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SAGE (Sound Advice for a Green Earth) is a project by advanced students in Earth Systems and other programs to answer sustainability questions. Submit questions.

Q: Should I take notes in class using paper and pen or type them on my laptop? (Let’s assume I’m going to own a laptop either way.) Which option is more environmentally friendly and energy-efficient?
— Anna Hallingstad, Stanford, Calif.

The Essential Answer

Every time I walk into class, I’m greeted by a sea of shiny Apple logos from the backs of my peers’ laptops. I feel like an outlier — and perhaps a Silicon Valley misfit — as I pull out my trusty spiral notebook, ready to fill it with another day’s worth of information. But how does the environmental impact of my notebook compare to that of my neighbor’s MacBook? Do the benefits of going paperless outweigh the laptop’s energy requirements?

To draw a fair comparison, let’s assume that my neighbor and I are enrolled in the same 15-unit, three-course quarter at Stanford.

I embrace the old-school study lifestyle, using one 100-page notebook for each of my three classes. The production and eventual disposal of the 3.6 pounds of paper in my notebooks releases 10 pounds of carbon dioxide, according to the Environmental Paper Network. This means that my notebooks have a carbon footprint roughly equal to that of a drive from Stanford to Sunnyvale.

My neighbor, on the other hand, adopts the tech-savvy approach of recording notes on his laptop. Like many Stanford students, he owns a MacBook, which has a lifetime carbon footprint of almost 950 pounds of carbon dioxide, according to Apple. (That’s the same amount you would release road-tripping from Stanford to Grand Junction, Colo.) This footprint includes all manufacturing, transportation and recycling of the laptop in addition to the electricity my classmate uses while on his laptop. Accounting for this overall impact and an estimated four-year laptop lifespan, we find that his quarterly note-taking releases about 15 pounds of carbon dioxide. However, if we consider only the electricity his laptop sucks up during his actual note-taking, we can attribute just one pound of carbon dioxide to his quarter’s worth of notes.

So if you count only the carbon consumed while he’s taking notes, the laptop gets the gold (er, green) medal. But, if you look at the computer’s other carbon impacts, then paper notebooks come out on top.

Which one should you use, then? I’m going to continue using my trusty spiral notebooks, but that has less to do with my carbon footprint than with my GPA. A Princeton professor’s 2014 study found that students who handwrote their notes generally learned better than those who typed them into a laptop — and my own fluctuating test scores have shown this to hold true for me too. That’s why I plan to stick with pen and paper this quarter. Meanwhile, you can use your laptop to check my calculations and read more SAGE columns here.


The Nitty Gritty

Above, I mentioned different ways of performing carbon footprint calculations and skimmed over the additional environmental impacts of notebooks and laptops. Let’s dive deeper into these nuances.

Notebooks

Carbon emissions—The essential answer crunched the numbers on the carbon dioxide released with the production and disposal of three 100-page notebooks. Those calculations assumed that the paper within these notebooks had no recycled content. However, the environmentally conscious student would likely grab notebooks with at least some recycled content. The Environmental Paper Network, a network of nonprofits dedicated to paper sustainability, estimates that the 3.6 pounds of paper comprising the three notebooks would represent 10 pounds of carbon dioxide emissions if the paper has no recycled content, eight pounds if it has 50 percent recycled content, and six pounds if it has 100 percent recycled content. Increasing the proportion of recycled content, then, significantly decreases a notebook’s carbon footprint.

Noncarbon impacts—The process of papermaking requires not only trees, which leads to deforestation and related problems, but also large amounts of energy, water, and toxic chemicals such as mercury, chlorine and absorbable organic halides. These chemicals seep into our ecosystems, waterways and bodies, causing health problems for humans and for the planet. Thankfully, the manufacturing process for recycled paper requires less energy, less water and fewer chemical inputs. Though all types of paper have their drawbacks, recycled paper wins out over its competitors for both its low carbon footprint and its reduced environmental impact during production. If you use notebooks, consider purchasing those that have recycled content to reduce your impact.

What about the writing implements?

Calculating the impact of all potential implements — pen or pencil, plastic or wooden, standard or mechanical — would be a SAGE column in itself. If you would like us to delve into those calculations, ask us to do so here.

Laptops

Calculating the carbon footprint of a portion of an electronic device’s lifetime can be done through two main approaches: the life cycle method and the customer-use method. The two lead us to opposite answers to the reader’s question, as explored below.

Carbon emissions: Life cycle method—The life cycle method accounts for the fraction of the product’s total life cycle carbon emissions—production, transport, customer use and recycling — proportional to the time span in question, as seen below:

SAGE-equation1



This method accounts for all greenhouse gas emissions (in carbon dioxide equivalents, CO2e) associated with the laptop, allowing a more apples-to-apples comparison with the life cycle carbon emissions calculated for the notebooks. I calculated the laptop’s carbon footprint for the time it would be used to take notes to be 15.2 pounds of carbon dioxide equivalent, which gives paper notebooks the environmental edge.

Carbon emissions: Customer-use method—The customer-use method ignores full life cycle carbon emissions and accounts only for the portion of the carbon emissions associated with the customer’s usage during the time span in question. Although this method overlooks the majority of the laptop’s environmental footprint, it could be a valid calculation if the student using the laptop to take notes would have owned the laptop regardless and if his or her using the laptop to take notes would not affect the laptop’s life expectancy. With this in mind, my calculation for the laptop’s quarterly note-taking initiatives using the customer-use method is shown below, given that customer use is 8 percent of the total carbon footprint of a MacBook.

SAGE-equation2



Now, with the laptop emissions totaling just over one pound of carbon dioxide compared with 10 pounds of carbon emissions from the three notebooks, laptops appear to be the greener option.

Noncarbon impacts—Beyond their carbon footprints, laptops leave their impact on the environment through their component materials and through what happens to those materials once the laptop no longer functions. Laptops contain rare earth metals, which are quickly being depleted and are infrequently recycled, and toxic heavy metals, which can make their way to our water systems and cause health problems. And the physical laptop is just the tip of the iceberg; we often store our electronic files in the cloud, requiring far more energy and infrastructure than our computer’s hard drives alone. But there is hope! We can educate ourselves about the carbon trade-offs of various data storage systems, and proper laptop recycling significantly improves successful reclamation of the rare earth metals while minimizing toxic leaks. Want to know more? Check out this past SAGE answer about recycling laptops, and click here to find a recycling location near you.

Overall

Taking into account various ways of calculating carbon footprints and the noncarbon impacts of each option, neither laptops nor notebooks can be crowned the definitive winner. However, for each method of note-taking, simple steps — such as buying recycled paper products and recycling your old laptops — can make studying a little greener.

SAGE-chart

Lauren Gibson, ’17, plans to complete her master’s degree in Earth Systems this month.