Which Is Greener?
When people begin to examine how green their lifestyles are, there’s always a moment of weighing the ecological statistics for each choice. Sometimes they are obvious — being a vegetarian over a meat eater, for instance. In other cases, they’re not so obvious. Are cloth diapers really better than disposable diapers once you factor in the sky-high amount of energy and water used to produce the cotton, the hot water used to wash the diapers, the laundry soap released into septic systems and the electricity used to dry them? On a hot day, is it better to drive with the car’s air-conditioning on or roll down the windows — a scenario that produces a lot of wind drag and reduces the car’s gas mileage? Let’s explore.
Cloth Diapers Versus Disposable Diapers
This is an issue that all eco-minded parents face. While it may seem that cloth diapers are more energy intensive to manufacture, given that cotton production is incredibly energy- and water-intensive, this is not necessarily the case.
A 20-year-old study by Franklin Associates found that manufacturing a year’s supply of disposable diapers took an average of 6,900 megajoules of energy. The equivalent amount of cloth diapers took only 1,400 megajoules of energy to manufacture. So at this point, cloth would appear to be the clear leader.
But what about post-manufacture, after the diaper has met its odoriferous destiny on the output end of a baby? At the
time the Franklin Associates study was conducted, given the high cost of washing diapers in hot water, disposables came out as the clear winner, using about 39 percent less energy overall than cloth diapers.
But hold on for a moment. That was 20 years ago, before the debut of high-efficiency washing machines. So a study was carried out again in 2005 by the UK’s Environment Agency. That research used washing machine efficiency statistics from 1997. The result? Cloth and disposables were even in terms of energy use.
What about now? A lot of technological innovation can happen in 15 years, and washing machines have come a long way. For people who observe green-minded laundry practices — washing in the coolest temperatures possible, never running the washing machine less than optimally full and drying clothes outdoors on a clothesline — it seems probable that cloth is going to come out ahead.
Washing diapers consumes a lot of time, however, and if it means that you have to skip bicycling to work and jump in the car instead because you’re running late, well…the variants are wild. And then again, there are greener options when it comes to disposables, as well: chlorine-free diapers that contain more paper than plastic and make use of some recycled materials.
There are also the “after-aftereffects” to consider. While a cotton diaper can decompose quickly and quietly, conventional disposable diapers — which make up 2 percent of the world’s garbage, by some accounts — may still be around when the next ice age arrives. (It’s possible to buy disposables that claim to be made of biodegradable plastic, but biodegradable plastic won’t break down unless it has access to air, which doesn’t happen when the diaper is tightly rolled in a plastic bag in a landfill.)
So let’s give this contest to cloth diapers washed with some simple energy-saving practices in mind.
Gasoline Versus Diesel
Are you doing the environment any favors when you choose a car that burns diesel instead of gasoline? The answer to this one is yes and no.
Why both? Diesel engines get better fuel economy than gasoline engines. But anyone who has ever owned or just observed a diesel vehicle knows that they are prone to belch out what seems like far more exhaust than what conventional cars cough up. So it’s important to examine the primary components of this exhaust and determine how much a diesel vehicle emits versus a gasoline vehicle.
Both types of cars emit at least some of the following: carbon dioxide, carbon monoxide, nitrogen oxide, hydrocarbons and particulate matter. It’s how much of each of these components they emit that determines whether one is greener than the other.
- Carbon dioxide, a greenhouse gas, is produced by both types of vehicles, but how much a car emits depends on its fuel consumption. Since diesels tend to get better gas mileage (by about 30 to 40 percent over standard cars), vehicles that run on diesel tend to emit the same amount of CO2 — 30 to 40 percent less. So that’s a check for diesel in this category.
- Carbon monoxide, a particularly dangerous gas, is produced in large quantities by engines running on ordinary gasoline. Diesel engines produce almost no carbon monoxide. Diesel wins.
- Hydrocarbons, which include the very dangerous benzene, are damaging chemicals to both the environment and humans. Gasoline engines emit more hydrocarbons than diesel engines. Diesel gets another check mark.
- Nitrous oxide is a primary component of city smog. While the air we breathe is loaded with nitrogen, when nitrogen is subjected to heat and pressure, it combines with oxygen to form nitrous oxide. Since diesel engines contain more air than gasoline engines, they produce more nitrous oxide than their gasoline-powered counterparts. Gasoline wins this round.
- Particulate matter is the chunky, visible exhaust emitted from a vehicle’s exhaust pipe. Diesels put out far more “stuff” than ordinary gasoline engines, and particulate matter is dangerous to breathe in, as it can get lodged in the lungs and lead to respiratory diseases. This would seem to be a win for gasoline engines, except when one considers the size of the particulate matter. The smaller the matter, the more easily it becomes lodged in the lungs. While diesel engines put out far more of what’s known as “PM10” particles, or particles with a diameter of 10 microns, conventional gasoline engines put out more “PM1” particles, or extremely tiny particles less than one micron in diameter. The latter are more dangerous to human health, as they are more likely to penetrate lung tissue. Therefore, this one is probably a draw between ordinary gasoline engines and diesel engines.
So diesel wins three of the five categories, and one is a draw. Does that make diesel greener? It would depend on how much “weight” you give each of the pollutant categories, but it certainly looks that way, particularly given the better fuel efficiency of diesel vehicles.
Windows Down Versus Air-Conditioning
Nobody likes to drive in a baking-hot car. Most of us either crank the windows down or hit the AC button. But which option is greener? While it seems somewhat obvious — using air-conditioning in a car requires powering a compressor, which takes more energy, causing your car to burn more fuel — this isn’t necessarily the case. Opening a car’s windows and driving at 65 miles per hour creates a lot of drag on the car, which causes the engine to work harder and burn more fuel to keep up the desired speed.
So which one is greener? Again…it depends. A study conducted by the Society of Automotive Engineers (SAE) in wind tunnels and on a desert track found that driving with the windows up and the air-conditioning on is generally more fuel efficient at speeds of at least 50 miles per hour. However, there are a lot of factors at play, including the type of car, the cross-winds, the vehicle’s speed, the ambient temperature and even small details like the type and condition of the vehicle’s tires.
A Consumer Reports study conducted in 2005 (reported here by CNN) came up with similar results: at lower speeds, windows down was the way to go, but hit the highway and you’re better off rolling up the windows and turning on the air-conditioning to the lowest setting that provides comfort. Using air-conditioning reduced fuel economy by approximately one mile per gallon only.
In the same study, Consumer Reports also killed the myth that restarting your car too often uses more gasoline and, therefore, one should leave it running during short trips to the store or while waiting to pick up the kids from school. While this may have been true with cars of decades past, modern fuel-injection technology means that shutting off the car, even if only for a short time, saves on gas and emissions.
Paper Versus Plastic at the Supermarket
While paper seems like the obvious choice for grocery bags, this is not necessarily the case. According to the Natural Resources Defense Council, it depends entirely on where you live. Plastic bag litter is a real problem in the oceans and other other large bodies of water, so if you’re a coastal dweller, pick paper bags. If you’re landlocked, however, plastic may be the better choice.
Why? While plastic isn’t as biodegradable as paper, it doesn’t cut down any trees to manufacture. Making paper is still an energy- and resource-intensive prospect (manufacturing paper bags produces 70 percent more air pollution than making plastic bags, says the NRDC) and given how many grocery bags Americans use, paper bags are responsible for a whole lot of deforestation and factory emissions.
At the back end, of course, paper bags will have turned to dust long before plastic bags even start thinking about decomposing. The decision? Skip both and buy reusable cloth grocery bags.
E-books Versus Paper Books
As millions of Americans ditch paper books in favor of e-readers and tablet computers such as Apple’s iPad, Amazon’s Kindle and Barnes &
Noble’s Nook, it begs the question: Is reading books with an e-reader better for the environment than using paper books? It must be, since you’re skipping using all that paper….right?
Not so fast, Don Carli, executive vice president of SustainCommWorld LLC, and senior research fellow with the Institute for Sustainable Communication, told News Media Innovation.
“Making a computer typically requires the mining and refining of dozens of minerals and metals including gold, silver and palladium as well as extensive use of plastics and hydrocarbon solvents,” said Carli. “To function, digital devices require a constant flow of electrons that predominately come from the combustion of coal, and at the end of their all-too-short useful lives electronics have become the single largest stream of toxic waste created by man. Until recently, there was little, if any, voluntary disclosure of the life-cycle ‘backstory’ of digital media,” he said.
While paper, of course, also has a “backstory,” it may be considerably less epic than that for digital media. You can find studies, research and opinions that will favor either paper or e-books, depending on the parameters of the study. The conclusion could fall either way, depending on a number of factors: How much do you read? How big is your tablet or e-reader and how long will you keep it? Are you disposing of it properly at the end of its life cycle? Are you buying paper books from publishers that observe sustainable printing practices? When you plug your e-reader into the wall, how much of your power comes from renewable sources? Are you using your e-reader in the dark at night with your bedroom lights off?
If you’re a voracious reader who devours hundreds of books a year or several newspapers each day, or a student making use of digital textbooks, you can probably give a check mark in favor of the e-reader. If not, the answer to this particular question– digital versus print — will remain unanswered for now.
Dishwasher Versus Hand-Washing
Conventional wisdom tells you that using a dishwasher uses less hot water and thus less energy. So does a lot of research on the issue (unsurprisingly, often carried out by appliance manufacturers). But there’s more to it than the amount of hot water used per dish.
According to Treehugger, the average dishwasher uses about 6 gallons of water to run a cycle. Move to an Energy Star-rated dishwasher and you can cut that number down to about 4 gallons of water. Then there’s hand-washing, which is a little harder to quantify. The average kitchen sink tap will produce about 2 gallons of water per minute when kept running. At that rate, and given you need to wash and then rinse the dishes with clean water, it won’t be long before you exceed those 4 gallons used by the dishwasher.
But what most of these studies fail to take into account is the considerable energy used to manufacture, sell and ship the dishwasher, and the end-of-life-cycle pollution involved when you ditch the dishwasher in a landfill. In short, if you already have a dishwasher installed in your home, feel free to use it (always at max capacity, of course, and skip the drying cycle).
As you’ve undoubtedly noticed, none of these questions are answered with hard-and-fast conclusions. The extenuating factors are numerous, and conclusive calculations that factor in all possible circumstances would take the effort of a team of mathematicians and statisticians — and, ironically, a great deal of computing power, which would use more energy, create more emissions and use up more rare earth minerals.
All of this does leave us with one conclusion, though: Use the resources we have wisely and efficiently as possible.