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Water Today Title May 27, 2024

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Update 2020/2/4


By Suzanne Forcese

As a Doctoral student at Cal-Tech University in 1989, Distinguished Professor of Mechanical and Industrial Engineering at Northeastern University, Dr. Yiannis Levendis had been living in Pasadena, California, for five years when a group of friends asked him to go hiking in the mountains. His response was, “What mountains?”

The San Gabriel Mountains are an hour’s drive from Pasadena but a thick blanket of industrial smog had obscured them from view for his entire residency in California.

He knew he was in the right place. Levendis had wanted to do his research in the most polluted city he could find – one that was just as polluted as his native Athens, Greece.

“Ever since I can remember, I have wanted to do something about the environment,” Dr. Levendis told WaterToday in a captivating interview.

Professor Yannis Levendis

A leading authority in combustion and emissions, specializing in Energy Harvesting, Combustion and Air Pollution as well as Fire Containment and Extinction, Dr. Levendis was recently elected as a Fellow to the National Academy

of Inventors, an honor reserved for individuals whose inventions “have made a tangible impact on quality of life, economic development and the welfare of society.”

In his life-long commitment to protect the environment Dr. Levendis has acquired over 200 patents of engineering solutions, including specialized ceramic filters to clean both oil and gas emissions.

He has also designed a combustion system that burns waste plastics for fuel as cleanly as natural gas and has the added capability of producing carbon nanotubes that can be used in many applications including electronics, optics and nanotechnology.

“Only about 8% of plastic waste makes its way to recycling. The rest makes its way to landfills where it is burned, creating extremely pollutant by-products. Eventually those toxins seep into our groundwater, our waterways and finally the oceans. There is even plastic in our food. I wanted to find an alternative.”

Dr. Levendis and his team have added a step to the combustion process of plastic waste. “Pyrolytic gasification.” A reactor heats the plastic to 800° Celsius in a completely oxygen free environment. “This causes the plastic to become gas (up to 96%) which is then mixed with air before it can be burned as a clean fuel.”

Another surprising result occurred when “we added a bit of stainless steel into the reactor we found it acted as a catalyst for growing uniform carbon nanotubes. Not only can our plastic waste problem be rerouted to generate clean fuel, it can also be upcycled to generate one of the market’s most popular new materials.”

“The inspiration behind my research is the quest to develop clean, cost-efficient power sources in the face of dwindling fossil fuel reserves.”

Dr. Levendis and his research team have also shown that the same process works for burning biomass, a leading alternative fuel source that is rapidly gaining traction.

“We’re looking to substitute coal with renewable biomass and waste biomass for fuel.” Coal burning releases a number of harmful pollutants as well as excess carbon dioxide. Many of the potential fuels come from corn stalks and rice husks. Burning plant waste still creates carbon but “since plants take in carbon dioxide as they grow, burning the waste creates a carbon neutral position,” Dr. Levendis said.

He is also putting out fires.

Industrial fires, whether they occur in a power or chemical plant, a fuel storage site or a warehouse are frequently difficult to control and often these types of fires burn for a sustained period of time posing environmental threats. The use of water or chemical extinguishants to control such fires can cause extensive water damage, air pollution or underground water contamination posing considerable risks to water resources and ecosystems.

“We are using liquid nitrogen (a cryogenic fluid). Dangerous fires can be extinguished instantaneously with direct application of liquid nitrogen. And there’s no environmental damage because it vaporizes back to nitrogen gas immediately.”

A single cup of liquid nitrogen can put out a square metre of burning diesel fuel. “In principle nitrogen may be applied to many types of fires both open and closed. Established technologies already exist and installations are in place for the production, handling, distribution and storage of liquid nitrogen. It is also safe for the environment and inexpensive. Applying liquid nitrogen directly on a burning surface causes an abrupt phase change and subsequently a thermal expansion occurs, forming a cloud over the surface. The fire is starved and re-ignition is impeded.”

Dr. Levendis is also working at suppressing and extinguishing forest fires with liquid nitrogen. “It is an ecological disaster witnessing the fires burning in the world today. If we can do anything to minimize the destruction and pollution of our air and water, we have to do it.”

Certainly there are some obvious limitations – the cryogen (liquid nitrogen) should be applied to locations it the absence of living beings since it is both a freezing and asphyxiating agent.

Forest fires are becoming increasingly frequent catastrophic events. Global population and concomitant energy consumption are growing at a fast pace causing encroachment into forested lands, global climate change and droughts. Extreme weather conditions tend to make wildfire events more frequent and more severe year after year. An example of the devastation wrought by a wildfire event is evidenced in the 2016 fire in Fort McMurray, Alberta where 570,000 acres burned; 2,400 buildings were destroyed at an estimated insurance loss of $9 billion; and 88,000 people were evacuated. Such fires point to the urgent need for wildfire control.

“Current fire containment methods cannot keep pace with the number and intensity of forest fires seen today.” Dr. Levendis and his research team have developed a two-phase system. First liquid nitrogen is introduced to suppress the flames followed by an application of water to extinguish any smouldering wood. This proposed sequential approach is expected to maximize the amount of water that reaches a fire.

“The effectiveness of this method has been demonstrated in expedient suppression and extinguishment of pool fires of hydrocarbon fuel,” Dr. Levendis states.

“It is expected that application to forest fires will be particularly challenging because such fires become deep-sited in the burning wood. Extinction of the pyrolizing wood flames can still leave smoldering chars burning behind. It would be prudent to confine this fire suppression technique to addressing only limited areas of critical need, such as critical infrastructure.”

Although not yet tested on wildfires, Dr. Levendis has designed insulated capsules of cryogen for aerial delivery to a fire site. Their particular shape and design would facilitate the gradual dispersion of the cryogen onto burning trees and address all sections of a forest fire – the crown, mid-level and surface sections.

The catastrophic ecological destruction caused by wildfires also threatens infrastructure and communities. Dr. Levendis is presently working on solutions to protect houses and other buildings. “We are using fire nets to cover the buildings. They are metallic blanket screens that can intercept flying embers. Usually in a forest fire it is the embers transported by the wind that threaten communities. We are still working on this as we have to determine a few factors.”

It would appear the fervor to make a difference in the challenges of our world is an ever- evolving work in progress for this Distinguished Professor.

He may be putting out the fires of climate change and pollution but true to his word, Dr. Yiannis Levendis is not extinguishing his passion “to do something about the environment.”



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