#hydroxyl radicals

[biology-geology-beaches-india]

The Science Research Diaries of S. Sunkavally, page 346.

[tenth-sentence]

In the same manner as hydroxyl, the nitrate radical is able to add to the double bond of olefins:

"Environmental Chemistry: A Global Perspective", 4e - Gary W. VanLoon & Stephen J. Duffy

[whats-in-a-sentence]

ROS generation occurs in several cellular compartments and as a result of the activities of specialized oxidases, such as NADPH oxidases, amine oxidases, and cell wall-bound peroxidases (Table 24.2).

"Plant Physiology and Development" int'l 6e - Taiz, L., Zeiger, E., Møller, I.M., Murphy, A.

[mindblowingscience]

How OH itself forms in the atmosphere was viewed as a complete story, but in new research published in Proceedings of the National Academy of Sciences, a research team that includes Sergey Nizkorodov, a University of California, Irvine professor of chemistry, report that a strong electric field that exists at the surface between airborne water droplets and the surrounding air can create OH by a previously unknown mechanism.

It's a finding that stands to reshape how scientists understand how the air clears itself of things like human-emitted pollutants and greenhouse gases, which OH can react with and eliminate. "You need OH to oxidize hydrocarbons, otherwise they would build up in the atmosphere indefinitely," said Nizkorodov.

"OH is a key player in the story of atmospheric chemistry. It initiates the reactions that break down airborne pollutants and helps to remove noxious chemicals such as sulfur dioxide and nitric oxide, which are poisonous gases, from the atmosphere," said Christian George, an atmospheric chemist at the University of Lyon in France and lead author of the new study. "Thus, having a full understanding of its sources and sinks is key to understanding and mitigating air pollution."

Continue Reading

[tearsinthemist]

The invention is a powder that almost instantly kills thousands of waterborne bacteria when simply mixed with water and exposed to normal sunlight for a few seconds. It consists of nano-sized flakes of aluminum oxide, molybdenum sulfide, copper, and iron oxide, which combine with sunlight to form hydrogen peroxide and hydroxyl radicals, Phys.org reported.

These newly formed chemical byproducts work quickly to kill off any bacteria and then dissipate just as quickly.

The powder has several advantages over existing methods of cleaning drinking water. It does not use any chemicals that create lasting toxic byproducts, and it does not require ultraviolet light, which takes a long time and requires electricity, according to Phys.org.

In addition, the powder is recyclable. It can be removed from the now-clean water with a magnet, and researchers were able to reuse the same powder 30 times.

[imaec-digital]

Cidaltek W10

Description:

Proper disinfection and cleaning of dental work surfaces are vital in preventing infectious pathogens’ transmission to healthcare workers and patients. The CDC defines disinfection as the destruction of pathogenic microorganisms, physically or chemically. It offers guidelines on environmental surface disinfection for dental offices. Environmental surface disinfection is the cleaning and disinfecting of non-critical environmental surfaces using low-level to intermediate-level surface disinfectants.

CidalTek-W10 is a multi-component disinfectant containing Hydrogen peroxide as an oxidizing agent with combination of stabilizing agents to form a complex solution. A long-lasting disinfectant effect is achieved with addition of silver ions to the formula. It is Non-Carcinogenic, Bio-Degradable, Eco-friendly, and most importantly easy to use highly effective in dental clinic & dental labs.

Composition: Each 100 ml contains

Salient Features:

Broad spectrum against micro-organisms

Penetrates the biofilms formed by microorganisms

Sporicidal in action

Environment friendly & Bio-degradable

Non-Carcinogenic

Generates highly reactive hydroxyl radical in synergy with Ag+

Tasteless, Colorless & Odorless disinfectant

No toxic disinfection by-products

Direction Of Use:

For Surface & Environmental Disinfection

Add 100 ml (10%) of CidelTek-W10 disinfectant to 900 ml of water and mix well, apply on surface for 30 min contact time.

For Sporicidal action on surface use 20% Conc. Solution of CidalTek-W10 for 60 min contact time.

After thoroughly wetting the surface with lint free cloth, mop, sponge.

Treated surface must remain wet for respective contact time & allow to air dry.

Use 2-3 Bucket system for surface cleaning & disinfection

For Aerial Disinfection

Add 200 ml (20 %) of CidalTek W10 in 950 ml of water for 1000 cubic feet area.

For Sporicidal action on use 20% Conc. Solution of CidalTek-W10 for 60 min contact time.

Fogging machine should be mounted 2-3 feet from the floor level.

The angle of fogger machine kept at approximately 45 degrees.

Ensure the room is thoroughly cleaned before & after fogging with CidalTek W10 solution.

Area Of Application:

In the dental operatory to decontaminate environmental surfaces.

For disinfection of housekeeping surfaces (floors, walls, and sinks) have risk of disease transmission in dental healthcare settings.

For disinfection of dental environmental surfaces by removing organic matter, salts, and visible soils in dental settings such as area in dental laboratory, bathroom, and reception room in dental.

Soil surfaces (e.g., Blood, or body fluid) disinfection at dental clinic.

For disinfection of walls, and other vertical surfaces which are visibly contaminated by blood or OPIM (Other Potentially Infectious Material) in dentistry.

For cleaning and disinfection of environmental surfaces including blood and body substance spills.

For disinfecting spills of blood and other body fluids in dental clinic.

For aerial fogging in dental surgery unit, labs etc.

Microbial Efficacy:

Bactericidal, Fungicidal, Yeasticidal, Tuberculocidal, Virucidal & Sporicidal.

[blueoaknx]

Mitochondrial Dysfunction in the Pathogenesis of Parkinson’s Disease

Introduction

Parkinson's disease (PD) is a progressive neurodegenerative disorder primarily affecting motor function due to the selective degeneration of dopaminergic neurons in the substantia nigra pars compacta. The pathogenesis of PD is multifactorial, with emerging evidence pointing to mitochondrial dysfunction as a pivotal event in the onset and progression of the disease. This article provides a comprehensive technical analysis of the role of mitochondrial dysfunction in PD, focusing on key molecular mechanisms, genetic factors, and potential therapeutic strategies.

Mitochondria and Their Cellular Roles

Mitochondria are essential organelles that generate the majority of the cell's ATP via oxidative phosphorylation in the electron transport chain (ETC). In addition to their role in energy production, mitochondria are involved in maintaining cellular homeostasis by regulating calcium signaling, apoptosis, and reactive oxygen species (ROS) production. The proper functioning of mitochondria is crucial for neurons, particularly dopaminergic neurons, which have a high metabolic demand.

Mitochondrial Dysfunction and Parkinson's Disease Pathogenesis

Mitochondrial dysfunction in PD primarily manifests through alterations in mitochondrial bioenergetics, increased oxidative stress, defective mitophagy, and calcium dysregulation. These abnormalities converge on exacerbating neuronal injury, particularly in dopaminergic neurons.

1. Impaired Mitochondrial Complex I Activity

One of the hallmark features of mitochondrial dysfunction in PD is the impairment of mitochondrial complex I, the first enzyme complex in the ETC. Complex I is responsible for transferring electrons from NADH to ubiquinone, a critical step in ATP synthesis. Studies consistently show that PD patients exhibit significant reductions in complex I activity in the substantia nigra, which leads to defective ATP production. This mitochondrial dysfunction results in energy deficits, rendering dopaminergic neurons more susceptible to stressors.

Inhibition of complex I activity is not limited to genetic mutations; environmental toxins such as rotenone and paraquat, which inhibit complex I, have been implicated in Parkinsonian syndromes. Furthermore, complex I dysfunction increases the production of ROS, exacerbating oxidative stress in neurons and contributing to mitochondrial damage.

2. Oxidative Stress and ROS Generation

Mitochondria are both the primary source and target of ROS. The process of oxidative phosphorylation inevitably generates ROS as byproducts, particularly superoxide anion, hydrogen peroxide, and hydroxyl radicals. Under normal conditions, ROS are detoxified by endogenous antioxidant systems. However, in PD, mitochondrial dysfunction leads to an imbalance between ROS production and the cell’s antioxidant defenses.

The substantia nigra, which is particularly vulnerable in PD, is exposed to elevated ROS levels due to the high metabolic rate of dopaminergic neurons and the catabolism of dopamine, which generates additional ROS via the action of monoamine oxidase (MAO). Accumulation of ROS results in lipid peroxidation, protein misfolding, and mitochondrial DNA (mtDNA) mutations, all of which contribute to neuronal death and the progression of Parkinson’s pathology.

3. Mitophagy and Dysfunctional Quality Control Mechanisms

Mitophagy, a selective autophagic process that removes damaged or dysfunctional mitochondria, is crucial for maintaining mitochondrial quality and function. In PD, mitophagy is impaired, leading to the accumulation of damaged mitochondria within neurons. The PINK1-parkin pathway plays a pivotal role in the initiation of mitophagy. PINK1, a mitochondrial kinase, accumulates on depolarized mitochondria and recruits the E3 ubiquitin ligase parkin, which ubiquitinates outer mitochondrial membrane proteins to tag them for autophagic degradation.

Mutations in the PINK1 and parkin genes, which are associated with autosomal recessive forms of PD, disrupt this process and contribute to the accumulation of dysfunctional mitochondria. This failure to remove damaged mitochondria exacerbates oxidative stress and promotes the activation of apoptotic signaling pathways. As mitochondrial dysfunction progresses, neuronal survival becomes increasingly compromised, accelerating disease progression.

4. Calcium Homeostasis and Mitochondrial Regulation

Mitochondria play a critical role in buffering cytosolic calcium levels. Neurons, due to their high metabolic activity, are particularly dependent on mitochondrial calcium buffering to prevent cytotoxic calcium overload. However, in PD, mitochondrial dysfunction leads to impaired calcium handling, resulting in an increase in cytosolic calcium concentrations.

Elevated calcium levels activate a variety of calcium-dependent enzymes, such as calpains and phospholipases, that further damage cellular structures. Additionally, excessive calcium in mitochondria can activate the mitochondrial permeability transition pore (mPTP), leading to mitochondrial depolarization, the release of pro-apoptotic factors such as cytochrome c, and eventual cell death.

Genetic Factors in Mitochondrial Dysfunction in PD

Genetic mutations that directly affect mitochondrial function have been identified in familial forms of PD. These mutations often impair mitochondrial dynamics, quality control, and bioenergetics, contributing to the pathogenesis of the disease.

PINK1 and Parkin Mutations: Mutations in the PINK1 gene and the parkin gene, both involved in the regulation of mitophagy, lead to impaired mitochondrial quality control. PINK1, a serine/threonine kinase, normally accumulates on damaged mitochondria and recruits parkin to initiate mitophagy. Loss of PINK1 or parkin function results in the accumulation of dysfunctional mitochondria, contributing to neuronal degeneration.

LRRK2 Mutations: The LRRK2 gene encodes a large protein kinase involved in multiple cellular processes, including mitochondrial dynamics and autophagy. Mutations in LRRK2 are the most common genetic cause of PD, particularly in late-onset forms. LRRK2 is implicated in the regulation of mitochondrial fission and fusion, processes that control mitochondrial morphology and function. Dysregulation of these processes leads to the fragmentation of mitochondria, impaired mitochondrial function, and increased susceptibility to oxidative stress.

Alpha-Synuclein and Mitochondrial Interaction: Alpha-synuclein, the protein most notably associated with Lewy body formation in PD, has also been shown to interact with mitochondrial membranes. Aggregation of alpha-synuclein disrupts mitochondrial dynamics, leading to decreased mitochondrial respiration and increased ROS production. This interaction exacerbates mitochondrial dysfunction and accelerates neurodegeneration.

Environmental Toxins and Mitochondrial Dysfunction

Environmental exposures, particularly to pesticides like rotenone and paraquat, have been shown to inhibit mitochondrial complex I, leading to oxidative stress and mitochondrial dysfunction. These toxins induce PD-like symptoms in animal models, supporting the hypothesis that environmental factors contribute to the pathogenesis of the disease.

Therapeutic Approaches Targeting Mitochondrial Dysfunction

Given the central role of mitochondrial dysfunction in PD, therapeutic strategies aimed at restoring mitochondrial function are being actively explored. These include:

Antioxidant Therapies: Antioxidants such as coenzyme Q10 (CoQ10) have been proposed to alleviate oxidative stress by scavenging ROS. CoQ10 functions as an electron carrier in the ETC and may help restore mitochondrial bioenergetics in PD. Clinical trials, however, have shown mixed results, necessitating further research.

Gene Therapy: Gene therapy approaches aimed at correcting genetic defects that impair mitochondrial function are under investigation. For example, restoring PINK1 or parkin function in neurons may enhance mitophagy and mitigate mitochondrial damage.

Mitochondrial Replacement Therapy: Mitochondrial replacement or mitochondrial transplantation holds promise as a therapeutic strategy for restoring mitochondrial function in PD. Early-stage studies are exploring the feasibility of mitochondrial transplantation into dopaminergic neurons to restore cellular function.

Exercise and Lifestyle Interventions: Regular physical exercise has been shown to stimulate mitochondrial biogenesis and improve mitochondrial function. Exercise-induced upregulation of mitochondrial regulators such as PGC-1α may provide neuroprotective benefits in PD by enhancing mitochondrial turnover and reducing oxidative damage.

Conclusion

Mitochondrial dysfunction is a central event in the pathogenesis of Parkinson's disease, contributing to the degeneration of dopaminergic neurons through mechanisms such as impaired mitochondrial complex I activity, oxidative stress, defective mitophagy, and disrupted calcium homeostasis. Genetic mutations in key mitochondrial regulators such as PINK1, parkin, and LRRK2 exacerbate these defects, while environmental toxins further contribute to mitochondrial damage. Targeting mitochondrial dysfunction through antioxidant therapies, gene therapy, and lifestyle interventions holds promise for mitigating the progression of Parkinson's disease. Understanding the intricate molecular mechanisms linking mitochondrial dysfunction to neurodegeneration in PD will be crucial for developing effective therapeutic strategies.

[entomoblog]

ROS et régénération : un casse-tête évolutif - Strange Stuff And Funky Things

See on Scoop.it - EntomoScience

... On pourrait alors être surpris d'apprendre que lorsque nos cellules respirent, elles produisent naturellement de l’eau oxygénée. Et sachez que le peroxyde d’hydrogène n’est pas tout seul dans nos cellules ! Il fait partie d’un groupe de molécules oxygénées générées par la respiration cellulaire qui, parce qu’elles présentent des électrons libres, sont très fortement réactives chimiquement.

  Régénérer à l’eau oxygénée - Strange Stuff And Funky Things

  Chronique préparée pour l'émission "La Science, CQFD" du 06/01/2025 : L’homme de Denisova / Régénération chez les animaux / Deepfakes

    Présentation des sombres ROS

  "On regroupe ces molécules instables sous l’acronyme ROS (pour Reactive Oxygen Species en anglais ce qui donne Dérivés Réactifs de l’Oxygène). Sous la bannière des ROS on trouve des molécules aux noms inquiétants comme l'anion superoxyde (O2−) ou encore l’une des plus réactives d’entre elles, le radical hydroxyle (HO•).

    L’arsenal métabolique des ROS

"Pour explorer le lien entre les ROS et la capacité de certains animaux à régénérer des parties du corps après amputation, Aurore Vullien aurait pu se lancer dans des dissections frénétiques. Mais elle a tout d'abord opté pour une approche plus subtile : disséquer leurs génomes !

  Grâce à des études dites de “phylogénomique”, elle a pu dévoiler les mécanismes complexes qui régulent la teneur cellulaire en ROS, autrement dit, le métabolisme des ROS. Ces analyses ont, par exemple, révélé que les organismes vivants maîtrisent la gestion des ROS depuis au moins 3,8 milliards d’années, coïncidant avec l’apparition des premiers organismes capables de photosynthèse. Depuis ce moment, les ROS ont cessé d’être de simples menaces pour devenir un véritable atout évolutif !

  Sous la supervision d’Eve Gazave et du regretté Michel Vervoort, Aurore Vullien a ainsi mené une ambitieuse étude phylogénomique pour comprendre l’arsenal métabolique des ROS chez les animaux. Et pour cela, il faut être particulièrement patient et méticuleux, car c’est pas moins de 89 génomes qu’il a fallu passer au peigne fin pour détecter tous les gènes impliqués dans ce processus. Et le bilan évolutif est pour le moins… troublant !

  En effet, il semble que tous les animaux de l’étude ont les gènes leur permettant de réaliser les quatre grandes différentes actions liées à ce métabolisme, à savoir la production, la conversion, la détoxification et la régulation des ROS. Par contre la composition de ces gènes varie beaucoup d’une espèce à l’autre, comme si ce qui comptait n’était pas tant la nature des outils employés pour ce métabolisme, mais juste leurs fonctions. En d’autres termes, si telle espèce utilise un tournevis pour planter un clou, l’évolution ne semble pas avoir grand chose à redire.

  ROS et régénération : un casse-tête évolutif

  Pour aller plus loin, Aurore Vullien a mené des études sur l’implication des ROS dans les capacités de régénération chez deux espèces animales très différentes, mais championnes de la régénération : un ver marin appelé Platynereis dumerilii et une anémone d’eau saumâtre répondant au nom de Nematostella vectensis. L’un porte des petites pattes, et une tête, l’autre une couronne de tentacules sans pouvoir discerner un côté gauche et un côté droit : on part sur des bestioles assez éloignées d’un point de vue évolutif !

  Après une amputation, empêcher la production de ROS conduit au même résultat chez les deux organismes modèles : la régénération est compromise. 

  Mais c’est dans le détail de ces expériences d’inhibition de production de ROS que les découvertes d’Aurore Vullien sont les plus intéressantes. En effet, lors d’une régénération optimale, on observe tout d’abord une vague de cellules qui meurent et de cellules qui se multiplient.

Or, chez le ver marin, l’inhibition des ROS perturbe principalement la prolifération cellulaire et le devenir de certaines cellules. À l’inverse, chez l’anémone, c’est la mort cellulaire induite par l’amputation qui est la plus affectée.

En d’autres termes, bien que les ROS soient indispensables à la régénération chez ces deux animaux, leur rôle s’exprime à travers des mécanismes fondamentalement différents.

  Un casse-tête évolutif qui s’ajoute au domaine de la recherche sur la régénération, où en plus, le monde n’est pas tout ROS…"

(...)

[whumpster-fire]

H: a hydrogen atom all by itself. This isn't stable in high density environments like anywhere on Earth because hydrogen atoms on their own want to form bonds with anything and everything, including other hydrogen atoms, but neutral monoatomic hydrogen can be found in the interstellar medium. Splitting hydrogen molecules in half with an electric arc and then letting them recombine apparently generates temperatures hot enough to weld tungsten.

H2: Good old hydrogen gas. Forms the majority of the atmospheres of giant planets. On lighter planets, the molecule is too light and is easily removed from the exosphere by solar wind and whatever other funky high energy stuff happens up there. Also really wants to react with oxygen and turn itself into water, making it a pretty good rocket fuel and a suboptimal lifting gas for balloons and dirigibles.

O: Again, this is too reactive to exist on Earth's surface except for an extremely short time in the middle of chemical reactions. In the exosphere/thermosphere it's relatively common due to splitting of oxygen molecules.

O2: Molecular oxygen, a notoriously highly reactive gas. It is a corrosive air pollutant harmful to organic life, and in high concentrations it can literally set many substances, including metals and organic matter, on fire. We take it for granted because we are among the descendants of the life that evolved to withstand and take advantage of its properties after oxygen-producing bacteria and archaea devastated Earth's biosphere.

O3: Ozone. An even more reactive form of oxygen formed by splitting oxygen molecules with electricity or UV radiation, and another one we're dependent on due to its ability to block a lot of the sun's UV output from reaching Earth's surface.

O8: Oxygen atoms in a cuboid shape. A solid oxygen phase that can form at very high temperature and pressure.

HO: Hydroxyl radical. Very reactive due to its unpaired valence electron. Found in the interstellar medium and is a short lived intermediate in some chemical reactions in our atmosphere.

H2O: Dihydrogen Monoxide, AKA water. One of the deadliest chemicals known to science: nearly 100% of people who have touched or ingested it have died. /s

HO2: Hydroperoxyl. Yet another highly reactive oxygen radical with important roles as an intermediary in chemical reactions.

H2O2: Hydrogen peroxide. This fun substance is in the sweet spot of sketchy chemicals where it's extremely reactive with other chemicals and also readily decomposes into water and oxygen gas, but it's stable enough that you can actually store enough of it to cause an explosion. I don't think it's quite in the "Hypergolic with test engineers" category, but high enough concentrations might be hypergolic with clothing, and high-concentration hydrogen peroxide can cause severe chemical burns.

H2O(n) where n > 2: assorted unstable stuff.

[organicsupplement]

The Power of Organic Quercetin: A Natural Antioxidant for Your Daily Wellness

Organic quercetin, a powerful natural antioxidant, is gaining attention for its impressive health benefits and versatility in promoting overall wellness. This plant compound, found in various fruits, vegetables, and herbs, plays a crucial role in protecting the body from oxidative stress.

 And supporting immune function. Whether you’re looking to enhance your energy, reduce inflammation, or support your cardiovascular health, organic quercetin could be the natural supplement you’ve been searching for. Few reports have suggested that the best organic quercetin supplement has anti-aging properties. 

The origin of quercetin

The name quercetin comes from the Latin word quercetum, which means “oak forest”. Quercetin is a naturally occurring flavonoid found in many plants, including fruits, vegetables, and grains. Quercetin is recognized as safe, it has not shown any side effects in humans or animals.

What is Organic Quercetin and Why You Should Care?

Organic Quercetin is a flavonoid found in fruits and vegetables that has many potential health benefits organic quercetin destroys harmful particles in the body known as free radicals which damage cell membranes.

Top Sources of Organic Quercetin for the Diet

Dark-colored grapes, apples, berries, kale, red onions, broccoli, buckwheat, and green tea are natural and top sources of quercetin organic apart from the best organic quercetin supplement.

The Antioxidant Benefits of Quercetin for Daily Wellness

Organic Quercetin has antioxidant and anti-inflammatory effects that might help reduce swelling, kill cancer cells, control blood sugar, help prevent heart disease, and may help reduce blood pressure levels.

Supercharge Your Workouts with Quercetin: The Ultimate Exercise Aid

Studies show that intake of quercetin may improve endurance and increase strength while working, an individual consuming organic quercetin supplements are less likely to feel tired while doing heavy lifting.

The Synergy of Quercetin with Other Nutrients for Optimal Health

When consumed with other nutrients like carbohydrates and proteins, organic quercetin improves glucose utilization in peripheral tissues antiviral properties of quercetin may prevent fevers.

The Science Behind Quercetin’s Anti-Cancer Potential

The antitumor efficacy of organic quercetin derivatives varied from quercetin based on the subunit location and chain length. Insertion of Phenolic hydroxyl group such as etherification (O-alkylation) cancer cell proliferation may effectively be suppressed.

Quercetin’s Role in Supporting Healthy Gut Function

Organic Quercetin can improve gut microbiota dysbiosis (the ecosystem of microorganisms that reside within a host), by increasing the diversity of the gut microbiota and promoting beneficial bacteria like Bifidobacterium, Bacteroides, and Lactobacillus. It can also suppress pathogens like E. coli and proteobacteria.

Quercetin: A Secret Weapon for Allergy Sufferers 

Researchers have concluded that organic quercetin may help reduce symptoms of allergies, including runny nose, watery eyes, hives, and swelling of the face and lips. By preventing immune cells from releasing histamines.

Conclusion  

Organic quercetin is a powerhouse antioxidant with a wide array of health benefits, from supporting the immune system and reducing inflammation to improving heart health and combating oxidative stress. By incorporating quercetin-rich foods into your daily routine, you can naturally enhance your wellness and potentially prevent the onset of chronic conditions. Always consider consulting with a healthcare professional before adding any new supplements to your routine, especially if you have pre-existing health conditions.

[biology-geology-beaches-india]

TSRNOSS, p 489.

[sunaleisocial]

New climate chemistry model finds “non-negligible” impacts of potential hydrogen fuel leakage

New Post has been published on https://sunalei.org/news/new-climate-chemistry-model-finds-non-negligible-impacts-of-potential-hydrogen-fuel-leakage/

New climate chemistry model finds “non-negligible” impacts of potential hydrogen fuel leakage

As the world looks for ways to stop climate change, much discussion focuses on using hydrogen instead of fossil fuels, which emit climate-warming greenhouse gases (GHGs) when they’re burned. The idea is appealing. Burning hydrogen doesn’t emit GHGs to the atmosphere, and hydrogen is well-suited for a variety of uses, notably as a replacement for natural gas in industrial processes, power generation, and home heating.

But while burning hydrogen won’t emit GHGs, any hydrogen that’s leaked from pipelines or storage or fueling facilities can indirectly cause climate change by affecting other compounds that are GHGs, including tropospheric ozone and methane, with methane impacts being the dominant effect. A much-cited 2022 modeling study analyzing hydrogen’s effects on chemical compounds in the atmosphere concluded that these climate impacts could be considerable. With funding from the MIT Energy Initiative’s Future Energy Systems Center, a team of MIT researchers took a more detailed look at the specific chemistry that poses the risks of using hydrogen as a fuel if it leaks.

The researchers developed a model that tracks many more chemical reactions that may be affected by hydrogen and includes interactions among chemicals. Their open-access results, published Oct. 28 in Frontiers in Energy Research, showed that while the impact of leaked hydrogen on the climate wouldn’t be as large as the 2022 study predicted — and that it would be about a third of the impact of any natural gas that escapes today — leaked hydrogen will impact the climate. Leak prevention should therefore be a top priority as the hydrogen infrastructure is built, state the researchers.

Hydrogen’s impact on the “detergent” that cleans our atmosphere

Global three-dimensional climate-chemistry models using a large number of chemical reactions have also been used to evaluate hydrogen’s potential climate impacts, but results vary from one model to another, motivating the MIT study to analyze the chemistry. Most studies of the climate effects of using hydrogen consider only the GHGs that are emitted during the production of the hydrogen fuel. Different approaches may make “blue hydrogen” or “green hydrogen,” a label that relates to the GHGs emitted. Regardless of the process used to make the hydrogen, the fuel itself can threaten the climate. For widespread use, hydrogen will need to be transported, distributed, and stored — in short, there will be many opportunities for leakage. 

The question is, What happens to that leaked hydrogen when it reaches the atmosphere? The 2022 study predicting large climate impacts from leaked hydrogen was based on reactions between pairs of just four chemical compounds in the atmosphere. The results showed that the hydrogen would deplete a chemical species that atmospheric chemists call the “detergent of the atmosphere,” explains Candice Chen, a PhD candidate in MIT’s Department of Earth, Atmospheric and Planetary Sciences (EAPS). “It goes around zapping greenhouse gases, pollutants, all sorts of bad things in the atmosphere. So it’s cleaning our air.” Best of all, that detergent — the hydroxyl radical, abbreviated as OH — removes methane, which is an extremely potent GHG in the atmosphere. OH thus plays an important role in slowing the rate at which global temperatures rise. But any hydrogen leaked to the atmosphere would reduce the amount of OH available to clean up methane, so the concentration of methane would increase.

However, chemical reactions among compounds in the atmosphere are notoriously complicated. While the 2022 study used a “four-equation model,” Chen and her colleagues — Susan Solomon, the Lee and Geraldine Martin Professor of Environmental Studies and Chemistry; and Kane Stone, a research scientist in EAPS — developed a model that includes 66 chemical reactions. Analyses using their 66-equation model showed that the four-equation system didn’t capture a critical feedback involving OH — a feedback that acts to protect the methane-removal process.

Here’s how that feedback works: As the hydrogen decreases the concentration of OH, the cleanup of methane slows down, so the methane concentration increases. However, that methane undergoes chemical reactions that can produce new OH radicals. “So the methane that’s being produced can make more of the OH detergent,” says Chen. “There’s a small countering effect. Indirectly, the methane helps produce the thing that’s getting rid of it.” And, says Chen, that’s a key difference between their 66-equation model and the four-equation one. “The simple model uses a constant value for the production of OH, so it misses that key OH-production feedback,” she says.

To explore the importance of including that feedback effect, the MIT researchers performed the following analysis: They assumed that a single pulse of hydrogen was injected into the atmosphere and predicted the change in methane concentration over the next 100 years, first using four-equation model and then using the 66-equation model. With the four-equation system, the additional methane concentration peaked at nearly 2 parts per billion (ppb); with the 66-equation system, it peaked at just over 1 ppb.

Because the four-equation analysis assumes only that the injected hydrogen destroys the OH, the methane concentration increases unchecked for the first 10 years or so. In contrast, the 66-equation analysis goes one step further: the methane concentration does increase, but as the system re-equilibrates, more OH forms and removes methane. By not accounting for that feedback, the four-equation analysis overestimates the peak increase in methane due to the hydrogen pulse by about 85 percent. Spread over time, the simple model doubles the amount of methane that forms in response to the hydrogen pulse.

Chen cautions that the point of their work is not to present their result as “a solid estimate” of the impact of hydrogen. Their analysis is based on a simple “box” model that represents global average conditions and assumes that all the chemical species present are well mixed. Thus, the species can vary over time — that is, they can be formed and destroyed — but any species that are present are always perfectly mixed. As a result, a box model does not account for the impact of, say, wind on the distribution of species. “The point we’re trying to make is that you can go too simple,” says Chen. “If you’re going simpler than what we’re representing, you will get further from the right answer.” She goes on to note, “The utility of a relatively simple model like ours is that all of the knobs and levers are very clear. That means you can explore the system and see what affects a value of interest.”

Leaked hydrogen versus leaked natural gas: A climate comparison

Burning natural gas produces fewer GHG emissions than does burning coal or oil; but as with hydrogen, any natural gas that’s leaked from wells, pipelines, and processing facilities can have climate impacts, negating some of the perceived benefits of using natural gas in place of other fossil fuels. After all, natural gas consists largely of methane, the highly potent GHG in the atmosphere that’s cleaned up by the OH detergent. Given its potency, even small leaks of methane can have a large climate impact.

So when thinking about replacing natural gas fuel — essentially methane — with hydrogen fuel, it’s important to consider how the climate impacts of the two fuels compare if and when they’re leaked. The usual way to compare the climate impacts of two chemicals is using a measure called the global warming potential, or GWP. The GWP combines two measures: the radiative forcing of a gas — that is, its heat-trapping ability — with its lifetime in the atmosphere. Since the lifetimes of gases differ widely, to compare the climate impacts of two gases, the convention is to relate the GWP of each one to the GWP of carbon dioxide. 

But hydrogen and methane leakage cause increases in methane, and that methane decays according to its lifetime. Chen and her colleagues therefore realized that an unconventional procedure would work: they could compare the impacts of the two leaked gases directly. What they found was that the climate impact of hydrogen is about three times less than that of methane (on a per mass basis). So switching from natural gas to hydrogen would not only eliminate combustion emissions, but also potentially reduce the climate effects, depending on how much leaks.

Key takeaways

In summary, Chen highlights some of what she views as the key findings of the study. First on her list is the following: “We show that a really simple four-equation system is not what should be used to project out the atmospheric response to more hydrogen leakages in the future.” The researchers believe that their 66-equation model is a good compromise for the number of chemical reactions to include. It generates estimates for the GWP of methane “pretty much in line with the lower end of the numbers that most other groups are getting using much more sophisticated climate chemistry models,” says Chen. And it’s sufficiently transparent to use in exploring various options for protecting the climate. Indeed, the MIT researchers plan to use their model to examine scenarios that involve replacing other fossil fuels with hydrogen to estimate the climate benefits of making the switch in coming decades.

The study also demonstrates a valuable new way to compare the greenhouse effects of two gases. As long as their effects exist on similar time scales, a direct comparison is possible — and preferable to comparing each with carbon dioxide, which is extremely long-lived in the atmosphere. In this work, the direct comparison generates a simple look at the relative climate impacts of leaked hydrogen and leaked methane — valuable information to take into account when considering switching from natural gas to hydrogen.

Finally, the researchers offer practical guidance for infrastructure development and use for both hydrogen and natural gas. Their analyses determine that hydrogen fuel itself has a “non-negligible” GWP, as does natural gas, which is mostly methane. Therefore, minimizing leakage of both fuels will be necessary to achieve net-zero carbon emissions by 2050, the goal set by both the European Commission and the U.S. Department of State. Their paper concludes, “If used nearly leak-free, hydrogen is an excellent option. Otherwise, hydrogen should only be a temporary step in the energy transition, or it must be used in tandem with carbon-removal steps [elsewhere] to counter its warming effects.”

[tenth-sentence]

Considering the various hydrocarbon reactants, there are two principal mechanisms by which hydroxyl radicals initiate oxidation.

"Environmental Chemistry: A Global Perspective", 4e - Gary W. VanLoon & Stephen J. Duffy

[whats-in-a-sentence]

The most common forms of ROS in plant cells are superoxide (O2•-), singlet oxygen (¹O2), hydrogen peroxide (H2O2), and hydroxyl radicals (OH•) (Figure 24.3).

"Plant Physiology and Development" int'l 6e - Taiz, L., Zeiger, E., Møller, I.M., Murphy, A.

[jcmarchi]

New climate chemistry model finds “non-negligible” impacts of potential hydrogen fuel leakage

New Post has been published on https://thedigitalinsider.com/new-climate-chemistry-model-finds-non-negligible-impacts-of-potential-hydrogen-fuel-leakage/

New climate chemistry model finds “non-negligible” impacts of potential hydrogen fuel leakage

As the world looks for ways to stop climate change, much discussion focuses on using hydrogen instead of fossil fuels, which emit climate-warming greenhouse gases (GHGs) when they’re burned. The idea is appealing. Burning hydrogen doesn’t emit GHGs to the atmosphere, and hydrogen is well-suited for a variety of uses, notably as a replacement for natural gas in industrial processes, power generation, and home heating.

But while burning hydrogen won’t emit GHGs, any hydrogen that’s leaked from pipelines or storage or fueling facilities can indirectly cause climate change by affecting other compounds that are GHGs, including tropospheric ozone and methane, with methane impacts being the dominant effect. A much-cited 2022 modeling study analyzing hydrogen’s effects on chemical compounds in the atmosphere concluded that these climate impacts could be considerable. With funding from the MIT Energy Initiative’s Future Energy Systems Center, a team of MIT researchers took a more detailed look at the specific chemistry that poses the risks of using hydrogen as a fuel if it leaks.

The researchers developed a model that tracks many more chemical reactions that may be affected by hydrogen and includes interactions among chemicals. Their open-access results, published Oct. 28 in Frontiers in Energy Research, showed that while the impact of leaked hydrogen on the climate wouldn’t be as large as the 2022 study predicted — and that it would be about a third of the impact of any natural gas that escapes today — leaked hydrogen will impact the climate. Leak prevention should therefore be a top priority as the hydrogen infrastructure is built, state the researchers.

Hydrogen’s impact on the “detergent” that cleans our atmosphere

Global three-dimensional climate-chemistry models using a large number of chemical reactions have also been used to evaluate hydrogen’s potential climate impacts, but results vary from one model to another, motivating the MIT study to analyze the chemistry. Most studies of the climate effects of using hydrogen consider only the GHGs that are emitted during the production of the hydrogen fuel. Different approaches may make “blue hydrogen” or “green hydrogen,” a label that relates to the GHGs emitted. Regardless of the process used to make the hydrogen, the fuel itself can threaten the climate. For widespread use, hydrogen will need to be transported, distributed, and stored — in short, there will be many opportunities for leakage. 

The question is, What happens to that leaked hydrogen when it reaches the atmosphere? The 2022 study predicting large climate impacts from leaked hydrogen was based on reactions between pairs of just four chemical compounds in the atmosphere. The results showed that the hydrogen would deplete a chemical species that atmospheric chemists call the “detergent of the atmosphere,” explains Candice Chen, a PhD candidate in MIT’s Department of Earth, Atmospheric and Planetary Sciences (EAPS). “It goes around zapping greenhouse gases, pollutants, all sorts of bad things in the atmosphere. So it’s cleaning our air.” Best of all, that detergent — the hydroxyl radical, abbreviated as OH — removes methane, which is an extremely potent GHG in the atmosphere. OH thus plays an important role in slowing the rate at which global temperatures rise. But any hydrogen leaked to the atmosphere would reduce the amount of OH available to clean up methane, so the concentration of methane would increase.

However, chemical reactions among compounds in the atmosphere are notoriously complicated. While the 2022 study used a “four-equation model,” Chen and her colleagues — Susan Solomon, the Lee and Geraldine Martin Professor of Environmental Studies and Chemistry; and Kane Stone, a research scientist in EAPS — developed a model that includes 66 chemical reactions. Analyses using their 66-equation model showed that the four-equation system didn’t capture a critical feedback involving OH — a feedback that acts to protect the methane-removal process.

Here’s how that feedback works: As the hydrogen decreases the concentration of OH, the cleanup of methane slows down, so the methane concentration increases. However, that methane undergoes chemical reactions that can produce new OH radicals. “So the methane that’s being produced can make more of the OH detergent,” says Chen. “There’s a small countering effect. Indirectly, the methane helps produce the thing that’s getting rid of it.” And, says Chen, that’s a key difference between their 66-equation model and the four-equation one. “The simple model uses a constant value for the production of OH, so it misses that key OH-production feedback,” she says.

To explore the importance of including that feedback effect, the MIT researchers performed the following analysis: They assumed that a single pulse of hydrogen was injected into the atmosphere and predicted the change in methane concentration over the next 100 years, first using four-equation model and then using the 66-equation model. With the four-equation system, the additional methane concentration peaked at nearly 2 parts per billion (ppb); with the 66-equation system, it peaked at just over 1 ppb.

Because the four-equation analysis assumes only that the injected hydrogen destroys the OH, the methane concentration increases unchecked for the first 10 years or so. In contrast, the 66-equation analysis goes one step further: the methane concentration does increase, but as the system re-equilibrates, more OH forms and removes methane. By not accounting for that feedback, the four-equation analysis overestimates the peak increase in methane due to the hydrogen pulse by about 85 percent. Spread over time, the simple model doubles the amount of methane that forms in response to the hydrogen pulse.

Chen cautions that the point of their work is not to present their result as “a solid estimate” of the impact of hydrogen. Their analysis is based on a simple “box” model that represents global average conditions and assumes that all the chemical species present are well mixed. Thus, the species can vary over time — that is, they can be formed and destroyed — but any species that are present are always perfectly mixed. As a result, a box model does not account for the impact of, say, wind on the distribution of species. “The point we’re trying to make is that you can go too simple,” says Chen. “If you’re going simpler than what we’re representing, you will get further from the right answer.” She goes on to note, “The utility of a relatively simple model like ours is that all of the knobs and levers are very clear. That means you can explore the system and see what affects a value of interest.”

Leaked hydrogen versus leaked natural gas: A climate comparison

Burning natural gas produces fewer GHG emissions than does burning coal or oil; but as with hydrogen, any natural gas that’s leaked from wells, pipelines, and processing facilities can have climate impacts, negating some of the perceived benefits of using natural gas in place of other fossil fuels. After all, natural gas consists largely of methane, the highly potent GHG in the atmosphere that’s cleaned up by the OH detergent. Given its potency, even small leaks of methane can have a large climate impact.

So when thinking about replacing natural gas fuel — essentially methane — with hydrogen fuel, it’s important to consider how the climate impacts of the two fuels compare if and when they’re leaked. The usual way to compare the climate impacts of two chemicals is using a measure called the global warming potential, or GWP. The GWP combines two measures: the radiative forcing of a gas — that is, its heat-trapping ability — with its lifetime in the atmosphere. Since the lifetimes of gases differ widely, to compare the climate impacts of two gases, the convention is to relate the GWP of each one to the GWP of carbon dioxide. 

But hydrogen and methane leakage cause increases in methane, and that methane decays according to its lifetime. Chen and her colleagues therefore realized that an unconventional procedure would work: they could compare the impacts of the two leaked gases directly. What they found was that the climate impact of hydrogen is about three times less than that of methane (on a per mass basis). So switching from natural gas to hydrogen would not only eliminate combustion emissions, but also potentially reduce the climate effects, depending on how much leaks.

Key takeaways

In summary, Chen highlights some of what she views as the key findings of the study. First on her list is the following: “We show that a really simple four-equation system is not what should be used to project out the atmospheric response to more hydrogen leakages in the future.” The researchers believe that their 66-equation model is a good compromise for the number of chemical reactions to include. It generates estimates for the GWP of methane “pretty much in line with the lower end of the numbers that most other groups are getting using much more sophisticated climate chemistry models,” says Chen. And it’s sufficiently transparent to use in exploring various options for protecting the climate. Indeed, the MIT researchers plan to use their model to examine scenarios that involve replacing other fossil fuels with hydrogen to estimate the climate benefits of making the switch in coming decades.

The study also demonstrates a valuable new way to compare the greenhouse effects of two gases. As long as their effects exist on similar time scales, a direct comparison is possible — and preferable to comparing each with carbon dioxide, which is extremely long-lived in the atmosphere. In this work, the direct comparison generates a simple look at the relative climate impacts of leaked hydrogen and leaked methane — valuable information to take into account when considering switching from natural gas to hydrogen.

Finally, the researchers offer practical guidance for infrastructure development and use for both hydrogen and natural gas. Their analyses determine that hydrogen fuel itself has a “non-negligible” GWP, as does natural gas, which is mostly methane. Therefore, minimizing leakage of both fuels will be necessary to achieve net-zero carbon emissions by 2050, the goal set by both the European Commission and the U.S. Department of State. Their paper concludes, “If used nearly leak-free, hydrogen is an excellent option. Otherwise, hydrogen should only be a temporary step in the energy transition, or it must be used in tandem with carbon-removal steps [elsewhere] to counter its warming effects.”