Category Archives: Automotive

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

Locked down so long, it’s looking up: the up-side of COVID-19.

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I’m not crazy about the COVID isolation, but there are up-sides that I’ve come to appreciate. You might too. Out of boredom, I was finally got into meditation. It was better than just sitting around and doing nothing.

It’s best not to look at isolation as a problem, but an opportunity. I’ve developed a serious drinking opportunity.

And it’s an opportunity to talk to myself. I told myself I’ should quit drinking. Then I figured, why should I listen to a drunk who talks to himself.

A friend of mine was on drugs, but then quit. Everyone in his house is happy, except for the lamp. The lamp won’t talk to him anymore.

The movies are closed, and the bars, and the gyms. It gives me another reason not to go to the gym.

Did you know that, before the crowbar was invented, crows used to drink at home.

The real reason dogs aren’t allowed in bars: lots of guys can’t handle their licker.

There’s time to spend with my children. And they look like me.

I like that I don’t commute. Family events are over zoom, funerals (lots of funerals), meetings, lectures. They come in via the computer, and I don’t have to dress or attend. No jacket, no pants… no travel …. no job.

My children are spending more time with us at home. We have virtual meals together. I discovered that I have a son named Tok. He seems to like my dad-jokes.

My wife is finding it particularly tough. Most every day I see her standing by the window, staring, wondering. One of these days, I’ll let her in.

I asked wife why she married me. Was it for my looks, or my income, or my smarts. She smiled and said it was my sense of humor. 🙂

My wife is an elementary school teacher. She teaches these days with a smart board. If the board were any smarter, it would go work for someone else. It’s necessary, I guess. If you can’t beat them, you might as well let the smart board teach. I think the smart board stole the election. It began by auto-correcting my spelling. Then it moved to auto correct my voting. The board is smarter and better than me (Hey, who wrote this?)

some mask humor
I’ve learned to love masks, though some of them are hot.

You’d think they’d reduce the number of administrators in the schools, given that it’s all remote. Or reduce the price of college. It would be nice if they’d up the number of folks who can attend. So far no. Today the Princeton alumni of Michigan is sponsoring video-talk by Princeton alumnus, George Will. I wanted to attend, but found there was limited seating, so I’m on the waiting list (true story). By keeping people out, they show they are exclusive. Tuition is $40,000 / year, and they keep telling us that the college is in service of humanity. If they were in the service of humanity, they’d charge less, and stream the talk to whoever wants to listen in. I have to hope this will change sooner or later.

Shopping for toilet paper was a big issue at the beginning of the pandemic, but I’ve now got a dog to do it for me. He goes to the store, brings it back. Brings back toothpaste too. He’s a lavatory retriever. (I got this joke from Steve Feldman; the crowbar joke too.)

I don’t mind that there are few new movies. There are plenty of old movies that I have not seen, and old TV shows too.

This fellow is the new head of Biden’s COVID-19 task force. He’s got a science-based plan for over-population and the disease.

I like that people are leaving New York and LA. It’s healthy, and saves on rent. Folks still travel there, mostly for the rioting, but lockdowns are nicer in Michigan.

More people are hunting, and hiking, and canoeing. These are active activities that you can do on lockdown. The old activities were passive, or going out to eat. Passive activities are almost a contradiction in terms.

We’re cooking more at home, which is healthier. And squirrel doesn’t taste half bad. If I live through this, I’ll be healthy.

I’m reading more, and have joined goodreads.com. I’ve developed a superpower: I find can melt ice cubes, just by looking at them. It takes a while but they melt.

A lot more folks have dogs. And folks have gotten into religion. Wouldn’t it be great, if after death we fond that dyslexic folks were right. There really is a dog.

Let’s love the virus. If we don’t, the next crisis will be worse.

There was an election last week. My uncles voted for Biden, which really surprised me. They were staunch Republicans when they were alive. My aunt got the ballot and convinced them. She was a Democrat when she was alive.

I got pneumonia vaccine shot, and a flu shot. That wasn’t a joke. I think it’s a good idea. Here’s why. People mostly die from pneumonia not the virus.

Before COVID, the other big crisis was global warming. Al Gore and Greta Thunberg claimed we had to shutter production and stop driving to save the planet. COVID-19 has done it. The next crisis is over-population. COVID is already curing that problem — not so much in China, but in the US, Europe, and South America.

Just As a final thought, let’s look at the bright side of the virus. If we don’t, the next crisis will be worse. Take Monty Python’s advice and Always look at the bright side of life.

Robert Buxbaum, November 20, 2020.

The Great, New York to Paris, Automobile race of 1908.

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As impressive as Lindberg’s transatlantic fight was in 1926, more impressive was George Schuster driving and winning the New York to Paris Automobile race beginning in the dead of winter, 1908, going the long way, through Russia. As of 1908, only nine cars had ever made the trip from Chicago to California, and none had done it in winter, but this race was to go beyond California, to Alaska and then over the ice through Russia and to Paris. Theodore Roosevelt was president, and Americans were up to any challenge. So, on February 12, 1908 there congregated in Times Square, New York, a single, US-made production car, along with five, specially made super-cars from Europe; one each from Italy and Germany; and three from France. The US car, a Thomas Flyer (white), is shown in the picture below. The ER Thomas company sent along George Schuster, as an afterthought: he was a mechanic and test-driver for the company, and was an ex bicycle racer. The main driver was supposed to be Montague Roberts, a dashing sportsmen, but the fellow dropped out in Cheyenne, Wyoming. Schuster reached the Eiffel tower on July 30, 1908, 169 days after leaving New York. The Germans and Italians followed. None of the French super-cars got further than Vladivostok, and one dropped out after less than 100 miles.

The race was sponsored by The New York Times and Le Matin, a Paris newspaper. They offered a large trophy, a cash prize of $1000, not enough to pay for the race, and the prospect of fame. The original plan was for drivers to go from New York to San Francisco, then to Seattle by ship, and Northern Alaska, driving to Russia across the Arctic ice. That plan was abandoned when Schuster, the first driver to reach Alaska, discovered ten foot snows outside of Valdez. The race was modified so that travel to Russia would be by ship. Schuster took his Thomas to Russia from Alaska, the other two drivers reached Russia from Seattle by way of Japan. Schuster was given a bonus of days to account for having taken the longer route. Because of his detour, he was the last to arrive in Russia. From Japan, the route was Vladivostok, Omsk, Moscow, St. Petersburg, Berlin, and Paris, 21,900 miles total; 13,341 miles driven. Schuster drove most of those 13,341 miles, protected by his own .32-caliber pistol, and mostly guided by the stars and a sextant. He’d taught himself celestial navigation as there were no roadmaps, and hardly any roads.

George Schuster driving the Thomas Flyer, the only American entry, and the only production motorcar in the race.

George Schuster driving the Thomas Flyer with another mechanic, George Miller, the Flyer was only American entry, and the only production motorcar in the race. Note that the flag has only 45 stars.

The ship crossing of the Pacific was a good idea given that, even in the dead of winter, global warming meant that the arctic could not be relied upon to be solid ice. As it was, Schuster had to content with crossing the Rockies in deep snow, and crossing Russia in the season of deepest mud. He reached the Eiffel tower at 6 p.m. on July 30, 1908. The German car had arrived in Paris three days ahead of Schuster, but was penalized to second place because the German team had avoided the trip to Alaska, and had traveled some 150 km of the Western US by railroad while Schuster had driven. The Italian team reached Paris months later, in September, 1908. That the win went to the only production car to compete is indicative, perhaps of the reliability that comes with mass production. That Mr. Schuster was not given the fame that Lindberg got may have to do with the small size of the prize, or with him being a mechanic while Lindberg was a “flyer”. Flyers were sexy; even the car was called a flyer. The Times saw fit to hardly mention Schuster at all, and when it did, it spelled his name wrong. Instead the Times headline read, “Thomas Flyer wins New York to Paris Race.” You’d think the car did it on its own, or that the driver was named Thomas Flyer.

The Flyer crossing a swollen river in Manchuria.

Schuster in his Flyer crossing a swollen river in Manchuria.

The Times could not get enough of Montague Roberts; the driver of the first leg was famous and photographic. They tried to get Roberts to drive the last few miles into Paris, “once the roads were good”. And Roberts was the one chosen to drive in the hero-parade in New York, Schuster rode too, but didn’t drive. Schuster was feted by Theodore Roosevelt, though, who said he liked people “who did things.” Schuster said he’d never do a race like that again, and he never did race again.

The race did wonders for the reputation of American automobiles, and greatly spurred the desire for roads, but it did little or nothing for the E.R.Thomas company. Thomas cars were high cost, high power models, and they lost out in the marketplace to Henry Ford’s, low-cost Model T’s. You’d think that, in the years leading up to WWI, the US Army might buy a high cost, high reliability car, but they were not interested, and the Thomas company did little to capitalize on their success. The Flyer design that won the race was discontinued. It was a 60 hp, straight 4 cylinder engine version, replaced by lower cost Flyers with 3 cylinders and 24 hp. Shortly after that, Edwin R. Thomas, decided to drop the Flyer altogether. His company went bankrupt in 1912, and was bought by Empire Smelting. The original Flyer was sold in 1913 at a bankruptcy action, lot #1829, “Famous New York to Paris Racer.”

ER Thomas went on to found another car company, as was the style in those days. Thomas-Detroit went on make similar cars to the Flyer, but cheaper. The largest, the K-30, was only 30 hp. The original Thomas Flyer is now in the National Automobile Museum, Reno Nevada. after being identified by Schuster and restored. Here is a video showing the original Flyer being driven by a grandson of George Schuster. There is a lower-power Thomas Flyer (black) in a back space of the Henry Ford museum (Detroit). Protos vehicles, similar to the one that came in second, were produced for the German military through WWI. Their manufacturer, Siemens, benefited, as did the German driver.

Advertisement for the Protos Automobile, a product of Siemens motor company. The race did not include a production Protos but one made specially for the race.

Advertisement for the Protos Automobile, a product of Siemens motor company. The race did not include a production Protos but one made specially for the race.

The Thomas engine (and the Protos) engine) live on in a host of cars with water-cooled, four-cylinder, straight engines. In 1922, Chalmers-Detroit merged with Maxwell and continued to produce versions of the old Flyer design, now with an internal drive-shaft. The original Flyer was powered via a gear-chain, like a bicycle. In 1928, Maxwell was sold to Chrysler. Chrysler persists in calling their high-power, four-cylinder engines by the name Chalmers. As for Schuster, when ER Thomas closed its doors, he had still not been paid for his time as a race driver. He went to work for Pierce-Arrow, another maker of large, heavy vehicles. The “cheaper by the dozen” family (two parents, 12 kids) drove a Pierce-Arrow.

The Great race appears in two documentaries and two general audience movies, both comedies. The first of these was Mishaps of the New York–Paris Race, released by Georges Méliès, July 1908, just about as the Flyer was entering Paris. The second movie version  “The Great Race” was released in 1965. It’s one of my favorite movies, with Jack Lemon as the Protos driver (called Dr. Fate in the movie), Tony Curtis as “The Great Leslie”, the Flyer driver. For the movie, the Flyer is called “The Leslie”, and with Natalie Wood as a female reporter who rides along and provides the love interest. In the actual race reporters from the New York Times, male, traveled in the Flyer’s rear seat sending stories back by carrier pigeon.

Path of the Great Race

Path of the Great Race

As a bit of fame, here’s George Schuster in 1958 on “What’s my secret.” He was 85, and no one knew of him or the race. Ten years later, in 1968, Schuster finally received his $1000 prize, but still no fame. A blow-by-blow of the race can be found here, in Smithsonian magazine. There is also an article about the race in The New York Times, February 10, 2008. This article includes only two pictures, a lead picture showing one of the French cars, and another showing Jeff  Mahl, the grandson of George Schuster, and a tiny bit of the flyer. Why did the New York Times choose these pictures? My guess is it’s the same reason that they reported as they did in 1908: The French car looked better than the Flyer, and Jeff Mahl looked better than George Schuster.

Robert Buxbaum, July 20, 2018. What does all this mean, I’ve wondered as I wrote this essay. There were so many threads, and so many details. After thinking a bit, my take is that the movie versions were right. It was all a comedy. Life becomes a comedy when the wrong person wins, or the wrong vehicle does. A simple mechanic working for a failing auto company beat great drivers and super cars, surpassing all sorts of obstacles that seem impossible to surpass. That’s comedy, It’s for this reason that Dante’s Divine Comedy is a comedy. When we see things like this we half-choose to disbelieve, and we half-choose to laugh, and because we don’t quite believe, very often we don’t reward the winner as happened to Schuster for the 60 years after the race. Roberts should have won, so we’ll half-pretend he did.

Most traffic deaths are from driving too slow

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About 40,100 Americans lose their lives to traffic accidents every year. About 10,000 of these losses involve alcohol, and about the same number involve pedestrians, but far more people have their lives sucked away by waiting in traffic, IMHO. Hours are spent staring at a light, hoping it will change, or slowly plodding between destinations with their minds near blank. This slow loss of life is as real as the accidental type, but less dramatic.

Consider that Americans drive about 3.2 trillion miles each year. I’ll assume an average speed of 30 mph (the average speed registered on my car is 29 mph). Considering only the drivers of these vehicles, I calculate 133 billion man-hours of driving per year; that’s 15.2 million man-years or 217,000 man-lifetimes. If people were to drive a little faster, perhaps 10% faster, some 22,000 man lifetimes would be saved per year in time wasted. The simple change of raising the maximum highway speed to 80 mph from 70, I’d expect, would save half this, maybe 10,000 lifetimes. There would likely be some more accidental deaths, but not more accidents. Tiredness is a big part of highway accidents, as is highway congestion. Faster speeds decreases both, decreasing the number of accidents, but one expects there will be an increase in the deadliness of the accidents.

Highway deaths for the years before and after Nov. 1995. Most states raised speeds, but some left them unchanged.

Highway deaths for the years before and after speed limit were relaxed in Nov. 1995. At that time most states raised their speed limits, but some did not, leaving them at 65 rural, 55 urban; a few states were not included in this study because they made minor changes.

A counter to this expectation comes from the German Autobahn, the fastest highway in the world with sections that have no speed limit. German safety records show that there are far fewer accidents per km on the Autobahn, and that the fatality rate per km is about 1/3 that on other stretches of highway. This is about 1/2 the rate on US highways (see safety comparison). For a more conservative comparison, we could turn to the US experience of 1995. Before November 1995, the US federal government limited urban highway speeds to 55 mph, with 65 mph allowed only on rural stretches. When these limits were removed, several states left the speed limits in place, but many others raised their urban speed limits to 65 mph, and raised rural limits to 70 mph. Some western states went further and raised rural speed limits to 75 mph. The effect of these changes is seen on the graph above, copied from the Traffic Operations safety laboratory report. Depending on how you analyze the data, there was either a 2% jump (institute of highway safety) in highway deaths or perhaps a 5% jump. These numbers translate to a 3 or 6% jump because the states that did not raise speeds saw a 1% drop in death rates. Based on a 6% increase, I’d expect higher highway speed limits would cost some 2400 additional lives. To me, even this seems worthwhile when balanced against 10,000 lives lost to the life-sucking destruction of slow driving.

Texas has begun raising speed limits. Texans seem happy.

Texas has begun raising speed limits. So far, Texans seem happy.

There are several new technologies that could reduce automotive deaths at high speeds. One thought is to only allow high-speed driving for people who pass a high-speed test, or only for certified cars with passengers who are wearing a 5-point harness, or only on roads. More relevant to my opinion is only on roads with adequate walk-paths — many deaths involve pedestrians. Yet another thought; auto-driving cars (with hydrogen power?). Computer-aided drivers can have split second reaction times, and can be fitted with infra-red “eyes” that see through fog, or sense the motion of a warm object (pedestrian) behind an obstruction. The ability of computer systems to use this data is limited currently, but it is sure to improve.

I thought some math might be in order. The automotive current that is carried by a highway, cars/hour, can be shown to equal to the speed of the average vehicle multiplied by the number of lanes divided by the average distance between vehicles. C = v L/ d.

At low congestion, the average driving speed, v remains constant as cars enter and leave the highway. Adding cars only affects the average distance between cars, d. At some point, around rush hour, so many vehicles enter the highway that d shrinks to a distance where drivers become uncomfortable; that’s about d = 3 car lengths, I’d guess. People begin to slow down, and pretty soon you get a traffic jam — a slow-moving parking lot where you get less flow with more vehicles. This jam will last for the entirety of rush hour. One of the nice things about auto-drive cars is that they don’t get nervous, even at 2 car lengths or less at 70 mph. The computer is confident that it will brake as soon as the car in front of it brakes, maintaining a safe speed and distance where people will not. This is a big safety advantage for all vehicles on the road.

I should mention that automobile death rates vary widely between different states (see here), and even more widely between different countries. Here is some data. If you think some country’s drivers are crazy, you should know that many of the countries with bad reputations (Italy, Ireland… ) have highway death rates that are lower than ours. In other countries, in Africa and the mid-east death rates per car or mile driven are 10x, 100x, or 1000x higher than in the US. The countries have few cars and lots of people who walk down the road drunk or stoned. Related to this, I’ve noticed that old people are not bad drivers, but they drive on narrow country roads where people walk and accidents are common.

Robert Buxbaum, June 6, 2018.

Hydrogen powered trucks and busses

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With all the attention on electric cars, I figure that we’re either at the dawn of electric propulsion or of electric propulsion hype. Elon Musk’s Tesla motor car company stock is now valued at $59 B, more than GM or Ford despite the company having massive losses and few cars. It’s a valuation that, I suspect, hangs on the future of autonomous vehicles, a future whose form is uncertain. In this space, I suspect that hydrogen-battery hybrids make more sense than batteries alone, and that the first large-impact uses will be trucks and busses — vehicles that go long distance on highways.

Factory floor, hydrogen fueling station for plug-power forklifts. Plug FCs reached their 10 millionth refueling this January.

Factory floor, hydrogen fueling station for fuel cell forklifts. This company’s fuel cells have had over 10 million refuelings so far.

Currently there are only two brands of autonomous vehicle available for sale in the US: the Cadillac CT6, a gasoline hybrid, and the Tesla, a pure battery vehicle. Neither work well except on highways because there are fewer on-highway driver-issues. Currently, the CT6 allows you to take your hands off the wheel — see review here. This, to me, is a big deal: it’s the only real point of autonomous control, and if one can only do this on the highway, that’s still great. Highway driving gets tiring after the first hundred miles or so, and any relief is welcome. With Tesla cars, you can never take your hand off the wheel or the car stops.

That battery cars compete, cost wise, I suspect, is only possible because the US government highly subsidizes the battery cost. Musk hides the true cost of the battery, I suspect, among the corporate losses. Without this subsidy, hydrogen – hybrid vehicles, I suspect, would be far cheaper than Tesla while providing better range, see my calculation here. Adding to the advantage of hybrids over our batteries, the charge time is much faster. This is very important for highway vehicles traveling any significant distance. While hydrogen fuel isn’t as cheap as gasoline, it’s becoming cheaper — now about double the price of gasoline on a per mile basis, and it’s far cheaper than batteries when the wear-and tear life of the batter is included. And unlike gasoline, hydrogen propulsion is pollution-free  and electric.

Electric propulsion seems better suited to driverless vehicles than gasoline propulsion because of how easy it is to control electricity. Gasoline vehicles can have odd acceleration issues, e.g. when the gasoline gets wet. And it’s not like there are no hydrogen fueling stations. Hydrogen, fuel-cell power has become a major competitor for fork-lifts, and has recently had its ten millionth refueling in that application. The same fueling stations that serve fork-lift users could serve the self-driving truck and bus market. For round the town use, hydrogen vehicles could use battery power along (plug-in hybrid mode). A vehicle of this sort could have very impressive performance. A Dutch company has begun to sell kits to convert Tesla model S autos to a plug-in hydrogen hybrid. The result boasts a 620 mile (1000 km) range instead of the normal 240 miles; see here. On the horizon, Hyundai has debuted the self-driving “Nexo” with a range of 370 miles. Self-driving Nexos were used to carry spectators between venues at the Pyongyang olympics. The Toyota Mirai (312 miles) and the Honda Clarity Fuel Cell (366 miles) can be expected to début with similar capabilities in the near future.

Cadillac CT6 with supercruise. An antonymous vehicle that you can buy today that allows you to take your hand off the wheel.

Cadillac CT6 with supercruise. An autonomous vehicle that you can buy today that allows you to take your hand off the wheel.

In the near-term, trucks and busses seem more suited to hydrogen than general-use cars because of the localization of hydrogen refueling, Southern California has some 36 public hydrogen refueling stations at last count, but that’s too few for most personal car users. Other states have even fewer spots; Michigan has only two where one can drive up and get hydrogen. A commercial trucking company can work around this if they go between fixed depots that may already have hydrogen dispensers, or can be fitted with dispensers. Ideally they use the same dispensers as the forklifts. If one needs extra range one can carry a “hydrogen Jerry can” or two — each jerry can providing an extra 20-30 miles of emergency range. I do not see electric vehicles working as well for trucks and busses because the charge times are too slow, the range is too modest, and the electric power need is too large. To charge a 100 kWhr battery in an hour requires an electric feed of over 100 kW, about as much as a typical mall. With a, more-typical 24kW (240 V at 100 Amps) service the fastest you can recharge would be 4 1/2 hours.

So why not stick to gasoline, as with the Cadillac? My first, simple answer is electric control simplicity. A secondary answer is the ability to use renewable power from wind, solar, and nuclear; there seems to be a push for renewable and electric or hydrogen vehicles make use of this power. Of these two, only hydrogen provides the long-range, fast fueling necessary to make self-driving trucks and busses worthwhile.

Robert Buxbaum March 12, 2018. My company, REB Research provides hydrogen purifiers and hydrogen generators.

Keeping your car batteries alive.

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Lithium-battery cost and performance has improved so much that no one uses Ni-Cad or metal hydride batteries any more. These are the choice for tools, phones, and computers, while lead acid batteries are used for car starting and emergency lights. I thought I’d write about the care and trade-offs of these two remaining options.

As things currently stand, you can buy a 12 V, lead-acid car battery with 40 Amp-h capacity for about $95. This suggests a cost of about $200/ kWh. The price rises to $400/kWh if you only discharge half way (good practice). This is cheaper than the per-power cost of lithium batteries, about $500/ kWh or $1000/ kWh if you only discharge half-way (good practice), but people pick lithium because (1) it’s lighter, and (2) it’s generally longer lasting. Lithium generally lasts about 2000 half-discharge cycles vs 500 for lead-acid.

On the basis of cost per cycle, lead acid batteries would have been replaced completely except that they are more tolerant of cold and heat, and they easily output the 400-800 Amps needed to start a car. Lithium batteries have problems at these currents, especially when it’s hot or cold. Lithium batteries deteriorate fast in the heat too (over 40°C, 105°F), and you can not charge a lithium car battery at more than 3-4 Amps at temperatures below about 0°C, 32°F. At higher currents, a coat of lithium metal forms on the anode. This lithium can react with water: 2Li + H2O –> Li2O + H2, or it can form dendrites that puncture the cell separators leading to fire and explosion. If you charge a lead acid battery too fast some hydrogen can form, but that’s much less of a problem. If you are worried about hydrogen, we sell hydrogen getters and catalysts that remove it. Here’s a description of the mechanisms.

The best thing you can do to keep a lead-acid battery alive is to keep it near-fully charged. This can be done by taking long drives, by idling the car (warming it up), or by use of an external trickle charger. I recommend a trickle charger in the winter because it’s non-polluting. A lead-acid battery that’s kept at near full charge will give you enough charge for 3000 to 5000 starts. If you let the battery completely discharge, you get only 50 or so deep cycles or 1000 starts. But beware: full discharge can creep up on you. A new car battery will hold 40 Ampere-hours of current, or 65,000 Ampere-seconds if you half discharge. Starting the car will take 5 seconds of 600 Amps, using 3000 Amp-s or about 5% of the battery’s juice. The battery will recharge as you drive, but not that fast. You’ll have to drive for at least 500 seconds (8 minutes) to recharge from the energy used in starting. But in the winter it is common that your drive will be shorter, and that a lot of your alternator power will be sent to the defrosters, lights, and seat heaters. As a result, your lead-acid battery will not totally charge, even on a 10 minute drive. With every week of short trips, the battery will drain a little, and sooner or later, you’ll find your battery is dead. Beware and recharge, ideally before 50% discharge

A little chemistry will help explain why full discharging is bad for battery life (for a different version see Wikipedia). For the first half discharge of a lead-acid battery, the reaction Is:

Pb + 2PbO2 + 2H2SO4  –> PbSO4 + Pb2O2SO4 + 2H2O.

This reaction involves 2 electrons and has a -∆G° of >394 kJ, suggesting a reversible voltage more than 2.04 V per cell with voltage decreasing as H2SO4 is used up. Any discharge forms PbSO4 on the positive plate (the lead anode) and converts lead oxide on the cathode (the negative plate) to Pb2O2SO4. Discharging to more than 50% involves this reaction converting the Pb2O2SO4 on the cathode to PbSO4.

Pb + Pb2O2SO4 + 2H2SO4  –> 2PbSO4 + 2H2O.

This also involves two electrons, but -∆G < 394 kJ, and voltage is less than 2.04 V. Not only is the voltage less, the maximum current is less. As it happens Pb2O2SO4 is amorphous, adherent, and conductive, while PbSO4 is crystalline, not that adherent, and not-so conductive. Operating at more than 50% results in less voltage, increased internal resistance, decreased H2SO4 concentrations, and lead sulfate flaking off the electrode. Even letting a battery sit at low voltage contributes to PbSO4 flaking off. If the weather is cold enough, the low concentration H2SO4 freezes and the battery case cracks. My advice: Get out your battery charger and top up your battery. Don’t worry about overcharging; your battery charger will sense when the charge is complete. A lead-acid battery operated at near full charge, between 67 and 100% will provide 1500 cycles, about as many as lithium. 

Trickle charging my wife's car. Good for battery life. At 6 Amps, expect this to take 3-6 hours.

Trickle charging my wife’s car: good for battery life. At 6 Amps, expect a full charge to take 6 hours or more. You might want to recharge the battery in your emergency lights too. 

Lithium batteries are the choice for tools and electric vehicles, but the chemistry is different. For longest life with lithium batteries, they should not be charged fully. If you change fully they deteriorate and self-discharge, especially when warm (100°F, 40°C). If you operate at 20°C between 75% and 25% charge, a lithium-ion battery will last 2000 cycles; at 100% to 0%, expect only 200 cycles or so.

Tesla cars use lithium batteries of a special type, lithium cobalt. Such batteries have been known to explode, but and Tesla adds sophisticated electronics and cooling systems to prevent this. The Chevy Volt and Bolt use lithium batteries too, but they are less energy-dense. In either case, assuming $1000/kWh and a 2000 cycle life, the battery cost of an EV is about 50¢/kWh-cycle. Add to this the cost of electricity, 15¢/kWh including the over-potential needed to charge, and I find a total cost of operation of 65¢/kWh. EVs get about 3 miles per kWh, suggesting an energy cost of about 22¢/mile. By comparison, a 23 mpg car that uses gasoline at $2.80 / gal, the energy cost is 12¢/mile, about half that of the EVs. For now, I stick to gasoline for normal driving, and for long trips, suggest buses, trains, and flying.

Robert Buxbaum, January 4, 2018.

The energy cost of airplanes, trains, and buses

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I’ve come to conclude that airplane travel makes a lot more sense than high-speed trains. Consider the marginal energy cost of a 90kg (200 lb) person getting on a 737-800, the most commonly flown commercial jet in US service. For this plane, the ratio of lift/drag at cruise speed is 19, suggesting an average value of 15 or so for a 1 hr trip when you include take-off and landing. The energy cost of his trip is related to the cost of jet fuel, about $3.20/gallon, or about $1/kg. The heat energy content of jet fuel is 44 MJ/kg. Assuming an average engine efficiency of 21%, we calculate a motive-energy cost of 1.1 x 10-7 $/J. The amount of energy per mile is just force times distance. Force is the person’s weight in (in Newtons) divided by 15, the lift/drag ratio. The energy use per mile (1609 m) is 90*9.8*1609/15 = 94,600 J. Multiplying by the $-per-Joule we find the marginal cost is 1¢ per mile: virtually nothing compared to driving.

The Wright brothers testing their gliders in 1901 (left) and 1902 (right). The angle of the tether reflects the dramatic improvement in the lift-to-drag ratio.

The Wright brothers testing their gliders in 1901 (left) and 1902 (right). The angle of the tether reflects a dramatic improvement in lift-to-drag ratio; the marginal cost per mile is inversely proportional to the lift-to-drag ratio.

The marginal cost of 1¢/passenger mile explains why airplanes offer crazy-low, fares to fill seats. But this is just the marginal cost. The average energy cost is higher since it includes the weight of the plane. On a reasonably full 737 flight, the passengers and luggage  weigh about 1/4 as much as the plane and its fuel. Effectively, each passenger weighs 800 lbs, suggesting a 4¢/mile energy cost, or $20 of energy per passenger for the 500 mile flight from Detroit to NY. Though the fuel rate of burn is high, about 5000 lbs/hr, the mpg is high because of the high speed and the high number of passengers. The 737 gets somewhat more than 80 passenger miles per gallon, far less than the typical person driving — and the 747 does better yet.

The average passengers must pay more than $20 for a flight to cover wages, capital, interest, profit, taxes, and landing fees. Still, one can see how discount airlines could make money if they have a good deal with a hub airport, one that allows them low landing fees and allows them to buy fuel at near cost.

Compare this to any proposed super-fast or Mag-lev train. Over any significant distance, the plane will be cheaper, faster, and as energy-efficient. Current US passenger trains, when fairly full, boast a fuel economy of 200 passenger miles per gallon, but they are rarely full. Currently, they take some 15 hours to go Detroit to NY, in part because they go slow, and in part because they go via longer routes, visiting Toronto and Montreal in this case, with many stops along the way. With this long route, even if the train got 150 passenger mpg, the 750 mile trip would use 5 gallons per passenger, compared to 6.25 for the flight above. This is a savings of $5, at a cost of 20 hours of a passenger’s life. Even train speeds were doubled, the trip would still take 10 hours including stops, and the energy cost would be higher. As for price, beyond the costs of wages, capital, interest, profit, taxes, and depot fees, trains have to add the cost of new track and track upkeep. Wages too will be higher because the trip takes longer. While I’d be happy to see better train signaling to allow passenger trains to go 100 mph on current, freight-compatible lines, I can’t see the benefit of government-funded super-track for 150+ mph trains that will still take 10 hours and will still be half-full.

Something else removing my enthusiasm for super trains is the appearance of new short take-off and landing jets. Some years ago, I noted that Detroit’s Coleman Young airport no longer has commercial traffic because its runway was too short, 1550 m. I’m happy to report that Bombardier’s new CS100s should make small airports like this usable. A CS100 will hold 120 passengers, requires only 1509m of runway, and is quiet enough for city use. Similarly, the venerable Q-400 carries 72 passengers and requires 1425m. The economics of these planes is such that it’s hard to imagine mag-lev beating them for the proposed US high-speed train routes: Dallas to Houston; LA to San José to San Francisco; or Chicago-Detroit-Toledo-Cleveland-Pittsburgh. So far US has kept out these planes because Boeing claims unfair competition, but I trust that this is just a delay. For shorter trips, I note that modern busses are as fast and energy-efficient as trains, and far cheaper because they share the road costs with cars and trucks.

If the US does want to spend money, I’d suggest improving inner-city airports, and to improve roads for higher speed car and bus traffic. If you want low pollution transport at high efficiency, how about hydrogen hybrid buses? The range is high and the cost per passenger mile remains low because busses use very little energy per passenger mile.

Robert Buxbaum, October 30, 2017. I taught engineering for 10 years at Michigan State, and my company, REB Research, makes hydrogen generators and hydrogen purifiers.

The hydrogen jerrycan

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Here’s a simple invention, one I’ve worked on off-and-on for years, but never quite built. I plan to work on it more this summer, and may finally build a prototype: it’s a hydrogen Jerry can. The need to me is terrifically obvious, but the product does not exist yet.

To get a view of the need, imagine that it’s 5-10 years in the future and you own a hydrogen, fuel cell car. You’ve run out of gas on a road somewhere, per haps a mile or two from the nearest filling station, perhaps more. You make a call to the AAA road-side service and they show up with enough hydrogen to get you to the next filling station. Tell me, how much hydrogen did they bring? 1 kg, 2 kg, 5 kg? What did the container look like? Is there one like it in your garage?

The original, German "Jerry" can. It was designed at the beginning of WWII to help the Germans to overrun Europe.

The original, German “Jerry” can. It was designed at the beginning of WWII to help the Germans to overrun Europe. I imagine the hydrogen version will be red and roughly these dimensions, though not quite this shape.

I figure that, in 5-10 years these hydrogen containers will be so common that everyone with a fuel cell car will have one, somewhere. I’m pretty confident too that hydrogen cars are coming soon. Hydrogen is not a total replacement for gasoline, but hydrogen energy provides big advantages in combination with batteries. It really adds to automotive range at minimal cost. Perhaps, of course this is wishful thinking as my company makes hydrogen generators. Still it seems worthwhile to design this important component of the hydrogen economy.

I have a mental picture of what the hydrogen delivery container might look like based on the “Jerry can” that the Germans (Jerrys) developed to hold gasoline –part of their planning for WWII. The story of our reverse engineering of it is worth reading. While the original can was green for camouflage, modern versions are red to indicate flammable, and I imagine the hydrogen Jerry will be red too. It must be reasonably cheap, but not too cheap, as safety will be a key issue. A can that costs $100 or so does not seem excessive. I imagine the hydrogen Jerry can will be roughly rectangular like the original so it doesn’t roll about in the trunk of a car, and so you can stack a few in your garage, or carry them conveniently. Some folks will want to carry an extra supply if they go on a long camping trip. As high-pressure tanks are cylindrical, I imagine the hydrogen-jerry to be composed of two cylinders, 6 1/2″ in diameter about. To make the rectangular shape, I imagine the cylinders attached like the double pack of a scuba diver. To match the dimensions of the original, the cylinders will be 14″ to 20″ tall.

I imagine that the hydrogen Jerry can will have at least two spouts. One spout so it can be filled from a standard hydrogen dispenser, and one so it can be used to fill your car. I suspect there may be an over-pressure relief port as well, for safety. The can can’t be too heavy, no more than 33 lbs, 15 kg when full so one person can handle it. To keep the cost and weight down, I imagine the product will be made of marangeing steel wrapped in kevlar or carbon fiber. A 20 kg container made of these materials will hold 1.5 to 2 kg of hydrogen, the equivalent of 2 gallons of gasoline.

I imagine that the can will have at least one handle, likely two. The original can had three handles, but this seems excessive to me. The connection tube between two short cylinders could be designed to serve as one of the handles. For safety, the Jerrycan should have a secure over-seal on both of the fill-ports, ideally with a safety pin latch minimize trouble in a crash. All the parts, including the over- seal and pin, should be attached to the can so that they are not easily lost. Do you agree? What else, if anything, do you imagine?

Robert Buxbaum, February 26, 2017. My company, REB Research, makes hydrogen generators and purifiers.

More French engineering, the Blitzkrieg motorcycle.

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There’s something fascinating that I find in French engineering. I wrote a previous essay about French cars, bridges, and the Eiffel tower. Here’s a picture or two more. Things I wanted to include but didn’t. First here’s a Blitzkrieg Vespa motorcycle; the French built some 800 of these from 1947 to 1962 and used them in Vietnam and Algeria. What’s remarkable is how bizarrely light and unprotected it is. It’s a design aesthetic that follows no one, and that American engineers would not follow.

French Blitzkrieg Vespa used in Vietnam

French Blitzkrieg Vespa used in Vietnam; cannon range is 4.5 miles.

The key engineering insight that allows this vehicle to make sense is that recoil-less rifles are really recoil-less if you design them right. Thus, one can (in theory) mount them on something really light, like a Vespa. Another key (French) insight is that a larger vehicle may make the soldier more vulnerable rather than less by slowing him down and by requiring more gasoline and commissariat services.

Americans do understand the idea of light and mobile, but an American engineers idea of this is a jeep or an armored truck; not a Vespa. From my US engineering perspective, the French went way overboard here. The French copy no one, and no one copies the French, as they say. Still, these things must have worked reasonably well or they would not have made 800 of them over 15 years. A Vespa is certainly cheaper than a Jeep, and easier to transport to the battle zone….

Robert Buxbaum, February 18, 2016. The Italians have a somewhat similar design aesthetic to the French: they like light and cheap, but also like maneuverable and favor new technology. See my blog about a favorite Fiat engine.

Alcohol and gasoline don’t mix in the cold

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One of the worst ideas to come out of the Iowa caucuses, I thought, was Ted Cruz claiming he’d allow farmers to blend as much alcohol into their gasoline as they liked. While this may have sounded good in Iowa, and while it’s consistent with his non-regulation theme, it’s horribly bad engineering.

At low temperatures ethanol and gasoline are no longer quite miscible

Ethanol and gasoline are that miscible at temperatures below freezing, 0°C. The tendency is greater if the ethanol is wet or the gasoline contains benzenes

We add alcohol to gasoline, not to save money, mostly, but so that farmers will produce excess so we’ll have secure food for wartime or famine — or so I understand it. But the government only allows 10% alcohol in the blend because alcohol and gasoline don’t mix well when it’s cold. You may notice, even with the 10% mixture we use, that your car starts poorly on the coldest winter days. The engine turns over and almost catches, but dies. A major reason is that the alcohol separates from the rest of the gasoline. The concentrated alcohol layer screws up combustion because alcohol doesn’t burn all that well. With Cruz’s higher alcohol allowance, you’d get separation more often, at temperatures as high as 13°C (55°F) for a 65 mol percent mix, see chart at right. Things get worse yet if the gasoline gets wet, or contains benzene. Gasoline blending is complex stuff: something the average joe should not do.

Solubility of dry alcohol (ethanol) in gasoline. The solubility is worse at low temperature and if the gasoline is wet or aromatic.

Solubility of alcohol (ethanol) in gasoline; an extrapolation based on the data above.

To estimate the separation temperature of our normal, 10% alcohol-gasoline mix, I extended the data from the chart above using linear regression. From thermodynamics, I extrapolated ln-concentration vs 1/T, and found that a 10% by volume mix (5% mol fraction alcohol) will separate at about -40°F. Chances are, you won’t see that temperature this winter (and if you you do, try to find a gas mix that has no alcohol. Another thought, add hydrogen or other combustible gas to get the engine going.

Robert E. Buxbaum, February 10, 2016. Two more thoughts: 1) Thermodynamics is a beautiful subject to learn, and (2) Avoid people who stick to foolish consistency. Too much regulation is bad, as is too little: it’s a common pattern: The difference between a cure and a poison is often just the dose.