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Getting Rid Of Hydrogen Sulfide | Earth Wise

December 20, 2022 By EarthWise Leave a Comment

Hydrogen sulfide gas produces the characteristic smell of rotten eggs, sewers, stockyards, and landfills. The petroleum industry produces thousands of tons of the stuff each year as a byproduct of the processes that remove sulfur from petroleum, natural gas, coal, and other products. The industry faces substantial fines for emitting hydrogen sulfide, but remediation is expensive.

Researchers at Rice University have developed a method for turning hydrogen sulfide into hydrogen gas and sulfur in a single step. Called plasmonic photocatalysis, it not only gets rid of an undesirable substance, it does so by producing valuable byproducts.

The established way of getting rid of hydrogen sulfide is called the Claus process. It requires multiple steps, including some that require combustion chambers heated to 1,500 degrees Fahrenheit. The end product is sulfur and water.

The Rice University process gets all of its energy from light. A surface of grains of silicon dioxide is dotted with tiny gold nanoparticles. These particles interact strongly with a specific wavelength of visible light and cause plasmonic reactions that create short-lived, high-energy electrons that drive the catalysis of hydrogen sulfide. Given that the process requires only visible light and no external heating, it should be relatively straightforward to scale up using solar energy or very efficient LED lamps.

The new hydrogen sulfide remediation technology has been licensed by a Houston-based startup company with more than 60 employees whose founders include some of the Rice researchers. The process may end up being efficient enough and cheap enough for cleaning up non-industrial sources of hydrogen sulfide such as sewers and animal waste.

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New catalyst can turn smelly hydrogen sulfide into a cash cow

Photo, posted July 8, 2021, courtesy of Doug Letterman via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Capturing Carbon Dioxide With Plastic | Earth Wise

May 11, 2022 By EarthWise 2 Comments

The world is awash in both waste plastic and in carbon dioxide emissions. Researchers at Rice University have discovered a chemical technique for making waste plastic into an effective carbon dioxide absorbent for industry.

Chemists at Rice reported in the journal ACS Nano that heating plastic waste in the presence of potassium acetate produces particles with nanometer-scale pores that trap carbon dioxide molecules. According to the researchers, these particles could be used to remove CO2 from the flue gas streams of power plants.

Significant sources of CO2 emissions like power plant exhaust stacks could be fitted with this waste-plastic-derived material to absorb large amounts of carbon dioxide that would otherwise enter the atmosphere.

The Rice University process is an enhancement to the current process of pyrolyzing waste plastic – that is, breaking it down in the presence of heat. By pyrolyzing plastic in the presence of potassium acetate, porous particles are formed that can hold up to 18% of their own weight in carbon dioxide.

According to the researchers, the cost of capturing carbon from a power plant would be $21 a ton, which is far less expensive than existing energy-intensive processes used to pull carbon dioxide from natural gas feeds.

The sorbent material can be reused. Heating it to about 167 degrees Fahrenheit releases trapped carbon dioxide from the pores and regenerates about 90% of the material’s binding sites.

The Rice process may represent a much better way to capture carbon dioxide from power plant exhaust stacks. It could be a way to make use of one environmental problem – waste plastic – to deal with another one.

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Treated plastic waste good at grabbing carbon dioxide

Photo, posted April 19, 2021, courtesy of Ivan Radic via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Destroying Forever Chemicals | Earth Wise

August 11, 2020 By EarthWise Leave a Comment

PFAS, short for poly and perfluoroalkyl substances, have been used in commercial products since the 1940s. There are more than 4,000 different chemicals in the class. Some of the most commonly used PFAS chemicals, like PFOS and PFOA, have long half-lives, which has earned them the moniker “forever chemicals.”

These dangerous chemicals have not been manufactured in the U.S. since the early 2000s, but they can still be found in various imported goods. PFAS chemicals have been linked to cancer, birth defects, thyroid disease, and liver damage. These forever chemicals linger in the environment and scientists have found them in the blood of virtually all Americans.

Researchers at Rice University have recently discovered an efficient catalyst for destroying PFAS forever chemicals. Unexpectedly, the catalyst was actually in the control group in a study they were performing.

The study, published in the journal Environmental Science and Technology Letters, found that boron nitride, acting as a light-activated catalyst, destroyed PFOA at a faster clip than any previously reported photocatalyst.

The catalyst, boron nitride powder, is a commercially available synthetic mineral that is widely used in makeup, skincare products, thermal pastes for cooling computer chips, and various other industrial products. The discovery began with dozens of failed experiments on a variety of more promising PFAS catalysts. But along the way, they found that the boron nitride control material repeatedly yielded positive results.

The research has already attracted the attention of industrial partners seeking to develop off-grid water treatment systems that both protect human lives and support sustainable economic development.

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Boron nitride destroys PFAS ‘forever’ chemicals PFOA, GenX

Photo, posted April 9, 2009, courtesy of Rex Roof via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

The Problem Of Gas Flaring | Earth Wise

January 9, 2020 By EarthWise Leave a Comment

Gas flaring is the burning off of flammable gas released by pressure relief values during over-pressuring of plant equipment at petroleum refineries, chemical plants, natural gas processing plants, and a variety of oil and gas production plants. Flaring is also used during plant startups and shutdowns.

A new study by Rice University concludes that reducing gas flaring would benefit both the environment and the economy. Flaring and venting of gas in West Texas’s Permian Basin and certain other parts of the U.S. have reached levels that the intended result of burning gas to allow oil extraction now looks more like wasting one resource to produce another.

At current rates, enough gas is flared in the Permian Basin to yield nearly 5 million metric tons of exportable liquid natural gas if it was captured and liquified. At these rates, the wasted gas could fill the largest sized LNG carrier every ten days. If that liquified natural gas was exported to China and used in a power plant, it would displace 440,000 metric tons of coal burned to generate electricity.

Burning natural gas to heat homes, power industrial processes, or generate electricity all emit carbon dioxide, but at least these things also perform valuable functions. Flaring gas produces CO2 as well as other combustion products but doesn’t even do anything useful. The venting of unburned gas, which also takes place with some frequency, is even worse since it is dumping methane directly into the atmosphere.

Across the U.S., some 14.1 billion cubic meters of natural gas was flared in 2018, equivalent to nearly 9 million metric tons per year of LNG. In energy terms, that is equivalent to more than one-third of the total LNG volume U.S. firms actually exported that year.

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Reducing gas flaring will benefit economy and environment, says Baker Institute expert

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Earth Wise is a production of WAMC Northeast Public Radio.

Safe And Simple Hydrogen Peroxide

November 29, 2019 By EarthWise Leave a Comment

We don’t think about hydrogen peroxide very often. Perhaps we have a bottle of it under our bathroom sink that we haven’t touched in a few years. But it is an important product manufactured in the millions of tons each year and the basis of a $6 billion global business.

Hydrogen peroxide is widely used as an antiseptic, a detergent, in cosmetics, as a bleaching agent, in water purification, and in many other applications. It is produced in industrial concentrations of up to 60% in solution with water in order to maximize the economics of transportation. This makes transportation hazardous and costly because the concentrated form is unstable. Most applications use a far more diluted form.

Researchers at Rice University have developed a new method for producing hydrogen peroxide that is much simpler and safer than the current technology, which actually dates back to the 1930s. The Rice technique requires only air, water and electricity to produce the chemical. The electrosynthesis process, which is detailed in the journal Science, uses an oxidized carbon nanoparticle-based catalyst.

The process could enable point-of-use production of pure hydrogen peroxide solutions, which would eliminate the need to transport the hazardous concentrated chemical. The use of a solid electrolyte instead of the traditional liquid electrolyte eliminates the need for product separation or purification that is part of the current technology.

In the future, instead of storing containers of hydrogen peroxide, hospitals that use it as a disinfectant could turn on a spigot and get, for example a 3% solution on demand. Instead of storing chemicals to disinfect swimming pool water, future homeowners could flick a switch and turn on their peroxide reactor to clean their pools.

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Water + air + electricity = hydrogen peroxide

Photo, posted April 19, 2009, courtesy of Robert Taylor via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

More Renewables Without Storage In Texas

February 27, 2019 By EarthWise Leave a Comment

Texas has a Texas-sized appetite for electricity and relies most heavily on natural gas, coal and nuclear power to get it. But in recent times, wind power has grown tremendously in the Lone Star State and it has already leapfrogged past nuclear power. Coal could be the next domino to fall.

In the past few years, solar power has become competitive with wind in terms of price. Texas is a large, coastal state in the sunny southwestern U.S. and has significant solar resources. As a result, the amount of solar power in Texas is now growing rapidly.

In order for a combination of solar and wind power to address the bulk of electricity demand in Texas, there needs to be a way to provide reliability that these intermittent sources don’t necessarily provide. Energy storage is a solution that ultimately is likely to be part of most electricity grids, but currently it is still expensive on a utility scale.

A new study from Rice University looked at the complementarity of solar and wind power in Texas. Complementarity refers to balancing the output of solar and wind systems. The peak performance of wind and solar occurs at very different times in different regions of the state. The study suggests that the right mix of solar and wind systems in the right parts of Texas could provide a continuously reliable energy system. On both a yearly and daily basis, wind and solar power resources in Texas complement each other in terms of peak performance. It is a matter of locating the solar power and wind farms in the right places.

With the Texas solar industry really starting to boom, there is a real opportunity to integrate far more renewable energy into the Texas grid.

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More Renewables with Less Energy Storage: Texas Shows How

Photo, posted June 8, 2018, courtesy of Laura Lee Dooley via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.