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Comment by klwejchkwejrhc | Hacker News Reader

>renewable electricity has a short-run marginal cost of zero, is cleaner environmentally, much easier to transport and could readily replace up to 40% of global oil demand

Hmm, not sure about that "much easier to transport" part. A cube 3 meters on a side can contain enough gasoline to power the average car for its entire lifespan. The gasoline is a liquid, it is relatively easy to move it between containers. Any technology that is capable of moving macroscopic amounts of matter is capable of moving gasoline. You can haul it on a bicycle, you can haul it on an airplane. To transport electricity you need to make sure there are power lines and batteries arranged in a certain way.

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That really is a remarkable visualization! So much so that I had to compute it for myself - 27,000 liters of gasoline will move an average car 287,000 km assuming 9.4L/100km which is the average 2017 fuel economy for a "car, light truck, SUV" in the US.[1]

[1] https://en.wikipedia.org/wiki/Fuel_economy_in_automobiles

Relatedly, fuel consumption can be measured in square meters:

https://physics.stackexchange.com/questions/325733/why-can-f...

Yes, and the grandparent's calculation can be accomplished by simply dividing the fuel volume by the "area" of the car's efficiency (or multiplying if using MPG, which is inverse area)

https://www.wolframalpha.com/input/?i=%283m%29%5E3*24.9mpg

Pico hectares are a good unit of area to use for this. For a car that gets N miles/gallon, for 1/N gallons/mile, that works out to 235/N pico hectares.

That results in nice small, but not too small, numbers for most current cars, around 50 pico hectares for a Humvee in the city to around 4 pico hectares for a Prius on the highway.

Square centimeters or millimeters seem easier to visualise. The area represents the size of the tube that feeds the engine to get this mileage. You could even express it in the form of a radius.

I cannot really find a standard definition of pico hectares, but am I correct in assuming we're talking about 0.01 mm²? Or 1 square hecto-micrometre, I guess.

2 other numbers I read today on HN that made me look at things differently, although I knew them in other units but those didn't 'click' as much: air (including the water in it) weighs about 4 kg/m3 (much more than I would have intuited), and the whole US uses 'only' 1.3 km3 of water per day.

With existing infrastructure, for most locations, electricity is far easier to transport than gas. Even with some necessary scaling to support widespread car charging, electrical infrastructure is far more robust, redundant and safe than the gas.

Not sure that's true. A gallon of gas has 33.4 kWh in it, and the US limits fuel pumps to 10 gallons per minute - it's moving 334 watt-hours per minute, or moving 20 megawatts.

It looks like electrical equipment of that scale tends to confined to substations, power plants, and other controlled areas.

When it comes to robustness, you often see power after a hurricane supplied by gasoline powered generators, with the gasoline supplied by any means necessary. (When the last hurricane hit here, gasoline was available for quite a long time before the grid was repaired.)

>Not sure that's true. A gallon of gas has 33.4 kWh in it, and the US limits fuel pumps to 10 gallons per minute - it's moving 334 watt-hours per minute, or moving 20 megawatts.

This is something often overlooked when comparing fossil to electric fuels, on any average car you can "charge" enough fuel for 600miles in 10min whereas on an electric you need to charge for 75min to be able to make 350miles and that's if you have a supercharge station available.

You should define “most locations”, because in my opinion that term does not include an entire continent, Africa, where power blackouts are more than common (that is where the power network had indeed arrived). You can also add an entire sub-continent, India, which granted doesn’t fare as bad as Africa but which also has its share of power cuts. And probably some parts of South America too, Venezuela most likely. This US- and Europe-centric view doesn’t do anyone any good.

Transport != store. I can transmit, assuming there's a sink on the other end (though loss is an issue over distance). Considering there is neither enough lithium nor enough cobalt to make a Tesla for every American, battery tech will be a huge bottleneck.

Who says that we don't have enough lithium?

There's likely plenty:

https://www.quora.com/Is-there-enough-lithium-in-the-world-t...

Future lithium batteries won't use cobalt.

Any source on this? I understand there alternative technologies, but most have disadvantages in terms of power density, longevity, price, etc.

Cobalt reduction has already been happening at a rapid pace. 2018 article mentioning Tesla cut their Cobalt needs by volume over 60%: http://www.digitaljournal.com/tech-and-science/technology/te...

Even if we can't get Cobalt to 0% (and there is plenty of research into other battery composites happening right now), the problems with Cobalt seem less to do with scarcity and a lot more to do with geopolitics (Cobalt is primarily sourced today as byproduct extracts of mines for minerals such as nickel in countries like Columbia and the Democratic Republic of the Congo). There's even indications that cobalt could be recycled from existing battery composites (as we do today already for lithium), but no economic incentive to do such because it isn't scarce enough to try.

That's a nice image, but you are making a case for storage, not transport.

Transportation of (flammable) liquids require either vehicles (and hence roads or rails if you go inland) down to the last mile. Electricity requires a wire, which is far less costly to build.

Also if you consider the logistics of bringing energy to different places of a building, wires are much easier to lay down than pipes.

Electricity requires a wire, which is far less costly to build.

Have you tried?

The marginal cost of driving an existing truck 10 mile down an existing road is negligible. Getting electricity to a place that is even half a mile from the nearest place that currently has electricity can be incredibly expensive and time consuming. Even just applying for the right permits and getting the go ahead from the local power company to start pricing out the job can take months.

Tried what? Running a wire vs building a road?

Of course non-existent wire vs existing road is not competitive.

If both exist, electricity wins. If neither exists, electricity wins. And electricity has that added advantage that you can buy an equipment that will produce it in place without consuming additional resources.

The only case where fuel is competitive is when roads exist, electricity distribution doesn't, and diesel generators are installed.

If neither exists, electricity wins.

Are you sure? I'm not. Especially not when we're talking the sort of electrical infrastructure that can support charging multiple electric cars and trucks (although there's no point in having an electric car if there aren't any roads).

Obviously electricity is the right long term answer and where we should be going, but I doubt it is the cheapest immediate solution in many parts of the world.

Electricity moves itself. You apply power on one end and it flows down the line at about the speed of light. There is literally nothing (other than superconductors) with lower marginal cost per joule transmitted than wire.

Wires never blow a tire, head gasket, or transmission - and in fact they cannot even crash into and kill people on the highway. They're just long pieces of copper or steel tied to a tower. How convenient!

If you instead compare the fixed costs, as you seem wont to do, you'll find that HV (500 kV) transmission lines and towers capable of carrying several gigawatts [1] continuously have substantially lower initial and lifetime costs per Joule-kilometre than oil pipelines, rail, trucks, tankers, or anything else that has to move oil. [2]

[1] https://www.power-technology.com/features/featurethe-worlds-...

[2] https://www.forbes.com/sites/jamesconca/2014/04/26/pick-your...

Since you need the road for the car to drive on, it's kind of fair to assume the road is a given.

Why did you compare existing sunk cost with non existing future Capex? The road will need replacing. The truck sending fuel will need replacing. These costs have to be borne. Yes a road exists. But electricity supply also exists.

Compare like with like please.

Never underestimate the bandwidth of a station wagon full of gas cans hurtling down the highway?

I guess that's a valid point, but mailing DVDs still lost out to streaming, same as trucking and piping gas will lose to wiring.

>A cube 3 meters on a side can contain enough gasoline to power the average car for its entire lifespan.

A cube 3 meters on a side can also contain almost 160,000 meters squared of solar cell wafers, given a common wafer thickness of around 170 micrometers.

Assuming around ten square meters per car, that could keep nearly 16,000 cars on the road for decades.

edit - to take this further, a standard shipping container could contain enough wafers for nearly 20,000 cars and in 2012, according to the US Bureau of Transportation Statistics, there were 254,639,386 registered vehicles in the US.

So that comes to under 14,000 shipping containers full of wafers, which could fit in one single ship delivery, for all of the vehicles in the USA.

> given a common wafer thickness of around 170 micrometers

> So that comes to under 14,000 shipping containers full of wafers, which could fit in one single ship delivery, for all of the vehicles in the USA.

Taking the thickness of 170 micrometers and extrapolating this measure of a solar waffer to the needs of US cars is just ... unreal. The OP came up with a serious relation. How many containers would be needed when you measue the thickness of handable solar cells, like 3mm?

I don't quite see why you think transporting wafers 170 micrometers thick is unreal or in some way extreme. 170 micrometers is the same thickness as 135 gsm art paper.

edit - Also, 170 micrometers is positively beefy compared to what is coming down the line. 1 micrometer thick flexible cells have already been developed - https://www.upi.com/Science_News/2016/06/20/New-flexible-sol... -

About 40 times as many. So 40 ships.

> much easier to transport

I understand this to mean “cheaper to transport at scale”. You need to truck gasoline to a gas station every time. Once cables are laid, electricity transport is practically free.

Imagine the delta between the electric infrastructure we need when we have a car fleet that is electric vs the electric infrastructure we need when we don't.

Given we need to transport electricity for a bunch of other things, this delta is small.

It's big relative to the electric fleet size when the fleet is small, but it's tiny when the electric fleet is a substantial fraction of the car fleet.

It's a shame that we don't have the technology to pull energy from the sun and turn it into electricity.

Or from the air.

https://en.wikipedia.org/wiki/World_Wireless_System

https://en.wikipedia.org/wiki/Nikola_Tesla_electric_car_hoax

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