Bombay’s new thermally insulating coating material shows record heat shielding

madhuriw — Fri, 23 Feb 2024 06:25:47 +0000

IIT Bombay’s new thermally insulating coating material shows record heat shielding madhuriw Fri, 02/23/2024 - 11:55

The new surface coating reduces the temperature under a coated material by up to 21 degree Celsius and can resist corrosion.

2023 was the second hottest year on record in India since 1901, reported the India Meteorological Department (IMD). Globally, owing to climate change, temperature rise has been consistent with each passing year. This rapidly rising temperature has driven the need for innovative and affordable solutions for thermal insulation and space cooling, that is cooling the insides of our homes and offices.

Cooling a room can be achieved in two ways: active and passive cooling. Active cooling involves the use of devices, like air conditioners and coolers, to actively remove heat from a room, thus reducing the temperature. This method inevitably relies heavily on energy, increasing global energy consumption, while also contributing to increased CO2 emissions. Passive cooling on the other hand relies on innovative design and materials that limit the heat of the sun from entering a space, thus avoiding or reducing the need for active cooling. Passive cooling relies on insulating materials like fibreglass or polystyrene or innovative architecture that increase air flow, to keep the heat out, but can often involve regular maintenance and upkeep costs.

Now, in a breakthrough in passive cooling, a team of engineers from the Indian Institute of Technology, Bombay (IIT Bombay) led by Prof. Smrutiranjan Parida from the Metallurgical Engineering and Material Science Department, has developed a new type of coating material that can effectively reflect the sun’s heat and reduce the amount of heat absorbed by the material, thus providing thermal insulation. The material is a hydrophobic (water-repelling) epoxy composite coating with fillers, which reduces heat conduction and imparts high infrared reflectance in a thin coating of just about 65 micrometres. “Our work mainly prepared ‘active additives’ (called fillers), which can be added to a suitable resin to make a temperature shielding coating,” says Prof. Parida. The innovative coating also protects against corrosion, making it an ideal solution for cooling our living spaces.

Schematic representation of thermally insulating coating material

Central to the success of the coating is the addition of two types of fillers. The first filler is made up of micron-sized silica-modified hollow microspheres (sHMS). The second filler, comprising surface-modified TiO2 nanoparticles, plays a pivotal role due to its high solar reflectance, meaning it can bounce back a significant amount of the sun's heat. “The hollow microspheres have a very low thermal conductivity due to their hollow air-filled structure. The presence of this component in the coating prevents the transfer of heat through the coatings and the TiO2 component is well-known for its higher solar reflectance (>85%),” explains Prof. Parida.

The surface modification made to the hollow microspheres and the TiO2 increases the ability of the two components to reduce thermal conduction and reflect sunlight. Both the fillers are added to a resin (a viscous liquid substance), such as epoxy, which can then be coated onto the surface of a material like concrete or metals, much like a layer of paint. “For coating of metals, resins like acrylics or polyurethane can be used instead of epoxy resins,” remarks Prof. Parida about the different base resins that can be infused with these fillers.

The researchers conducted tests where a coated surface was irradiated using an infrared (IR) lamp, placed at a location giving 60 °C on the surface of the coated metal panel. The novel composite coating on the surface decreased the temperature under the coated panel by 15 to 21
°C. This performance is better than any previously reported coatings. The composite coating also boasted a high solar reflectance of sunlight in the near-infrared (NIR) region of the
spectrum, exceeding 72%. At a thickness of just 0.065 to 0.1 millimetre when coated onto a surface, the new material can outperform other coatings that are usually three to twenty times thicker, making the new coating not just more efficient but also cost-effective.

Interestingly, owing to the surface modifications of its materials, the composite coating also proved extremely resistant to corrosion. In tests involving exposure to Sodium Chloride (NaCl) solution, a kind of salt-water test, the coating revealed an incredible 99% corrosion protection efficiency. This demonstrates that the coating can protect metal surfaces from the deteriorating effects of their environment, increasing longevity and decreasing maintenance costs.

The use of low-cost materials such as hollow microspheres, and a simple manufacturing process also ensures an economically viable product in the market. “The coating development procedures, including the surface modifications of the fillers, are easy to adopt, single-step, and do not require complex instrumentation. The hollow microspheres used are inexpensive and can be obtained from the industrial waste of coal plants, providing an effective waste management solution for coal plants,” remarks Prof. Parida about the additional advantages of the coating.

Prof. Parida and his team are now looking to add new features to their coating material, such as adding fire-retardant properties. They are also investigating the production of a VOC (volatile organic compounds)-free waterborne coating system to make it more environmentally friendly.

As we adapt to our changing environment and energy demands, innovative solutions like these are the need of the hour for the preservation and conservation of our natural resources, along with the reduction of harmful emissions and waste.

Article written by	Dennis C. Joy
Image/ Graphic credit	Lead image: Moralist, CC BY 3.0 via Wikimedia Commons Inline image: Prof Smrutiranjan Parida
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