The tablet has the potential to combat the dire consequences of resource depletion and soften its effect. Microprocessors are underway that merely use 100 milliwatt. Touch screens are being designed that use zero energy as long as the screen content does not change (like the Amazon kindle). The potential for education for example is enormous. You only need to record the teachings of a high quality teacher once and distribute it nationwide via the network, eliminating needs for school buildings, school buses, school books. Local teachers can make sure that the knowledge has been absorbed by taking regular tests. Setting up an internet based network for tablet clients could make more sense than investing in road infrastructure for Africa or India.
An iPad2 uses 3 W idle with screen on and WIFI and 0.4 W in standby mode with screen switched off.
An iPad3 running apps with heave computing demand consumes 10 W.