GHG Emissions from Smartphones: A Modest Estimate using Life Cycle Assessment
The world has and continues to experience technological penetration at rapid pace. Today, smartphones and computers are an indispensable part of our lives and the effect is profound particularly in developing countries. People who couldn’t imagine access to information and education in their wildest dreams are living their dream at this moment. Is it good? Definitely! However, the world is also seeing a steep rise in anthropological greenhouse gas (GHG) emissions and its consequence on earth’s climate in the form of climate change. One positive is that the words “GHG emissions” and “climate change” have become an important topic of discussion amongst policy makers and bureaucrats. Although less conspicuous, another positive is the rise of interest in the two words among people like you and me. The google trends plots for “climate change” and “GHG emissions” show a steady rise in interest clearly indicating people’s desire to know more about the subject. It is common knowledge that fossil fuels are the primary source of CO 2. However, this article explores the results of indirect GHG emissions and the global warming potential (GWP) from smartphones based on a study by Mine Ercan, Jens Malmodin, Permilla Bergmark.
Precursor: Understanding Life Cycle Assessment (LCA)
A life cycle assessment is a technique to assess the potential environmental impacts associated with a product, process or service [1]. The idea is to observe the product’s life cycle from “cradle-to-grave” or “birth-to-death” including all the intermediary processes involved. It is an assessment involving the following steps [2]:
- Determining the total energy, raw material inputs and outputs that could potentially impact the environment
- Evaluating the potential impact on the environment of the inputs and outputs.
- Interpreting the results to make an informed decision on whether to use product/service or not
While the above steps determine the overall environmental impact, I’ll limit the scope of this article to the GHG emissions and the GWP from smartphones. Thus, the assessment allows us to determine and estimate the emissions from all stages of a smartphone’s “life”. The energy and volume of material are typically used to estimate the GHG emissions and GWP, both expressed in CO 2 equivalents (or CO 2 e).
Results from The Study
The study was conducted for Sony Z3 and Sony Z5 and the average life time usage of the two smartphones including their accessories was assumed to be 3 years. Additionally, the impact from network usage viz. 4G and mobile network was only for Swedish mobile networks. While the results may not be directly applied to all networks, it provides a a fair assessment that can be used to estimate the global GHG emissions.
- The cradle-to-grave GWP of Sony Z5 and Sony Z3 including accessories and excluding network usage were 57 kg CO2e and 50 kg CO2e for a life time of 3 years. The corresponding annual impact was 19 kg CO2e and 17 kg CO2e respectively.
- Including the effects of network usage, the annual GWP increases by 43 kg CO2e. Thus, for 3 years the GWP increases by 129 kg CO2e.
- As shown above, about 48 kg CO2e was emitted from production processes primarily dominated by IC production. When the smartphone was in use (inclusive of battery charging), the resulting emissions amounted to 7 kg CO2e.
Extrapolating the Results to Estimate Global GHG Emissions from Smartphones
There are a few points to consider before I proceed to estimating the global emissions. Firstly, the study was conducted in 2016 for high-end smartphones. Considering the increase in the efficiency of production processes as well as the evolved 4G network, let us reduce the cradle-to-grave emissions over the life time by 10% and take the lower value of the two smartphones. So, the cradle-to-grave emissions over a life time of 3 years for is 45 kg CO 2e. Likewise, the annual impact is 15.3 kg CO 2e and the 3 year GWP including network effects reduces to 116.1 kg CO 2 e.
The total number of smartphone users in 2021 is approximately 3.8 billion and about 0.26 billion new users are added every year [4]. The data is about smartphone users and does not explicitly mention production of new smartphones. Now, I can make another assumption — “for every two new users added per year, one new smartphone is produced” implying a production of 0.13 billion new smartphones per year. Using the results from the study, I can estimate the global GHG emissions from smartphones.
The cradle-to-grave GHG emissions of 0.13 billion new smartphones per year excluding network usage is 15.3 kg CO 2e * 0.13 billion = 1.989 billion kg CO 2e or 1.981 million tonnes CO 2 e
The cradle-to-grave GHG emissions over the life time of 3 years is 0.13 billion new smartphones per year * 3 years * 45 kg CO 2e = 17.55 billion kg CO 2e or 17.55 million tonnes CO 2 e
This is a very conservative estimate because of the two major assumptions I made earlier.
Conclusion
For a more exhaustive calculation, feel free to segregate the emissions for each country based on their smartphone users. Furthermore, you can also account for whether the production processes and the battery charging/discharging is accomplished via a renewable energy source or not. Replacing the conventional generators with renewable sources might drastically reduce the GHG emissions from smartphones. To put the calculations into perspective, the annual fossil fuel and industry CO 2 emissions is approximately 33 billion tonnes. On comparing, the emissions from smartphones correspond to a thousandth of the fossil fuel and industry emissions. So, we are good for now! But it need not be the same forever.
It is quite possible that the emissions could increase due to the rise of global production rates of smartphones. As smartphones continue become affordable, the demand for other consumer electronics like laptops, PCs, music players and TVs may decrease, particularly in populated developing countries like India and China . This may lead to a decrease in GHG emissions from other consumer electronics. Is it good? Is it bad? Or this post doesn’t make sense at all? Only time will tell.
References
[2] US Environmental Protection Agency, Life Cycle Assessment, May, 2015, pg-7
