How many gallons of gasoline would it take to charge an iPhone? • Hacker News Board

Re: How many gallons of gasoline would it take to charge an iPhone?

#41

Post by subpixel » Wed, Feb 08, 2012, 6:07 PM UTC

Aqua_Geek wrote: post #19

jessriedel wrote: post #8

Earlier quoted context omitted.

All vehicles are incredibly power consuming (compared to iPods) and there are basic limits to improving this. If you want a vehicle that is large enough to hold a human and can push air out of the way at 60 mph, it's going to take a lot of energy. Driving habits, aerodynamics, and size can change this usage by a factor of order unity, but they can't do it by orders of magnitude. Thus, alternative energy sources must…

> If you want a vehicle that is large enough to hold a human and can push air out of the way at 60 mph But do we really need to go 60 mph? Vehicles seem to be optimized for less-common use cases (e.g. 5 people in the car traveling 60 mph) instead of their more common uses (e.g. one person commuting at 30-40 mph). I, for one, would like to see smaller vehicles - NOT SmartCars and the like but an actual rethinking of t…

When visiting family in SC and FL I usually gag when I see people driving around (even running errands) in golf carts. Maybe I should give them a high-five instead.

Re: How many gallons of gasoline would it take to charge an iPhone?

#42

Post by herge » Wed, Feb 08, 2012, 6:10 PM UTC

drcube wrote: post #24

Iphones run on oil too (and coal, gas, nuclear energy, and various renewable fuels). It's just that giant synchronous generators are more efficient than a million internal combustion engines, so they burn the oil at a central location and pipe it to you over wires in the form of electricity. It's like asking "how much gas does it take to run the LCD screen on my car stereo?", comparing it to how much electricity a ma…

How many times more efficient is a gas power plant than the average use of a car?

Re: How many gallons of gasoline would it take to charge an iPhone?

#43

Post by cperciva » Wed, Feb 08, 2012, 6:13 PM UTC

wickedchicken wrote: post #36

Gas has an incredible amount of energy density. You can do a fun calculation as follows: If you believe this calculator, it takes 2419kJ to go 20km while cycling. ( http://www.tribology-abc.com/calculators/cycling.htm ) A gallon of gas contains about 114,000BTU ( http://en.wikipedia.org/wiki/Gasoline_gallon_equivalent ). Note that the Exxon diagram is 'per fillup' not per gallon. So... http://www.wolframalpha.com/inp…

Considering that bicycle + cyclist is roughly an order of magnitude less massive than a car, that sounds about right. Of course, cars are also vastly more efficient at converting fuel into work than humans are.

Re: How many gallons of gasoline would it take to charge an iPhone?

#44

Post by colanderman » Wed, Feb 08, 2012, 6:16 PM UTC

teamonkey wrote: post #38

grecy wrote: post #11

They neglected to mention that even modern internal combustion engines can only capture about 18%-20% of that energy.[1] [1] http://en.wikipedia.org/wiki/Internal_combustion_engine#Ener...

Oil power stations are around 33% efficient[1]. Electric drives have up to 80% efficiency[2]. Given those rough figures, even when powered by oil stations battery-powered cars can theoretically be more efficient at using oil than a car with an ICE. [1] http://en.wikipedia.org/wiki/Oil_power_plant#Heat_into_mecha... [2] http://en.wikipedia.org/wiki/Electric_car#Energy_efficiency

Not disagreeing with you, but the point of an electric car is not drivetrain efficiency. It's regenerative braking and emission consolidation.

Re: How many gallons of gasoline would it take to charge an iPhone?

#45

Post by jbooth » Wed, Feb 08, 2012, 6:20 PM UTC

Tichy wrote: post #40

jbooth wrote: post #5

"I bet they're going to talk about the total amount of energy in a gallon of gas, without mentioning anything about how that's translated to electrity, and how much of the energy is lost in the process" click "Yup."

Well how much energy is lost? 50%? 80%? Assuming it is 50%, then the answer would be you could charge the iPhone for 10 years instead of 20 years. Still interesting.

Overwhelmingly most of it. Most generators run on diesel and not gasoline, and I gave up trying to figure gallons per KwH after a few minutes of googling. But you're talking about converting heat to mechanical energy with a ton of lossage, and then mechanical to electricity with a ton more lossage.

The original article isn't interesting. You may as well say that your mouse has enough energy to recharge your iphone for 10 years, provided we found a way to convert the mass into energy.

Re: How many gallons of gasoline would it take to charge an iPhone?

#46

Post by nilsbunger » Wed, Feb 08, 2012, 6:22 PM UTC

jbooth wrote: post #5

"I bet they're going to talk about the total amount of energy in a gallon of gas, without mentioning anything about how that's translated to electrity, and how much of the energy is lost in the process" click "Yup."

What do you expect? The author wrote the study for Exxon Mobil.

As others pointed out, you have to divide by about 5 to 7 to account for the losses in going from gas to available power at the wheels. Even then, gas wins against batteries by about a factor of two. And batteries are only getting better very slowly.

On the other hand, the cost per mile for an electric car is less than half the cost per mile for a gas powered vehicle. And the car is actually simpler.

The economics will favor electric cars soon because of this. The car won't be able to go 300 miles in one trip though. But If we have charging infrastructure in enough places, almost all trips can be satisfied with 100 mile range or less.

For a big road trip, you'll just rent a gas car, similar to how today you rent a U-Haul truck for that odd occasion where you have to move a huge pile of stuff.

Re: How many gallons of gasoline would it take to charge an iPhone?

#47

Post by billpatrianakos » Wed, Feb 08, 2012, 6:22 PM UTC

Wow. Let's try to convince people why it's alright for us to use a fuel we know to destroy the environment in countless ways and imply that it's someone else's job to advance alternative, less harmful alternatives to gasoline.

I think using gasoline is fine for now. I'm not a hard line environmentalist or anything. At the same time I don't get how these companies can justify this kind of propaganda. Yes, it is their duty to their investors to make as much money as possible but it's no secret that one day we won't have enough oil to go around. I don't get it, logic dictates that you'd sell gasoline for the time being but at the same time you'd be pumping huge amounts of money into research and development of alternative technologies. The oil company that brings the best alternative to market first has the most to gain in the long term. Articles like this are so blatantly disingenuous and short sighted it makes me want to puke.

Re: How many gallons of gasoline would it take to charge an iPhone?

#48

Post by iliis » Wed, Feb 08, 2012, 6:24 PM UTC

wickedchicken wrote: post #36

Gas has an incredible amount of energy density. You can do a fun calculation as follows: If you believe this calculator, it takes 2419kJ to go 20km while cycling. ( http://www.tribology-abc.com/calculators/cycling.htm ) A gallon of gas contains about 114,000BTU ( http://en.wikipedia.org/wiki/Gasoline_gallon_equivalent ). Note that the Exxon diagram is 'per fillup' not per gallon. So... http://www.wolframalpha.com/inp…

Yes, bicycles are quite efficient. Not only compared to cars, but interestingly also to animals. While a normal human is quite bad at converting food into motion, the system bicycle+human is comparable to some of the most efficient animals. Now, if they had bicycles as well...

[Source: Dad, hobby-bicyclist/mechanic]

Re: How many gallons of gasoline would it take to charge an iPhone?

#49

Post by baggachipz » Wed, Feb 08, 2012, 6:25 PM UTC

soren_dahl wrote: post #33

baggachipz wrote: post #31

Earlier quoted context omitted.

It would be a fair trade, but your whataboutery didn't include the true subsidies ( http://en.wikipedia.org/wiki/Energy_subsidies ) as well as the much larger environmental cost: CO2 production from burning fossil fuels. It's going to cost a lot to clean that up, and I sincerely doubt that ExxonMobil or their brethren are going to foot that bill.

I read the wikipedia link, it seemed inconclusive. Fossil fuel subsides are less than that of renewables (unless I am reading the article wrong) and that's a 1-1 comparison, fossil fuel must utterly dwarf renewable in terms of revenue. I'm not saying that big (or small) oil is innocent by any means, personally I believe the problem lies with the political side of it, but certainly I don't think the basics of oil extr…

The fact that fossil fuels get any subsidy is obnoxious. They're the entrenched necessary evil that needs to be made obsolete. So of course alternative fuels are subsidized, and should be until they displace fossil fuels.

Farming is most certainly a problem, and I fully understand and agree with the Harper's article -- but it is a straw man in this discussion. I merely pointed out that an article authored by an oil company neglected to include the true cost of their product vs. competitors. And, unless the true cost is realized (most likely in the form of taxes on carbon emissions), fossil fuels will remain the most viable source of energy. It doesn't mean I/we have to accept it, there is a better way.

Re: How many gallons of gasoline would it take to charge an iPhone?

#50

Post by calloc » Wed, Feb 08, 2012, 6:35 PM UTC

Aqua_Geek wrote: post #19

jessriedel wrote: post #8

Earlier quoted context omitted.

All vehicles are incredibly power consuming (compared to iPods) and there are basic limits to improving this. If you want a vehicle that is large enough to hold a human and can push air out of the way at 60 mph, it's going to take a lot of energy. Driving habits, aerodynamics, and size can change this usage by a factor of order unity, but they can't do it by orders of magnitude. Thus, alternative energy sources must…

> If you want a vehicle that is large enough to hold a human and can push air out of the way at 60 mph But do we really need to go 60 mph? Vehicles seem to be optimized for less-common use cases (e.g. 5 people in the car traveling 60 mph) instead of their more common uses (e.g. one person commuting at 30-40 mph). I, for one, would like to see smaller vehicles - NOT SmartCars and the like but an actual rethinking of t…

My commute is mostly highway, at 65 Mph. The most common use case for my vehicle is thus very different from yours. Your vehicle would add extra time to my commute, and would not be useful for me in any situations where I am travelling long distance (120 km/h is the norm in Europe, that is about 75 Mph) I want to go faster, I don't want my trip to take even longer.