AirScape Engineer's Blog » transportation

walking uphill

neil — Fri, 06 May 2011 17:47:08 +0000

As I was walking up a very steep hill this morning, I devoted my remaining oxygen to calculating my energy output. Once fully oxygenated, I rechecked the numbers and came out with a work output of 168 watts. This figure is just the energy to lift me up the 170 foot rise over 2 city blocks (10 % average slope as it turns out).

Me walking uphill

So how does this relate to energy, and its inherent value ? If I worked at that energy output rate for 40 hours per week, 52 weeks per year, for 5 years, I would have produced 1,747 kWh. As it turns out, a barrel of oil contains about 1,700 kWh of energy (if transformed at 100% efficiency).

Reference: Barrel of oil equivalent

Transportation energy use

neil — Sat, 10 Jul 2010 22:42:22 +0000

Since energy is a topic of conversation in our office, and I have been doing some bicycle commuting, it suddenly became important to have a table of transportation energy use.

Mode	kW-h/km	kcal/mile	Miles/gallon	kW-h/mile	beer-pints/mile
Bicycle	0.0361	50	629	0.058	0.23
747	0.2521	350	90	0.407	1.59
Electric Car	0.1550	215	146	0.250	0.98
SUV	1.5128	2098	15	2.440	9.54
Train	0.0820	114	277	0.132	0.52

Conclusions:

Bicycle wins the efficiency contest.
Electric car could win the efficiency contest if you fit 5+ people in your car.
Escalating that war, the tandem would probably be the next weapon of choice.
Trains are pretty good (no surprise), and perhaps could get better with regenerative braking.

Assumptions:

Bicycle uses 50 kcal/mile
747 90 mpg (FAA figure is lower,but…)
Electric car: .25 kwh/mile (from Tesla if you trust software ‘geniuses’ posing as a car company, or if you trust the old fashioned car company GM, their ‘Volt’ appears to be .34 kW-h/mile)
Tesla presents data like a software vendor (no surprise). Their claim a 70amp @220 volt charger, running for 3.5 hours charges the battery fully (capacity listed as 55kw-h). Energy = efficiency (always less than 1.0) x 70 x 220 x 3.5 = 53.9. Clearly credibility = 1/ efficiency
SUV 15 mpg
Train (swiss) .082kwh/passenger-mile
Pint of beer has 220 kcal
kcal (kilocalories) are the kind we eat (aka Calories with a big ‘C’) Yep, our system of measurement is THAT stupid. Small calories x1000 = Calories = kilocalories.

Conversion Notes:

It’s assumed that all liquid fuels have the same energy content as gasoline: 36.6 kwh/ gallon.
Liquid fuels have crappy energy conversion, unlike electricity which can be 100% efficient.

Railways should be open sourced.

neil — Wed, 19 May 2010 21:18:12 +0000

Even though railroads are much more energy efficient and deliver lower transportation costs without federal subsidies, why are trucks the preferred mode of transportation?

I think that the answer lies in the fact that the highway truck combination is effectively open source. The term open source is commonly used in the software world, but it applies here as well.

The platform is a highway, which just about anybody can use, provided they obey rules for weight, size, and safety of their modules (trucks in this case). This gives a tremendous amount of freedom to truckers and shippers to control their own destiny. Ask anybody who has used the railroads for shipping and you will see that a rigid central planning department controls how and when your freight arrives.

How about this for an idea. Let’s make the railroads into a regulated monopoly. (It works for electricity, water, and gas BTW). The railroad makes its income by maintaining the infrastructure.