Tablet Energy Considerations
What is the energy impact of a tablet like the iPad? Let’s make a few reasonable assumptions about the user and his tablet:
Newspaper, magazine and books can be made superfluous by the iPad. What would be the energy gain?
Let’s estimate the weight of a newspaper at 500 gram, that’s 940 * 0.5 kg = 470 kg in three years. Let’s assume that the magazine and book have similar weights and we arrive at ca. 550 kg paper in three years. The embodied energy of recycled paper is ca. 19 MJ/kg or 10.5 GJ in total. And that is just paper. Add to this the transport cost of wood from say, Scandinavia or Canada into the EU or USA. Add the cost of delivery to your doorstep, every day. How about the trip to the book store or library by car or bus, every two weeks? Let’s say 2 * 5 km/trip, makes 800 km in three years. That’s 70 liter of fuel.
Now, what about the embodied energy of an iPad? It is very difficult to retrieve data on that. Apple claims 105 kg CO2 for an iPad2, consisting of 60% production, 29% user energy consumption, 10% transport, 1% recycling.
We have 550 kg paper = 10.5 GJ, as well as 70 liter fuel. 70 liter of fuel = 0.7 * 2.3 * 70 kg CO2 = 112 kg. So the trip to the library/bookstore every two weeks already is equal to the entire energy usage of the iPad. Assume 1GJ = 15 kg CO2. That means that 10.5 GJ represent 158 kg CO2.
By replacing a newspaper/magazine/books with an iPad, we reduce the carbon footprint to 105 kg, coming from 112 kg + 158 kg + delivery cost newspaper = 270+ kg. But additionally the iPad delivers the potential to replace the television as well (1300 kg CO2!), or the desktop (1800 kg CO2) not to mention gaming, skype face-to-face communicating, endless internet browsing, internet shoping, and even cloud based working, all for the (energy) cost of 105 kg CO2 per three years.