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Science THEGREENLANTERN Meals on wheels: Good for the Earth?


BY NINA SHEN RASTOGI My city suddenly seems to be


awashwithfoodtrucksandfood carts — a major boon to my weekday lunch routine. But whenever I’m standing there, waiting for a slice of pizza, falafel or kimchi quesadilla, I always feel a twinge of guilt as I hear the generator chug away. Should I? Would buying my lunch at an actual restaurant makemymeal any greener? The Lantern comes froma peo-


ple fiercely devoted to street food (stinky tofu fromthe ShilinNight Market—nowthat’s fine dining). So she’s relieved to say that, as far as she can tell, there’s no strong environmental reason to shun your local street vendor. The truck-vs.-restaurant battle


won’tbewononthestovetop.The equipment they use is often quite similar, except that restaurants typically rely on piped-in natural gas to heat their fryers and grid- dles, while trucks and carts use tanks of propane. When burned, propane emits a bit more carbon dioxide than natural gas does, per unit ofheat it generates.Butunig- nited natural gas contains 95 per- centmethane,whilepropanecon- tains none. If methane reaches the atmosphere — through leaky pipes or equipment, or burners that don’t light properly — it’s a far more potent greenhouse gas than carbon dioxide. That generator is a greater con-


cern: The onboard electricity — used to run lights, fridges, ex- haust hoods, microwaves and air conditioning — is likely to be dirtier per kilowatt-hour than the electricity powering a restaurant. The small generators favored by carts and trucks are very ineffi- cient compared with a power plant. They may run on gasoline, propane or diesel, but regardless of fuel choice, they spew more hydrocarbons, carbon monoxide, nitrogen oxides and particulate matter than a power plant. Onboard generators also emit


more carbon dioxide than utility- delivered electricity.According to one emissions expert, the kind of generators typically used on food trucks and cartsmight emit 1.5 to 3 times as much of the carbon


EZ EE


KLMNO


TUESDAY, NOVEMBER 2, 2010


Post Carbon 6washingtonpost.com/postcarbon


Asia is most vulnerable towarming SeveralAsian countries are most vulnerable to the impacts


of climate change over the next three decades, according to a newstudy done by a British firm specializing in risk analysis. The Climate Change Vulnerability Index, created by the


firmMaplecroft, looks at42social,economicandenvironmen- tal factors in three core areas: exposure to climate-related natural disasters and sea-level rise; human sensitivity to global warming in areas ranging from agriculture to popula- tion shifts; and government ability to cope with climate impacts. Of 170 countries the firm evaluated, 16 rank at “extreme


risk,” including Bangladesh at the top of the list, immediately followed by India. Several other Asian countries made it into the highest-risk category, including the Philippines, at 6th on the list, Vietnam at 13th and Pakistan at 16th. The United States sits at the safer end of the spectrum,


receiving a “medium risk” ranking of 129th, while theNordic countries were ranked as best positioned to cope with global warming. Norway was judged the safest of the countries looked at, at 170 on the list; Finland came in next at 169, Iceland at 168,Swedenat 166 andDenmarkat 165. Ireland was the one non-Nordic nation to receive a lowest-risk ranking, at 167.


MatthewBunce, principal environmental analyst atMaple-


MICHAEL SLOAN FOR THE WASHINGTON POST


croft, said multinational businesses should take these findings into accountwheninvesting in developing nations inAsia and elsewhere, since firms “with operations or assets in these countries will become more exposed to associated risks, such as climate-related natural disasters, resource security and conflict. Understanding climate vulnerability will help com- panies make their investments more resilient to unexpected change.”


—Juliet Eilperin


dioxide, per unit of electricity, as the average power plant. That’s just a ballpark figure, though; there isn’t much decent informa- tion on this topic, since portable generators are small potatoes in the grand scheme of climate change.And, of course, these esti- mates depend on your utility’s specific fuelmix: If you’re buying breakfast sandwiches froma food truck in a coal-heavy state, the truck’s generatorwon’t look quite so bad compared with the local power plant. While food trucks may create


more emissions for every kilo- watt-hour they use, they don’t need to maintain a dining area and all the modern comforts it entails. In the average full-service restaurant, lighting, heating, ven- tilation and air conditioning can account for 41 percent of the es- tablishment’s total energy use. Once the lunch crowd leaves,


the comparison gets more com- plicated: Trucks and carts often


must be driven back to a commis- sary, where they dispose of their wastewater and used cooking oil, and receive other maintenance. Sometimes commissaries have food-prep areas and fridges as well, all of which you’d need to consider when tallying a truck or cart’s overall footprint. Indeed, therearesomanyother


issues to consider that, without more studies, it seems impossible to say whether restaurants or street vendors have a distinct ad- vantage. For instance, there’s the ques-


tion of driving. The Lantern isn’t convinced that driving is an envi- ronmental deal-breaker for food carts and trucks:With the excep- tion of ice cream trucks, street vendors don’t spend a lot of time puttering around city streets, since their income relies on their being parked as long as possible. Incitieswherepeoplehopintheir cars to grab lunch, a well-located street vendor canturnmany driv-


ers into walkers, giving the mo- bile kitchen a distinct environ- mental edge. So at this point, the Lantern


will issue one of her regular calls to young environmental analysts looking for thesis topics: Food trucks are hot! Please study them and then present us with your findings! In the meantime, dear hungry


reader, remember that there are simpler ways to reduce the envi- ronmental impact of your lunch, regardless ofwhere you buy it. First, eat less. (At the very least,


don’t buy more than you can fin- ish.) Second, scale back on meat and dairy. And if a van with tasty falafels is parked right outside your office building and the only decent restaurant is a 10-minute drive away, then by all means: Keep on truckin’.


Is there an environmental quandary that’s been keeping you up at night? Send it to ask.the.lantern@gmail.com.


SCIENCE NEWS


Big fish make a feast of small fry Howdo the largest fish in the world survive on a diet of tiny


crustaceans and worms? That’s what 12 researchers from five institutions — the University of South Florida; the Georgia Aquarium; theMoteMarine Laboratory in Sarasota, Fla.; the University of California at Irvine;andProyectoDomino,based in the Cancun, Mexico — set out to find when they studied whale sharks in the wild. According to a newstudy published in the journal Zoology,


the researchers documented how the sharks spend most of their time with theirmouthsopenandangledupwardat about 13 degrees to forcewaterandfood through filtering pads at the entrance to their throats. The scientists estimate that a whale shark measuring 20


feet long takes in more than 162,000 gallons of water an hour and consumes 6,721 calories per day. By contrast, healthy humans eat between 1,600 and 3,000 calories per day dependingontheir age, sexandactivity level, according toU.S. dietary guidelines. In an interview, Robert Hueter, one of the paper’s co-au-


thors, said the findings demonstrate that even as humans try to develop complex filters that resist clogging, “these animals invented them tens of millions of years ago.” But this same mechanism could prove problematic for


whale sharks passing through areas affected by the oil spill in the Gulf ofMexico, warnedHueter, who directsMote’s Center for Shark Research: “They’re highly vulnerable because of this need to feed by filtering, or straining, the water.” —Juliet Eilperin


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Health-careoverhaul The “Health-care debate —


again” articles [Oct. 19] were a good statement of the facts and goodanalysis.But it focusedsolely on criticisms. I suggest a second package focused on the claimed benefits: X million more Ameri- cans will have coverage, coverage will be better since those with health problems will not be dis- qualified, subsidy by the insured for those now visiting emergency rooms and hospitals without in- surance will be eliminated (no “free riders”), financial bankrupt- cyfor reasonofuninsuredmedical expenseswill end, etc. Ihavenever seenananalysis of


why the key provisions of the package were postponed until 2014.Didit take that long to intro- duceMedicare?


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Amissonmethane While “We’ll need more than


Scotch tape to capitalize onNobel discovery” [Oct. 26], on the future of graphene, provides a reason- able layperson’s summary of the stateof theart, itcontainsanerror. The article states thatmethane is “a molecule made of only carbon atoms,” but methane in fact con- tains four parts hydrogen to one part carbon. BenKeller,Washington,DC


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Video games’ punch can last for a day Action-packed, violent video games — those rated M for


mature—maymake people feel aggressive, but howlong does this feeling last after players put down the controls? Foryoungmenaskedto thinkabouttheir performanceafter


playing a violent game, belligerent feelings lasted as long as 24 hours after the game ended, according to a study published online by the journal Social Psychological and Personality Science. “These effects persistmuchlonger than a fewminutes,” said


BradBushman, an Ohio StateUniversity psychology professor and the report’s lead author. About 120 college students participated in the study for


extra credit. By a coin flip, researchers had each student play either a violent game such as “Resident Evil 5” or a nonviolent game such as “GuitarHero” for 20 minutes. When the session ended, researchers asked half the players


within each group to reflect on ways they could improve their scores; others weren’t asked to do anything. Researchers measured participants’ aggressiveness the


next day when the students competed in 25 computer contests, the winners of which were allowed to punish their opponents by blasting them with loud sound through head- phones. The students thought they were competing remotely


against a player of the same sex, but they were actually playing against a computer. Winners could choose both the duration and intensity of the losers’ punishment. The options ranged from something as painful as a fire alarm (105 decibels) to as painless as silence. As Bushman expected, young men who played the violent


games and thought about their gameplay were the most aggressive; they opted to punish opponents with long, blaring sounds. Women, nonviolent gamers and men who played violent games but were not asked to ruminate were not significantly aggressive. “Parents should be thinking that violent video games can


cause an increase in aggressive behavior,” Bushman added, “long after the game has been turned off—if the players think about the violent content.”


—Leslie Tamura


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