“Be kind, for everyone you meet is fighting a hard battle” - Often attributed to Plato but likely from Ian McLaren (pseudonym of Reverend John Watson)

Sunday, February 28, 2016

Off to arpe-a 2016

Image credit: arpe-e
I'm rather shocked to find that this is the sixth (!) arpa-e energy innovation summit that I've attended. I intend to blog about my adventures here and, in particular, about some of the energy storage sessions as it's my considered opinion that storage breakthroughs are key to a sustainable energy future.

But for this post, I'm going to discuss getting to Washington, DC. I used three modes of transportation: my (new) Jeep SRT Grand Cherokee (with apologies to commenters who had suggestions for my avoidance of such a joule hog) to KSNA, i.e., John Wayne Airport; two legs of air carrier transport (KORD, O'Hare Airport was a layover); and a SuperShuttle van from DCA, i.e., Reagan National Airport to the Gaylord National Harbor Resort.

The trip to KSNA was about 18 miles, the Jeep is currently displaying an average mileage of about 15.5 m.p.g. (as stated in my previous post, I'm not driving for economy) so I burned about 1.16 gallons of premium fuel, thereby converting something like 137,000,000 joules of chemical energy to thermal energy to turn the wheels, move air out of the way, heat the atmosphere, etc. Therefore, I my rate of energy use in "joules/(passenger*meter) was about 4,730.

The leg from KSNA to KORD was in a United Airlines Boeing 737-724 aircraft featuring two CFM International CFM56 turbofan engines (of the "dash 7B24" variety). These engines are rated at 24,200 pounds thrust each. It's not easy to estimate the fuel burn for airline flights, I wish that I'd remembered to ask the Captain or First Officer, they're very cooperative to sharing such data. But, as best I can estimate, we burned around 18,000 pounds or 8,165 kilograms of fuel (fuel calculations for airplanes are typically done in pounds since aircraft weight enters into literally every aspect of every maneuver and operation) to take 118 passengers 1,818 statute miles. A kilogram of jet A fuel releases 43.5 megajoules of energy upon oxidation, and so we converted 3.55*10^11 joules of thermal energy. The plane carried its full complement of 118 passengers, and so the energy use in "joules/(passenger*meter) was about 1,040. Of the 3.55*10^11 joules converted, I was responsible for about 3 billion of 'em.

I'll spare my patient readers the detail of the KORD to KDCA leg on an Embraer 175 regional jet. I estimate that we converted 1.14*10^11 joules traveling 650 miles. This works out to about 1430 (joules/passenger*meter) for the 76 passengers on board. My allocation was about 1.5 billion of those joules.

Finally, I rode a SuperShuttle van for the approximately eight miles to complete the journey. I estimate that it burned about 0.5 gallons and converted 42,800,000 joules of chemical energy to thermal over the eight miles. My rate of energy use was thus about 3,320 joules/(passenger*meter).

My grand total of turning the energy in chemical bonds to thermal energy in the atmosphere
Image credit: PowersaveSchools.org
(and a very small amount in ground) was 4.68 billion joules. Of these, 4.5 billion or about 96% were in aircraft (I can't say "in the air" because we did taxi). But note that, of the 2,495 miles traveled, 99% were in the air. Thus, purely in terms of energy conversion, the air travel was quite efficient in comparison to ground transport. Of course, I was the solo passenger in my vehicle as I was (surprisingly) in the van, and having several passengers would change the joules/(passenger*mile) metric significantly. And, as some will no doubt point out, so would staying home.

And, so I understand (not having read enough to know why), hydrocarbons oxidized in the upper troposphere/lower stratosphere are much more damaging than those oxidized on the ground.

I'll be responsible for more joules and a greater rate of conversion when I return to Southern California on Thursday, since we'll be flying against the prevailing winds. For a round number, I'll add 20% to the eastbound total for 10.3 billion joules. It is to be hoped that I'll learn enough here to be able to participate in saving many times that number, at least, that is, from the burning of fossil fuels.

Addendum: Perhaps 10.3 billion joules has little meaning for some. This is about 2,860 kilowatt hours. The average US home uses about 2,733 kilowatt hours of electrical energy in three months.

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