Here’s the summary:
This research investigates the carbon footprint of the lifecycle of console games, using the example of PlayStation®3 distribution in the UK. We estimate total carbon equivalent emissions for an average 8.8-gigabyte (GB) game based on data for 2010. The bulk of emissions are accounted for by game play, followed by production and distribution. Two delivery scenarios are compared: The first examines Blu-ray discs (BDs) delivered by retail stores, and the second, games files downloaded over broadband Internet. Contrary to findings in previous research on music distribution, distribution of games by physical BDs results in lower greenhouse gas emissions than by Internet download. The estimated carbon emissions from downloading only fall definitively below that of BDs for games smaller than 1.3 GB. Sensitivity analysis indicates that as average game file sizes increase, and the energy intensity of the Internet falls, the file size at which BDs would result in lower emissions than downloads could shift either up- or downward over the next few years. Overall, the results appear to be broadly applicable to title games within the European Union (EU), and for larger-than-average sized games in the United States. Further research would be needed to confirm whether similar findings would apply in future years with changes in game size and Internet efficiency. The study findings serve to illustrate why it is not always true that digital distribution of media will have lower carbon emissions than distribution by physical means when file sizes are large.
These findings are contrary to the naive idea that downloading information is ALWAYS environmentally preferable to delivering it via physical media. The issue is that the allocated electricity use and emissions grow in proportion to file size, and that large enough file sizes can offset the benefits of downloading.
Here’s what I wrote several years ago about this issue, focusing on our earlier study about downloading music versus buying it on physical media:
…consider downloading music versus buying it on a CD. A study that is now “in press” at the peer-reviewed Journal of Industrial Ecology showed that the worst case for downloads and the best case for physical CDs resulted in 40% lower emissions of greenhouse gases for downloads when you factor in all parts of the product lifecycle (Weber et al. 2009). When comparing the best case for downloads to the best case for physical CDs, the emissions reductions are 80%. Other studies have found similar results (see Turk et al. 2003, Sivaraman et al. 2007, Gard and Keoleian 2002, and Zurkirch and Reichart 2000). In general, moving bits is environmentally preferable to moving atoms, and whether it’s dematerialization (replacing materials with information) or reduced transportation (from not having to move materials or people, because of electronic data transfers or telepresence) IT is a game changer.
Our more recent work on downloading console games made me more carefully qualify these conclusions. Downloads of small files are often environmentally preferable, but for larger file sizes the situation can be reversed. As the Internet improves in efficiency larger file sizes can be more efficiently downloaded, but file sizes also increase over time, as programming becomes more sophisticated and more high definition content is included in such downloads. Data density on blu-ray discs also increases over time, though not quite as quickly as Internet data transfer efficiencies seem to increase.
Finally, this research raises an important point about how emissions from networked activities should be allocated. In the life cycle assessment (LCA) community there is ongoing debate between those who prefer what’s called “consequential” LCA and those who favor “attributional” LCA.
The first approach assesses the marginal effect on energy intensity of changes in network demand (i.e. the direct consequences of that change in demand), ignoring the fixed energy use associated with keeping the network running. The problem is that the fixed energy use is almost all of energy use for current networks, and energy use doesn’t vary much as load changes on a given network. Of course, if network traffic increases enough more equipment needs to be added, so the medium term marginal change in intensities is higher than in the short run. And in the long run, network technologies change, introducing additional complexity.
The attributional LCA approach allocates the fixed energy use based on some measure of the service demand, in this case gigabytes (GBs) of data transferred. This approach is the preferred one from my perspective, and it’s the one we used in this and other related analyses.
To illustrate this distinction in another way, consider the energy used for a subway train. The energy to move the train doesn’t vary much at all if I step onto it, but somehow that energy needs to be allocated. A consequential LCA approach would just calculate the tiny incremental increase in energy caused by my additional mass on the train. An attributional LCA would instead allocate all of the energy of the train over some metric of service delivered, like passenger kilometers.
Please look at our article, which is freely downloadable, and send me comments!