Tag Archives: pollution

Hythane and fuel cells to power buses and trains.

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Fuel cells are highly efficient and hardly polluting. They have a long history of use in space, and as a power source for submarines. They are beginning to appear powering city buses and intercity trains, at least in Europe, but not so much in the US or Canada. The business case for fuel cells is that they provide clean electric power to the train or bus, without the need for overhead wires. Avoiding wires helps make up for the high cost of hydrogen as a fuel. The reluctance to switch to fuel cells is the US is due to the longer distances that must be covered. The very low volumetric energy density of hydrogen means you need many filling stations with hydrogen fuel cells, and many fill ups per trip.

Energy density CNG, hydrogen, hythane.

On a mass-basis, hydrogen is energy dense, with 1 kg providing the same energy as 2-3 kg of gasoline. The problem with hydrogen (aside from the cost) is that its mass density is very low, less than 50g/liter, even at high pressure. This is terribly un-dense on a volume basis. It would take 20 liters of high pressure hydrogen (about 5 gallons) to take a car or bus as far as with one gallon of gasoline. Even with a huge tank of high pressure hydrogen, 150 gallons or so, a cross country trip would require some 12 fill ups, one every 250 miles, and this is an annoyance, besides being an infrastructure problem.

Then there is cost. In California, hydrogen costs far more than gasoline, between $12 and $15 per kg. That’s ten times as expensive as gasoline on a weight basis and 4 times as expensive on an energy basis. What’s needed is a cheaper, more energy-dense version of hydrogen, ideally one that can be used in both fuel cells and IC engines, and the version I’d like to suggest is hythane, a mix of methane (natural gas) and 20-30% hydrogen.

Hythane dispenser

Hythane has about 3 times the volumetric energy density of hydrogen, and about 1/3 the price. It makes less CO and CO2 pollution because there is far less carbon. On an energy basis, hythane costs just slightly more than gasoline, and requires less infrastructure. Natural gas is cheap and available, delivered by pipeline, without the need for hydrogen delivery trucks. Because hythane has about three times the volumetric energy density of hydrogen, the tank described above, that would give a 250 mile ride with hydrogen, would give 750 miles with hythane. This means a lot fewer fueling stations are needed, and a lot fewer forced stops. As a bonus, hythane can be used in (some) IC engines as well as in fuel cells.

Hydrogen for hythane-automotive use can be made on site, by electrolysis of water. Because there is relatively little hydrogen in the mix, only 25% by volume, or 8% on an energy basis, there is relatively little burden on the electric grid, and fueling will be a lot faster than with battery chargers. Hythane is already in use in buses in China and Canada. These are normal combustion buses but hythane works even better — more efficiently — with fuel cells (solid oxide fuel cells) and thus hythane provides a path to efficiency and greater fuel cell use.

Hythane bus, Montreal.

Natural gas does not work as well in fuel cells; it requires a pre-reformer to make some H2, and even then tends to coke. To be used in most fuel cells, the methane has to be converted, at lest partially into hydrogen and this takes heat energy and water.

CH4 + H2O + energy –> 3H2 + CO

Reforming is a lot easier with hythane; it can be done within the fuel cell. Within a SOFC, the hydrogen combustion, H2 + 1/2 O2 –> H2O, provides heat and water that helps feed the reforming reaction and helps prevent coking. Long term, fuel cells will likely dominate the energy future, but for now it’s nice to have a fuel that will work well in normal IC engines too.

Robert Buxbaum, April 28, 2021

If nothing sticks to teflon, how do you stick teflon to a pan? PFAS.

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When I was eight or nine year old, I went to the 1963-64 World’s Fair in New York. Among the attractions, in “the kitchen of the future”, I saw the first version of an amazing fry-pan that was coated with plastic. You could cook an egg on that plastic without any oil, and the egg didn’t stick. The plastic was called teflon, a DuPont innovation, whose molecule is shown below.

The molecular structure of Teflon. There is an interior carbon backbone that is completely enclosed with tightly bound fluorine atoms. The net result is a compound that does not bind readily to anything else.

Years later, I came to understand that Teflon’s high-temperature stability and non-stick properties derive from the carbon-fluorine bonds. These bonds are much stronger than the carbon-hydrogen bonds found in food, and most solid, organic things. Because of the strength of the carbon-fluorine bond, Teflon is resistant to oxidation, and to chemical interaction with other molecules, e.g. in food. It does not even interact with water, making it hydrophobic and non-wetting on metals. The carbon-carbon bonds in the middle remained high temperature stable, in part because they were completely shielded by the fluorine atoms.

This is a PFAS. The left side is just like teflon, and very hydrophobic. The right side is hydrophilic and highly bonding to pans, and many other things like water or cotton.

But as remarkable as teflon’s non-stick properties are, perhaps the most amazing thing was that it somehow sticks to the pan. For the first generation pans I saw, it didn’t stick very well. Still, the DuPont engineers had found a way to stick non-stick Teflon to a metal for long enough to cook many meals. If they had not found this trick, teflon would not have the majority of its value, but how did they do it? It turns out they used a thin coating of a di-functional compound called PFAS, a a polyfluoro sulphonyl (or polyfluoroalkyl) substance. The molecular structure of a common PFAS, is shown above.

Each molecule of PFAS has one end that’s teflon-like and another end that’s different. The non-Teflon end, in this case a sulfonyl group, is chosen to be both high temperature stable and sticky to metal oxides. The sulphonyl group above is highly polar, and acidic. Acidic will bind to bases, like metal oxides. The surface of the metal pan is prepared by applying a thin layer of oxide or amidine, making it a polar base. The PFAS is then applied, then Teflon. The Teflon-end of the PFAS is bound to teflon by the hydrophobicity of everything else rejecting it.

There are many other uses for PFAS. For example, PFAS is applied to clothing to make it wrinkle free and stain resistant. It can also be used as a super soap, making uncommonly stable foams and bubbles. It is also used in fire-fighting and plane de-icing. Finally, PFAS is the main component of Nafion, the most common membrane for PEM fuel cells. (I can think of yet other applications..) There is just one small problem with PFAS, though. Like teflon, this molecule is uncommonly stable. It doesn’t readily decompose in nature. That would be a small problem if we were sure that PFAS was safe. As it happens it seems safe, but we’re not totally sure.

The safety of PFAS was studied extensively before PFAS-teflon pans was put on the market, but the methodology has been questioned. Large doses of PFAS were fed to test animals, and their health observed. Since the test animals showed no real signs of ill-health though some showed a slight liver enlargement, PFAS was accepted as safe for humans at a lower exposure dose. PFAS was approved for use on pans and allowed to be dumped under conditions where humans would be exposed to 1/1000 of that used on the animals. The assumption was that there would be little or no health hazard at these low exposure levels.

But low risk is not no risk, and today one can sue for even the hint of an effect though use of a class action suit. That is, lawyers sue on behalf of all the people who might have been damaged. My city was sued successfully this way for complicity in sewage over-flows. Of course, since the citizens being paid by the suit are the same ones who have to pay for the damage, only the lawyers benefit. Still, the law is the law, and at least for some judges, putting anyone at risk is enough evidence of willful disregard to hand down a stinging judgement against the evil doer. Judges have begun awarding large claims for PFAS too. While no individual can get the claim more than a tiny amount of money, the lawyers can do very well.

There is no new evidence that PFAS is dangerous, but none is needed if you can get yourself the right judge. In this regard, an industry of judicial tourism has sprung up, where class-action lawyers travel to districts where the judges are favorable. For Teflon suits, the bust hunting grounds are in New York, New Hampshire, and California, and the worst are blood-red states like Wyoming and Utah. Just as different judges promote different precedents, different states allow vastly different PFAS concentrations in the water. A common standard, one used by Michigan, is 70 ppt, 1 billion times stricter than the amounts tested on animals. This is roughly 500 times stricter than the acceptable concentratios for lead, a known poison. The standard in New York is 7 times stricter than Michigan, 10 ppt. The standard in North Carolina is 140,000 ppt, in in several states there is no legal limit to PFAS dumping. There is no scientific logic to all of this, and skeptical view is that the states that rule more strictly for PFAS than lead do so make money for lawyers. Lead is everyone in the natural environment, so you can’t sue as easily for lead. PFAS is a man-made intruder, though, and a strict standard helps lawyers sue. You can find a summary of state by state regulations here.

Any guideline stricter than about 1000 ppt, presents a challenge to the water commissioner who must measure it and enforce the law. There are tricks, though. You can use the surfactant quality of PFAS to concentrate it by a factor of 100 or more. To do this, you take a sample of river water and create bubbles. Any bubbles that form will be highly concentrated in PFAS. Once PFAS can be identified this way, and the concentrators estimated, the polluters can be held liable. Whether we benefit from the strict rulings is another story. If I were making the law for Michigan, I’d probably choose a limit about 1 ppb, but I’m not making the law. The law, as written, may be an idiot, as Bumble said, but the Law is the Law.

In terms of Michigan fishing, while some rivers have PFAS concentrators above the MI-legal limit, they are generally not far over the line. I would trust the fish in the Huron River, even west of Wixom road but I’d suggest you avoid any foam you find floating there. The PFAS content of foam will be much higher than that of the water in general.

Robert E. Buxbaum, June 30, 2020, edited July 8, 2020. There are seven compounds known as PFAS’s: perfluorooctanesulfonic acid (PFOS), perfluorooctanoic acid (PFOA), perfluorononanoic acid (PFNA), perfluorohexanesulfonic acid (PFHxS), perfluoroheptanoic acid (PFHpA), and perfluorobutanesulfonic acid (PFBS).

China worse than the US in CO2 per output

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CO2 per year, 1965-2017, China and developed world

CO2 output per year, 1965-2017, China and developed world

For the last decade at least, China has been the industrial  manufacturer to the world. If not for Chinese shoes, the US would go barefoot. if not for Chinese electronics, Americans would be without iPhones, laptops, and TVs. China still trails the US and Europe in banking, software, movies and the like, but relying on China for manufactured goods is a dangerous position for the free world economically, and it’s not much better in terms of pollution.

China is among the world’s worst polluters. It burns coal for power to an extent that the air quality of China’s major cities would be unacceptable most everywhere else. On most days, it is thick with a yellow and grey haze. By 1969 China had passed the US and the European union in terms of CO2 production. And, as 2017, they produce nearly three times as much CO2 as the USA, four times more than the entire European Union. While China claims an interest in changing, the amount of pollution China’s CO2 output is still growing while ours and the EU’s is decreasing.

Manufacturing in the US, China, EU, Japan, Korea. Source: World Bank.

Manufacturing in the US, China, Germany, Japan, Korea. Source: World Bank.

China’s pollution would not be so bad if it were an efficient manufacturer, but there is a lot to suggest that it is not. China produces 50% more industrial goods than the US, but employs far more man hours, and generates more than three times the  CO2. Even in a fairly developed industry like steel, the US uses fewer man hours per ton and generates less CO2. I’m thus drawn to conclude that US companies off-load work to China mainly to get around US labor and pollution laws. Alternately, they off-load manufacture to gain entry to the Chinese market, a market that is otherwise closed to them. When US companies do this, they benefit the corporate managers and owners, but not the US worker. 

The hope (expectation) is that president Trump’s tariffs on Chinese goods will decrease the wage advantage of manufacturing in China, and will decrease the amount of US goods manufactured there. Some of that production, I expect, will move to the US, some will remain in China, and will be imported at a higher price-point. I expect a net decrease in CO2 as the US appears to be the more efficient producer, and because fewer ships will be crossing the Pacific bringing Chinese goods to the US. I expect some increase in tax revenue to the US, and some price inflation as well, as importers pass along the increased cost of Chinese goods. Overall, I think this is an acceptable trade-off, but what do I know.

Robert Buxbaum, November 29, 2018

Follow the feces; how to stop the poisoning

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In Oakland county, we regularly poison our basements and our lake St Clair beaches with feces — and potentially our water supply too. We have a combined storm and sanitary sewer system that mixes feces-laden sanitary sewage with rainwater, and our pipes are too old and small to handle the amount of storm water from our larger rains. A group called “Save Lake St. Clair” is up in arms but the current commissioner claims the fault is not his. It’s global warming, he says, and the rains are bigger now. Maybe, or maybe the fault is wealth: more and more of the county is covered by asphalt, so less rain water can soak in the ground. Whatever the cause, the Commissioner should deal with it (I’m running for water commissioner, BTW). As the chart of toxic outfalls shows, we’ve had regular toxic sewage discharges into the Red Run basically every other week, with no exceptional rainfalls: only 0.9″ to 1.42″.

Toxic outfalls into lake St Clair, Feb 20 to Mar 20, 2016. There were also two outfalls into the Rouge in this period. These are too many to claim they are once in hundred-year events.

Toxic outfalls into lake St Clair, Feb 20 to Mar 20, 2016. There were also two outfalls into the Rouge in this period. These are too many to claim they are once in hundred-year events.

Because we have a combined system, the liquid level rises in our sewers whenever it rains. When the level is above the level of a basement floor drain, mixed sewage comes up into the basement. A mix of storm water comes up mixed with poop and anything else you and your neighbors flush down. Mixed sewage can come up even if the sewers were separate, but far less often. Currently most of the dry outfall from our old, combined sewers is sent to Detroit’s Waste Water Treatment plant near Zug Island. When there is a heavy rain, the pipe to Zug is overwhelmed. We avoid flooding your basement every other week by diverting as much as we can of the mixed storm water and septic sewage to lake St. Clair. This is poop, barely treated, and the fishermen and environmentalists hate it.

The beaches along Lake St Clair are closed every other week: whenever the pipes to Detroit start getting overwhelmed, whenever there is about 1″ or rain. Worse yet, the sewage is enters the lake just upstream of the water intake on Belle Isle, see map below. Overflow sewage follows the red lines entering the Clinton River through the GW Kuhn — Red Run Drain or through the North Branch off the River. From there it flows out into Lake St. Clair near Selfridge ANG, generally hugging the Michigan shore of the lake, following the light blue line to poison the metro beaches. it enters the water intake for the majority of Oakland County at the Belle Island water intakes, lower left.

Follow the feces to see why our beeches are polluted. It's just plain incompetence.

The storm water plus septic sewage mix is not dumped raw into lake St. Clair, but it’s nearly raw. The only treatment is to be spritzed with bleach in the Red Run Drain. The result is mats of black gunk with floating turds, toilet paper and tampons. This water is filtered before we drink it, and it’s sprayed with more chlorine, but that’s not OK. We can do much better than this. We don’t have to regularly dump poop into the river just upstream of our water intake. I favor a two-prong solution.

The first, quick solution is to have better pumps to send the sewage to Detroit. This is surprisingly expensive since we still have to treat the rain water. Also it doesn’t take care of the biggest rains; there is a limit to what our pipes will handle, but it stops some basement flooding, and it avoids some poisoning of our beaches and drinking water.

This is our combined sewer system showing a tunnel cistern (yuk) and the outflow into the Red Run. We can do better

A combined sewer system showing a tunnel cistern. Outflow goes into the Red Run. We can do better.

A second, longer term solution is to disentangle the septic from the storm sewers. My approach would be to do this in small steps, beginning by diverting some storm runoff into small wetlands or French drain retention. Separating the sewers this way is cheaper and more environmentally sound than trying to treat the mixed flow in Detroit, and the wetlands and drains would provide pleasant park spaces, but the project will take decades to complete. If done right, this would save quite a lot over sending so much liquid to Detroit, and it’s the real solution to worries about your floor drains back-flowing toxic sludge into your basement.

The incumbent, I fear, has little clue about drainage or bio-treatment. His solution is to build a $40MM tunnel cistern along Middlebelt road. This cistern only holds 3 MM gallons, less than 1/100 of the volume needed for even a moderate rain. Besides, at $13/gallon of storage, it is very costly solution compared to my preference — a French drain (costs about 25¢/gallon of storage). The incumbents cistern has closed off traffic for months between 12 and 13 mile, and is expected to continue for a year, until January, 2017. It doesn’t provide any bio-cleaning, unlike a French drain, and the cistern leaks. Currently groundwater is leaking in. This has caused the lowering of the water table and the closure of private wells. If the leak isn’t fixed , the cistern will leak septic sewage into the groundwater, potentially infecting people for miles around with typhus, cholera, and all sorts of 3rd world plagues.

There is also an explosion hazard to the incumbent’s approach. A tunnel cistern like this blew up near my undergraduate college sending manhole covers flying. This version has much bigger manhole covers: 15′ cement, not 2′ steel. If someone pours gasoline down the drain during a rainstorm and if a match went in later, the result could be deadly. The people building these projects are the same ones who fund the incumbent’s campaign, and I suspect they influenced him for this mis-chosen approach. They are the folks I fear he goes to for engineering advice. If you’d like to see a change for the better. Elect me, Elect an engineer.

Dr. Robert E. Buxbaum, March 26, 2016. Go here to volunteer or contribute.

US cancer rates highest on the rivers, low in mountains, desert

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Sometimes I find I have important data that I can’t quite explain. For example, cancer rates in the US vary by more than double from county to county, but not at random. The highest rates are on the rivers, and the lowest are in the mountains and deserts. I don’t know why, but the map shows it’s so.

Cancer rate map of the US age adjusted

Cancer death rates map of the US age adjusted 2006-2010, by county. From www.statecancerprofiles.cancer.gov.

Counties shown in red on the map have cancer death rates between 210 and 393 per 100,000, more than double, on average the counties in blue. These red counties are mostly along the southern Mississippi, the Arkansas branching to its left; along the Alabama, to its right, and along the Ohio and the Tennessee rivers (these rivers straddle Kentucky). The Yukon (Alaska) shows up in bright red, while Hawaii (no major rivers) is blue; southern Alaska (mountains) is also in blue. In orange, showing less-elevated cancer death, you can make out the Delaware river between NJ and DC, the Missouri heading Northwest from the Mississippi, the Columbia, and the Colorado between the Grand Canyon and Las Vegas. For some reason, counties near the Rio Grande do not show elevated cancer death rates. nor does the Northern Mississippi and the Colorado south of Las Vegas.

Contrasting this are areas of low cancer death, 56 to 156 deaths per year per 100,000, shown in blue. These appear along the major mountain ranges: The Rockies (both in the continental US and Alaska), the Sierra Nevada, and the Appalachian range. Virtually every mountain county appears in blue. Desert areas of the west also appear as blue, low cancer regions: Arizona, New Mexico, Utah, Idaho, Colorado, south-west Texas and southern California. Exceptions to this are the oasis areas in the desert: Lake Tahoe in western Nevada and Lake Meade in southern nevada. These oases stand out in red showing high cancer-death rates in a sea of low. Despite the AIDS epidemic and better health care, the major cities appear average in terms of cancer. It seems the two effects cancel; see the cancer incidence map (below).

My first thought of an explanation was pollution: that the mountains were cleaner, and thus healthier, while industry had polluted the rivers so badly that people living there were cancer-prone. I don’t think this explanation fits, quite, since I’d expect the Yukon to be pollution free, while the Rio Grande should be among the most polluted. Also, I’d expect cities like Detroit, Cleveland, Chicago, and New York to be pollution-heavy, but they don’t show up for particularly high cancer rates. A related thought was that specific industries are at fault: oil, metals, chemicals, or coal, but this too doesn’t quite fit: Utah has coal, southern California has oil, Colorado has mining, and Cleveland was home to major Chemical production.

Another thought is poverty: that poor people live along the major rivers, while richer, healthier ones live in the mountains. The problem here is that the mountains and deserts are home to some very poor counties with low cancer rates, e.g. in Indian areas of the west and in South Florida and North Michigan. Detroit is a very poor city, with land polluted by coal, steel, and chemical manufacture — all the worst industries, you’d expect. We’re home to the famous black lagoon, and to Zug Island, a place that looks like Hades when seen from the air. The Indian reservation areas of Arizona are, if anything, poorer yet. 

Cancer incidence map

Cancer incidence,age adjusted, from statecancerprofiles.cancer.gov

My final thought was that people might go to the river to die, but perhaps don’t get cancer by the river. To check this explanation, I looked at the map of cancer incidence rates. While many counties repress their cancer rate data, the pattern in the remaining ones is similar to that for cancer death: the western mountain and desert counties show less than half the incidence rates of the counties along the southern Mississippi, the Arkansas, and the Ohio rivers. The incidence rates are somewhat elevated in the north-east, and lower on the Yukon, but otherwise it’s the same map as for cancer death. Bottom line: I’m left with an observation of the cancer pattern, but no good explanation or model.

Dr. Robert E. Buxbaum, May 1, 2014. Two other unsolved mysteries I’ve observed: the tornado drought of the last few years, and that dilute toxins and radiation may prevent cancer. To do science, you first observe, and then try to analyze.

Where does industrial CO2 come from? China mostly.

The US is in the process of imposing strict regulations on carbon dioxide as a way to stop global warming and climate change. We have also closed nearly new power plants, replacing them with cleaner options like a 2.2 billion dollar solar-electric generator in lake Ivanpah, and this January our president imposed a ban on lightbulbs of 60 W and higher. But it might help to know that China produced twice as much of the main climate change gas, carbon dioxide (CO2) as the US in 2012, and the ratio seems to be growing. One reason China produces so much CO2 is that China generates electricity from dirty coal using inefficient turbines.

Where the CO2 is coming from: a fair amount from the US and Europe, but mostly from China and India too.

From EDGAR 4.2; As of 2012 twice as much carbon dioxide, CO2 is coming from China as from the US and Europe.

It strikes me that a good approach to reducing the world’s carbon-dioxide emissions is to stop manufacturing so much in China. Our US electric plants use more efficient generating technology and burn lower carbon fuels than China does. We then add scrubbers and pollution reduction equipment that are hardly used in China. US manufacture thus produces not only less carbon dioxide than China, it also avoids other forms of air pollution, like NOx and SOx. Add to this the advantage of having fewer ships carrying products to and from China, and it’s clear that we could significantly reduce the world’s air problems by moving manufacture back to the USA.

I should also note that manufacture in the US helps the economy by keeping jobs and taxes here. A simple way to reduce purchases from China and collect some tax revenue would be to impose an import tariff on Chinese goods based, perhaps on the difference in carbon emissions or other pollution involved in Chinese manufacture and transport. While I have noted a lack of global warming, sixteen years now, that doesn’t mean I like pollution. It’s worthwhile to clean the air, and if we collect tariffs from the Chinese and help the US economy too, all the better.

Robert E. Buxbaum, February 24, 2014. Nuclear power produces no air pollution and uses a lot less land area compared to solar and wind projects.