Tesla to triple supercharger network by the end of June | Hacker News Reader

Tesla to triple supercharger network by the end of June

teslamotors.com

145 pointsjcdavis100 comments

If I were in the hospitality industry, I'd be buying adjacent shops next to every Tesla charging station. Having a captive, wealthy audience for ~30 minutes seems like a ripe opportunity, whether it is restaurants, masseuses, or cafes. I'd also offer free valet+ services so patrons would stay in my establishment longer: I'll look over your car, start the charging process (in case there is a queue), and make sure to move it when it is done charging.

What's important to remember is the dynamic nature of these improvements. I wouldn't do any development around these short of the standard gas station models. As time progresses I suspect these cars will get greater range and shorter charging times.

And existing gas stations will just grow chargers. These things don't really require a whole lot of infrastructure as I understand it. A standard industrial electrical drop is probably already present (my math says a single charging station will draw 600A). Just drop the station next to an existing parking place and plug it in. The cost is borne mostly by Tesla in producing them as I see it.

I think existing gas stations rely on customers only spending 5-10 mins to keep quantity high, to compensate for lower fuel pricing. Perhaps, in another 5 years, an advance in battery technology will push it down that low, but otherwise I would want to spend the 20 mins someplace with better service, like a grocery store, movie theater, or restaurant.

The model to follow here is oil change stations, like Jiffy Lube. Your car is tied up for 15-30 minutes, so they provide you with free coffee, donuts, TV with cable, wifi, some magazines, and a few nice chairs. All of the above is probably cheaper to add to a gas station than the cost of building a new hospitality facility.

Those places are sufficient for the "5k miles or 3 months" interval. I can endure that a couple times a year. If I was doing this regularly (or with the whole family), I would want more than a free coffee and a magazine. And most existing gas stations that do already have the room to add that already use that space for overpriced chips and candy. I don't see many gas stations I use giving up inventory space to make a lounge. To me, it would make more sense for places that are already equipped to have people stay for 20-30 minutes to drop a couple charging stations out front next to the disabled parking spaces.

If Tesla-class ranges are accepted, I'd think further battery density advances would translate into fewer batteries/lower-weight, rather than maintaining weight and adding additional range. Particularly if charging speed is also advancing, there wouldn't seem to be any call to increase the range beyond what's acceptable. (And using fewer cells would further-advance the charging-time-per-unit-range numbers)

Better to optimize the things people don't like (total charge time) or the things you don't like (high cost of batteries), than to further improve a thing people find acceptable (range).

That said, I wouldn't want to build any business plan that assumes the existence of dedicated charging stations simply because I don't see how they survive long-term.

Dedicated gas stations exist because fuel storage is a large-enough consideration and pumping a fast-enough endeavor that it just makes sense to make fuel pumps a destination in-and-of-themselves.

But if charging stations are a bit of additional electrical work to wire up a handful of spots and charging is going to take a bit of time, why wouldn't every already-viable roadside diner, attraction or hotel just add a few spots (and then a few more, and then a few more...)?

And if you're getting a bit of charge from every other stop you make on a road trip (for snacks, restrooms, meals, attractions, overnights, etc) who needs a 30 minute purgatory at a dedicated charging station?

Even if you needed a charge, choosing a destination that happened to have a charger would seem a more optimal move than choosing a charging station and then hoping it has a destination attached.

I misread that as "hospital" instead of "hospitality" on my first read, which actually brings up an interesting tangent.

If the Tesla stations make use of and store solar power, would they be a viable backup power source for hospitals? Or are the power requirements for a hospital on backup energy way too large for that sort of thing?

Aren't these stations just connected to the grid and any power is just put back into it to help offset charging costs? I don't think there's any actual storage. Not every Supercharger station has solar panels.

I think solar is too unreliable to be a backup power source for much of anything, especially something like a hospital.

The amount of solar panels you'd need to charge a Tesla at supercharger rates would be ridiculous.

They may have solar panels, but that is just something cute that might make a small dent in the installation's grid power consumption.

However, you are on to something [1], though it's more for cars that are parked for long periods during the day. The point of a supercharging station is contrary to donating your vehicle's power to the grid.

1: http://www.scientificamerican.com/article.cfm?id=how-to-sell...

Are you sure?

"plans are to install on-site grid storage to make them self-reliant with their own energy supply"

Well... let's do the math!

Incident solar radiation is about 1 kW per meter squared. Assume 10% end to end efficiency (including solar -> electric, storage, and actual charging efficiency... this is optimistic, but doable... certainly not the cheapest though). You now need 10 square meters of panel to supply 1 kW. Assume sun is out for 12 hours a day, and for the full 12 hours you get all 1 kW/m^2 incident radiation (this is very very generous). The car has a 60kWh battery. So if we want to find out how much panel it takes for one station to charge one car a day...

60kWh to charge, but 12 hours to charge it up, so you basically need 5kW, which is 50 m^2 of panel. Which honestly isn't -THAT- big. Its a 7 meter square. Now... from my random snooping around, and my own impressions, I would say that a 'large' gas station typically covers something like... 500-600 meters squares (thats 5300 to 6500 square feet). That would be enough to super optimistically charge 10-12 cars a day.

I saw optimistic, because incident solar radiation is not that kind. Can take a looksey here: http://rredc.nrel.gov/solar/old_data/nsrdb/1961-1990/redbook...

If you pick average, annual, and single axis east-west tracking (which I believe is the best bang for the buck), you see on the solar map, the BEST places in the US gets 5-6 kWh/m^2/day, compared to our assumption of 12 kWh/m^2/day.

The feasibility of superchargers being even 90% off the grid is of course completely dependent on the ratio of size of supercharger panel array and rate of cars charging. But given the above, I'm inclined to believe that it is highly impractical for the majority of super charger stations to become actually self reliant, especially in high traffic areas.

A supercharger network is going to have a lot of stations on lonely stretches of highway. Given how few Teslas there are being taken on those trips, you're going to want charging stations in places where there will be very, very little usage.

I can easily see a random station on I-10 near the CA/AZ border being entirely self-reliant...

It's a good thought, but I think it makes more sense to add Superchargers to existing service stations. I wouldn't be surprised if that's their plan going forward.

Here are two of the three on the East Coast right now: http://goo.gl/oWSbW. It's located on I-95, the busiest highway on the East Coast. There are two separate service areas, one on each side of the highway, both identical, and both with Superchargers. There's a Mobil gas station, 3 or 4 fast food restaurants, restrooms, and a convenience store.

I think this is brilliant on the part of Tesla. If they can get their charging network big enough & fast enough, new comers to the electric vehicle market would be wise to just use (license?) some of the tech needed to also charge their cars on these stations. Depending on how this is structured, Tesla could come out of this getting a piece of every electric vehicle that gets sold using their chargers. Unless the tech here is nothing special.

Forget whether the tech is something special; it's the value of the real estate. If tesla builds out the supercharger network before anyone else, then they'll be able to license the tech for close to whatever they want, because the cost to build a competitive competing product will be so great, similar to how there's not a lot of new tier 1 internet providers.

I'm not sure Tesla's first-mover advantage here is really going to last. Ultimately, I think it's likely that existing gas stations will slowly start converting to electric charging stations. If they can match Tesla's charging tech, it will even the playing field fairly quickly.

Now if Tesla were to start selling their charging tech to existing gas stations, they might get an even bigger piece of the pie.

Actually, I think putting them into gas stations would be a horrible idea. When was the last time you wanted to sit at a gas station for 20+ minutes to fill your car? They need to put them in places that you are willing to spend a little more time (and quite possibly money) while you charge. Grocery stores, restaurants. I guess they have mostly been putting them in rest stops which also makes some sense along those longer stretches between cities. But while 20 minutes is a great charge time... it sucks to have to sit for 20 minutes if you have nothing to do. It doesn't take me 20 minutes to stretch my legs and have a piss.

I agree with you in principle about the necessity of needing something to do in the meantime, but a huge number of gas stations already have convenience stores attached to them. Perhaps not in bigger cities, but pretty much anywhere where space is not a concern.

ok... maybe "horrible" was too strong of a word. But 20 minutes even with a mini mart attached is too long. Next time you fill up your car, start a timer when you start filling. And then wander around the convenience store until the timer reaches 20 minutes before you can leave. I bet that feels like a life time. :)

The station is not meant for day to day "fillups." It is for long interstate trips... the kind where 30 minutes out walking or having lunch is quite welcome.

We're so used to standard gasoline cars that it can be hard to remember that you never visit a charging station in normal use. You charge your electric car overnight at home.

There are already a good deal of gas stations that fit the supercharger model -- they sell gas, but also have attached restaurants (often fast food, but often up-scale too). Basically the sort of place truckers like to stop -- food and gas in one go.

I would think Tesla would see that as a win, not a loss. Tesla is a car company, not a charging-station company. They're only building supercharger stations because supercharger stations have to exist for Tesla to sell their cars, and nobody else is building them. If gas stations started putting them in it'd mean Tesla could sell their cars without having to deal with the expense and hassle of building out a huge amount of infrastructure.

I see the super chargers (and electric cars in general) more as a way of putting many gas stations out of business. Who will need to ever "fill up" their electric car when they can charge it over night each day? The only time you'll need to charge on the road is on long trips, which is exactly the void that the superchargers fill for Tesla.

Elon was asked about that in the call. Tesla is open to working with other manufacturers, but the superchargers are pretty finely tuned to the battery that Tesla is using. Other manufacturers would have to make their batteries to Tesla's specs for it to work.

>> Other manufacturers would have to make their batteries to Tesla's specs for it to work.

Or buy batteries from Tesla.

I understand the manner in which the battery is put together is a company secret.

I've read that as well, but it's hard to imagine that it can really be that much of a secret. If a competitor wanted to find out how it's put together, all they'd have to do is buy one and take it apart, no?

Another interesting bit at the end is the improved supercharging tech: "The new technology, which is in beta test mode now and will be fully rolled out to customers this summer, will allow Model S to be charged at 120 kW, replenishing three hours of driving in just over 20 minutes."

BTW: 120kW = 160 horsepower, so it's providing the power of your Honda Civic at full throttle for 20 minutes.

That's nuts!

That sure is a big power boost. Welcome to the future.

No, no. The future is 1.21 jigawatts, IIRC.

> In addition to the expansion of the Tesla Supercharger network itself, Tesla is improving the technology behind the Tesla Supercharger to dramatically decrease the amount of time it takes to charge Model S, cutting charging time in half relative to early trials of the system. The new technology, which is in beta test mode now and will be fully rolled out to customers this summer, will allow Model S to be charged at 120 kW, replenishing three hours of driving in just over 20 minutes.

i find this the most interesting part of the release. it sounds like existing model s' currently on the road will be able to take advantage of these upgraded superchargers.. i always assumed advances in charging tech would require upgrades to both the chargers and the cars themselves. anyone know how this is supposed to work?

..i know its wishful thinking, but this gives me hope that my lowly focus electric may someday see its charging capabilities upgraded as well.

when musk unveiled the super chargers he said they were designed for 120kW but that they were testing them out at 90kW first.

"Without spending a cent!"

At some point states are going to start taxing for electricity going into electric vehicles to make up for lost revenue for their road and highway funds. I wonder if Tesla will pay for that or start charging?

On another note, I do hope we don't end up with every manufacture building their own recharging network.

More likely I'd expect such a tax to be imposed in the form of additional taxes/fees on EV purchase/registration. Most EV charging is done at home, and it'd be logistically impractical to try to measure and tax only the electricity used to charge cars. Then again, I think it'll be a while until we see anything like this, since right now the trend is toward subsidizing EVs more than taxing them.

Bear in mind also that the Supercharger network can be free because it's not intended for frequent use; the stations are typically placed at highway rest stops between cities, with the intent to allow occasional long road trips that would normally be outside the vehicle's battery range.

As a Model S owner in Texas, I would think the easiest solution would be to record the mileage on the car at each annual state inspection and tax me on the net mileage driven between inspections.

In California we don't have annual inspections. We have smog tests every 2 years.

I hope they don't invent a "smog test" for electric cars.

Yeah, good observation... Anyone have any info on that?

In Texas, the inspection checks for emissions, windshield cracks, headlight and signal light operation, and tire wear. When I lived in Massachusetts, the inspection wrote me up because my headlights weren't in the same plane (the service station actually had a large cross painted on the wall to see where the lights pointed to). I'm surprised California doesn't have something similar.

california cops issue an obscene amount of fixit tickets. cops pull you over if they notice anything wrong and you have to go through a whole bunch of bullshit to get the fixes signed off.

however my personal theory on why CA doesn't have inspection is because californians take their car aesthetics very seriously and you won't find massive inspection stickers on peoples' windows (an inspection regime demands proof of inspection)

also, the dealerships don't put their own badges on the back of the cars, and parking passes are generally the kind that hang from the rear view mirror. we don't want that shit cluttering up our vehicles

As a californian who used to live in texas, I concur. Cars are like bling here.

Might be close enough, but it's possible you're driving most of your miles outside the state where you live. Gas tax gets closer to tying your spending to where you drive (unless you're able to always refuel in one state).

If they adopted that model for every car, it would be devastating to lower income people. That is why we have withholding on our federal / state taxes. The current model is much easier for people on a budget. We are not talking about a hundred $, we are talking thousands for many[1]. This is especially true where housing is too expensive in the city and lower income people need to commute[2].

1) http://en.wikipedia.org/wiki/Fuel_taxes_in_the_United_States assuming that electricity would need to be taxed at a equivalent level

2) mass transit is not everywhere

At some point states are going to start taxing for electricity going into electric vehicles to make up for lost revenue for their road and highway funds.

Or they'll increase gas taxes to make up for the lost difference until everyone is driving electric cars. Mission accomplished!

That'll get the votes for sure!

There is some logic to it. In my State (Washington) the legislature is currently looking at raising the gas tax rate to adjust for the fact that average fuel economy has gone up a whole bunch in the years since we set the tax rate.

http://www.nwnewsnetwork.org/post/backers-washington-gas-tax...

As we literally have parts of the interstate freeway falling into rivers at the moment, I think I'm OK with some more infrastructure spending.

"Bridges are collapsing and our roads are in disrepair. Rep. Barney voted to put the burden of fixing those roads and bridges on you and let Tesla-driving millionaires pay NO TAXES for those same roads and bridges. Vote Fred - he cares about you."

I'm thinking that might not work.

Actually what will happen is that the tax would move from the fuel source to the mileage source. So you'll have to declare your odometer for the last 12 months and pay taxes on mileage driven.

Today I read an article that said Honda is now offering the fully EV Fit for $259 per month as a lease over 36 months. That is unlimited mileage, includes car insurance and a home charger (!) Tesla's whole model was to eventually create a mass mileage car for $25,000 to $30,000. I'm now convinced that by the time they get there the market will be hyper competitive and they'll be squeezed out or marginalized. They may become the Apple of the car market - high margin, great brand, small marketshare %'s - which is nothing to sneeze at. But I'm worried now they've missed their opportunity to really make it as a stand alone brand. Perhaps they'll become a service supplier to the overall industry with charger stations and batteries etc.

Just like with gas cars, not everyone wants the same thing from an electric car. I wouldn't buy a gas Fit, what makes you think I'd buy an EV one?

It's not really much of a rebuttal to my point though is it?

I think it is. For any product you are going have a range of prices. $15k cars exist... but people still buy $150k cars. So just because Honda gets an EV Fit onto market doesn't mean Tesla missed any mark. If they become the Apple of the EV market, then there is no missed mark.

I won't buy a gas fit but I'll get a EV fit because it's 4 door (bettern than spark ev) and has better looking than leaf.

right... so not everyone wants the same thing from a car.

Many of the major car companies are building electric cars, but often in low volumes, and only in select markets. Building electric vehicles is a way for them to satisfy clean air requirements in California and other states.

For the Honda EV Fit in particular, they are making just 1,100 of them [1].

[1] http://www.latimes.com/business/autos/la-fi-hy-autos-honda-f...

That's a fair point. This article included a comment "Honda says it is expanding certified dealers for the Fit EV, sold in eight states, from the current 36 up to 200 by this summer." - that is, this is a serious push vs just something to offset the clean air requirements.

There's more than a bit of hype in this press release. Tripling the number of superchargers only gets them to 27 with almost half of the stations in California.

Can someone smarter than me comment on the danger of having one of these next door to an apartment or office building? I assume that we're talking about lots of volts and amps here. Are these stations any more or less dangerous than a gas station?

I'm going to guess that they are orders of magnitude safer than gas stations.

Firstly: no ground pollution. Gas stations are terrible for the land they are built on as they leak lots of organic compounds into the soil.

Secondarily: no large reservoirs of combustible materials. I don't know the details of the supercharging stations, but I'd guess that they are at least as safe as the electric transformers we see on telephone poles everywhere.

It looks like their superchargers output 120 kW, which is 12 times the output of the "high voltage outlet" they cite. If you're just talking about the high power output of these chargers, then I doubt it's particularly dangerous.

It's not any more powerful than all of the other power lines that run under, above or near your building. I wouldn't be concerned about it.

Far, far, less dangerous than a gas station. Gas stations are environmental disasters. All sorts of chemicals and fumes emitted by those.

Without spending a cent! I know there was speculation about using solar to power the superchargers eventually, but until then, are they hoping to forever give free fuel to Tesla owners with the hope of recouping supercharger energy costs by selling access to other brands of cars? Any idea how much it will cost Tesla on every free Tesla fill-up?

I was under the impression that the superchargers already had solar power. Tesla partnered with Solar City (another Musk company) to accomplish this.

EDIT: Looks like they're not all solar at this point. Last question in the FAQ at the very bottom: http://www.teslamotors.com/supercharger

Very cool--the last I remember reading was that they were going to see about using his Solar City canopies. Anyone know what the risks are of the solar canopies not keeping up with demand?

I imagine that they would also have a connection to the grid, so that in the case that the solar capacity is insufficient to charge the cars, they could just switch over.

Also, with net metering becoming more wide spread, they could sell back any excess electricity produced from their solar installation back to the grid, which could possibly offset some of the costs of purchasing electricity during periods of high demand.

Typical US electricity rates are around $0.10/kWh, and a baseline Model S having a 60kWh battery, so if I totally guess at a charging efficiency of 50% then a full charge should cost somewhere in the vicinity of $12. On the 60kWh model, it costs $2000 to enable the supercharger hardware, so I can't imagine they'd lose too much money off these.

Keep in mind that these aren't really intended for frequent use: they generally have been placing them on highways in between large cities, with the intent to enable the occasional long-distance road trip that would otherwise be outside the car's battery range. Even if Tesla loses a bit of money per car on average, it's probably worth it just for the value it adds to the cars in peoples' minds.

Except they are feeding the electricity back into the grid, so I don't think it will cost them more than the installation and maintenance of the charger itself.

Is there ever going to come a point where rather than hooking my Tesla up and charging it I just drive up to the station and swap out the battery for a new charged one? This seems to help mitigate one of the biggest problems which is how long charging takes and could, I imagine, be made to be a pretty speedy process if need be.

they have a patent for dual batteries where you keep your main one but get another battery for long trips. there is also an ideal area in the back of the frunk for putting another battery. however there is no indication they are moving to that strategy.

The problem is that it's 7 feet long, 4 feet wide, and weighs 1,000 lbs. It's also sealed into the chassis and makes up the floor of the car.

Probably not anytime soon. You can charge 240 miles of honest, comfortable, real-world, freeway-speed range while you sleep at night, and the same while you're at the office. Cross-country road trips are just about the only time the vast majority of people will ever need to charge at a location other than the origin or destination. Waiting for a supercharge doesn't add much time to the trip unless you normally tend to drive 10 hours straight without answering the call of nature. The superchargers are intended to be at locations and intervals where you would ordinarily stop anyway (to eat, use the facilities, stretch your legs, etc.). There are, of course, cases where a battery swap would be handy, but that's on the wrong side of the 80/20 problem.

Better Place was trying to do that in partnership with Renault. Unfortunately they didn't make it.

The charging stations should be able to accommodate a lot more cars than a gas station. You don't have to have a lot of machinery to pump fluids around as electrons get around on their own. The physical size and expense of equipment per charging station should also be a lot smaller when compared with a gas station.

But keep in mind that I will occupy some space at the supercharger 4-5 times longer than with a regular gas station.

Yesterday I was driving from Waterloo to Toronto and saw two Tesla S models within 30 min from each other. What a nice car! Does anyone know if there are charging stations along 401? Maybe that's why I can't find anything online ...

See map here:

http://www.teslamotors.com/supercharger

They're located between major cities so you can make a road trip, not in them because the idea is when you're home you just plug them into your wall at night.

I wonder if they are using all the data they collect from drivers to help them with planning how the distribute they stations?

In my case, I don't think the data would help. I'd like to drive from Houston to Dallas in my Tesla, but won't until they install the superchargers along the way.

I hope not. Supercharger stations don't exist everywhere, so people don't drive their Teslas freely right now. Choosing where to put them based on where drivers drive their Teslas right now would make the supercharger network have good coverage of where Teslas are today, not where they want Teslas to reach in the future!

From what I have read they are planning the locations based on car purchases, logistics and marketing. States with more cars get more stations, they put stations where people want to be able to go, and where they want people to buy cars.

Devil's advocate here: You can't charge up your car when your power goes out for a few days. Wheras gas stations have generators and gas rolls in on time, supercharger networks and home power drink from the same power grid.

There's a word for all this: stranded and on-the-grid more than ever before.

When power goes out, the city of electric cars also grinds to a halt. And heaven forbid all the people have their cars plugged in ready to charge when the grid comes back on.

Does this mean I need to have a hefty 2 stroke generator with 8 gallons of gas ready to go to charge up the car when the power is out for a few days? You'd probably need a $1000 generator to provide the watts and amps.

lack of gasoline is also a problem periodically. especially during disasters like hurricanes and massive tornados.

Add multi-day electrical outages to the list. During the Northeast Blackout in 2003 you simply could not buy gas for several days in many places because gas pumps run on, you guessed it, electricity.

Actually, I think owning an EV would make me less worried about multi-day blackouts. You can charge an EV from a gas or diesel generator or solar (or wind or...), but a gas car can only run on gas.

What's stopping you from keeping your own generator?

I suppose you'd be effectively limited to the max range of your vehicle from the generator, but if there's no power for 200-300 miles then there's probably bigger problems.

or better yet... lots of people are getting solar panels from elon's other company Solar City.

In the 1st world I think very few people would ding you for building a business model that relied on a predictable steady supply of electricity. Non issue.

Couldn't agree more. Data centers anyone?

Data centers are supposed to have backup generators and systems in place to fuel them up should the need arise. Can't do the same for every house in a city.

However I agree, building something that depends on the grid is not crazy. For example: TVs, computers, light bulbs, fridges, ...

I'm pretty sure the supercharges are hooked up to solar panels for power generation as well as the grid. I'm sure without the grid they won't be able to charge at full output but they should still work.

If you going to think up worse case scenarios then I could think of few for gas-powered cars too. You can't be always prepared for every highly unlikely corner cases.

It's a sad time when people seriously think it is easier to have deep-well pumped, shipped, refined, shipped again toxic substances supplied than electricity.

Use the money you would take to buy your 2-stroke generator and invest it into a bunch of solar panels. Also, donate some money to your local power company, because power outages are not at all a common thing in the european half of the developed world.

In the other HN thread on this announcement, chaz posted [1] about "contingency anxiety", which was an excellent post.

You're doing exactly that.

[1] https://news.ycombinator.com/item?id=5791114

A multi-day power outage has happened to me 1 time in my 40+ years. My various internal combustion cars have failed maybe 5 or 6 times. That's a small sample size, but I suspect that overall the grid is more reliable than vehicles (electric or gas) themselves.

Being able to use your EV to power your home in an emergency, at least low level stuff like minimal lighting and keeping the freezer frozen, might be awesome. Have a house storage battery fed by solar, too, but the EV could ferry out to pick up charge from a remote location which still has power.

From your post, I'm fairly confident that you are young enough to not have visceral memories of this: http://en.wikipedia.org/wiki/1979_energy_crisis .

Look at the picture of that line for gas on that web page. I can assure you that that was not an anomaly. It looked like that all over the country. There were probably cars in that gas line which did not fit into the picture. Those cars I'm sure were moving very slowly. At some point the gas station would run out of gas. Then cars would race to the next gas station.

Americans are used to turning on the water faucet, and always having warm, clean water come out of it. They are used to flipping a light on, and if the switch is not flipped again, that bulb burning for weeks on end until it burns out. Once you travel outside the US, especially if it is not somewhere like western Europe or Japan, you begin to see that this is not the case in much of the world. And I'm not talking about the poorest slum in Bangladesh or deep in the Amazon, I'm talking in large cities, in locally middle class surroundings in much of the world. It gives one perspective on such things. Warm, clean water does not consistently pour out of faucets by magic, it requires an infrastructure which a great deal of the world does not have. In the same manner, political troubles, wars, natural disasters and the like have a way of stopping oil shipments. It is not until this stops unexpectedly that most people realize the fragility of such things.

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